Jiangzhi offers various types of surface treatment. Normally, our surface finishing based on SPI or VDI standard 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 have influence on unit price. Choose the correct surface based on own budget.
SPI refers to Social Plastic Industry, which set a standard of mold finishes from high polishing to texture. The usage and material of injection parts, the structure and raw material of the mold, as well as the treatment method, all of these aspect will effect the injection molded parts roughness, brightness, flatness, etc.
SPI Mold Finishes Standard Chart
| Finish type | Description | Comment |
|---|---|---|
| A-1 | Grade #3 diamond buff | for mirror or optical finishes |
| A-2 | Grade #6 diamond buff | most time consuming and costly finishes to achieve |
| A-3 | Grade #15 diamond buff | steel grade important to results |
| B-1 | 600# grit paper | removes all tools and machining marks |
| B-2 | 400# grit paper | provides good mold release |
| B-3 | 320# grit paper | ligh reflecting finish on molded parts, some sheen |
| C-1 | 600 stone | removes all tools and machining marks |
| C-2 | 400 stone | provides good mold release |
| C-3 | 320 stone | mute finish on molded parts, no sheen |
| D-1 | dry blast glass bead | for decorative finishes |
| D-2 | dry blast #240 oxide | helos hide shrink mardks and other imperfections |
| D-3 | dry blast #24 oxide | dull non-reflecting finish on molded parts |
VDI 3400 Surface Finish
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 |
|---|---|---|
| VDI 12 | 600 stone | low polish |
| VDI 15 | 400 stone | low polish |
| VDI 18 | dry blast glass bead | satin finish |
| VDI 21 | dry blast #240 oxide | dull finish |
| VDI 24 | dry blast #240 oxide | dull finish |
| VDI 27 | dry blast #24 oxide | dull finish |
| VDI 30 | dry blast #24 oxide | dull finish |
| VDI 33 | dry blast #24 oxide | dull finish |
| VDI 36 | dry blast #24 oxide | dull finish |
SPI vs VDI 3400
A brief comparison between SPI standard and VDI standard
The most common finishes used include those from the Society of the Plastics Industry (SPI), which are a set of standard mold finishes starting from heavily polished (SPI A) to semi-gloss (SPI B) to fine and coarse matte (SPI C and SPI D). Where polished textures can increase a parts’ cosmetic reflection or transparency on transparent polymers, matte finishes can help provide more subdued tones and even help prevent fingerprints on handled products (e.g., your laptop’s frame and keyboard).
Special Surface Finishing Parts Show
