Design for Manufacturing - Class 9 - Quality

DRAGON INNOVATION, INC. !

CLASS 9: QUALITY !

SEPT 8, 2014 !!!!!!!

WILLIAM DRISLANE | VP ENGINEERING | @DRAGONINNOVATE | WWW.DRAGONINNOVATION.COM

WHAT IS QUALITY? !

HOW DO I ACHIEVE IT?

What is Quality?

1. Customer-Based Fitness for use, meeting customer expectations.

2. Manufacturing-Based Conforming to design, specifications, or requirements. Having no defects.

3. Product-Based The product has something that other similar products do not that adds value.

4. Value-Based The product is the best combination of price and features.

5. Transcendent It is not clear what it is, but it is something good...

from http://mot.vuse.vanderbilt.edu/mt322/Whatis.htm

The Price of Failure - Safety

M16 Rifle

• “We left with 72 men in our platoon and came back with 19. Believe it or not, you know what killed most of us? Our own rifle. Practically every one of our dead was found with his [M16] torn down next to him where he had been trying to fix it.”- Marine Corps Rifleman, Vietnam.

from http://en.wikipedia.org/wiki/M16_rifle

The Price of Failure - Safety

Ford Pinto Gas Tank Explosion

• Design defect known prior to production

• Cost to remedy $11 per vehicle, according to Ford’s cost-benefit analysis justifying not fixing the problem.

• At least 27 people died and more were injured.

• $ 6MM awarded in just one lawsuit

• Ford had to recall and repair 2 million vehicles

from http://en.wikipedia.org/wiki/Ford_Pinto

The Price of Failure - Economics

• Example – Consumer Product

• Sales - $ 100MM

• Profits – $ 10MM (10%)

• Retail return rate increase from budgeted 5% to 15% ->Zero profits

• A product recall could easily cost $ 15MM and put the company into severe economic difficulty

The Benefits of Success

• High-quality products command higher prices, deliver higher profits, and build brand value for their owners:

• Honda, Toyota

• BMW, Mercedes

• Apple

• Google

• FedEx, DHL

Design is the Ultimate Constraint

• Manufacturing quality can only live up to design quality, but not beyond.

• What you design is as good as the product will ever be.

• The folks downstream cannot fix any problems you create, except through re-design, which was your job in the first place.

http://news.bbc.co.uk/2/shared/spl/hi/pop_ups/06/sci_nat_1986_challenger_disaster/html/1.stm

http://www.westga.edu/~jstrickl/webquests/challenger1.html

http://www.space-video.info/shuttle/challenger-sts51l.html

Succeeding Despite Your Management

Challenger Explosion• O-ring failure on solid rocket booster led to catastrophic failure of the shuttle main fuel

tank.

• No data existed on o-ring performance below 53 F.

• Engineers had established a ‘red line’ minimum temperature of 40 F.

• Ambient temperature during the night before the morning launch reached a low of 18 F.

• Ambient temperature at time of launch was 31 F.

• Heavy ice was all over the support structures and launch pad.

• Previous missions had experienced partial o-ring failure under much more benign conditions. These seals were a ‘criticality 1’ component – it is not allowed to rely on the backup o-ring to meet safety requirements.

• During a pre-launch meeting, engineers had expressed concern about potential failures.

• The decision to launch was made anyway.

àWHAT WERE THEY THINKING?

DESIGNING IT RIGHT

Anticipating All Possible Uses

• The customer does not read your specifications and has his own ideas about how to use your product.

• 10/12 pages in the manual for a power tool are all about “do not”…

• Inadvertent or unintended effects of the product

• Numerous examples from the drug and chemical industries.

Characterizing Problems

• Severity

• Personal injury or perception of same

• Property damage

• Product return

• Irritation and dissatisfaction

• Likelihood

• Probability of occurrence

Characterizing Problems

• Detectability – is the hazard readily apparent, or hidden?

• Examples:

• Sharp knife

• Hidden sharp edge on handle

• Garment steamer valve trigger

• http://www.cpsc.gov/cpscpub/prerel/prhtml02/02529.html

àHidden hazards are the most dangerous and result in the biggest penalties

Designing Safe Products• What is an acceptable level of hazard?

• Suppose you have 3 MM products shipped

• What is an acceptable risk of fire?

• Intrinsic Safety

• Example – toaster oven design

• Counter-example – coffee maker

• Example – multi-voltage power supplies/chargers

• Redundancy vs. Fake Redundancy

• True redundancy is obtained when the first failure of a redundant element can be detected.

• POST (Power On Self Test) is a very powerful tool.

Brief Introduction to FMEAs

• Failure Modes and Effects Analysis (FMEA) is a systematic tool used to ferret out potential failure modes that would otherwise be missed, and ensure that they get addressed.

DESIGNING RELIABILITY INTO A PRODUCT

Just Another Engineering Discipline

• Engineering operates within multiple constraints:

• Cost budget

• Weight and volume budgets

• Performance budgets

• Power

• Waste heat

• …and Quality and Reliability budgets.

Failure Budgeting

• Example – You are designing a vacuum cleaner. How reliable does it need to be?

• The allowed rate of retail returns is 4%.

• Non-defective returns are estimated to be 2.4%

• Defective returns are budgeted to be 1.6%

• 0.55% is budgeted for unanticipated problems

• 0.65% is budgeted for factory quality, per AQL

• 0.40% is left over for actual defects in the warranty period

Component Budgeted Warranty Failure Rate

Suction Motor 0.05%Brush Motor 0.10%Belt 0.05%AC Cord 0.10%Switch 0.05%Hose 0.05%Total 0.40%

Failure Budgeting

Where Did the Name Six Sigma Come From?

• Motorola found that, in order to build a product such as a cell phone and achieve high levels of quality without having to sort and scrap bad products, a very high level of component quality was required:

• +/- Six standard deviations of the component’s natural quality distribution had to fit within the values required for proper function. This corresponds to a nominal failure rate of 2 ppb, but reality will be worse, and 4.3 ppm is assumed.

• Example – a resistor is required to have a resistance between 100 and 112 ohms for a cell phone to function properly. A large batch of resistors is tested and found to have a mean value of 106 ohms and a standard deviation of 1 ohm. The requirement is satisfied.

Effect of Parts Count and Failure Rates

Reliable products require counter-intuitive, almost absurdly high levels of component reliability.

àMany times, most life tests you can afford to run should have zero failures.

Failure Distributions and Their Implications

from http://www.asknumbers.com/WhatisReliability.aspx

Early vs. Late Failures

• MTBF is not the only, or even the most important, reliability measurement

• The distribution of failures over time, independent of MTBF, is very important

• Consistency and repeatability drive down early failures and decrease warranty costs.

• Improving consistency and repeatability is often much cheaper than using more expensive components