Machining plastic to meet design goals. (certain shapes are more easily machined than cast)

While injection molding is often the process of choice when making parts from high-performance plastic, machining parts from extruded stock shapes can offer advantages. In addition to being more economical for small or intermediate quantities, machining can be the only way to fulfill certain design...

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Bibliographic Details
Published in:Machine design 1991-10, Vol.63 (21), p.84-85
Main Author: Holcomb, Richard G
Format: Magazinearticle
Language:English
Subjects:
Advantages
Design
Injection molding
Machining
Manufacturing
Methods
Molding
Plastics
Plastics molding
Techniques
Online Access:Get full text
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Summary:While injection molding is often the process of choice when making parts from high-performance plastic, machining parts from extruded stock shapes can offer advantages. In addition to being more economical for small or intermediate quantities, machining can be the only way to fulfill certain design requirements. In general, machined parts can be held to closer tolerances than molded parts. Unlike injection molding, machining allows part design to be modified at a moment's notice because there is no mold to be changed. Experts recommend a maximum wall thickness of 1/4 inch for injection molding most thermoplastics, but with machining, this rule does not apply. Machined parts do not have gate areas, which makes them prime candidates for seals and rings. Unlike molded parts, machined parts have no weld lines that can act as stress risers.
ISSN:0024-9114
1944-9577