Plastic Surface Finishes

Engineers and designers often ask questions regarding surface finish in plastic machining. Usually, they have had a negative experience working with a metal shop or realize that a good, burr-free finish is essential to the success of the product.

With 20-plus years of experience, Connecticut Plastics will produce on average a 32 finish for most components and materials. This includes more difficult soft materials such as polypropylene and UHMW-PE. Machining without burrs is a cornerstone of our success. The surest way to manage burrs in plastic is to not make them.

Requirements for machined finishes below 32 are increasingly more difficult. In this range, material type and part configuration play a more dominant role. However, using proprietary tooling, a superior finish can be achieved with some materials. Values have reached 10-15 micro inches in certain instances.

Specialized tooling is also capable of near optical-quality finishing. Materials such as polycarbonate and acrylic can be machined clear. This process can be configuration limited, however, and is best suited for exterior work. Interior work — such as bores or cavities — have some success, while this technique is not applicable to features such as tapped holes.

Please see our polishing section for more information on finishes.