Tham khảo tài liệu 'designing capable and reliable products episode 1 part 8', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Case study - revisiting the solenoid design 125 Variance contribution 60 50 - 40 30 20 10 0 z Nominal target 4 2 3 6 1 5 Characteristic number Figure Pareto chart showing variance contribution of each characteristic to the final assembly variance for the paper-based analysis Rating 5 to give the target Cpk- The program initially calculates a primer tolerance rf the statistical sum of the primer tolerances equals the assembly tolerance ra and allocates this to each dimension. The primer tolerances are calculated using equation which is derived from equation . They are used to start the optimization routine and their respective risk values J are calculated from the process capability maps V n where rf bilateral primer tolerance for ith component characteristic ta bilateral tolerance for assembly n number of component tolerances in the assembly stack. Figure shows the results of the optimization routine for the tolerances. For capability at this first level to be realized all the component risks must be below the line on completion of the optimization routine and subsequently the capability required with this design configuration cannot be achieved. It is evident from Figure two out the six components characteristics are preventing optimization as was determined in the paper-based analysis and therefore redesign effort here is required specifically the base tolerance of the solenoid body and the pole thickness which are both impact extruded. A feature of the design related to these two tolerances is the bobbin dimensional tolerance which sets the position of the pole from the solenoid base. Further redesign ừ shown on the final CAPRAtol screen in Figure . Redesign data includes a basic estimate for Cpk and an assembly tolerance calculated from the process capability maps that would be achievable for the given design parameters. A redesign solution of the tolerance stack is shown in Figure . It involves a small design alteration .
