tailieunhanh - 21st Century Manufacturing Episode 1 Part 5

Tham khảo tài liệu '21st century manufacturing episode 1 part 5', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 74 Manufacturing Analysis Some Basic Questions for a Start-Up Company Chap. 2 with standard cable connection to a computer. The top surface of the enclosure has to be smooth and ergonomic for the finger to sit comfortably on the sensing array. Detail Design At the detail design stage a CAD representation in SDRC-IDEAS was created to check the fit of the electronics and the basic form factor. The top lid was designed to package the PCBs single- and double-board versions and to provide a comfortable support for the user s finger. The base provided additional space for connection ribbon cables and a power cable. Both the top lid and the base were designed to be fastened together. Prototyping The next step was to decide among the different rapid prototyping methods. It was important to fabricate a prototype that was strong enough to be structurally safe when assembled and handled during the evaluation period. At the same time relatively high tolerances were needed to allow the PCBs to be securely fastened to the top lid. The strength tolerance and surface finish achieved by the SLA process seemed to meet these needs and was thus chosen for prototyping. An informal group of human users was asked to evaluate the ergonomic aspects of the upper surface. The user group recommended that a flat slope be replaced with a more contoured slope that would mirror the inside surface of the index finger. To create this more comfortable contour for finger positioning an important decision was made. It was decided to switch to a Web-based freeform design tool Wang and Wright 1998a 1998b to create the freeform shape on the top surface. The key issue was again time-to-market. Fứst it was important to have a design tool that would produce the freeform surface. Second and equally important the Web-based freeform design tool incorporated a design rule checker for downstream mold machining Urabe and Wright 1997 . This software assisted the designer to create both the part and a