Tham khảo tài liệu 'process selection - from design to manufacture episode 2 part 5', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 244 Selecting candidate processes sensor design is supplied to a leading tier 1 manufacturer whose generic throttle pedal design places it well to meet the requirements of many major Original Equipment Manufacturers OEM . Given the safety-critical nature of accelerator pedal sensor it is essential to electronically test each completed assembly to make sure it works correctly. The product comprised eight components and was to be assembled on a 9 s cycle-time. Process and assembly machine design The process is essentially automatic but requires two operators to load critical components. Each operation is checked to make sure that it took place correctly any incorrect assemblies are flagged on the pallet and pass through without further work . Laser trimming calibrates the resistance of the unit and an electronic test also ensures that each completed assembly works properly. A modular approach was adopted for the design of the machine. The operator first loads a housing and rotor onto a flagged pallet. The first automatic station then loads the substrate ensures that it is laid flat and heat stakes it into position. The system checks only that the substrate is present not that it performs correctly. Electronic testing of the final unit is carried out later in the process. Further operations load the spring rotor and cover which are heat staked into position to complete the assembly. Three of the assembly operations are particularly technically demanding wire bonding spring contact assembly and laser trimming. A proprietary wire bonding station is used to weld the thin wire contacts into position to link the substrate with the electrical contacts molded in the sensor body. The spring contact assembly positions three small twin-spoked contacts and heat stakes them in position. The contacts must be secured without deformation and a force gauge is used to measure the pressure exerted by every spoke of the contact on the substrate track to ensure proper connections are .
