Gorm Simonsen 2007

Engineering Responsibility

• Quality •

definition standards mistakeproofing

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Quality - Some Definitions

Quality is the totality of features and characteristics of a product or service that bear on its ability to satisfy implied or stated needs (ANSI/ASQC Standard A3 - 1987)The least expensive method of achieving quality is to deliver a design that cannot fail to satisfy the customer (Genichi Taguchi - ISO 9000)Quality is a characteristic of thought and statement that is recognized by a non-thinking process. Because definitions are a product of rigid, formal thinking, quality cannot be defined. But even though Quality cannot be defined, you know, what Quality is! (Robert Pirsig)

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Definitions

Conformance to specificationsFitness for useValue for priceSupport (etc.)Psychological criterias

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Loss functions

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Costs of Quality

Prevention costs.Costs of preparing and implementing a quality plan.

Appraisal costs.Costs of testing, evaluating, and inspecting quality.

Internal failure costs.Costs of scrap, rework, and material losses.

External failure costs.Costs of failure at customer site, including returns, repairs, and recalls.

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Cost of defect

Design Production Customer

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Quality Timeline

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Quality Gurus

Every one of the gurus use the term in their own way.They can be divided into:

The early americans - eg. Deming, Feigenbaum and Juran

The Japanese respons - eg. Ishikawa, Taguchi, Shingo

The new western wave - eg. Crosby, Moller, Oakland

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Quality / Juran

Juran’s theory of quality management is called the quality trilogy: quality planning, quality control and quality improvement.

Major ideas:Quality management cuts costsQuality does not happen by accident, but must to be planned and improved

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Quality / Shingo

Shingo defines quality as zero defects. He explains that if the fault is found by normal inspection afterwards, it will be a very costly and slow (production) process.

Use of source inspections100% inspections in stead of samplingminimise time for feed-backuse of Poka-Yoke devices

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Quality / Feigenbaum

Quality is meeting the customers requirements.Feigenbaum developed “Total Quality Management” which takes a systems view of quality management - from sales over design and production to delivering the product.

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Total qualitybut also focus on: change internal customers a way of managing measurement teamwork prevention

Customer focus continuous improvement

Employee empowerment

Use of quality tools

Product design

Process management

Managing supplier quality

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Standards

Not legal requirements but guidelinesbut may be incorporated in legislation

Standards may be basis for management systems and lead to certificationWhy standards?: communication, efficiency and usability of productsWho makes the standards?: local and international committees (DS, CEN, ISO etc.)

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Product-orientedSoftware quality (ISO/IEC 9126)

FunctionalityReliabilityPortabilityUsabilityEfficiencyMaintainability

•Incomplete or erroneous specifications: 28%•Violation of programming standards: 10%•Inaccurate documentation: 8%

(Yang, 2001)

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Process Oriented standard

management and leadershipproduction processescontinuous improvementscustomers (other parties)involvement of peopleprocess approachfact-based decision makingsupply-chain considerations

ISO 9000 - principles

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ISO 9000 model

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Software quality as example

Increasingly used in products (pervasive)Increasing global usageA wide range of methodologies (TickIT, CMMI, SPICE)

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CMMI (staged)

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Frameworks quagmire

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Need for new approach

The focus on systems and standards has to be expanded to encompass:

Internal customers’ views and competenceBringing anticipations of quality early in the development phase (e.g. QFD)

- to (minimise and) prevent defects

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What tools are used to achieve zero defects?

Cultural factors: Teams, management commitment

VarianceStatistical methods, Taguchi

ComplexityProcess Mapping, DFM /DfQ

MistakesMistake-proofing, Poka-Yoke, or ZQC

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Mistakes: to err is human

Defects:unnecessary consequences of

mistakes

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A New Attitude toward Preventing Errors

“Think of an object’s user as attempting to do a task, getting there by imperfect approximations. Don’t think of the user as making errors; think of the actions as approximations of what is desired.”*

- also your own work ! *Source: The Design of Everyday Things, by D.A. Norman, 1988, Doubleday

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A New Attitude toward Preventing Errors

Make wrong actions more difficultMake it possible to reverse actions —to “undo” them—or make it harder to do what cannot be reversed.Make it easier to discover the errors that occur.Make incorrect actions correct.

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Inspections

Judgement inspection- final test of product to specifications

Informative inspection- monitoring the productions process to correct errors

Source inspection- establishing that the right conditions exist before the production starts

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Zero Quality Control

Zero QC System is:Source (& informative) inspections 100% inspectionsmin. time to carry out corrective actionPoka-yoke deviceschange in process

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Poka-Yoke: Detection

Detection devices:A process whereby the user is signaled when a mistake has been made, so that the problem can quickly be rectified.However, the device does not enforce rectificationExamples:

Beeping noise when lights in car are left onFlashing light on dashboard if seatbelt is not engaged

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Poka-Yoke: Prevention

Prevention devices:A process engineered such that it is impossible to make a mistakeExamples:

Microwave will not function with the door openLight will not illuminate in an airplane if door is not locked

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Characteristics of Effective Poka-Yoke Devices:

Simple to implementInexpensive to implementAre applied to each product or service (i.e.. 100% inspection)Placed near to where mistakes occur so that feedback is quick and easily rectified

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Poka-Yoke has benefits:

Reduce cost of manufacturingSubstantially reduce defects & improve qualityProvide a strategy for continuous improvement through the input of all employees

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…and Very Effective

Dana corporation has reported a $500,000 savings resulting from a $6 device. [Grout] (83,000:1) AT&T Power Systems (Lucent Technologies) reported net saving of $2545 per device (3300 devices) [Marchwinsky, 1997]. (25:1*)Weber Aircraft reports saving $350,000 during their first year of implementation of approximately 300 devices. [Grout] (11:1*)

*Assumes an average devise cost $100

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Everyday Examples

New lawn mowers are required to have a safety bar on the handle that must be pulled back in order to start the engine. If you let goof the safety bar, the mower blade stops in 3 seconds or less.

Fueling area of car has three error-proofing devices: 1. insert keeps leaded-fuel nozzle from being inserted 2. tether does not allow loss of gas cap 3. gas cap has ratchet to signal proper tightness and prevent overtightening.

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Other examples

A conveyor carries the product under a pivoting flag. A correctly assembled product passes under the flag. An incorrectly assembled product tips the flag, and a sensor detects the flag movement.

Detection Prevention

This is example of product mistake-proofing, that is, designing in part features to mistake-proof the assembly by only allowing assembly one way, the correct way.

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Exercise

1. Describe in your own words what is “Continuous Improvement” according to Reid & Sanders: Operations Management. 2. What is, according to Reid & Sanders, preventive costs of quality?3. What is the difference between judgement and source inspection, according to Michael Fisher? 4. What are audits in ISO 9000 quality management? 5. Describe three examples of poka-yoke devices in your project work: are they detective or preventive?