Electronics, PCB Design and PCB Layout Daycounter, Inc.
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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
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: Colorant and Color Matching Supplier Links:

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 consistant 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.






Daycounter specializes in contract electronics design.  Do you need some help on your project?  Contact us to get a quote. 



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