Hardware Development Methods and Tools

Hardware Development Methods and Tools

Design MethodologiesComponent Variations

MisuseExtended TRIZ

Six Sigma

Six Sigma is a revolutionary business process geared toward dramatically reducing organizational inefficiencies that translate into bottom-line profitably. The steps are:

• Define• Measure• Analyze• Improve• Control.

The basis of Six Sigma is measuring and improving processes re: defects

• Six Sigma: 3.4 defects per million opportunities

• Most current methodologies operate at 3 to 4 sigma, allowing ~ 25% loss of revenue because of failure rates due to defects

• Result: unhappy, non-returning customers!

Design for Six Sigma

Design for Six Sigma (DFSS) is an approach to designing or re-designing product and/or services to meet or exceed customer requirements and expectations (VOC). It begins by conducting a “gap analysis” of your entire product development system. This analysis finds the gaps in your processes that are negatively affecting new product performance…

Methodology 1: DMADV

• Define – determine goals, VOC requirements• Measure – assess customer needs & specs.• Analyze- examine solution options• Design – develop to meet requirements• Verify – verify that you met requirements

Other Methods:

• DMADOV – prior + Optimize• IDEAS – Identify/Design/Evaluate/Affirm/Scale up• IDOV – Identify/Design/Optimize/Validate• DMEDI –

Define/Measure/Explore/Develop/Implement• DCCDI –

Define/Customer/Concepts/Design/Implement

In General, Design for Six Sigma

• Is a structured approach to responding to the voice of the customer

• Is augmented by standard tools such as QFD, Failure Modes and Effects Analysis, Pareto Charts & analyses, Feather Diagrams, designsafe analyses, input from reliability groups, input from QA and customer complaint inputs, possible analyses from MAUDE data, etc.

Some Six Sigma Tools:

• Robust design – Taguchi Method• Quality Function Deployment – QFD (done)• Design Failure Modes and Effects Analysis• Axiomatic Design – Nam Suh

Robust Design

By considering the noise factors (variation & component deterioration) and the cost of failure this method helps ensure customer satisfaction. The focus is on improving the fundamental function of the product or process, facilitating flexible designs and concurrent engineering. It assists in reducing product cost, improving quality, while simultaneously reducing development interval.

Your Circuit Choice?

• Compensate the customers for their losses.• Screen out circuits having large offset voltage at

the end of the production line (discard).• Institute tighter tolerances through process

control on the manufacturing line (inspect).• Change the nominal values of critical circuit

parameters such that the circuit's function becomes insensitive to the cause, namely, manufacturing variation.

Parameter Diagram, aka P-Diagram

Robust Design – Overview Step 1

Problem Formulation:This step consists of identifying the main function, developing the P-diagram, defining the ideal function and S/N ratio, and planning the experiments. The experiments involve changing the control, noise and signal factors systematically using orthogonal arrays.

Robust Design – Overview Step 2

Data Collection/Simulation:The experiments may be conducted in hardware or through simulation. It is not necessary to have a full-scale model of the product for the purpose of experimentation. It is sufficient and more desirable to have an essential model of the product that adequately captures the design concept. Thus, the experiments can be done more economically.

Robust Design – Overview Step 3

Factor Effects Analysis:The effects of the control factors are calculated in this step and the results are analyzed to select optimum setting of the control factors.

Robust Design – Overview Step 4Prediction/Confirmation:In order to validate the optimum conditions we predict the performance of the product design under baseline and optimum settings of the control factors. Then we perform confirmation experiments under these conditions and compare the results with the predictions. If the results of confirmation experiments agree with the predictions, then we implement else repeat.

Design for Failure Modes Effect Analysis – Form Data & Process

1. Number (No.):2. Item/Function:3. Potential Failure Mode: 4. Potential Effect(s) of Failure:5. Severity (S):6. Potential Cause(s)/Mechanism(s) of Failure:7. Occurrence (O):

Design for Failure Modes Effect Analysis – Continued

8. Classification:9. Current Mitigations:10.Verification:11.Detection (D):12.Recommended actions:13.Action Results:

Classification

Code To Indicate Criteria

SC A potential Safety Characteristics Severity = 5 and Occurrence = 2 to 5

KCA potential Key Design

Characteristics

Severity = 4 and Occurrence = 3 to 5

Severity = 3 and Occurrence = 3 to 5

Severity = 2 and Occurrence = 4 to 5

AO Action Is Optional Not SC nor KC

Axiomatic Design

• CTS – “Critical To Satisfaction” (or CR, customer requirements)

• FR – Functional Requirements• DP – Design Parameters• PV – Process VariableMatrix based, aim is to develop FR vectors that

are independent wrt DPs and result in minimal complexity.

Redundancy

• Active redundancy: MTBF = 1/ => 3/2• Standby redundancy: MTBF = 1/ => 2/

• Active – units are in parallel & always active• Standby – units “swap out” when bad

Component Selection Considerations

• Component reliability– Vendor assessment (Hx, failure, etc.)– Vendor audit (check facility)– Vendor evaluation (inspect incoming)– Vendor qualification (on-list?)

• Component history – military & reliability groups – government info bases

• Safety (FMEA, etc.)

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• Component Derating– Practice of limiting the stresses– Use 2 watt R in 1 watt situation, decrease failure

rate >30% (T, humidity, P, V, I, friction, vibration)– Usage ratio = max stress/stress rating (.5-.9)– Goal is reliability! – Pacemaker example

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• Safety Margin– =(mean safety factor) - 1 =(mean strength/mean stress) - 1– Elevator – safety margin~2– Medical devices – Fries - .5 and up.

• Load Protection• Environment• Product misuse • Design for variation (6 sigma)

Product misuse: Plan for

• excess application of cleaning solutions• physical abuse• spills• excess weight applied to certain parts• excess torque applied to controls or screws• improper voltages, frequencies or pressures• improper or interchangeable electrical or

pneumatic connections.

The Clean-Room Approach To Reverse-Engineering:

“One person or group takes a device apart and describes what it does in as much detail as possible at a higher level of abstraction than the specific code. That description is then given to another group or person who has absolutely no knowledge of the specific device in question. This second party then builds a new device based on the description. The end result is a new device that works identically to the original but was created without any possibility of specifically copying the original. “

-Mathew Schwartz

Extended TRIZ Design TechniquesExample: Effect of a grounding pad

Problem Statement

• Grounding pad is needed in order to conduct current from scalpel to ground

• Grounding pad must adhere to the body, otherwise there might be hot spots or burns

• Removal of the grounding pad causes injury, as seen in the photo. Injuries may include tearing of the skin, not just what is seen here.

Concept Map for Skin Problem

Ideation Process: Fill in the blanks -

• Brief description of the problem …• Problem Formulation … build the diagram:

Formulate …

• » 1. Find an alternative way to obtain [the] (conducts electricity well) that does not require [the] (Adheres tightly to skin).

• » 2. Consider transitioning to the next generation of the system that will provide [the] (conducts electricity well) in a more effective way and/or will be free of existing problems.

Continued…• » 3. Find an alternative way to obtain [the] (Adheres tightly to

skin) that offers the following: provides or enhances [the] (conducts electricity well), does not cause [the] (Tears skin).

• » 4. Try to resolve the following contradiction: The useful factor [the] (Adheres tightly to skin) should be in place in order to provide or enhance [the] (conducts electricity well), and should not exist in order to avoid [the] (Tears skin).

• » 5. Find a way to eliminate, reduce, or prevent [the] (Tears skin) under the conditions of [the] (Adheres tightly to skin).

Continued -

• Select likely suggestions, • Expand upon• Select solution• …

End of chapter -