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Tooling
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Premold Corporation offers you a choice of prototyping, short run, and full production molding services. Generally, projected part quantities will determine which tooling best suits your needs.
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Part Quantities
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Tooling Type
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1 - 25 pcs.
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Prototype - Silicone Mold
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25 - 700 pcs.
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Short Run - CNC Cut Epoxy
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700 pcs. & Up
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Production - CNC Cut Aluminum
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Wall Thickness
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Wall thicknesses are usually a function of physical characteristics needed and UL requirements. Try and keep wall thicknesses consistent throughout. This will help eliminate warpage problems.
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Draft
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Three degrees is best. The minimum is usually one degree.
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Radii
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Generally speaking, radii on the outside surfaces of a part can be kept as large or small as you would like. We would, however, encourage you to keep inside surface radii as liberal as possible. This facilitates material flow and eliminates air entrapment. Where your design will allow for it, we would recommend .060 to .120 radii on inside surfaces.
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Bosses
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Bosses should be designed so that they can be "ribbed" to nearby wall sections wherever possible. For free standing bosses we suggest gusseting on two sides. Location of gussets may require knowledge of gate and vent design. Contact us for assistance.
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Inserts
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Utilize threaded inserts in bosses when mating parts are going to be disassembled frequently. Pilot holes and self-tapping screws work very well for permanent assemblies.
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Ribs
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Although sink marks are generally not a concern with urethanes, try and keep thicknesses of rib sections 70% to 80% of surface wall thickness.
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Tolerancing
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Typical tolerances are:
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Molded Dimensions
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± 0.002 in./in.
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Post Machined Dimension
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± 0.005 in.
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Insert Locations
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± 0.005 in.
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Flatness
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± 0.0015 in./in.
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Finishing
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Most of our finished parts are painted with a Sherwin Williams Polane urethane based paint. All colors and textures are custom matched.
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