Injection molding provides the structural foundation, but strategic surface treatment defines the final user experience. For engineering and procurement teams, choosing a post-processing method is a design decision that bridges functionality and market appeal, and it affects tooling, material choice, assembly, validation, and cost.
Painting and Coating
Painting offers the widest color range and the best cost per unit for high volume. It requires good surface preparation and a primer to avoid adhesion problems, and it adds environmental and labor steps. Soft-touch coatings create a premium feel but wear at edges, so film thickness and application method matter.
Plating
Electroplating adds corrosion resistance and a metallic look on ABS and PC/ABS. The process combines etching, activation, and copper, nickel, and chromium layers. Adhesion depends on substrate and surface prep, and thickness changes dimensions, so critical features need allowance.
IMD and OMD
In-mold decoration and in-mold forming place a decorated film inside the tool, so the graphic becomes part of the part with no secondary step. IMD suits flat or gently curved surfaces; OMD handles deeper 3D shapes. Both protect graphics from wear, which painting cannot match, but they require tooling changes and careful film handling.
PVD and NCVM
Physical vapor deposition produces hard, decorative, and functional coatings with excellent wear resistance, at higher cost and usually in a vacuum process. Non-conductive vacuum metalization gives a metallic appearance without electrical conductivity, which matters for housings that must stay insulated.
Texture and Mold Finish
The cheapest finish is the one built into the tool. Textures hide minor flow marks, reduce visible scratches, and change the tactile feel. Texture depth must be agreed before machining, since it changes release force and cleaning requirements.
Choosing by Function
- Color and cost: painting
- Graphic protection: IMD or OMD
- Metallic look with wear: PVD
- Metallic look without conductivity: NCVM
- Corrosion resistance: plating
- Feel and scratch hiding: texture or soft-touch coating
Frequently Asked Questions
Which method is cheapest at volume?
Usually painting or texture, depending on the visual target.
Can IMD replace painting?
For flat graphics, yes, and it adds wear protection. For complex 3D shapes, OMD is the better route.
Does PVD work on plastic?
Only on a pre-treated or plated surface; plastic alone cannot carry a PVD coating.
Conclusion
Surface finishing techniques should be selected by function, then by cost. For related reading, see surface technology reference, our electroplating guide, and surface treatment overview. Contact TCHD to define your finish.