Manufacturing the Safe Product Chapter 19

Generating Hazardous Characteristics Improper production techniques Failure to remove metal burrs, points or sharp edges Removing too much wire insulation

Unauthorized Changes To reduce production costs, difficulties or both Attempt to minimize work schedule interruption Prevention requires control of changes

Evaluation of Changes Change evaluated by design engineering department Consider impact of possible change Consider safety aspects with safety engineer

Controls on Changes Imposed / carried out for: Manufacturer’s operations Supplies Components Assemblies from vendors / subcontractors

Care of Safety-Critical Items Require more care than non safety-critical Determined from safety analyses Always include: Materials & components that are dangerous in themselves Materials whose combinations are dangerous & must be separated Safety devices

Safety-Critical Items Tendency to minimize number of critical items Too many critical items are ignored

Testing Inspection / testing of every item is prohibitive Develop & follow test plan for greatest beneficial effect Knowledge of criticality Means to indicate if requirements are met Indicates testing for maximum effectiveness

Manufacturing Defects Production Deficiencies - Welding: Poor welds degrade strength Welding in contaminated conditions produce porous welds Failure to clean welds leads to corrosion & loss of strength Gaps producing short circuits

Manufacturing Defects Production Deficiencies - Excessive Heat: Degrade surface finishes to failure Degrade metals Heat can cause deformation or melting of plastics

Manufacturing Defects Production Deficiencies - Assembly: Critical parts separate in use Stresses in assembly leading to failure under load

Manufacturing Defects Production Deficiencies - Warning Labels: Manufacturers vulnerable to claims of “failure to warn” Obligation for replacement parts

Manufacturing Defects Production Deficiencies - Components: More failure due to weak connections between components Connections may separate Fittings may not be adequately tightened Lack of cleanliness leads to clogging Welds may fail Hoses may be damaged or separate from couplings & whip

Production Errors Rush to meet production quotas or premium pay Employee fatigue Inadequate selection / training of workers Lack of proper supervision

Production Errors Poor motivation / distraction Unsatisfactory working conditions Inadequate / poorly designed equipment, tools or facilities Lack of instructions, drawings or specs

Quality Control Responsible for high quality output Not responsible for production processes Wouldn’t be necessary if faultless products were produced

Facts of Life All mechanics will eventually make mistakes leading to poor workmanship All inspectors will make mistakes & accept bad work Some material will progress or be delivered with unknown / undetected defects

Quality Control Inspecting & testing Manufacturer is responsible for product including parts from subcontractors Responsible suppliers make own inspections & tests Some manufacturers re-test suppliers’ critical items

Quality Control Records must be maintained Identification of specific lots Proof of passage of inspection Inspections & tests done at times & locations where most effective 100% sampling for critical items

Quality Control Inspections & tests reveal failure to reach prescribed limits Inadequate or loose quality control leads to greater possibilities of failure

Quality Control Personnel Parameters product must meet Deficiencies possible Criticality of items inspected Recordkeeping reports

Definitions Critical - fault likely to result in serious consequences (danger of loss of life or serious injury or certainty of major complain & damage to reputation) Major / Serious - Probability of product failing to give good performance, likelihood of complaint

Definitions Major / Less Serious - Some failure possible during use, likely to cause trouble for consumer, major defects in appearance or finish but no bearing on performance Minor - slight defects in appearance & finish, technical faults unlikely to cause trouble or poor performance

Standardized Quality Control Need detailed instructions on: Means of verification Frequency of sampling & levels of defectiveness Records to be retained Frequency of instrument calibration

Standardized Quality Control Need detailed instructions on: Action for out-of-control process Procedure for design deviation Means of identification for acceptable items Marking of non-conforming items / segregation

Quality Control All deficiencies brought to production personnel immediately All deficiencies reported in writing to production manager Report to design engineer if warranted

Deficiency Report Identify deficiency Where and when first encountered Number of items / lots affected Actions of quality control personnel to limit effects of problem

Advantages - Reduction in: Costs of scrap / re-work Ordering extra materials Shipping costs on returns Payment delays Time for explaining problems to consumer

Advantages - Reduction in: Consumer cost of removing / reinstalling replacement Sales losses Lost income Damage caused

Manufacturing Checklist Figure 19- 5 Page 252

Other Production Records P.O.’s, advertising literature, test reports on suppliers’ items Manufacturers’ reports on materials used in production Lot numbers & quantities, components, serial numbers, dates of manufacture Test reports of outside laboratories

Prototype Testing Last important phase Reviewed by knowledgeable safety engineer