Injection Molding Surface Finish of Your Plastic Molding Parts

Injected molding parts are often finished using a variety of procedures. Some of these include surface finishing, which is a process that gives a part a certain look and feel. It is often performed for aesthetic reasons as well as functional ones. The surface finish can be a critical factor in either the appearance or performance of your product as it serves both a cosmetic and functional purpose.

SPI Standard Mold Finish

Many of the features on plastics surfaces must meet the requirements of the Society of the Plastic Industry, or SPI. These standards help identify the plastic's cosmetic quality.

A-1 through A-3 are polished tool steel mold finishes that feature a mirror finish. These finishes are super smooth and are usually expensive to make optical goods.

B-3, B-1, and B-2 are semi-gloss finishes that are made with hardened steel mold components. These parts can't show mold marks or show tool marks.

Matte to Dull—SPI grades C-1, C-2, and C-3 specify matte finished from steel molds polished with fine stone powders. These finishes are finished from steel molds with fine stone powders. They can’t show tool marks or mold details.

The Society of Plastics Engineers' mold finish standard has superseded other finishing standards. Some customers may choose to use old finish grades instead of new ones. Since each type of mold has its own unique characteristics, it’s important that you partner with a molder who can help you select the best mold for your injection molding production life and cost objectives.

Visual Appearance or Functionality?

For instance, if a part designer wants to hide imperfections, texture may be used. It can also be used to provide a surface finish that is durable enough to withstand staining.

Other additional advantages of texture include:

Paint Adhesion—Paint holds firmly to a textured part during additional molding operations.

Plastic Flow Creases—These creases can be eliminated through the additional of textured thickness while also adding strength and non-slip qualities.

Improved Grip—Adding texture makes the part easier to hold, improving usability and increase of safety in certain applications.

Creating Undercuts—If your part doesn't consistently come across the moving part of a mold, textures on some surface could help.

Contact TEAM MFG for Your Injection Projects

Having a skilled plastic injection molder helps you make the right decision regarding the surface finish of your part. This step can affect the type of material used, the process, and the final product. Want to learn more about surface finishing options for your plastic part? Contact the experts at TEAM MFG!