PECO ME 493 Final Report - Year 2008 Group Members Jonathan Boschiero Kiehl Mclntyre Jeff Bennett Ryan Ernst Portland State University Advisor Dr. David A. Turcic
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PECOME 493 Final Report - Year 2008
Group Members
Jonathan Boschiero
Kiehl Mclntyre
Jeff Bennett
Ryan Ernst
Portland State University Advisor
Dr. David A. Turcic
Executive Summary
The project team undertook a project to retrofit Lola, a unique manufacturing unit used by
PECO Manufacturing to heat and press two kinds of metal inserts into nylon panels. The team
compiled PECO’s desired improvements into a PDS that was used to evaluate various design
alternatives in four major areas:
Insert material identification
Consistent and satisfactory insert heating
Insert pressing depth monitoring
Rapid heating tube evacuation
After many experiments to gather data on the behavior of the existing system, a single design
for each area was chosen for further development by the team. Insert identification would be
achieved by an inductive proximity sensor coupled with a material selective sensor. The
consistency of the heating tube’s performance would be improved by blocking the convective
air flow through the column. The insert pressing depth would be monitored using a pair of
sensors to first locate the surface of the panel and then determine the ram travel relative to the
panel surface. Minor alterations to existing machine components and system programming
would allow the machine to purge the heating tube automatically.
Further work led to completed designs for all of the systems except for the insert depth
monitoring, which was deemed too expensive and complicated for results that were not
important to PECO. Acquisition and fabrication of the necessary components was undertaken
completely by PECO Manufacturing with collaboration from the team members to deal with
unforeseen complications.
Due to delays that arose in the final stages of PECO’s fabrication process, the modification of
the existing parts was not completed in time for the project team to install and validate the
designed improvements. However, based on experimental data, results of prototyping and
current system behavior, the group expects that all of the improvements would deliver
substantial gains in performance.
Table of ContentsExecutive Summary....................................................................................................................... 2
Introduction to the Product...........................................................................................................1
Mission Statement.........................................................................................................................3
Main Design Requirements (PDS)..................................................................................................3
Design Concept Comparison..........................................................................................................4
Final Design....................................................................................................................................6
Performance Evaluation.............................................................................................................. 14
Conclusions..................................................................................................................................16
Appendix A Product Design Specification...................................................................................18
Appendix B Initial Experiments...................................................................................................25
Appendix C Insert Free Convection Coefficient...........................................................................29
Appendix D Insert Pressing Temperature...................................................................................31
Appendix E Heating Tube Temperature Profile...........................................................................34
Appendix F Heating Tube Plugging Validation............................................................................41
Appendix G Insert Identification Validation.................................................................................43
Appendix H Bill of Materials........................................................................................................ 45
Appendix I Production Drawings..................................................................................................46
Introduction to the Product
PECO Manufacturing, Inc. is the sole producer of fuel tank access doors for installation on
certain Boeing aircraft. One step in the manufacturing of these doors is the pressing of twenty
three internally threaded inserts into pockets around the perimeter as shown in Figure 1. A
complete fuel access panel with inserts installed.. There are two types of doors, one made with
aluminum inserts and the other with stainless steel inserts. Currently this process is performed
by a machine, referred to as Lola, which heats the inserts before pressing them into the pockets
on a door.
For this process to be successful the inserts must be heated to a temperature within a defined
range. When a heated insert is being pressed into a pocket in the door heat is transferred from
the insert to the pocket. This heat softens a thin layer of nylon which flows around the chevron
and knurled grooves of the insert outer surface shown in Figure 2. The softened nylon will later
harden, mechanically capturing the insert in the door.
Figure 1. A complete fuel access panel with inserts installed.
Figure 2. A nut-retaining insert.
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There are four problems with the operation of the machine:
The wrong type of insert could be pressed into a panel.
Inserts are often at an insufficient temperature when pressed.
Inserts could be pressed an incorrect depth.
The heating tube is difficult to empty during job changes.
Insert type is incorrect.
It is possible for the wrong type of insert to be pressed into a panel because two models of fuel
access door are manufactured by PECO. One model requires stainless steel (SS) inserts; the
other model requires aluminum (Al) inserts. Both insert types have identical geometry. Lola
cannot distinguish SS from Al inserts and will press whichever is loaded in the machine.
There are two paths that could lead to the wrong insert being pressed; inserts may be left in the
machine between set-ups or the inserts loaded into the machine could be mixed. To prevent
inserts from being left in the machine, a quick and reliable method to remove unused inserts
between set-ups is needed. Also, inserts loaded into the machine need to be identified as the
proper type before being pressed.
Insert pressing temperature is insufficient.
If the insert temperature is too low when pressed, the nylon will not flow enough to fill the
recesses in the outer surface and the insert will either fail to meet pull-out and torque-out
specifications or will not press into the door deeply enough. If the temperature is too high,
nylon will flow out from around the insert causing undesirable features. Control of insert
temperature before pressing is needed to ensure pull-out, torque-out, insertion depth and
surface geometry specifications are met.
Pressing depth was inadequate.
The maximum pressing depth of the inserts is limited by a flange feature on the pressing ram.
The flange makes contact with the door surface, preventing the insert from being pressed too
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deeply. There is no counterpart system in place to ensure that inserts are pressed to at least
the minimum depth. Inserts not pressed to the specified depth can be difficult to detect,
possibly leading to expensive processing on a part that will only be scrapped later on. The
depth to which inserts are pressed needs to be verified as correct during machine operation.
Heating tube is difficult to empty.
Frequently between the operating cycles and occasionally during a typical operating cycle the
tube in which the inserts are heated needs to be emptied. There is no formalized system for
doing so other than a simple hook-on-rod with which a technician or machine operator tries to
pull the inserts up and out of the column. An easier system would save time and effort and
improve safety.
Mission Statement
The PECO capstone project team redesigned Lola to eliminate deficiencies in its existing design.
The group set out to design, prototype and install systems that would prevent incorrect insert
types from being pressed, assure consistent and correct insert temperature, verify pressing
depth and empty the heating tube quickly. The design would be completely documented by a
design report including: analysis, detailed drawings, and a bill of material.
Main Design Requirements (PDS)
Based on information provided by PECO, a set of Product Design Specifications was created to
guide the project team. Presented below are the most relevant items from the PDS and their
respective targets.
Lola should detect and reject inserts of the incorrect material, allowing only 1 incorrect
insert per 10,000 to pass through the detection process.
Inserts of both material types should be heated to within 10° of 810°F.
Aluminum inserts should be pressed so their top edge is 0.080” below the door surface
with a tolerance of 0.010”.
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Steel inserts should be pressed so their top edge is 0.056” below the door surface with a
tolerance of 0.010”.
Lola’s operator should be able to empty the heating tube within 1 minute.
Because Lola is a one-of-a-kind, immobile manufacturing device certain considerations such as
ease of assembly, aesthetics and portability did not influence the design.
Once the modifications to Lola were completed, tests could be conducted to determine the
satisfaction of the PDS requirements.
Design Concept Comparison
Solutions to the four problems described in the introduction were divided into four subsystems
and the alternative design comparisons are presented similarly.
Material Identification
Since the two insert types have identical geometry, a system to differentiate between the two
would need to utilize differences in their material properties that could be tested without
altering the inserts themselves. The first option explored was an optical property evaluation
system that could use either reflectivity or emissivity to separate aluminum from stainless steel.
Unfortunately, optical properties are extremely difficult to measure outside of highly controlled
processes and it was observed by the team that the inserts changed color after being in the
heating column, thus changing their optical properties. Another option considered was
electrical resistance, which is much greater for stainless steel than for aluminum. However, it
was quickly determined that a reliable process to measure resistance would be difficult to
implement since small and hard to control variables could influence resistance readings enough
to result in numerous false results. The last rejected design concept was a weight measurement
system that would exploit the difference in mass density between aluminum and steel. This was
eventually discarded due to concerns as to how the vibratory bowl feeder would affect a
system trying to measure insert weight.
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Insert Heating and Verification
The project team considered two solutions to the problem of accurately heating the inserts,
one was to discard the heating tube entirely and use inductive heating and the other was to
control the free convection in the heating tube by applying forced convection. Inductive heating
has many advantages in terms of time and accuracy, but designing a system that could heat up
both stainless steel and aluminum would have been extremely costly and most likely outside of
the capabilities of the project team. For the forced convection approach, the group designed a
system that used a U-shaped tube and a fan to induce recirculation of the hot air in the heating
tube. This recirculation concept was scrapped in favor of a simpler, more compact system that
promised to produce similar results.
Also PECO initially put forward the idea of an infrared sensor located at the bottom of the
heating tube to measure insert temperature prior to pressing, but results from the group’s
experiments showed that view angle and surface qualities introduced too much error to rely on
such a system.
Heating Tube Evacuation
Two alternate approaches for emptying the heating tube were initially evaluated; moving the
heating tube itself to allow the inserts to fall out or changing the shuttle assembly/operation in
some way to get inserts out other than through the pressing operation. Moving of the heating
tube was quickly rejected due to complications it would raise with the heating system. Allowing
the operator to “dry run” the machine in order to cycle out inserts one at a time was deemed a
safety hazard because the operator would have to reach into the safety enclosure surrounding
Lola numerous times during such a procedure. Altering the shuttle assembly slightly in order to
clear a fall path for inserts straight down from the tube was considered before it became
apparent that there were too many obstructions that could not be easily moved directly
underneath the heating tube.
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Pressing Depth
Several technologies and systems were researched that could provide adequate measurement
of the piston’s travel relative to the surface of the panel. These could be grouped into one of
two major categories: door surface measurement and door surface placement. The first
category used one of a wide variety of technologies and/or methods to measure the position of
the door’s surface and measure the pressing ram’s travel relative to this surface. The second
category used an active or passive system to place the door’s upper surface in a known location
and then measure only the pressing ram’s travel relative to this known location. In the end,
PECO decided that all of the presented options were either too complex or too costly for too
little gain and it was agreed that the team would not implement any system that addressed the
pressing depth. Additionally, both the team and the engineers at PECO predicted that the
inserts would consistently press to the correct depth once their temperatures were adequately
controlled.
Final Design
Similar to the Design Concept Comparison, the Final Design is presented in three subsections.
Insert Identification
A system that identifies the insert material prior to loading the insert in the heating tube has
been developed. The insert identification system uses two inductive proximity sensors to
identify the insert material. When the insert identification system detects the incorrect insert
type the feeding process is stopped so that the incorrect insert can be removed by the machine
operator.
The two inductive proximity sensors used in the insert identification system are commonly
available off-the-shelf items.
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Figure 3: Two inductive proximity sensors in the feed block are used to identify the insert material.
To identify the material type an 18mm shielded aluminum selective inductive proximity sensor
is used. The features of the sensors match the application. The sensor diameter determines
the maximum sensing distance. Shielding allows for flush mounting with a metallic surface.
The aluminum selective feature indicates that the sensor will detect aluminum but not stainless
steel.
To determine the presence of an insert a 5mm shielded inductive proximity sensor is used.
Again, the features of the sensor match the application. The sensor indicating presence is not
material selective and detects either type of insert.
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Figure 4: The truth tables show the outcomes of all combinations of sensor states of the insert identification system.
A logic circuit receives the output of each sensor and determines if an incorrect material is
present. This logic circuit was first prototyped using integrated circuit logic gates on a
breadboard. Tests of the prototype system followed the predictions made by the truth table.
In the final design system the logic circuit is programmed into a programmable relay. If the
incorrect insert type is detected the programmable relay disables the vibratory feeder.
Insert Evacuation
The two problems addressed by the tube evacuation system are: inserts of the incorrect type
were being left in the tube between job changes and the old removal method was time
consuming and dangerous. A new method of removing inserts that is fast, easy, and safe has
been developed to solve those problems. The new method relies on slight modifications to the
machine’s existing parts, the installation of new parts and a new programming sequence. The
new method of removing inserts is to run an evacuation cycle program on the machine during
which the machine empties all inserts from the tube under automatic operation. During the
automatic cycle one insert is dropped into the rear hole in the shuttle, and shuttled to a
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Heating Tube
Rear Hole
Evacuation Tube
Stop RailBearing Rail
Spacer
Front Hole
rearward position where the insert falls through an open tube in the bottom of the machine
into an awaiting receptacle. The automatic cycle is repeated until all inserts are removed from
the heating tube.
Modifications required for the new method are to: widen the space between the shuttle
bearing rails, extend the stop rail, create a new hole for sensor view, and install the evacuation
tube.
The distance between the bearing rails must be widened to provide space for the insert to pass
through. To widen the space between the bearing rails spacers are installed between the
shuttle and the bearing rail. Because the bearing rails have moved new bolt holes are required
in the shuttle assembly base that they are mounted to.
Figure 5: The modified shuttle assembly allows the inserts to be evacuated from the heating tube.
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The stop rail in the new system is extended to prevent the insert from falling through the
shuttle until the shuttle reaches the rearward position where the insert will be allowed to fall.
To reduce wear the stop rail is hardened by heat treatment. The extended stop rail requires
that additional mounting bolt holes be machined in the shuttle assembly base.
An additional sensor view hole through the rear hole in the shuttle provides information to the
machine program regarding the presence of an insert in the shuttle. With the additional hole
the same sensor system used during the manufacturing cycle operation is used during the
evacuation cycle.
The evacuation tube is a simple section of 1 in. rigid EMT tubing. A hole in the shuttle assembly
base allows the evacuation tube to pass through. Mounting brackets support the evacuation
tube above and below the machine.
Tube Blocking
The most significant problem with the old machine design is that the temperature at which
inserts are pressed is not well controlled. Based on the findings of several experiments,
explained further in Appendices B through F, the group came to the conclusion that inserts in
the heating tube were experiencing substantial heat loss from convection of room temperature
air up through the tube, a phenomenon known as stack effect. The proposed solution is a
system that blocks off the top and bottom of the tube, preventing stack effect from occurring.
The tube blocking system consists of two sliding doors; one door at the bottom of the tube and
one door at the top. During machine operation at least one door will always be closed so that
there is never an open path where stack convection can occur.
Implementation of the tube blocking system requires modifying the heating tube design,
manufacturing door assembly components, purchasing pneumatic pistons and an additional
sensor, and adding programming in the manufacturing cycle. The modifications to the heating
tube design are to provide clearance for the doors, mounting for the door assemblies, and a
view path for the sensor. The door assembly consists of a sliding door, a door mount to attach
the door to the heating tube, and a bushing to guide the door in the door mount. A pneumatic
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piston will move the door in and out of the tube. A sensor will be used to provide information
to the control program regarding the presence of inserts in the heating tube.
The new heating tube is similar to the old heating tube in overall geometry, however new holes
are added for the new system to function. The door housings insert into holes in the side of the
heating tube. Horizontal slots in the door housing and heating tube inner surfaces align and
support the door. Threaded bolt holes are provided for mounting of the door assemblies.
Additionally, a view hole is located at the top is for a photoelectric sensor so it can view the
presence of an insert and provide that information to the control system. The size of the view
hole was minimized to 0.25 in., slightly larger than the smallest view area of the photoelectric
sensor to minimize air flow through the view hole.
The door assembly mounts to the heating tube as a unit. The door mount provides support to
the door and allows the door to slide into and out of the heating tube. The material for the
door mount is AISI 304 stainless steel to match the thermal expansion characteristics of the
heating tube. The bushing hole in the door mount is toleranced to provide a light press fit for a
bushing. The bronze bushing is pressed into the door mount to provide alignment and a
bearing surface for the door. SAE 932 bronze is selected for the bronze bushing material for
suitability at the 800F operating temperature. The square hole in the bronze bushing is
specified to prevent rotation and is manufactured using a wired EDM machine. The corners of
the square hole have a radius to account for the minimum radius that can be produced by the
wire EDM process. The door consists of a square shaft with a flat plate on the end which
provides tube closure. The square shaft of the door is ground to provide a smooth bearing
surface and accurate tolerances for the sliding fit with the bushing. The door is manufactured
from 8630 steel to provide hardness and wear resistance at the elevated temperature.
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Figure 6: Sliding doors have been added to the top and bottom of the heating tube. A photoelectric sensor controls the level of the inserts.
A pneumatic piston moves the door in and out of the tube. A pneumatic piston was selected
because pneumatics are used for all other position control on the machine so the air supply is
already present. Mounting brackets are manufactured to position and support the pistons in
the correct location. A flexible coupling is installed between the piston and arm to compensate
for misalignment between the door and piston travel. Stops on the piston shaft are used to
limit door travel in either direction.
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Heating Tube Door Assemblies
Photoelectric Sensor
Figure 7: Exploded view of the door assemblies used to accomplish sealing of the heating tube at the top and bottom.
A photoelectric sensor is used to provide the control system information about the number of
inserts in the heating tube. A sensor views the location below the upper door and detects the
presence of an insert. When no insert is present the control system initiates insert loading. The
sensor is mounted 3 in. away from the heating tube to prevent the sensor from exceeding
maximum operating temperature of 120F. Careful alignment of the sensor view with the view
hole is required. Adjustment of the sensor is provided by the sensor mounting bracket.
The control system program is modified to operate the doors. In the new manufacturing cycle
program the lower door operation is linked to the lower pin operation. A similar programming
loop is added for the operation of the upper door. The upper door opens when two conditions
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Door Housing
Bushing
Bracket
Flex Coupling
Air Cylinder Assembly
Door
are satisfied: the photoelectric sensor indicates that there is no insert below the upper door
and the lower door is closed. The sensor is placed to allow room for one insert to be seen by
the sensor and an additional insert above it in the event that two inserts are fed into the tube
rather than one. When the upper door opens the vibratory feeder activates until the
photoelectric sensor detects the presence of an insert at which time the feeder is deactivated
and the door is shut.
Performance Evaluation
Because of conflicts with production and manufacturing delays leading up to the installation of
the designed systems, the modifications were not able to be completed on Lola before the
writing of this report. Because of these circumstances design verification was based on
experiments, prototyping and comparison. The insert identification system was prototyped and
tested independently of the rest of the components using the specified sensors, a simple
prototyping board with integrated circuits and inserts provided by PECO. The tube evacuation
system was evaluated based on the existing system and simple analysis of machine parts and
basic physics. Perhaps the most important feature of the redesign, the heating tube alterations,
could not be adequately prototyped in the limited time the team had available after discovering
that retrofitting could not be completed. Instead the group used the results from the Heating
Tube Plugging Experiment as detailed in Appendix F to extrapolate what the completed
system’s performance would be. Details on the characteristics of each of these three features
are provided below.
The feeding channel that leads from the vibratory feeder to the heating tube was
reproduced in wood as shown in Figure 27 in Appendix G. A simple electric circuit was
constructed with a warning light that would activate when an insert of the incorrect material
was detected. A switch determines if aluminum or stainless steel is the correct insert material.
The team ran tests using this apparatus and as described in Appendix G and determined that
the performance was adequate to meet the PDS demands. Every insert used to test the insert
identification prototype was correctly identified and the warning light was activated when
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expected. The team was very satisfied with the design and felt confident that the system would
have performed well within the PDS requirements when installed on Lola.
Since the insert evacuation system designed by the team relied on existing functionality
built into the present Lola design, conclusions regarding the new system’s performance were
made based on the existing system and the team’s understanding of basic physics. The shuttle
mechanism currently installed on Lola has a rear hole to capture an insert in the event that an
additional insert drops out of the heating tube during the pressing operation. Currently that
rear hole only catches the extra insert and restrains it horizontally while a stop rail keeps the
insert from falling all the way through the shuttle. When the shuttle retracts, the extra insert
falls down between the rails supporting the shuttle where it is sufficiently out of the way of
moving parts to keep it from hindering continued machine operation. The changes proposed to
the system widened the space between the shuttle support rails to make room for a through
hole that would allow an insert in the rear hole to fall into a receptacle placed below the
machine and extended the stop rail to retain the insert in the shuttle hole until it is over the
evacuation hole. Since the existing system performs reliably and the alterations to the
machine’s behavior were deemed to be easily achievable by PECO personnel, the team felt that
the insert evacuation system would satisfy the requirements laid out in the PDS.
Criteria to evaluate the performance of the tube blocking system were derived from the
results of the Heating Tube Plugging Experiment which can be seen in greater detail in
Appendix F. The team found that the inserts heated up faster, achieved higher final
temperatures and avoided cooling at the bottom of the tube when the heating tube was
plugged at either end. The team’s expectation from these findings is that the tube blocking
system could consistently deliver inserts heated to the temperatures specified in the PDS after
additional testing and calibration. Unfortunately, those tests and calibrations could only be
performed on Lola after the installation of the design systems which could not be performed
due to a lack of required components and unavailability of extensive downtime. Thus, while the
alterations laid out in the team’s design would deliver substantial improvements to the
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performance of the heating column, it is impossible to quantify the extent of those
improvements at present.
Conclusions
The purpose of this project was twofold; to design, prototype, build and test
modifications to an existing system to enhance its performance, and to gain valuable
experience with managing and executing a start to finish engineering project. As such, two
conclusions will be presented, one related to the improvements made to Lola’s performance
and another related to the lessons learned by the group.
As can be seen in the Mission Statement, the group’s original goals were to design,
prototype and install systems that would prevent incorrect insert types from being pressed,
assure consistent and correct insert temperature, verify pressing depth and empty the heating
tube quickly. At the time of this report’s writing, three of the named systems were completed
but none of them could be installed. The pressing depth verification aspect of the project was
canceled, a joint decision made by PECO and the team that resulted from an unfavorable cost
to benefit ratio. The remaining systems that would identify insert materials, provide correct
insert temperature and allow for rapid heating tube emptying were completely designed and
the necessary manufacturing and downtime schedule were undertaken. Although installation of
the actual systems could not be completed, results from prototyping, experiments and existing
system comparison led the group to conclude that the modifications to Lola would have
resulted in the desired performance improvements, fulfilling the requirements specified in the
PDS according to the Mission Statement.
In terms of a learning experience, the project was of unquestionable benefit to
everyone of the team. Since no member of the team had previously performed any sort of
engineering outside of a purely academic environment every obstacle, complication and
mistake was a lesson in real-world application of the group’s education. The first lesson learned
was that often times only the symptoms of a problem have been identified while the problem
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itself is a mystery. PECO knew only that the inserts were not leaving the heating tube at the
desired temperature but did not know why. Finding the cause and thereafter how to fix it was
left to the group. Related to the group’s efforts to characterize the relevant behavior of the
heating tube was the next major lesson, namely that oftentimes the results from an experiment
simply lead to more experiments. In total the team members spent dozens of hours collecting
and analyzing the data from several experiments in an effort to arrive at a solid conclusion
regarding what was occurring inside the heating tube and how to fix it. During the final stages
of design the team learned that many times the cost of an improvement outweigh the potential
benefits. This was seen with regards to the depth monitoring system, which either involved
expensive components or potentially unreliable moving parts while delivering performance
improvements that were deemed marginal.
Finally, the last and potentially most valuable lesson gained during this project was the
need to be in constant communication with an outside collaborator. Although the group had
PECO’s full cooperation and support during the extent of the project’s timeline, there were
numerous occasions where details regarding parts, deadlines, dates and other requirements
were either missed or misinterpreted by either PECO or the capstone team. It’s possible that a
more experienced group of engineers working on this project would have seen warning signs
that miscommunication had occurred, but the members of this project team did not. This led to
one experiment getting drastically shortened, part designs not being completed on time and, in
the end, an incomplete retrofitting due to missing parts, improperly designed components and
scheduling difficulties. All of these learning experiences have left the members of the capstone
team much better prepared to take on further engineering projects in the future.
To summarize, the members of the PECO capstone group felt that the project was a
success on two fronts; not only does the team feel confident that the proposed redesigns to the
existing system would deliver substantial improvements to performance in compliance with the
PDS but a great deal of valuable experience was gained as a result of all the difficulties that
arose during the various stages of the project. The group as a whole feels satisfied with the
results of this endeavor.
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Appendix A Product Design Specification
The Product Design Specification (PDS) is a reference stating the designers’ intentions and
customer requirements.
Product Design Specification
The criteria used to evaluate the overall worth of the design are listed in the following table
along with their respective priority ranking. In the following tables the same criteria are
presented by order of priority with further information on each criterion’s main customer, the
customer’s requirements, metrics, targets, bases for criteria, and verification method.
Product Design SpecificationsCriteria Priority
Performance HighQuality and Reliability HighLife in service MediumMaintenance MediumInstallation MediumSafety MediumMaterials MediumSize and Shape MediumApplicable codes and standards MediumTesting MediumCompany constraints and procedures MediumDocumentation MediumTimelines MediumEnvironment LowQuantity LowWeight LowErgonomics LowManufacturing facilities LowCost of production per part (material and labor) N/AShipping N/APackaging N/AAesthetics N/ALegal (Related patents) N/ADisposal N/A
Legend: High Priority Medium Priority Low Priority Not Applicable
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PerformanceCustomer Requirements Metrics Targets Basis Verification
PECO Material Identification
Improperly Identified
Inserts1 per 1000
Group Decision with
Customer Input
Analysis and Testing
PECO Accurate Insert Heating
Insert Temperature 810±10°F Customer
Feedback Testing
PECO Reliable Insertion Depth
Insert Depth Relative to
Panel Surface
Al: .080±.01” SS: .056±.01”
Customer Feedback Testing
Quality and ReliabilityCustomer Requirement Metric Target Basis Verification
PECO High Level of Repeatability
Improperly Sorted, Heated
or Inserted Parts
1 per 1000 inserts
Customer Feedback Testing
Life in ServiceCustomer Requirement Metric Target Basis Verification
PECO
Continued Operation for Foreseeable
Future
Expectable Remaining
Lifetime15 Years Customer
Feedback
Parts and Process Analysis
MaintenanceCustomer Requirements Metrics Targets Basis Verification
PECO Low Maintenance
Maintenance Interval 30 days Customer
Feedback
Similar System
Comparison
PECO Rapid TubeEmptying
TubeEmptying Time 1 minute Customer
Feedback Testing
InstallationCustomer Requirement Metric Target Basis Verification
Project Team Retrofitting Time to Modify 1 business Group Decision Similar
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Time Budget and Test Lola week with Customer Input
Procedure Comparison
SafetyCustomer Requirement Metric Target Basis Verification
PECOSafe Operation
and Maintenance
Machine Force Available
When Powered Down
0 NGroup Decision with Customer
Input
Part Selection and Testing
MaterialsCustomer Requirement Metric Target Basis Verification
PECONo Chemical Interactions
Between Parts
Number of Chemically
Incompatible Parts
0 partsGroup Decision with Customer
Input
Study of Material
Properties
Size and ShapeCustomer Requirement Metric Target Basis Verification
PECOLola Cannot
Occupy More Facility Space
Increase in Lola’s Volume 1 cubic foot Customer
Feedback Measurement
Applicable Codes and StandardsCustomer Requirement Metric Target Basis Verification
PECOElectrical
Wiring Standards
Incorrect Wirings 0 wirings Safety
StandardsStudy of
Standards
OSHA Workplace Safety Codes Violated Codes 0 codes Legal
NecessitiesStudy of
Regulations
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TestingCustomer Requirement Metric Target Basis Verification
Project Team
Team Must Perform All Necessary
Tests
Tests That Cannot be Conducted
With Current Resources
0 tests Group DecisionAnalysis of
Testing Methods
Company Constraints and ProceduresCustomer Requirement Metric Target Basis Verification
PECO and Boeing
Minimal Changes to
Material Properties
Alterations in Panel Material
Properties0 changes Customer
Feedback
Study of Methods Changes
DocumentationCustomer Requirement Metric Target Basis Verification
PECOAll
Modifications Need Prints
Undocumented Modifications
0 missing documents
Customer Feedback Arithmetic
TimelinesCustomer Requirement Metric Target Basis Verification
ME 492 Progress Report
Reports Submitted 1 report Course
Requirements Grade
ME 493 Design Report Reports Submitted 1 report Course
Requirements Grade
PECO Completed Retrofitting
Lola is Fully Modified 1 Lola
Customer Feedback and
Course Requirement
Grade
EnvironmentCustomer Requirement Metric Target Basis Verification
PECO
Lola operates in a low-moisture,
clean room
Contamination of Surroundings
No Detectable Contamination
Customer Feedback
Materials and Processes Histories
Quantity
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Customer Requirement Metric Target Basis Verification
PECO Lola Requires Retrofitting
Machines to be Retrofitted 1 Lola Customer
Feedback Not Necessary
WeightCustomer Requirement Metric Target Basis Verification
PECO
No Additional Support
Structure Needed
Increase in Lola’s Mass 50 kilograms
Group Decision with Customer
InputMeasurement
ErgonomicsCustomer Requirement Metric Target Basis Verification
PECOEasy Access to
Necessary Machine Areas
Time to Access Typically Used
Areas1 minute Customer
Feedback
Existing System Comparison and Testing
Manufacturing FacilitiesCustomer Requirement Metric Target Basis Verification
Project Team and PECO
PECO Will Fabricate
Specialty Parts
Material and Personnel Cost for Single Part
$150Group Decision with Customer
Input
Estimation from Material and Process
Not ApplicableCriteria Reason
Cost of production per part (material and labor) Only one Lola is being modified.Shipping Lola is a stationary piece of manufacturing
equipment.Packaging Lola does not require packaging at this time.Aesthetics There are no appearance requirements.
Legal There are no unique legal constraints.Disposal There are no plans to scrap Lola at the moment.
22 | P a g e
House of Quality
The highest priority parameters are shown below in the following table with selected engineering criteria that are expected to influence the final performance, both those that can be controlled by the project team and those that are controlled by PECO.
Parameter
Impo
rtan
ce
Cust
omer
Engineering Criteria Competition
Vibr
ation
Tol
eran
ce
Pow
er U
sage
Cyc
le T
ime
Cost
Geom
etry
Mat
eria
ls
Inst
rum
enta
tion
Current Design
Performance 10
PECOInsert
Identification 3 **** ** *** ***** ** *** ***** *
Insert Heating 4 ** ***** ***** ***** *** ***** *** **Insert Depth 3 **** *** **** ***** ** *** ***** ***
Reliability 8 PECO **** **** **** **** * *** ***** ***Life in Service 5 PECO **** * ** **** * ***** *** *****Maintenance 6
PECOService Interval 2 *** ** *** **** * *** ** ***
Tube Purging 4 * * * ** **** * * *
Installation 6 Project Team ** ** * * **** ** * N/A
Current Design ***** *** **** *** ***** *** **
Legend: Each criteria is given an influence rating relative to each parameter ranging from *
meaning little to no known influence to ***** meaning critically influential.
In the case of the Current Design, * indicates lowest possible performance against the criteria
and ***** indicates highest possible performance against the criteria.
Product Design Specification Conclusion
PECO desires to keep their position as the exclusive supplier of fuel tank access doors to Boeing.
To satisfy Boeing, PECO will only supply parts of good quality. Lola plays an important role in
23 | P a g e
the manufacture of fuel tank access doors. If Lola does not consistently produce good panels,
many will be scrapped for not meeting quality expectations.
Presently, Lola does not perform to an acceptable level of consistency. Too often the inserts are
not heated properly, not pressed to sufficient depth or even pressed into the wrong panel. Such
failures produce parts that cannot be reworked and thus are scrapped. Additionally, if the
failures are not detected before subsequent manufacturing process, resources are wasted on
parts that will ultimately be rejected, or worse, delivered to Boeing.
The Capstone Team will improve Lola’s performance by enhancing the machine’s heating
system, improving the pressing system to ensure that each insert is pressed to specifications,
and implementing a new system to identify insert type before pressing. These improvements
must be made within time and monetary limitations without reducing Lola’s expected
operational lifetime or significantly increasing maintenance requirements.
By correcting the current deficiencies in Lola, the successful completion of this project will help
PECO maintain their valuable relationship with Boeing.
24 | P a g e
Appendix B Initial Experiments
Insert Pressing Temperature Experiment
Purpose
The purpose of this experiment is to characterize the insert temperature when pressed under
normal operating conditions. To fully characterize the insert temperature the average value
and standard deviation of a temperature sample will be determined and the insert temperature
vs. cycle time will be plotted. Normal operating conditions will be accounted for by five
separate scenarios:
1. Warm up – Inserts begin at room temperature and sit in heated columnfor 10 min then
pressing cycle starts.
2. Steady state – The tube is at operating temperature and inserts are cycled through the
tube at a constant rate.
3. Door change – The steady state cycle is interrupted by a door change.
4. Jamming – The steady state cycle is interrupted by a jammed insert.
5. Irregular feeding – Vibrating machine does not load inserts at a uniform rate.
Procedure
The regular Lola startup procedure was performed including the 10 minute waiting period after
the heating tube reached temperature. The machine was cycled at the production rate and the
temperature of each insert was measured with an infrared pyrometer as it was pressed out of
the shuttle. Measurements were taken for the duration of three doors. Any jamming or
abnormalities in the cycling time were noted.
25 | P a g e
Results
A chart of the raw insert temperature data is presented in Figure 8. Inspection reveals the
insert temperatures are at or above the required range only at the beginning of the production
run and at steady state are too low. The temperature of the fist 31 inserts can be mapped to
their position in the tube during warm up. The inserts at the bottom of the tube were low with
the insert temperature rising as the insert position rises in the tube. A maximum is reached and
then the temperature decreases to unacceptably low levels. Inserts that are cycled through
the tube at production rates never reach the required temperature.
0 100 200 300 400 500 600 700 80050
100
150
200
250
300
350
400
450
500
Time (s)
Inse
rt Te
mpe
ratu
re (C
)
Insert TempTarget Range
Figure 8. Experiment data showing the insert temperature after pressing and the target
temperature range.
26 | P a g e
Heating Tube Temperature Profile
Introduction
The inserts are heated as they travel down the tube to be loaded into the shuttle. The final
temperature of the insert will vary depending on several factors, including
When a new door is loaded
How many jams occurred during decent
The insert position in the tube when the door loading or jamming occurred
How many inserts were in the tube when it was loaded
To fully characterize the tube temperature profile the insert temperature must be recorded at
each of the 31 steps in the decent. Because a new door could be loaded or jamming could
occur when the insert is at any of the 31 positions in the tube an impractical number of
temperature profiles is required to gather data points for each possible event.
To reduce the required number of profiles it will be assumed that the effect of loading a new
door can be adequately determined by having this interruption occur when the insert is in the
middle of the tube. The effect of jamming is assumed to be negligible because the added dwell
time is very small relative to the overall dwell time.
To account for the reduced dwell time resulting from delays in loading the worst case scenario
will be used to determine the profile. This will be assumed to be 10 cycles without loading.
Purpose
The purpose of this experiment is to characterize the insert temperature as it travels down the
heating tube during normal operating conditions.
27 | P a g e
Procedure
The heating tube was preheated and one door was processed. The machine continued to cycle
at the normal operating rate until 14 inserts were pressed and 13 inserts were loaded.
Temperature data logging was began and the insert instrumented with a thermocouple was
loaded into the heating tube. The machine was cycled until the instrumented insert was at the
bottom of the tube. Data logging was continued for a few minutes in this position.
Results
The insert temperature as it travels down the heating tube during normal operation is
presented in Figure 9. The insert never reaches the target temperature and actually cools as it
approaches the bottom of the tube. The rate of heat transfer decreases at about the 12th
position and then again at the 22nd position as it approaches the tube air temperature.
0 50 100 150 200 250 3000
50
100
150
200
250
300
350
400
450
Time(s)
Tem
p(C
) & In
sert
#
TemperatureInsert # x 10Target Range
Figure 9. Experiment data showing the temperature of the insert as it traveled through the
heating tube, the insert position for the time and the target temperature range.
28 | P a g e
Appendix C Insert Free Convection Coefficient
Purpose
The purpose of this experiment was to determine the cooling rate in free air and the theoretical
free convection coefficient for aluminum and stainless steel inserts.
Procedure
An insert instrumented with a calibrated Type K thermocouple was heated to a temperature
above the 810⁰F and allowed to cool in free air. The insert temperature and time was recorded to
provide a cooling curve. A theoretical heat transfer model was developed which calculated the heat loss
due to convection and radiation as the insert cooled from 810⁰F. The theoretical cooling curve was
plotted against the experimental cooling curve and the value of the convection coefficient, h, varied.
The h value resulting in the best correlation between the curves was determined to be the free
convection coefficient.
The theoretical heat transfer from the insert is the sum of heat loss due to radiation and
convection. This heat transfer is governed by equation (1) for convection and equation (2) for radiation.
q ' convection=A sc h (T ∞−T s ) (1)
q ' radiation=A srϵσ (T sur4 −T s4 ) (2)
where A sc is the surface area contributing to convection, h is the convection coefficient, T∞ is the
temperature of the air passing over the insert, Ts is the surface temperature of the insert, A sr is the
surface area contributing to radiation, 𝜖 is the material emissivity, 𝜎 is Boltzmann’s constant, and Tsur is
the temperature of the surrounding air.
Results
Plots of the theoretical and empirical cooling curves for stainless steel and aluminum inserts are
presented in Figure 10 and Figure 11.
29 | P a g e
0 50 100 150 200 250 300 350 400100
150
200
250
300
350
400
Time (sec)
Tem
p (F
)
TheoreticalEmpirical
Figure 10. Theoretical and empircal cooling curves for stainless steel insert with a convection coefficient h=1.6.
0 50 100 150 200 250 300 350 400100
200
300
400
500
600
700
800
900
Time (sec)
Tem
p (F
)
TheoreticalEmpirical
Figure 11. Theoretical and empircal cooling curves for aluminum insert with a convection coefficient h=1.6.
Conclusion
A convection coefficient of h=1.6 provides a high correlation between the theoretical and
empirical data sets for both the stainless steel and aluminum inserts.
30 | P a g e
Appendix D Insert Pressing Temperature
Purpose
The purpose of this experiment was to characterize the insert temperature at the time when it is
pressed from the shuttle into the fuel access panel.
Procedure
To attain accurate temperature readings a calibration curve was created for the infrared
pyrometer. An insert was instrumented with a calibrated type K thermocouple and heated to a
temperature above 850⁰F. As the insert cooled to 250⁰F the insert temperature reported by the
thermocouple and the IR pyrometer were recorded. An equation correcting the IR pyrometer reading to
the thermocouple reading was determined using a least squares curve fit of the data. Separate
correction equations were determined for aluminum and stainless steel due to their different
emissivities.
Thirty-one room temperature inserts were loaded into the heating tube and allowed to heat
soak for ten minutes simulating startup. A device instrumented with an IR pyrometer was placed under
the ram which captured the inserts as they were pressed from the shuttle. The IR pyrometer measured
and recorded the insert temperature. Data was collected for sixty-nine inserts (three door cycles).
31 | P a g e
Results
IR pyrometer calibration data is presented in Figure 12 and Figure 13.
0 10 20 30 40 50 60 70 80100
150
200
250
300
350
400
450
TC ValueIR ValueIR Corrected
Figure 12. Thermocouple and IR pyrometer temperature measurement data and correction results for stainless steel.
0 20 40 60 80 100 120 140 160 180150
200
250
300
350
400
450
500
TC ValueIR ValueIR Corrected
Figure 13. Thermocouple and IR pyrometer temperature measurement data and correction results for aluminum.
Plots showing insert temperature when pressed is presented in Figure 14 and Figure 15.
0 100 200 300 400 500 600 700 80050
100
150
200
250
300
350
400
450
500
Figure 14. Pressing temperature for stainless steel inserts.
600 700 800 900 1000 1100 1200 13000
50
100
150
200
250
300
350
400
Figure 15. Pressing temperature for aluminum inserts.
32 | P a g e
Conclusion
For both materials the inserts are significantly below the required temperature at steady state.
The steel inserts show a large temperature variation for the inserts in the tube during start up;
beginning below the steady state temperature, increasing to the target temperature in a bell curve and
reducing to the steady state temperature. This suggests the heating tube has an uneven temperature
profile with the center of the tube being hottest.
There is significant variation in the pressing temperature of the inserts during steady state
operation. Testing the IR pyrometer’s sensitivity to deviations in insert axial alignment revealed that the
IR sensor reading could vary by as much as 10% for small axial misalignments. This alignment error can
explain the variation in steady state temperatures and prevents us from determining the average
temperature and temperature standard deviation for steady state conditions. However, it can be
concluded that inserts are well below the required temperature for steady state conditions and suggests
the temperature profile within the tube may not be consistent.
33 | P a g e
Appendix E Heating Tube Temperature Profile
Introduction
This experiment characterizes the performance of the heating tube. The heating tube is a
vertical steel tube, open at both ends, with heating elements on the exterior surface. The inserts are
loaded into the tube at the top and are removed for pressing at the bottom. During operation the tube
holds 31 inserts. It takes 23 inserts to complete one door. The insert passes through the tube in 31
positions and remains at each position for 8.7 seconds while pressing occurs except for when a door
change occurs extending the dwell time in that position to 16.7 seconds.
The required insert temperature is 432 ± 5⁰C (810 ± 10⁰F). Measurements have shown that the
inserts are significantly below this temperature when exiting the heating tube. One possible explanation
for this is stack affect caused by heated air convecting up the tube and out into the room drawing
unheated air into the tube through the open bottom. This colder air would be cooling the inserts in the
bottom portion of the tube.
Heat transfer to the insert occurs by convection and radiation. This heat transfer is governed by
equation (1) for convection and equation (2) for radiation.
q ' convection=A sc h (T ∞−T s ) (1)
q ' radiation=A srϵσ (T sur4 −T s4 ) (2)
where A sc is the surface area contributing to convection, h is the convection coefficient, T∞ is the
temperature of the air passing over the insert, Ts is the surface temperature of the insert, A sr is the
surface area contributing to radiation, 𝜖 is the material emissivity, 𝜎 is Boltzmann’s constant, and Tsur is
the temperature of the heating tube inner wall. The total heat flux into the insert is the sum of
equations (1) and (2).
By measuring the temperature of an insert at each position as it passes through the heating tube
it is possible to determine if the inserts are cooling at the bottom of the tube. By comparing this
measured value against the calculated theoretical value assuming no stack effect it is possible to
determine if stack effect is a possible cause of the insert cooling.
34 | P a g e
Purpose
The purpose of this experiment was to determine if stack effect decreased insert heating at the
bottom of the tube by comparing the actual heat transfer to the insert to the theoretical heat transfer
assuming no stack effect.
Procedure
The procedure consisted of three parts: calibrating the temperature measurement instruments,
determining the material emissivity values, and gathering experiment data.
Calibration
A 1/16” hole was drilled in the inside base of two steel and two aluminum inserts. A Type K
thermocouple was installed in the hole and secured in place using high temperature epoxy. The TC’s
were calibrated against a laboratory standard using water baths at various temperatures.
Determining Emissivity
The thermocouple was connected to a data acquisition system with internal cold junction
compensation. The instrumented insert was heated to a temperature above 432⁰C. The insert
temperature was then measured by a calibrated infrared pyrometer. The emissivity setting on the
infrared pyrometer was adjusted until its reading matched the thermocouple reading. The emissivity of
both materials was determined.
Experiment
The machine was started using the production startup procedure and cycled 32 times after
which the instrumented insert was fed into the top of the heating tube. The machine was cycled an
additional 31 times as inserts continued to be loaded into the tube. After the 31 cycles the
instrumented insert was at the bottom of the heating tube at which time the cycling was stopped and
the TC was allowed to heat soak for at least 30 sec. This procedure was repeated twice for each
material.
Analysis
The thermocouples were calibrated to ensure proper readings using the least squares method.
35 | P a g e
Determining Heat Flux
The total heat flux into the insert was calculated for each position in the tube using equation (3)
and assuming constant specific heat.
q total=ρVC △T (3)
where ρ is the density, V is the volume, C is the specific heat, ∆T is the change in temperature of the
insert from the end of the previous position to the end of the current position.
The convection coefficient was calculated using equation (4) based on the steady state
conditions present when the insert remained at the bottom of the tube. At steady state
qradiation ,∈¿¿q convection,out ¿.
h=A sr ϵσ (T sur4 −T s
4 )A sc (T∞−T s )
(4)
The heating tube temperature is controlled by the machine and was measured at 432⁰C. It was
assumed that T sur was 432⁰C over the tubes entire length.
The total heat flux into the insert per position is predicted by heat transfer theory was
approximated using equation (5).
q theoret ical=A sr ϵσ (T sur4 −T s4 ) Δt+A sch (T ∞−T s ) Δt (5)
where Δt is the dwell time for the insert in each position. For the theoretical calculations T sur and T∞
were given the value 432⁰C.
Results
Plots of the insert temperature as it descends through the tube are presented in Figure 16,
Figure 17, Figure 18 and Figure 19The space between the red crosses indicates insert positions, the
crosses indicate when the insert dropped one position. The top row of temperature plots represent the
aluminum test runs, the bottom row represents the stainless steel test runs.
36 | P a g e
0 100 200 300 4000
50
100
150
200
250
300
350
400
Time (sec)
Tem
pera
ture
(C)
Insert TempEnd Time/Temp for Insert Position
Figure 16. Aluminum insert temperature with indicated tube position.
0 100 200 300 4000
50
100
150
200
250
300
350
400
Time (sec)
Tem
pera
ture
(C)
Insert TempEnd Time/Temp for Insert Position
Figure 17. Aluminum insert temperature with indicated tube position.
0 100 200 300 4000
50
100
150
200
250
300
350
400
Time (sec)
Tem
pera
ture
(C)
Insert TempEnd Time/Temp for Insert Position
Figure 18. Stainless steel insert temperature with indicated tube position.
0 100 200 300 4000
50
100
150
200
250
300
350
400
Time (sec)
Tem
pera
ture
(C)
Insert TempEnd Time/Temp for Insert Position
Figure 19. Stainless steel insert temperature with indicated tube position.
Bar graphs presenting a comparison of the theoretical and experimental heat energy transfer
values for each run are presented in Figure 20, Figure 21, Figure 22 and Figure 23. The top row of bar
graphs represent the aluminum test runs, the bottom row represents the stainless steel test runs.
37 | P a g e
0 5 10 15 20 25 30 35-50
0
50
100
150
200
250
Insert Number
J/kg
-K
TheoreticalExperimental
Figure 20. Comparison of theoretical and experimental heat energy transfer per insert position for aluminum insert test 1.
0 5 10 15 20 25 30 35-50
0
50
100
150
200
250
Insert Number
J/kg
-K
TheoreticalExperimental
Figure 21. Comparison of theoretical and experimental heat energy transfer per insert position for aluminum insert test 2.
0 5 10 15 20 25 30 350
50
100
150
200
250
Insert Number
J/kg
-K
TheoreticalExperimental
Figure 22. . Comparison of theoretical and experimental heat energy transfer per insert position for steel insert test 1.
0 5 10 15 20 25 30 350
50
100
150
200
250q Stored per Insert Position
Insert Number
J/kg
-K
TheoreticalExperimental
Figure 23. . Comparison of theoretical and experimental heat energy transfer per insert position for steel insert test 1
Conclusion
While conducting the experiment it was noticed that the top 4 inserts are being held in an
unheated tube suspended above the heating tube. Therefore the heating of the insert in the first 4
positions are not considered when determining the temperature profile of the heating tube. Because
the purpose of this experiment is to investigate the effect of cooling in the bottom of the tube the error
in the first five positions can be ignored.
From the temperature plots in Figure 16 through Figure 19 it is shown that at no point in the
heating does the insert reach the required temperature and the insert is well below the required
temperature when it is ejected from the heating tube to be pressed. The aluminum inserts reach a
maximum temperature and then begin to cool. The steel inserts do not cool, but the rate at which they
38 | P a g e
are heating is slowed significantly. The significant reduction in heating at the bottom position provides
strong evidence that the stack effect is present and is interfering with the heating process.
From the temperature plot the aluminum insert temperature rises faster than the stainless
steel, but evaluating equation (3) for both inserts theory predicts the stainless steel temperature rises
faster. Because of their different densities and heat capacities it takes 7 joules to raise the aluminum
insert temperature 1⁰C while it takes only 4.5 joules to raise stainless steel insert 1⁰C. This discrepancy
may be due to differences in thermal conductivity. The thermocouples are inserted in the thickest part
of the insert and the lower thermal conductivity of stainless steel may increase the time constant of the
insert such that its internal temperature is significantly lower than the surface temperature.
The insert temperature curve for the first aluminum tests reaches equilibrium at 376⁰C. This
value was used as the steady state condition for determining the convection coefficient.
Figure 20 through Figure 21 provide further support the hypothesis that stack effect is interfering with
insert heating. These bar graphs represent the amount of heat energy stored in the insert while in each
position in the heating tube. The amount of energy stored per unit time is related to the difference
between the insert temperature and the temperature of its surroundings. As the insert approaches the
temperature of the environment the heat transfer rate decreases. This is represented clearly in the
theoretical heat transfer values. In all four cases the experiment data shows a significant decrease in
the heat transfer values for the last 10 positions. For the aluminum inserts the heat transfer is negative
in the last four positions. The difference between the theoretical and experimental values of the heat
transfer for the bottom 10 positions is likely due to cool air convecting heat from the inserts and cooling
the heating tube inner surface reducing radiation heat transfer to the inserts. The large spike around
the 10th position is caused by the increased dwell time at that position due to a door change.
The theoretical model of the stainless steel inserts predicts less heat transfer than actually
occurs for the middle of the heating tube. This could be explained by an erroneous emissivity value.
The emissivity value found in tables for machined stainless steel is within 0.03-0.10. Our experiment
measuring the stainless steel emissivity provided a value of 0.64, significantly above the table values.
Because emissivity increases with oxidation and the inserts visibly oxidize in the tube we assumed our
value accurately represented the insert emissivity. If the emissivity is actually much lower than that
used in the theoretical calculations the ratio between the heat gained by radiation in to heat lost by
radiation out would be much higher. This could explain the discrepancy between the theoretical and
experimental heat transfer values for the stainless steel. If this is the case, the heat lost due to stack
effect would be greater than indicated on Figure 22 and Figure 23.
39 | P a g e
From the analysis of the experiment data it is likely that the stack effect is present and adversely
effecting insert heating and significantly reducing the insert temperature at the end of the heating
process.
40 | P a g e
Appendix F Heating Tube Plugging Validation
Introduction
Previous experiments have shown that stack effect significantly reduces the heating of the insert
in the bottom 10 positions in the heating tube. The stack effect, hot air rising out of the top of the
heating tube and cool air being drawn into the bottom, is due to natural convection. Closing the heating
tube at the top and bottom will block the stack effect.
A mechanism was designed which seals the tube ends when and insert is not being loaded into
or removed from the heating tube. By timing the opening of the tube such that the top and bottom are
never open at the same time the stack effect can be almost completely eliminated.
Purpose
The purpose of this experiment was to determine if the process of sealing the tube ends
eliminates the stack effect and results in an increased final insert temperature.
Procedure
Open Tube
The machine was started using the production startup procedure and cycled 32 times after
which the instrumented insert was fed into the top of the heating tube. The machine was cycled an
additional 31 times as inserts continued to be loaded into the tube. After the 31 cycles the
instrumented insert was at the bottom of the heating tube at which time the cycling was stopped and
the TC was allowed to heat soak for at least 30 sec. This procedure was repeated twice for each
material.
Plugged Tube
All openings in the sides of the tube were plugged with aluminum foil. Because of the limited
clearance between the shuttle and the heating tube bottom it was not possible to plug the bottom of
the heating tube. Instead, an aluminum foil plug was inserted into the hole in the rear of the shuttle.
When the shuttle was in the pressing position the aluminum plug prevented air from flowing through
the hole in the shuttle into the tube. Some air was able to flow between the shuttle and the heating
tube base, but the air flow was assumed to be significantly decreased. An operator plugged the top of
41 | P a g e
the heating tube with aluminum foil accept when an insert was hand fed into the tube. The procedure
for the open tube was repeated with the plugging in place.
Results
Plots of the insert temperature as it descends through the tube are presented in Figure 24 and
Figure 25. The space between the red crosses indicates insert positions, the crosses indicate when the
insert dropped one position.
0 50 100 150 200 2500
100
200
300
400
500
600
700
800
Time (sec)
Tem
pera
ture
(F)
Plugged Tube Insert TempOpen Tube Insert TempEnd Time/Temp for Insert Position
Figure 24. Stainless steel insert temperature at each position in the heating tube for plugged and open heating tube condition.
0 50 100 150 200 2500
100
200
300
400
500
600
700
800
Time (sec)
Tem
pera
ture
(F)
Plugged Tube Insert TempOpen Tube Insert TempEnd Time/Temp for Insert Position
Figure 25. Aluminum insert temperature at each position in the heating tube for plugged and open heating tube condition.
Conclusion
The data shows an increase in insert temperature at the lowest position of 16⁰F for the stainless
steel insert and 22⁰F for the aluminum insert. In addition, the aluminum insert did not cool in the
lowest position. The results show an increase in the heating rate for the insert at the lowest position
suggesting the design will improve the performance of the heating tube. Taking into account how
incomplete the seal was at the bottom and top of the tube compared to the proposed design, the
results of implementing the design can be expected to be as good, or better, than this validation data.
42 | P a g e
Appendix G Insert Identification Validation
Introduction
Previously no system was in place to identify the insert material. A system using two proximity
sensors and a logic circuit has been developed to trigger a warning when the target insert material is
detected.
Purpose
The purpose of this experiment was to determine the effectiveness of the insert identification
system.
Procedure
A prototype of the logic circuit shown in Figure 26 was constructed on a prototype board.
Figure 26: Wiring diagram for the insert identification system.
43 | P a g e
A wooden frame with a channel was constructed to model the feed block on the existing machine. The sensors were installed into the wooden frame in the same orientation as they would be in the actual machine. Power was applied to the circuit. The inserts were passed through the sensors in an alternating order of material as shown in Figure 27.
Figure 27: Test apparatus used in the experiment with the power supply not present. The light colored inserts are aluminum and the darker inserts are stainless steel.
Results
One hundred inserts were passed through the sensors in each detection mode: both aluminum
detecting and stainless steel detecting. In the trial no inserts were misidentified.
Conclusion
The insert identification system using two inductive proximity sensors is effective in correctly
identifying insert material.
44 | P a g e
Appendix H Bill of Materials
Heating Tube:Quantity Name Modle Number
1 Photoelectric Sensor HD11NC31 Sensor Bracket 1 Heating Tube 2 Shaft Cupling 9861T72 Door 2 Door Housing 2 Bronze Bushing 4 Bracket, Air Cylinder 2 Inner Block 2 Outer Block 2 Double Acting Air Cylinder 6498K1334 Silicone Rubber Bumper 7665k23
Insert Evacuation:Quantity Name Modle Number
1Bracket, Evacuation Tube Lower
1 Bracket, Tube Mounting 1 Bracket, Tube Top 1 Evacutation Tube 1 Front Stop Plate 1 Shuttle Assembly Base 1 Shuttle 2 Spacer, Modified 1 Stop Rail
Insert Identification:Quantity Name Modle Number
1 Feedblock, Modified 1 8mm sensor 150391
1 18 mm sensorNMB5-18GM55-E2-NFE
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Appendix I Production Drawings
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