tailieunhanh - Designing Capable and Reliable Products Episode 1 Part 2

Tham khảo tài liệu 'designing capable and reliable products episode 1 part 2', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | statement of the problem 5 A critical link between design and manufacture Production cost Process selection Resultant dimensions Fit and function Competing requirements Design limits Performance Sensitivity Robust to variation Tight Loose Machine tools Operator skill Tooling fixtures Inspection precision Assemblability Scrap and rework Figure Tolerances - the critical link between design and manufacture Chase and Parkinson 1991 anticipate production variability on the shop floor. The need for more than 40 of the rework was not identified until production commenced. The reasons for the rework described in Figure can be classified into four groups Customer driven changes including technical quality Engineering science problems stress analysis errors etc. Manufacturing assembly feasibility and cost problems Production variability problems. This indicates that customer related changes occurred throughout concept design detailing prototyping and testing with some amendments still being required after production had began. Engineering science problems which represented less than 10 of the changes on average were mostly cleared before production commenced. The most disturbing aspect is the acceptance by the businesses that most of the manufacturing changes and more so manufacturing variability changes were taking place during production product testing and after release to the customer. Because the cost of change increases rapidly as production is approached and passed the expenditure on manufacturing quality related rework is extremely high. More than 50 of all rework occurred in the costly elements of design for manufacture and production variability. Further evidence of the problems associated with manufacturing variability and design can be found in published literature Lewis and Samuel 1991 . Here an investigation in the automotive industry showed that of the 26 quality problems stated 12 resulted from process integrity and the integrity of assembly. Process