SPI (Society of Plastic Industry) establish standards for plastic part finishes. It defines the polishing standard on mold finish.
Nowadays, china’s Ra standard is very much in line with SPI. Chinese manufacturing industry is using chinese standard equivalent to SPI.
In this article we will discuss various available finishes in SPI standard.
|Finish||SPI Standard||Finish Method||Surface Roughness (Ra Value)|
|Very High Glossy Finish||A1||6000 Grit diamond buff||0.012 to 0.025|
|High Glossy Finish||A2||3000 Grit diamond buff||0.025 to 0.05|
|Normal Glossy Finish||A3||1200 Grit diamond buff||0.05 to 0.1|
|Fine Semi Glossy Finish||B1||600 Grit Paper||0.05 to 0.1|
|Medium Semi Glossy Finish||B2||400 Grit Paper||0.1 to 0.15|
|Normal Semi Glossy Finish||B3||320 Grit Paper||0.28 to 0.32|
|Fine Matte Finish||C1||600 Grit Stone||0.35 to 0.4|
|Medium Matte Finish||C2||400 Grit Stone||0.45 to 0.55|
|Normal Matte Finish||C1||320 Grit Stone||0.63 to 0.70|
|Satin Textured Finish||D1||600 stone prior to dry blast glass bead #11||0.8 to 1.0|
|Dry Textured Finish||D2||400 stone prior to dry blast #240 oxide||1.0 to 2.8|
|Rough Textured Finish||D3||320 stone prior to dry blast #24 oxide||3.2 to 18.0|