Page 48 - Engineering Plastics Handbook

22 Introduction

materials properties, and shell thicknesses. The company’s proprietary
Variation Technology™ is used for structural analysis of alternative design
parameters. ATA Engineering services include assembly tasks, FEA, and
®
I-DEAS for design and manufacturing tasks such as configuration illus-
®
tration and drawing creation. I-DEAS software was developed by SDRC,
which was acquired by EDS, the parent company of UGS Corporation. EDS
provides Unigraphics Solutions. Principal competitors include PTC’s
Pro/Engineer and Dassault’s CATIA. The consulting firm Engineering
Mechanics Research Corporation develops FEA and CAE software for
design analysis of fatigue and fracture configurations for dynamic systems.
The company uses the NISA family of FEA software programs. Following
is a list of design considerations.

Design Considerations
1. Final product application
2. Final product performance requirements
3. The number of functionalities the part will perform
4. Type of applied loads: constant, dynamic; intermittent, cyclical
5. Stress and strain
6. Maximum allowable deflection
7. Wall thickness
8. Wall taper from thicker to thinner walls
9. Radii
10. Ribs and bosses: geometry, locations, spacing between ribs or bosses
11. Draft angles for part demolding
12. Tolerances
13. Environmental requirements (e.g., humidity, weatherability, underwater, space,
multiple environments)
14. Temperature range
15. Chemical resistance
16. Finishing, e.g., oven cure, in-mold decorating (IMD)
17. Component integration versus joints
In-mold assembly (IMA)
Joint design
Method of joining, e.g., ultrasonic, spin welding
Seam location
18. Code requirements
19. Process selection
20. Mold and tool design, e.g., gate selection and location
21. Product life expectancy
22. Use abuse (safety factor)
SOURCE: Based on “Designing with Plastics and Advanced Composites—Technical Advances
in Vehicle Design,” Proceedings of the International Association for Vehicle Design, and D. V.
Rosato, “Designing with Plastics: A Guide to Product Design,” Interscience Enterprises Ltd.,
Geneva-Aeroport, Switzerland, 1986.

Design engineering has three primary objectives: (1) satisfying the
application performance requirements, (2) preventing product failure,
and (3) containing costs.