Chapter 20Miscellaneous Issues

Learning From Failure Technicians in an ambulance taking a heart

attack victim to a hospital lost use of their heart machine every time they attempted to use their radio transmitter. (Unshielded RF interference) The patient died.

Thalidomide was sold in Europe in the late 1950s, causing over 8,000 births of malformed children. The drug had not been tested adequately prior to market release.

Design for Failure Should consider and plan for failure For safety and convenience

Safety Considerations Sprinkler Systems – the increase in

temperature due to a fire causes melting of a metal plug and the opening of a sprinkler or gas quenching system to put out the fire

In the event of a power failure, a lead shield drops in front of a cobalt therapy delivery unit

Continued …

Shear pins, medicine coatings, bubble wrap medicine, bimetalic temperature sensors, bottle tops, peanuts in packing, feathers, eggshells, pine seeds, …

Design for Convenience Postage Stamps – sheets of postage stamps

typically contain individual stamps separated by perforations. A slightly skilled user can easily separate out an individual stamp by causing failure along the perforations.

Scoring of a surface to enhance breakage is a common way to ensure easily opened bags of coffee and pop-top cans of various designs

Design for assembly A design process that tries to guarantee

simple interconnections of elements that generally can only be connected in a sinple goof-proof manner.

GE design of jet engines, etc….

Prevention through design A relatively new NIOSH based effort to train

designers to “design out” the likelihood of errors/mistakes/potential accidents, etc. in a device or process (~ 2007)

“at the source” effort to decrease deaths/injuries in the workplace…

Design for the environment… Goal is cleaner manufacturing processes …easier mothballing or disposal Minimal impact …

Poka-Yoke A stylized manner of approaching zero

defect manufacturing, etc. Proper contact? Proper movements?

Proper steps done? Forces a logical progression in assembly

Product Life Issues Necessary to determine how a product is

performing during actual use Analysis of field service reports Failure analysis of failed units Warranty analysis

Analysis of Field Service Reports (FSR) Type of Product Serial # Date of Service Activity Symptom of the problem Diagnosis List of parts replaced Labor hours required Service representative

Data Analysis Determine most significant problem

information & trend causes Pareto Analysis – a histogram of problems Graphical Plots

Determine what pt in life cycle Determine efficiency of manufacturing process

Useful for analyzing warranty costs

Failure Analysis of Field Units Focus on cause of problem based on

symptom Fault- tree analysis

Warranty Analysis Warranty cost as a % of sales Warranty cost per unit Installation cost per unit % of shipped units experiencing problems

Product Testing Issues HALT Testing – may indicate problems

early in testing that would take some time to occur in the field.

More severe parameters Misuse of product (type & severity testing) Must keep data and analyze and prove

responsiveness to the FDA!!!!