SPI Guidelines – Mold Polish
SPI standards are determined by the Society of the Plastics Industry for the plastic industry. Texas Injection Molding uses these SPI mold polish standards to specify mold polish finishes for multiple applications, guides, and finishes.
The below specifications provide guidelines for SPI mold surface finishes as provided by the Society of the Plastic Industry. For more information visit Society of Plastic Industry.
|
|
Guide |
Typical Finishes |
Typical Surface Roughness |
| A-1 | Grade #3 Diamond | Lens / Mirror – requires 420 SS material | 0.012 to 0.025 |
| A-2 | Grade #6 Diamond | High Polish parts | 0.025 to 0.05 |
| A-3 | Grade #15 Diamond | High Polish parts | 0.05 to 0.10 |
| B-1 | 600 Grit paper | Medium Polish parts | 0.05 to 0.10 |
| B-2 | 400 Grit paper | Medium Polish | 0.10 to 0.15 |
| B-3 | 320 Grit paper | Med – Low polish | 0.28 to 0.32 |
| C-1 | 600 Stone | Low Polish parts | 0.35 to 0.40 |
| C-2 | 400 Stone | Low Polish parts | 0.45 to 0.55 |
| C-3 | 320 Stone | Low Polish parts | 0.63 to 0.70 |
| D-1 | Dry Blast Glass Bead | Satin finish | 0.80 to 1.00 |
| D-2 | Dry Blast # 240 Oxide | Dull Finish | 1.00 to 2.80 |
| D-3 | Dry Blast # 24 Oxide | Dull finish | 3.20 to 18.0 |
Glossy Finish
|
|
A-1 |
A-2 |
A-3 |
| ABS | Average | Average | Good |
| Polypropylene (PP) | Not Recommended | Average | Average |
| Polystyrene (PS) | Average | Average | Good |
| HDPE | Not Recommended | Average | Average |
| Nylon | Average | Average | Good |
| Polycarbonate (PC) | Average | Good | Excellent |
| Polyurethane (TPU) | Not Recommended | Not Recommended | Not Recommended |
| Acrylic | Excellent | Excellent | Excellent |
Semi-Glossy Finish
|
|
B-1 |
B-2 |
B-3 |
| ABS | Good | Good | Excellent |
| Polypropylene (PP) | Good | Good | Excellent |
| Polystyrene (PS) | Excellent | Excellent | Excellent |
| HDPE | Good | Good | Excellent |
| Nylon | Good | Excellent | Excellent |
| Polycarbonate (PC) | Good | Good | Average |
| Polyurethane (TPU) | Not Recommended | Average | Average |
| Acrylic | Good | Good | Good |
Matte Finish
|
|
C-1 |
C-2 |
C-3 |
| ABS | Excellent | Excellent | Excellent |
| Polypropylene (PP) | Excellent | Excellent | Excellent |
| Polystyrene (PS) | Excellent | Excellent | Excellent |
| HDPE | Excellent | Excellent | Excellent |
| Nylon | Excellent | Excellent | Excellent |
| Polycarbonate (PC) | Average | Not Recommended | Not Recommended |
| Polyurethane (TPU) | Good | Good | Good |
| Acrylic | Good | Good | Good |
Textured Finish
|
|
D-1 |
D-2 |
D-3 |
| ABS | Excellent | Excellent | Good |
| Polypropylene (PP) | Excellent | Excellent | Excellent |
| Polystyrene (PS) | Excellent | Excellent | Good |
| HDPE | Excellent | Excellent | Excellent |
| Nylon | Excellent | Excellent | Good |
| Polycarbonate (PC) | Excellent | Not Recommended | Not Recommended |
| Polyurethane (TPU) | Excellent | Excellent | Good |
| Acrylic | Average | Average | Average |