SPI Mold Finish Specifications … complete guide for injection mold cavity and core finishing

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SPI Mold Finish Specifications used for Injection Molds.

SPI Finish ~ Specification ~ Appearance ~ Typical Use

A-1 ~ Grade #3 – 6,000 Grit Diamond Buff ~ Very High Gloss Mirror Finish ~ Clear parts, lenses, optical parts, fine cosmetic parts

A-2 ~ Grade #6 – 3,000 Grit Diamond Buff ~ High Gloss Finish ~ Cosmetic surfaces that don’t require a mirror finish

A-3 ~ Grade #15 – 1,200 Grit Diamond Buff ~ Gloss Finish ~ Cosmetic surfaces that don’t require high gloss finish

B-1 ~ 600 Grit Paper ~ Fine Polish Finish, very fine pattern ~ Cosmetic surfaces that require a very fine finish without diamond polishing, chrome plated or painted parts

B-2 ~ 400 Grit Paper ~ Fine-Medium Polish Finish, fine pattern ~ Cosmetic surfaces that require a fine finish with less shine where a directional surface pattern is required or acceptable

B-3 ~ 320 Grit Paper ~ Medium Polish Finish, fine-extra light pattern ~ Cosmetic surfaces that require a fine-extra light finish with minimal shine where a directional surface pattern is required or acceptable

B-4 ~ 240 Grit Paper ~ Medium-Low Polish Finish, extra light pattern ~ Cosmetic surfaces that require an extra light finish with very minimal shine where a directional surface pattern is required or acceptable

B-5 ~ 180 Grit Paper ~ Low Polish Finish, light pattern ~ Cosmetic surfaces that require a light finish with almost no shine where a directional surface pattern is required or acceptable

C-1 ~ 600 Grit Stone ~ Fine Finish, light draw pattern ~ Some cosmetic surfaces or non-visual internal surfaces where a directional surface pattern is required or acceptable

C-2 ~ 400 Grit Stone ~ Fine-Medium Finish, light-medium draw pattern ~ Some cosmetic surfaces or non-visual internal surfaces where a directional surface pattern is required or acceptable

C-3 ~ 320 Grit Stone ~ Medium Finish, medium draw pattern ~ Non cosmetic surfaces or non-visual internal surfaces where a directional surface pattern is required or acceptable

C-4 ~ 220 Grit Stone ~ Medium-Course Finish, medium-heavy draw pattern ~ Non cosmetic surfaces or non-visual internal surfaces, usually used to remove machine cutter marks

C-5 ~ 150 Grit Stone ~ Course Finish, heavy draw pattern ~ Non cosmetic surfaces or non-visual internal surfaces, usually used to remove heavy machine cutter marks

D-1 ~ 600 Grit Stone followed by #11 Glass Bead Dry Blast ~ Satin Finish ~ Cosmetic surface finish that mimics a fine matte finish texture

D-2 ~ 400 Grit Stone followed by #240 Aluminum Oxide Dry Blast ~ Satin-Dull Finish ~ Cosmetic surface finish that mimics a light matte finish texture

D-3 ~ 320 Grit Stone followed by #24 Aluminum Oxide Dry Blast ~ Dull Finish ~ Cosmetic surface finish that mimics a medium matte finish texture

NOTE: Paper Grit finishes are approximately twice as fine as the equivalent Stone Grit value.
All surface finishes will vary depending on steel type, aluminum type or other material type.
Dry Blast finishes will vary depending on surface material type, pressure, distance and time.

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