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Surface Finishing

Enhance the appearance and functionality by variours surface finishing. From smooth, glossy coating to textured or matte finishes, we tailor our services to suit your specific needs.

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Jiangzhi offers various types of surface treatment. Normally, our 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 Surface Finishes

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 structurer and raw mateiral of the mold, as well as the treatment method, all of these aspect will effect eh injection molded parts roughness, brightness, flatness, etc.

SPI mold finishes standard chart

Finish	Description	Description
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 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
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).