What quantities are needed?
All injection molds are not made alike. If you are interested in smaller quantities or a shorter production run, an aluminum mold might be the best option. If your project requires large quantities over a longer time span, then a hardened stainless steel mold would be the best choice. The upfront cost of the latter option is much greater; however it pays for itself over the life of the tool.
What is the size and complexity of the part?
While many plastic parts are made through injection molding, there are other molding processes that can be used to produce a part. You can read about them in a related article. Briefly, smaller parts that are more complex are ideally suited to the injection molding process. Larger parts may be produced with injection molding or compression molding. Very large parts lend themselves to rotational molding while hollow objects, like bottles, are made with blow molding.
What types of polymers or resins are required for the part?
You may need to do some initial fact finding, but having an understanding of the type of plastic material you feel best suits your project gives the molder a starting reference point. In the long-run, a qualified molder will recommend the resin and or additives they feel will provide the best result.
If your project requires manufacturing plastic parts, you need to do a bit of homework prior to getting an accurate quote. By answering these five questions, you should be well on your way to establishing mutually beneficial vendor contacts that can help move your project along.