Palletizing

An Introduction to

Automated Palletizing

By Michael A. Hernan I

Copyright: April 21, 2000

Published By:

Anderson Technical Services, Inc. 850 Morrison Road

Chillicothe, Ohio 45601 740-775-1962 www.atsi.cc

An Introduction to Palletizing “Choosing the Right System”

by Michael A. Hernan I

Abstract Machines that automatically place cartons onto pallets, called “Palletizers”, vary greatly in design and functionality. Selection and comparisons can be difficult if the user does not know some of the basic design and functional parameters of the different equipment offerings. This paper reviews the different types of Palletizers and how they are best applied. Palletizers are not stand alone machines; they work best within an integrated system or in a “cell “ concept. This paper looks at Palletizers in systems and in a cells plus reviews the before (in-feed) and after (out-feed) design requirements. It lists the throughputs and flexibility of each machine type listed and provides application comparisons. This paper endeavors to inform the reader about the general capabilities and specifications of different types of palletizer. It will help the reader identify many of the necessary considerations to determine the best machine type for their specific application. Introduction This paper will focus on palletizing, which is a form of unitizing. Palletizing refers to a uniform load stacked on a wooden pallet, using a pre-determined case pattern sequence and given number of layers. Unitizing refers to any load forming or unit load building process. Loads can be formed using the same stacking procedure as palletizing, without necessarily using a pallet, or loads may be stacked on slip sheets or on the floor. The process of palletizing typically involves the stacking of cases, trays, bundles, bags, pails or drums in a predetermined pattern configuration with a predetermined number of layers. This paper will focus on the use of cases only, as they make up the vast majority of palletizing applications. No matter what type of palletizing equipment is used, several factors are constant. Cases, case patterns, pallets, along with slip, pull pack and tie sheets are things every palletizer must contend with. Before we look at the different equipment types, we will review what they have to handle.

Revision 0 Introduction to Palletizing Page 3

Cases & Case Patterns The palletizers we will review can handle products from a small as 5” to 6” square boxes with as many as 64 cartons per layer, up to a single carton size of 50” x 40” stacked one to a layer. The product weight per carton can vary from 2 pounds up to 250 pounds with a full pallet loads ranging up to 6,000 pounds. An ideal case for building a formed load, is one that is rectangular and has a height that approximates the width of the case. A case with a height that is 1-1/2 times the width of the case or greater is termed a “high center of gravity case”. In some applications special attention is required in order to avoid tipping over “high center of gravity cases” during pattern forming. Rectangular cases enable stacking configurations that create a load that has each layer rotated 180-degrees for interlocking purposes. In this way a very stable load is built. Square cases are less desirable in pallet forming than rectangular cases. Loads built using square cases can only be column stacked and no interlocking of the cases can occur.

A fully automated palletizer needs to have a high level of sophistication to handle the many possible pallet loading configurations. Some applications call for only one pallet pattern, while other call for more than 20 patterns. Each pattern many have a different number of layers and require a different size pallet. In addition, the machine may have to account for slip and tie sheets to be part of the finished load.

Some case sizes do not allow the patterns to be configured without gaps in the pattern either side to side or front to back. However, the palletizer has the ability to create the pattern with these gaps in both directions. Slip, Pull Pack and Tie Sheets The terms “slip sheets” and “pull sheets” are synonymous. (Please reference Exhibit I). They refer to a sheet on which the load is stacked, in place of or on top of a pallet. This sheet is generally made from heavy corrugated and requires a special lift truck attachment, which enables the load to be moved by the lift truck. Conventional fork trucks do not have this attachment and cannot be used. Tie sheets refer to sheets that are placed between the layers of a load to obtain load stabilization. These are used predominantly when the cases to be stacked are square and/or no interlocking case pattern sequence can be employed. Tie sheets can be thin “butcher” paper, corrugated or fiberboard.


Pallets For most applications, the machines must handle the most common pallets used in palletizing, conventional 2-way and 4-way wooden pallets together with solid plywood pallets (slave pallets), that are often used in AS/RS (Automated Storage & Retrieval Systems) or AGV (Automatic Guided Vehicle) systems. (Please reference Exhibit I) Recently more companies are using plastic reusable pallets. These actually help palletizing effectiveness as they are offer more consistency between individual pallets and are less prone to damage than wood pallets. Defining Speed In palletizing speed is always a relative term. Speed primarily depends on the size of cartons to be handled, but is directly affected by the system’s layout. The assumption that the higher the price of the machine, the faster the speed, is inaccurate. One of the basic fundamentals of palletizing is that the more cases per layer, the faster the speed. Larger cartons fill the pallet faster, thus making the palletizer appear faster. Smaller cartons and intricate stacking patterns require more time. Therefore, a machine that can handle a 12 case per layer pattern configuration at a speed of 34 cases per minute may have a speed limitation of 22 cases per minute for a 6 case per layer pattern configuration. The palletizer’s method of building a layer directly affects its speed. In-Line Palletizers pick-up and move an entire layer, as opposed to a robotic–style machine that moves a single case or two with each movement. Robotic Palletizers can build a load with a line of waiting, accumulated, cartons faster than building with an intermittent flow of cartons coming directly from production. Thus the infeed of cartons to the palletizer directly affect its throughput speed. The same is true for the outfeed of cartons. If completed pallets are not taken away fast enough the line becomes full and the palletizer has to stop. The infeed and outfeed conditions directly affect all types of palletizers. When considering speed requirements for a palletizing system, the rule of thumb is that the palletizer-machine must be able to handle 25% more than the incoming packaging line(s) can produce. Carton size, carton mix and the case pattern configuration must be considered to calculate the palletizer speed with the aforementioned safety factor. This “speed” must be based on round-the-clock operation and are sustainable speeds, not surge rates. Generally, when the manufacturer for a given model quotes speeds, they are based on an 8 to 10 case per layer configuration. A fully automatic low speed palletizer will operate


at a speed of 10 to 25 cases per minute and on the upper end of the speed range, palletizers are available that can handle 120 to 160 cases per minute. A Systems Approach An automated palletizer is rarely intended to function as a stand-alone unit. It is not a commodity piece of equipment that can be judged or compared on it own, like a bay of rack or shelving. Instead, it should be viewed as one component that is designed to fit seamlessly into a larger, integrated materials handling or packaging system. Regardless of the type of palletizer you select the interfaces both upstream and downstream must match the rated operating speed of the palletizer or palletizing cell or you new solution will cause more problems than it solves. After reviewing the characteristics of each type of palletizer we will look at some typical systems layouts to illustrate how they are used in everyday operations. Palletizers In-Line Palletizers These machines are dedicated to a line or lines to handle limited product/carton types. The style you choose depends on your flow of cases at the end of the line and the type of product you are handling. Row-Stripping Palletizer These are the most common machines. They are what most people envision when they think of automated palletizing. These machines are designed for high speeds at continuous duty. This machine gets its name by the method it palletizes product. It first forms a row of cartons. Once a row is completed, a pusher mechanism moves the row to the palletizer’s make-up area. Several rows are combined to build a layer of products. To form the load, the completed layers are stacked on a pallet or other unit load platform.

Types of Palletizers In-Line Palletizers Row Stripping

High Level Low Level

Vacuum Head Robotic Articulated Arm (SCARA) Arm Gantry (Cartesian)

The many different types of palletizing machines can be categorized into two groups: In-Line and Robotic. In-Line Palletizers offer speed while Robotic Palletizers offer flexibility. The approach to layout is different for In-Line & Robotic Palletizers. Exhibit II illustrates the difference and other examples are provided in this paper.


Each row contributes to the building of a layer of cartons. Once a layer is complete, the palletizer deposits it either to the bottom, if it is a low level unit or on top of another layer if it is a high level unit. Row stripers can produce very high throughput speeds; speeds that can reach 160 cartons per minute. This type of palletizer can also palletize products of different shapes and sizes, provided that they are not intermixed. This type of machine has two basic types of infeed configurations: high level and low level. High level machines have case entry elevations from 7’-12’. They are more suited to situations where the palletizer is located some distance from the case packer or sealer, and an overhead conveyor is required to transport the cases form the case sealer to the palletizer. This type of arrangement frees up a great deal of floor space. (Please refer to Exhibit III). This is especially important when you have a very high speed operation (over 50 cases per minute) and you have long conveyor accumulation line(s) feeding the machine. Low level units have an entry elevation of approximately 30”. This makes it ideal for close coupling to case packers and case sealers, which have discharge elevations of anywhere from 20” to 36”. If you have abundant floor space, this type of arrangement offers several advantages over high level machines.

As the infeed elevation is about waist high, operators can monitor operations from the floor or from a forklift. You can monitor machine operations while filling the pallet magazine or removing full loads from the discharge conveyor. A high level machine requires a mezzanine with a stairway since the operating portion of the machine is at 7’-12’ above the floor. Jams will take longer to detect and if a high level palletizer goes down for any reason, it is far more difficult to hand stack,

since cases are entering the machine at such a high elevation. Maintenance work will need to be done above on high level, where cases are turned and arranged into layers. Biggest difference between low level and high level machines is that on low level machines during the load building process, the elevator lifts one layer at a tine and the load is built on a heavy-duty discharge conveyor, while the high level machine requires an elevator to support the full load as it is being built. The added mechanical complexity of a high level machine elevator results in more maintenance concerns compared to a low level machine.


Vacuum-Head Systems At the infeed end of the palletizer, a layer-makeup section within the machine forms the products into layers prior to the stacking operation. It uses stops and case turners to rotate cases to form the desired pallet pattern. Then a series of connected pneumatically powered suction cups grip the entire completed layer of products. Depending on the product, a clam shell clamping device can be used in place of the suction cups. The palletizer then lifts the cartons as a group and places them into a pallet. Top operating speed for this type of palletizer is typically about 25 cartons per minute. An ideal application for a vacuum-head palletizer is one in which it handles rigid products with a sturdy, flat tops. It is also an excellent choice for bags, drums and pails. In-Line Palletizer Applications A single conveyor feeds the majority of palletizers from a packaging or production line. This is why they are referred to as a dedicated machine. It is also common to have several packaging lines feeding into one higher speed palletizer thereby reducing the number of palletizers required. This arrangement is not unlike a funnel, pouring goods quickly into a smaller opening. However, if the opening (palletizing operation) is too slow or gets jammed, everything else upstream gets messy—quickly. The need to accumulate product before and after palletizing is essential to smooth and effective operations. When a single line is fed to a single dedicated palletizer, only the product on that line is delivered to the palletizer. If the palletizer cannot keep-up or pauses, the line backs-up, and eventually production on that line stops. When feeding multiple product lines into a single high-speed palletizer back-up or pause in palletizing can cause your operations to halt. That is why careful considerations must be given to the accumulation. Please refer to Exhibits IV, V &VI for sample layouts that illustrate this point. The rule of thumb is to accumulate at least 1.5 times a full pallet load of each product prior to feeding them to the palletizer. In the case of multiple product (conveyor) lines being fed into a single high-speed palletizer, the palletizer must be capable of running at a speed of approximately 10-20% greater than the total accumulated rates of each of the conveyor lines feeding it. Thus, if three packaging lines, running at an accumulated rate of 10 cases per minute per line were feeding into one palletizer, the palletizer must run at 10-20% faster than the 30 cases per minute being accumulated. In othe r words, the palletizer must handle 33 to 36 cases per minute. This does not include the 25% safety factor mentioned before.


Accumulation Length The length of each line of accumulation conveyors from production into the packaging/palletizing cell should be 1.5, minimum to 2 times a full pallet load of product. This allows additional accumulation while one line is metering cases to the palletizer. Thus, if one packaging line is producing 16” long cartons and requires 80 cases to complete a full load, this equates to a full load length of 107’ (1280” times 1.5, which give a total accumulation conveyor length of 160’. This equation is repeated for each additional line feeding the palletizer. Robotic Palletizers A robot’s strength is the ability to rapidly arrange mixed pallets while serving several lines at the same time. These palletizers, depending on end-effector (end-of-arm-tooling) can better handle thinner-walled corrugated and more fragile case. Robotic Palletizers run at low to medium rates and are best used in applications that require a high degree of flexibility, and intermixed product with different shapes and sizes. Speeds of 10 to 30 cases per minute are common. If your operation requires different pallet patterns or uses different size cartons, the controls and software programs for robotic palletizers give you the highest degree of flexibility and quick reprogrammability you require. There are three predominant types of robotic palletizers

Ø SCARA Arm Ø Articulated Arm Ø Gantry

All three types use end-effectors that are custom designed to handle the customer’s product. Most often the design includes pneumatic cups, like the ones used by vacuum-head palletizers; or they may use various types of mechanical grabs. SCARA Arm Palletizers SCARA (Selective Compliant Articulated Robot Arm) robots have joints in the horizontal plane, which allows the arm to swivel about its base and fold in on itself like a "folding screen." Its work envelope is cylindrical. These robots maneuver cartons through four-axis movement using a mast and cross arm. The entire unit is often placed on a pedestal on rails so the robot can palletize up to 6-8 pallets at a time. (Please refer to Exhibit VII)


Articulated Arm Palletizers An articulated arm palletizer also features four-axis movement, but relies on a mechanical arm equipped with at least three or four rotary joints: waist, shoulder, elbow, and wrist joints. This robot is an excellent choice for placing mixed loads on 1-4 pallets at a time. Like a SCARA arm robot this unit can also be placed on a pedestal on rails so it can palletize additional pallets at a time. (Please refer to Exhibit VIII& IX) The layout configurations of these two “arm” type robots are very similar. (Please review Exhibit II). In many cases they can be used interchangeably. Articulated arms are better at building difficult intermixed loads on pallets, while SCARA arms are a bit faster at building multiple pallet loads and usually cost less than articulated arm units. Gantry Robot (Catresian) Palletizers This unit uses a robotic arm placed on an overhead structure, a gantry, to achieve four-axis movement. The arm has three prismatic joints, whose axes are coincident with a Cartesian coordinator. The arm or end effector is mounted to a bridge that moves above the loads. The arm can be a suction cup, gripper or hybrid combination of the two. This palletizer is ideal for palletizing 8-60 pallets at a time. If more speed is required two or more bridges with arms can be place on the gantry. (Please refer to Exhibit X, XI & XII) Robotic Palletizer Applications Robotic Palletizers, in a sense work opposite to dedicated In-Line Palletizers. Instead of funneling multiple lines together, a robotic palletizer usually receives product from one line and places cases on several pallets at a time. (Please refer to Exhibit II) Robotic palletizers are seen most often in manufacturing applications where one-main production line carries various product types from different production machines. They accumulate at the end of the line and the robot places the correct product on the correct pallet. Two to sixty pallets can be built simultaneously, depending on the type of robot used and the throughput requirements of the system The need to accumulate product before and after palletizing is still just as essential for smooth and effective operations. The rule of thumb is to accumulate at least 1-1/2 full pallet loads of product on the infeed line prior to feeding them to the palletizer. In the case of multiple product (conveyor) lines being fed into a single robot palletizer, the palletizer must be capable of running at a speed of approximately 10-20% greater than the total accumulated rates of each of the conveyor lines feeding it. Thus, if three packaging lines, running at an accumulated rate of 5 cases per minute per line were


feeding into one palletizer, the palletizer must run at 15-25% faster than the 15 cases per minute being accumulated. In other words, the palletizer must handle 17 to 20 cases per minute. This does not include the 25% safety factor mentioned before. Accumulation Length The length of each line of accumulation conveyors from production into the packaging/palletizing cell should be 1.5, minimum to 2 times a full pallet load of product. Robots offer flexibility over speed. The infeed configurations are usually simpler than In-Line Palletizers, however, the design of the palletizing cell is more critical. The placement of the pallet(s), feeding pallets into and out of the system, all directly affect throughput and systems’ functionality. Other Considerations An automated palletizer is usually part of a total packaging system. The palletizer may have to interface or integrate with some of the following items: Ø Case sealers Ø Slip or tie sheet feeders Ø Packaging machine Ø Stretch wrappers Ø Checkweighers Ø Bar code labelers and applicators Ø Pallet collector/dispensers Ø Depalletizing

Often after installation as your system grows, demands for increased speed, flexibility and capability happen. Often increases in speed are affected more by efficient system configurations and changes in the inbound or outbound lines, than palletizer machine speed. Other challenges come with a specific stacking pattern for each type of product. Sophisticated Palletizer Controllers can help to meet many of these challenges.


Controls The number of case patterns that can be programmed into a fully automatic palletizer is virtually limitless. However, when a pattern is programmed into a palletizer, it is not simply a software change in the controller itself. One of the biggest challenges manufactures must meet is building loads to customer’s specifications. More vendors are requiring manufactures to build the pallet load so the bar code labels are readable on all cases after stacking. Programmable controllers, systems’ controls, and software must work together to fulfill this requirement. There are several ways to solve the problem. If your application requires cases and you are not using Robotic Palletizing, the turning function can be achieved with turning posts or more elaborate things like side flaps, rotators, or lifting rotators. For In-Line Palletizers mechanical stops are required in the machine, in order to separate the cases during pattern forming. The hardware involves more than the case stops themselves, it also includes cylinders to operate the stops, pneumatic valves to operate the cylinders, and the software program to control them. All of which means additional cost when the numbers of case pattern sequences are determined. For Robotic Palletizers, the considerations and costs are somewhat less. Additional axes of rotations (extra joints) are added to the end-of-arm tooling or end effector. With robotic palletizers, the label is read up stream of the palletizer, the data is collected, and then information to turn the carton is transmitted to the robot’s operating software. The robot then uses its rotors to stack the carton properly on the pallet Advances in controls, both PC and PLCs (programmable logic controllers) make synchronizing palletizers and conveyor lines easier. Cases can be accumulated and released in slugs to the palletizers, or cases can move in a single-speed line to be arranged by the palletizers.

Like other kinds of material handling equipment, controls bring better functionality to palletizers. You can find models with touch screen operator interfaces. These screens make controlling, maintaining and diagnosing problems very user friendly. No matter what type of palletizer you use, the higher the throughput or the

more flexibility required, the more elaborate and the more critical the layout configurations systems’ becomes. (Please also refer to Exhibit XIII)


Why Automatically Palletize? Automated palletizers are complex and expensive. In low throughput palletizing, 10 cases per minute or less, it is difficult to justify the cost of these machines using labor savings alone. In moderate to high-speed operations, above 15 cases per minute, some form of automated palletizing is the better choice. When reviewing the justification of an automated palletizer, more than just direct labor savings should be considered. The benefits produced by implementing an automated palletizing operation are impressive: Ø Increased line flexibility; Ø Increased Throughput; Ø Reduced worker injuries; Ø Increased Load Accuracy; Ø Better cube utilization; Ø Tighter, more uniform pallet loads; Ø Reduced handling-related product damage; Ø Increased Line Speed.

All of these factors should be calculated into your return on investment (ROI) formula when considering automating your palletizing/packaging operations. Making the Right Decision To make the correct palletizer purchase, it is essential to understand how your business will change in years to come. The higher throughput capacity your system requires, the more elaborate the palletizing scheme becomes. Plan ahead for accessories such as turning devices, pre-forming zones, slip sheet feeders, pallet dispensers, or parallel line feeds. Table 1 is a chart that summarizes the speed and flexibility of the types of palletizers we have reviewed. The best machine is dependant on ones requirements and future needs. Like all major capital decisions, proper research and thought should be given to operations requirements and overall goals of the project before sending out bid requests or settling on a machine to purchase.


Table 1:

Characteristics of Automated Palletizers

Palletizer Type

Operating Speed

(cartons/ minute)

Capacity Stacking Height

(ft)

Degree of Flexibility Comments

In-Line Row Stripping

40-160 250 lb/ctn

800 lb/layer 6,000 lb/load

5.5 -10 Low FAST! Many manufactures offer both low level & high level designs.

Vacuum-Head 10-25 100 lb/ctn 6-7.5 Medium

Typically used with products that have flat, rigid tops; or delicate product.

Robotic SCARA Arm 10-30 200 lb/ctn Up to 9 High Excellent degree of

flexibility. Articulated Arm

10-30 400 lb/ctn Up to 6 High Excellent for building intermixed loads on one pallet.

Gantry 10-30 400 lb/ctn Up to 12

High Excellent for building up to 60 pallet simultaneously

About the author: Michael A. Hernan I is a designer and implementer of automation & ergonomic systems. Mr. Hernans background is in project development, systems' design and profit improvement. He has more than 20 years experience as a project manager, design engineer, and consultant.

Exhibit I

Pallets & Case Patterns

Using programmable controllers and advanced controls, automated palletizers have the ability to stack loads in anynumber of pattern configurations. The also have the ability to incorporate tie, slip, and pull sheets into the load configuration. Loads can be built on pallets of all types, on slip sheets, or in the case of robotic palletizers, unitized on the floor.

Slave Pallet; often used in AS/RS &

AGV applications 4-Way Pallet 2-Way Pallet

Column stacked load on a pallet slip with slip sheets

Interlocked load stacked on a slip sheet only

Exhibit II

In Line Vs. Robotic Arm Palletizers

This simple diagram illustrates a typical layout for a fully automated In-Line Palletizer. In high speed applications particular attention must be given to the design of the infeed and outfeed materials handling system. If designed incorrectly many problems in operations will occur.

This simple diagram illustrates a typical layout for a robotic arm palletizer. The robot is on a pedestal that moves on rails to build several pallets at once. In robot applications, the layout of the cell is more critical. The deign of the end-effector is a key element in systems’ flexibility & capability.

Exhibit III

Row Stripper Palletizer High Level

Row Stripper palletizers are built for speed. A row of cartons is assembled before the unit. Once a row is completed, a pusher mechanism moves the row to the palletizer’s make-up area. Several rows are combined to build a layer of products. To form the load, the completed layers are stacked on a pallet or other unit load platform. Each row contributes to the building of a layer of cartons. Once a layer is complete, the palletizer deposits it either to the bottom, if it is a low level unit or on top of another layer if it is a high level unit.

These pictures illustrate the “make-up” area of row stripping machines. A series of stops and turning devices forms a row. A stripping device places the layer on the pallet.

Shown on this page are high level machines. The center diagram shows a machine with a automated pallet dispenser, high level infeed and in- line make-up area.

Exhibit IV

Row Stripper Palletizer High Level

To have an effective palletizing operation Row Strippers need long accumulation lines to feed the machine. They can palletize different products, but are limited to one product or pattern per pallet. Thus long accumulation lines for each product is required. The layout above illustrates a typical arrangement for a high level row stripping machine. The infeed lines enter the machine at a high elevation (10’-12’), thus saving valuable floor space. The oufeed is equally important. This layout uses a shuttle transfer (T-Car) to take full loads from the palletizers to a stretch wrapper. After stretch wrapping they accumulate on an a staging conveyor and await removal by lift truck.

Exhibit V

Row Stripper Palletizer Low Level

The layout above illustrates a typical arrangement for a low level row stripping machine. The infeed lines enter the machine at a low elevation (24”-36”), making it easier for maintenance and jam detection. Like all row stripping machines, to have an effective operation they need long accumulation lines to feed the machine. They can palletize different products, but are limited to one product or pattern per pallet. Thus long accumulation lines for each product is required. The oufeed is equally important. This layout uses a shuttle transfer (T-Car) to take full loads from the palletizers to a stretch wrapper. After stretch wrapping they accumulate on an a staging conveyor and await removal by lift truck.

Exhibit VI

Vacuum Head

This layout illustrates a typical arrangement for a vacuum head machine. The layout approach is very much like a low levelrow stripping unit. Like all in- line machines, to have an effective operation they need long accumulation lines to feed the machine. They can palletize different products, but are limited to one product per layer. Because they use a suction cup or clap device to lift an entire layer some intermixing of product on a pallet is possible.. The oufeed is less critical in this machine because the rates are not as fast. This layout shows a small length of staging conveyor at the exit end of the palletizer where full pallets await removal by lift truck.

Exhibit VII

SCARA Arm Palletizer Layouts

This illustration details a SCARA Robot palletizing cell. This cell accounts for future the growth of the operations. This is an excellent example of palletizing in a “cell concept”. The robot has the capability of handling an additional production line. Semi-automated at present, the addition of pallet dispensers, exit conveyors and a lift table will make this palletizing operation fully automated.

Exhibit VIII

Articulated Arm Robot Palletizer Layouts

The layout above illustrates a typical arrangement for a Articulated Arm Robot. The robot can palletized multiple pallets at one time handling different loads. A single end effector can be designed to handle cartons, slip sheets and pallets. Good end effector design adds greatly to the versatility of these machines.

From Production

Exhibit IX

Articulated Arm Robot Palletizer Layouts

The layout above illustrates the robot building intermixed loads by depalletizing existing-built pallets on the floor and palletizing a new pallet on a production conveyor. The picture shows a palletizing cell that palletizes product from three production lines. The line drawing shows a unit that builds intermixed loads from a single main production line.

Exhibit X

2& 3-Axis Gantry Palletizer Layouts

A gantry can come in 2, 3 or 4-axis configurations. The one shown to the right has an x,z, and r axis. Different end effectors shown above-right allow for robot style palletizers to handle almost any type of product and allows for superior operations flexibility. The layout above shows a 2-axis gantry palletizing cylinders. The advantage of a gantry is the ability to stack loads high and to build many pallets at a time. The layout approach to gantries is somewhat different than arm robots, but the overall design philosophy is the same.

Exhibit XI

4-Axis Gantry Palletizer Layouts

A 4-axis gantry allows for great flexibility in manufacturing palletizing operations. On this page all pallets are placed and taken away in the gantry cell by fork lift. The drawing shows a layout where product is sorted before palletizing. Then two pallets can are built simultaneously. Intermixed product comes from one main production line. The fish-eye picture to the right shows reusable totes filled with production parts being palletized. The loaded pallets move to the end of the line where they accumulated and await pickup by a forklift.

Exhibit XII

4-Axis Gantry Palletizer Layouts

The layout to the far right is a classic example of a 4-axis gantry palletizing 24 pallets. This fully automated system includes a transfer (T-Car) on rails that feeds the cell empty pallets and takes away full pallets. Intermixed product comes from one main production line. The product’s bar code is scanned and the information transmitted to a robot controller. The carton is identified, then pick-up and transported to the proper pallet, where it is built into the proper case configuration or pattern. At the outfeed, the T-Car brings full pallets onto an exit conveyor system that brings loads to a stretch wrapper. After wrapping, the pallet travels onto accumulation conveyor where loads wait for transportation to the warehouse by forklift.

Exhibit XIII

Palletizer Controllers

Programmable controllers and software allow palletizers to handle limitless case and forming patters. The flexibility and capability of palletizers is greatly enhanced by their use. User friendly graphics and touch screen interfaces make palletizers easy to change pallet configurations or handle different products. However, it must be remembered the machine must also have the physical capabilities to execute the controllers commands.

Palletizing

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