Finishes Polypropylene parts are a natural off-white color. PP does not accept surface finishes like paints very well. Its hydrophobic nature also makes it very difficult to dye.
As Machined: The most common surface finishing option for anyone CNC machining in polypropylene is to simply leave the part in an as-machined state. Machined faces may have visible tool marks. Bead Blast: CNC machining in polypropylene tends to leave burrs on part edges and the polypropylene easily melts when in contact with the cutting tool, which can result in a sub-par surface finish. Bead blasting helps mitigate this by removing these minuscule imperfections with blasted media that also help remove tooling marks to produce a more consistent and uniform surface finish.

Cost-saving Design Tips CNC machining in polypropylene can be cost-effective thanks to the low cost of the material. However, reducing excessive machine and post-processing time is critical to keeping costs low. One way this can be achieved is by keeping the tolerances standard:

+/- 0.010” for features of size (length, width, height, diameter) +/- 0.010” for location (position, concentricity, symmetry)

Avoid calling out tighter tolerances when they are not necessary. This is especially important because machining plastics generates heat, which can cause the plastic to warp or lead to dimensional creep.