Desktop Injection Molding Tips
Plastic will shrink from when its melted state to its solid form. To compensate and have the part be the correct size, the mold should be made slightly larger, so that it shrinks to the correct size. In addition, it should be noted that the mold will expand when it is heated very slightly, and for high precision situations, this should also be factored it.
| Common Linear Shrinkage Values | ||
| Material | Shrinkage |
Processing
Temperature |
| ABS- High Impact | .005 - .007 | |
| ABS- Medium Impact | .005 - .008 | |
| ABS-High Heat | .004 - .006 | |
| ACETAL | .020 - .035 | |
| ACRYLIC- General Purpose | .002 - .009 | |
| ACRYLIC- High Flow | .002 - .007 | |
| ACRYLIC- High Heat | .003 - .010 | |
| ACRYLIC- Impact | .004 - .008 | |
| NYLON- 6,6 | .010 - .025 | |
| NYLON- 6 | .007 - .015 | |
| NYLON- Glass Reinforced | .005 - .010 | |
| POLYCARBONATE | .005 - .007 | |
| POLYESTER .025 - .050 thick | .006 - .0012 | |
| POLYESTER .050 - .100 thick | .012 - .017 | |
| POLYESTER .100 - .180 thick | .016 - .022 | |
| POLYETHERIMIDE | .005 - .007 | |
| POLYETHYLENE- LDPE | .015 - .035 | |
| POLYETHYLENE- HDPE | .015 - .030 | |
| POLYPROPYLENE | .010 - .030 | |
| PPO/HIPS (NORYL) | .005 - .007 | |
| POLYSTYRENE- Crystal | .002 - .008 | |
| POLYSTYRENE- Impact | .003 - .006 | |
| POLYURETHANE | .010 - .020 | |
| PVC-RIGID | .002 - .004 | |
| PVC-FLEXIBLE | .015 - .030 | |
| SAN | .002 - .006 | |
Plastic Resin for Injection Molding Suppliers and Distributors
The hardest part in doing desktop injection molding is finding a distributor who will sell you less than a truckload of plastic. One good supply source is ebay.
The other problem is custom color. Most plastics come in either natural (white) or black.
Resin Supplier Links:- Advanced Elastomer Systems: Source of thermoplastic Elastomer (moldable rubber)
- Bayer Plastics Business Group: Makrolon polycarbonate, Bayblend polycarbonate/ABS blend
- Dupont Plastics: Delrin acetal, Zytel nylon, etc.
- Lanxess: Lustran ABS
- Polyone Distribution: Provides more than 3,500 grades of resin to more than 5,000 plastic processors across North America
- RTP Plastics: Compounder; huge selection of fill/resin combinations; excellent selection of bearing resins
- www.sabic-ip.com
- Polymerland - GE Company. Will sell in 50LB bags. Good customer support. They have tinted polycarbonate.
Plastic is typically manufactured in natural color or black. If you want a different color you need to add colorant. The colorant comes as pellets, and doesn't necessarily mix well in your machine. To get a good consistent color the plastic needs to be mixed, extruded, and chopped into pellets. Companies that do this for you are called compounders.
- Accek Color: Custom formulated coloring systems for plastics. They mainly sell colarant, but they will do compounding, if you send the uncolored plastic to them. This cost was about $7 per pound for 100 pounds.
- Chase Plastic: Full-service specialty engineering thermoplastic distributor serving plastic processors throughout North and Central America
- Interfacial Solutions: Plastic additives and specialty compounded resins. Service based company.
- Compounding Solutions: Specialty compounder for the medical industry. Min Quantity 25LBS. Nate Doyle. To compound a green ABS: 25LBS= $13.47, 50LBS = $8.74, and 100LBS= $6.74.
