Aloha, fun & authoritative answers -- no cost, no registration, no passwords, no popups
(as an eBay Partner & Amazon Affiliate we earn from qualifying purchases)

Where the
world gathers for metal finishing
Q&As since 1989

-----

Comparing surface finish of a molded part to a machined part

The company I work for currently is machining a part that I want injection mold. If the surface finish of my machined part is 32 microinch what SPI surface finish do I need to meet on my molded part?

James Wolfe
mfgr - Memphis, Tennessee, USA
2005

Not very much info to give a satisfactory answer but, as a rule, molded plastic parts replicate the interior surface finish of the mold pretty accurately. Mirror finish is required for transparent parts whereas sandblasted, EDM'ed or chemically etch interior surfaces will show the reverse pattern on the plastic. So, a straight answer would be, a 32 RMS finish inside the mold is what you need. Whether it would be suitable for the injection process is unknown.

Guillermo Marrufo
Monterrey, NL, Mexico
2005

(No "dead threads" here! If this page isn't currently on the Hotline your Q, A, or Comment will restore it)

Q, A, or Comment on THIS thread -or- Start a NEW Thread

Disclaimer: It's not possible to fully diagnose a finishing problem or the hazards of an operation via these pages. All information presented is for general reference and does not represent a professional opinion nor the policy of an author's employer. The internet is largely anonymous & unvetted; some names may be fictitious and some recommendations might be harmful.

If you are seeking a product or service related to metal finishing, please check these Directories: