Injection Mold Surface Finishing Service
Enhance the appearance and functionality of your injection-molded parts with optimized mold surface finishes. From glossy to matte or textured, our tailored finishes ensure your parts meet exact specifications.
Jiangzhi offers various types of injection molding finishes. Normally, our plastic surface finishing is based on SPI or VDI standards for molded parts. Finishes applied to the surface of the mold cavity transfer to the surface of the molded part. Adding a finish may change the mold price, but won’t influence the unit price. Choose the correct surface based on your own budget.
SPI mold finishes standard chart
| Finish | Description | Description | Typical Applications |
|---|---|---|---|
| SPI A-1 | Grade #3 diamond buff | for mirror or optical finishes | Optical parts, transparent covers |
| SPI A-2 | Grade #6 diamond buff | most time consuming and costly finishes to achieve | Cosmetic housings, clear components |
| SPI A-3 | Grade #15 diamond buff | steel grade important to results | Consumer products |
| SPI B-1 | 600# grit paper | removes all tools and machining marks | Smooth molded surfaces |
| SPI B-2 | 400# grit paper | provides good mold release | Electronic housings |
| SPI B-3 | 320# grit paper | ligh reflecting finish on molded parts, some sheen | Functional plastic parts |
| SPI C-1 | 600 stone | removes all tools and machining marks | Industrial components |
| SPI C-2 | 400 stone | provides good mold release | Utility parts |
| SPI C-3 | 320 stone | mute finish on molded parts, no sheen | Non-reflective surfaces |
| SPI D-1 | dry blast glass bead | for decorative finishes | Decorative surfaces |
| SPI D-2 | dry blast #240 oxide | helos hide shrink mardks and other imperfections | Defect masking surfaces |
| SPI D-3 | dry blast #24 oxide | dull non-reflecting finish on molded parts | Grip surfaces |
VDI 3400 Surface Finishing
VDI 3400 Surface Finish refers to the texture standard Verein Deutscher Ingenieure, the Society of German Engineers. VDI has set a standard of mold cavity surface for Europe market or even the whole world. The VDI 3400 is mainly processed by EDM while machining the mold. VDI consist of different electric spark particle in size, depth and density.
Common VDI 3400 finish chart
| VDI VALUE | Description | COMMENTS | Common Applications |
|---|---|---|---|
| VDI 12 | 600 stone | low polish | Cosmetic plastic parts |
| VDI 15 | 400 stone | low polish | Consumer products |
| VDI 18 | dry blast glass bead | satin finish | Electronic housings |
| VDI 21 | dry blast #240 oxide | dull finish | Industrial components |
| VDI 24 | dry blast #240 oxide | dull finish | Appliance housings |
| VDI 27 | dry blast #24 oxide | dull finish | Automotive interior parts |
| VDI 30 | dry blast #24 oxide | dull finish | Functional plastic parts |
| VDI 33 | dry blast #24 oxide | dull finish | Grip applications |
| VDI 36 | dry blast #24 oxide | dull finish | Industrial molded parts |
| Comparison | SPI | VDI 3400 |
|---|---|---|
| Finish Type | Polishing standard | Texture standard |
| Method | Polishing / sanding | EDM texture |
| Appearance | Gloss to matte | Uniform texture |
| Common Market | North America | Europe |
| Typical Use | Transparent & cosmetic parts | Industrial & textured parts |
Custom Parts Surface Finishing Case
SPI A
High Gloss Finishing Part
Diamond - polished mirror finish for clear or premium parts.
SPI B
Semi-Gloss Finishing Part
Fine-polished smooth surface with controlled shine.
SPI C
Matte Finishing Part
Non-reflective sanded finish for uniform, low-glare parts.
SPI D
Textured Finishing Part
Grit-blasted surface for grip, coverage, and defect masking.
Can a textured or polished mold be repaired if it gets damaged?
Repairs are possible but limited. Textures can be deepened but not easily lightened, and polishing may remove material. We verify finishes during sampling to minimize irreversible rework.
Will complex mold geometries cause inconsistent surface results?
Slight variations may occur in deep cavities, corners, or core-pulled areas, but our optimized design and sampling ensure consistent final surfaces.
How many injection or casting cycles can your mold surface treatments withstand?
Our reinforced mold surfaces can withstand up to 50,000–100,000 cycles, depending on part complexity and maintenance.
Are there any hidden costs when I make molds?
No, our mold pricing is fully transparent. All surface treatments, texturing, polishing, and other additional processes are clearly listed in the quotation, there are absolutely no hidden costs.
