Injection-molded plastic parts replicate the Injection mold surface finish (Refer to SPI surface finish chart). Therefore injection mold core and cavity surface finish are as per the specified part drawing.
SPI (Society of Plastic Industry) has defined a standardized surface finish for injection molds to facilitate industrial designers, design engineers, and mold manufacturers. These standardized finishes are known as SPI mold finish. This article covers various SPI surface finish, their roughness values, and recommendation for plastic parts.
SPI Surface Finish For Injection Molded Plastic Parts
Designers specify SPI surface finish in a part drawing. Injection molds are polished as per injection molded part surface finish requirements. As a result, the mold SPI finish replicates on injection molded plastic parts.
Following SPI mold finish options are available to finish injection molded plastic parts according to SPI standards.
SPI Surface Finish Chart
SPI Surface Finish Recommendations For Plastic Part
SPI Mold Finish look, feel, and quality depends on the thermoplastic material’s mechanical properties and part color. Plastic material properties also impact the selection of the injection molding surface finish. For example, engineers do not recommend highly glossy finishes on the P22 tool material.
The below table can give you an idea about recommended SPI mold finish for given plastic material.
To sum up, SPI finish is one of the best ways to convey the required plastic finish to the manufacturer. SPI mold finishes are accepted all around the world. Ra and VDI surface finish are good alternatives to the SPI Finish standard.
We will keep adding more information on SPI surface finish for injection molding plastic parts. Add your suggestion, comments, or questions on the SPI surface finish in the comment box.
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