Kaizen

INTRODUCTION TO DESIGN FOR MANUFACTURING

Introduction https://www.youtube.com/watch?v=6b2 9TW05o0o

Design for Manufacturing (DFM) occurs early in product development, before tooling and assembly process, when the product is being designed.

This will make manufacture less time- consuming, which will reduce cost and increase ease of manufacturing basis principles.

Introduction to DFM

THE DFM METHOD  DFM involves simultaneously considering design goals and manufacturing

constraints in order to identify manufacturing problems while parts are being designed; thereby reducing the lead time for product development and improving product quality can be concluded that the design stage is very important in product development. Often an otherwise good design is difficult or impossible to produce.

 Typically a design engineer will create a model or design and send it to manufacturing for review and invite feedback.

 This process is called as design review.

 If this process is not followed diligently, the product may fail at manufacturing stage.

 If the DFM guidelines are not followed, it will result in iterative design, loss of manufacturing time leading to longer time to market.

 Hence the present work aims to apply the DFM approach for the process and product improvement of medical equipment

Several DFM/DFA guidelines have been developed to assist the designer. Consequently product competitiveness has been improved by applying these DFM techniques. Nevertheless, the decision- making process and the expertise of the designer continue to be the key aspects to ensure the success of DFM, due in part to the availability of DFM information [6, 7, 10]. The DFM method is illustrated in the following figure. It consists of five steps plus iteration [7]: i. Estimate the manufacturing cost. ii. Reduce the costs of components.

iii. Reduce the costs of assembly. iv. Reduce the costs of supporting production. v. Consider the impact of DFM decisions on other factors.

Elements of the manufacturing cost of a product. From “Product Design and Development”, by K. Ulrich, 2003, p. 258.

DFM method begins with the estimation of manufacturing cost of the proposed design. This helps the team to determine at a general level which aspects of design- components, assembly or support- are.

DFM approach was applied for the productivity improvement of one of the Electrocardiograph (ECG) model called as ―CARDIART 108T DIGI‖, manufactured by one of the leading medical equipment company in India. The following problems were identified in its production:

1. Low productivity. The model was initially designed by the company for a low volume of production around 50 to 60 units per month. But presently the production volume is insufficient to meet the demand.

2. Obsolete tools and related quality issues. 3. High manufacturing cost.

The Figure shows the various causes for low productivity of the model:

• The average monthly production of the model was around 200 units. The production capacity has to be increased to meet varying demands from 250 to 1000 units per month. So in order to achieve this target, re- engineering of the product is necessary.

• The major objectives of re- engineering are to improve the volume and reduce the cost of production. Various parts in top panel, bottom panel and the final assembly of CARDIART 108T DIGI are shown in figures 3, 4 &5 and the BOM is shown in Table1.

A. Manufacturing Cost Analysis of Present Model

B. Reducing the Cost of Components and Cost of Assembly: 1. Redesign components to

eliminate processing steps 2. Integrate Parts 3. Standardize Components 4. Evaluation of Assembly

Efficiency

Before the design modification

After the design modification

The assembly efficiency of the product is measured as an index which is the ratio of the theoretical minimum assembly time to an estimate of the actual assembly time for the product.

This concept is useful in developing an intuition for what drives the cost of assembly.

To determine the theoretical minimum number of parts, the following three questions are asked in the assembly for each part. Only parts satisfying one or more of these conditions must ―theoretically‖ be separate:

1. The part need to move relative to the rest of the assembly. Small motions that can be accomplished using compliance (e.g., elastic hinges or springs) do not count.

2. The part is to be made of a different material from the rest of the assembly for fundamental physical reasons.

3. The part has to be separated from the assembly for assembly access, replacement or repair.

The 3 seconds‖ in the numerator reflects the theoretical minimum time required to handle and insert a part that is perfectly suited for assembly. It can be taken as the average time (sustainable over a whole work shift) required to assemble a small part that is easy to grasp, requires no particular orientation, and demands no special insertion effort.

• The results of the case study emphasize the relevance of DFM methodologies in product design and manufacturing.

• It also gives idea regarding how manufacturing complexity and costs can be reduced in early design stages.

• The application of DFM principles resulted in improvements in three major areas; Product Quality, Cost and Delivery.

• With the help of improved design, the company attained the ability to execute mass orders of 1000 to 1500 units per month without any extra investment in assembly line.

• Also, the return of investment (cost of new die) was possible within a year.

• The major quality issues like breakages in castings and noise disturbance in ECG due to aluminum components were averted.

• With this improved design and processes, the production lead time was reduced from 2 weeks to 1 week.

• The total production cost and time were also reduced considerably.

• Although further iterations in the DFM process are not presented, it is recommended that the results of the process should then be fed back into the design process to provide further DFM iterations and improvements through modifications that optimize detailed manufacturability issues.

Conclusions

EXAMPLE CUBO PACE https://www.youtube.com/watch?v=tEEHFt9uACI

Video to watch https://www.youtube.com/watch?v=C31RPvtFw6k

• Activities for DFM: • Watch the following video and respond the following questions: • What is the most important consideration when eliminating product components?

• In addition, identify a simple product you are very familiar with, use the video as a hint to apply DFM into your product

• Apply DFM methodology following the example from the video. Follow the steps: conceptualization, analysis, redesign, and conclusion.

• Construct the Assembly diagram by hand or a software • Create a list of questions to help you decide what components are necessary and

what components you may need to eliminate without the lost of functionality • Provide sketch (made by a software or by hand) to indicate the original design

and the redesigned product

Lean Six Sigma-Tools  Project Selection, NPV, SIPOC Diagram, VOC,

CTQ, Pareto Chart, Process Mapping  C&E Analysis, Process Capability Analysis,

Sampling, Basic Statistics  Hypothesis Test, Correlation, Regression, Multi-

Vari, CI’s, ANOVA  DOE, Poka-Yoke, FMEA, RSM  Control Plans, SPC, SOP’s

Agenda • What is FMEA? • Why is an FMEA

important? • History of FMEA • Benefits of FMEA • Limitations of FMEA • How to conduct an

FMEA?

What is FMEA? Failure Mode and Effect Analysis • A systemized group of activities designed to:

o recognize and evaluate the potential failure of a product/process and its effects

o identify actions which could eliminate or reduce the chance of potential failure

o document the process • FMEA is a process that identifies all the possible types of failures that could

happen to a product and potential consequences of those failures. • The Failure Mode is what could go wrong • The Effect Analysis is how it would happen; how likely is it to go wrong; how

bad would it be

https://www.systems2win.com/solutions/FMEA.htm

• Failure mode - the way in which something might fail

• Effects analysis – studying the consequences of the various failure modes to determine their severity to the customer

FMEA Terms

FMEA Terms  Effects analysis – studying the consequences of the various failure

modes to determine their severity to the customer.

 The blowout of a tire is likely to have the most serious consequence, since when a tire suddenly explodes, the car might go out of control.

 On the other hand, a puncture problem usually allows the tire pressure to decrease gradually, allowing the driver time to sense the problem before he looses control.

 Neither failure mode is something the driver wants but of the two the puncture is preferred.

• Preventing problems is cheaper and easier than cleaning them up.

• Some things are too risky or costly to incur mistakes. • Healthcare is a good example of this because we have

very costly and risky procedures. An FMEA is critical for healthcare procedures because preventative medicine is less costly than curative medicine. We want to prevent problems before they happen and that is exactly what an FMEA does.

Why do an FMEA?

The Reasons for FMEA • Get it right the first time • Identifies any inadequacies in the development of the

product and to get it right the first time so that there are no costly mistakes later.

• Tests and trials may be limited to a few products • Regulatory reasons • Continuous improvement • Preventive approach • Team building • Required procedures

FMEA Provides the Potential to: • Reduce the likelihood of customer complaints • Reduce the likelihood of campaign changes • Reduce maintenance and warranty costs • Reduce the possibility of safety failures • Reduce the possibility of extended life or

reliability failures • Reduce the likelihood of product liability claims

• Identify potential and known failures • Reduce the number of engineering changes • Reduce product development time • Lower start-up costs • Greater customer satisfaction • Increased cooperation and teamwork between various

functions • Continuous improvement

Benefits

• FMEA was proposed by ARMY about 60 years ago. It was used as a reliability evaluation technique to determine the effect of failures.

• Failures were classified according to their impact on mission success and personnel/equipment safety.

• Formally developed and applied by NASA in the 1960’s to improve and verify reliability of space program hardware.

History

• Used to analyze concepts at the early stages before hardware is defined (most often at system and subsystem)

• Focuses on potential failure modes associated with the proposed functions of a concept proposal

• Includes the interaction of multiple systems and interaction between the elements of a system at the concept stages.

Concept FMEA

DESIGN FMEA  A design FMEA is used to evaluate design requirements and design

alternatives.

 It aids in the initial design and provides additional information to aid in the planning process for manufacturing and assembly

 Increases the probability that potential failure modes have been considered

 Provide additional information to aid in the planning of efficient design testing

PROCESS FMEA

Identify potential product related process failure modes Assess the potential customer effects of the failures Identify the potential manufacturing causes on which to

focus on Develop a ranked list of potential failure modes Document the results of the manufacturing of a product

TYPES OF FMEA

• The main difference between the two is that:

• A Design FMEA is done during the design phase of a product to ensure failure modes have been addressed

• A Process FMEA is done to a process to ensure failure modes have been addressed.

RESOURCES NEEDED

Commitment of top management Knowledgeable individuals with expertise in: Design

Manufacturing, Assembly, Service, Quality, Reliability

 Individuals who want to identify failure modes before a design or process failure mode happened

People resources. They may be internal or external to the business or a combination of both

FMEA TIMING

FMEA should be updated:  at the conceptual stage  when changes are made to the design  when new regulations are instituted  when customer feedback indicates a

problem

ADVANTAGES

Enhance design and manufacturing efficiencies

Alleviate late change crises Minimize exposure to product failures Augment business records Improve “bottom line” results Add to customer satisfaction

LIMITATIONS

Employee training requirements  Initial impact on product and manufacturing schedules Financial impact required to upgrade design,

manufacturing, and process equipment and tools

These limitations should be recognized and treated as short term to minimize interruptions to a business.

RISK ASSESSMENT FACTORS Severity (S): A number from 1 to 5, depending on the severity of the

potential failure mode’s effect

1 = no effect

5 = maximum severity

Probability of occurrence (O): A number from 1 to 5, depending on the likelihood of the failure mode’s occurrence

1 = very unlikely to occur

5 = almost certain to occur

RISK ASSESSMENT FACTORS Probability of detection (D): A number from 1 to 5, depending on

how unlikely it is that the fault will be detected by the system responsible (design control process, quality testing, etc.) 1 = nearly certain detention 5 = impossible to detect

Risk Priority Number (RPN): The failure mode’s risk is found by the formula RPN = S x O x D.

RPN = Severity x Probability of Occurrence x Probability of Detection.

RISK PRIORITY NUMBER The risk priority number is found by multiplying the severity rating by the probability of occurrence by the probability of detection.

How to conduct an FMEA? -find severity rating -find probability of occurrence -find probability of detection -find the risk priority number. It is found by multiplying the severity rating by the probability of occurrence by the probability of detection.

Process Steps:

1: Identify modes of failure (e.g.: car won’t stop) 2: Identify consequences & related systems for each mode 3: Rate the Severity (S) of each effect 4: Identify potential root causes for each failure mode 5: Rate the Probability of Occurrence (O) of each root cause 6: Identify process controls and indicators (e.g.: brake squeal) 7: Rate Detectability (D) of each mode/root cause (we cannot detect it) 8: Calculate risk priority (S*O*D) and criticality (S*O) 9: Use design to mitigate high-risk or highly critical failures, and re- assess to ensure goals have been achieved

Example:

Battery Headlight

Switch

Possible Failure Modes: • Light doesn’t turn on • Light doesn’t turn off

Possible Consequences: • Light doesn’t turn on

• Driver can’t see obstacles • Car inoperable at night

(8) • Light doesn’t turn off

• Battery died • Car won’t start (10)

Possible Root Causes: • Light doesn’t turn on

• Battery dead (8) • Broken wire (3) • Headlight out (10) • Switch corroded (2) • Switch broken (3)

Example:

Battery Headlight

Switch

Possible Failure Modes: • Light doesn’t turn on • Light doesn’t turn off

Possible Consequences: • Light doesn’t turn on

• Driver can’t see obstacles • Car inoperable at night

(8) • Light doesn’t turn off

• Battery dies • Car won’t start (10)

Possible Root Causes: • Light doesn’t turn off

• Short circuit in switch (2) • Operator error (left on) (8)

Example:

Battery Headlight

SwitchControls/indicators: • Light doesn’t turn on

• User notices lights on in dark • Light doesn’t turn off

• User notices lights on in dark

Detectability: • Light doesn’t turn on (6)

• User notices lights on in dark • User doesn’t notice lights not

on during day

• Light doesn’t turn off (6) • User notices lights on in

dark • User doesn’t notice lights

not on during day

Example: Possible Effect

Root Cause S O D RPN Crit.

Car inoperable at night

Battery dead

10 8 6 480 80

Broken wire 8 3 144 24

Headlight out

8 10 6 480 80

Switch corroded

8 2 96 16

Switch broken

8 3 144 24

Failure Mode: Light doesn’t turn on

Risk Priority Number (RPN)

Example:

Possible Effect

Root Cause

S O D RPN Cri t.

Car inoperable at night

Battery dead

10 8 2 160 80

Broken wire

8 3 60 30

Headli ght out

6 10 2 120 60

Switch corrod ed

8 2 40 20

Switch broken

8 3 60 30

Failure Mode: Light doesn’t turn on

Redesign: Use two headlights instead of one, add visual lights- on display in console.

Risk Priority Number (RPN)

Example:

Possible Effect

Root Cause

S O D RPN Crit .

Car won’t start

Short circuit in switch

10 2 7 140 20

Operator error

10 8 7 560 80

Failure Mode: Light doesn’t turn off

Example:

Possible Effect

Root Cause

S O D RPN Crit .

Car won’t start

Short circuit in switch

10 2 2 40 20

Operator error

10 8 2 160 80

Failure Mode: Light doesn’t turn off

Redesign: Add audible indicator when driver’s door is opened while lights are on, add visual lights-on display in console.

REFERENCES

 Lean Six Sigma - http://www.leansixsigma.com/

 Stunell Technology - http://www.stunell.com/images/fmea.jpg

Thank you!!!