Injection molding is the most
common plastic molding
process and is used to create a wide variety of complex parts of different size and shape. Whether it’s an overcap for a water bottle or a vinyl window part being manufactured, injection molding is efficient and economical, especially if high volumes of parts are being produced.
Injection molds represent the greatest expense in upfront production costs. With any custom injection molding project, your injection molder should be able to provide you with a quote that breaks down the costs. Procurement and purchasing managers have the unenviable task of obtaining quotes for each project. Depending on the input (in terms of drawings, prototypes or sample parts), the quotes can vary greatly.
Molds made with tighter tolerances, more cavities and a longer production life will take longer to build and will cost more upfront. The savings with a high-quality mold are long-term. These molds require less maintenance and last longer than lower quality molds.
Getting an injection molding quote is the first step in determining feasibility; however, there are many questions that should be answered before an accurate quote can be supplied.
Here are the top six questions you should able to provide initial answers to:
1. Are there CAD drawings, prints or samples of the part to be quoted?
To begin to form an accurate quote, the molder needs to know what you are asking them to make. Detailed dimensional drawings provide information on the size and complexity of the part. A sample or prototype can especially help the molder begin to determine how to maximize the design for manufacturability.
2. Are you running the parts from an existing mold?
If so, it would be up to the molder to decide if they can run your parts from the existing mold. At Rodon, we look for a mold that can run in an automated fashion, unattended and one that is made from a quality stainless steel material. If we can run the mold the way it was originally designed and built then we will certainly consider it.
3. What is the part application? Are there chemical or environmental issues the part will be exposed to?
The injection molder you are working with needs to understand the end-use application of the part. This explanation will help the manufacturer determine how sturdy the part needs to be and what the wear and tear will be over time. The information you provide will help your molder make recommendations on the resins and/or additives required for your project.
4. 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 higher; however, it pays for itself over the life of the tool. High volume, precision molders like The Rodon Group specialize in building tools with hardened steel.
5. What is the size and complexity of the part?
While many plastic parts are made through injection molding, other molding processes can be used to produce a part. Briefly, smaller parts that are more complex are ideally suited to the injection molding process. Larger parts may be produced by injection molding or compression molding. Oversize parts lend themselves to rotational molding while hollow
objects, like bottles, are made with blow molding. You can learn more about each in this related post.
6. 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 additives they think will provide the best result.