There are different types of injection molds based on their characteristics, such as part capacity, plate amount, and runner system. Understanding what each of these categories means for your injection molding process will help prepare you to choose the right type of mold for your part.
Selecting the correct mold type for your production is critical. This is because it will directly affect your production speed, product quality, and overall costs. Based on different features of the mold, there are several ways to classify it:
This is a single mold base with two or more cavities that allow it to produce two or more parts at the same time. You can also choose to use shut-offs to isolate production to the cavities you want. For best results in injection molding, we recommend choosing the parts that are similar in resin, shape, size, and estimated volumes. This is especially if you want to run all parts at the same time. If the volumes are low and mold cost is a significant factor, a family mold is an ideal option.
High or Low Cavitation
As you can imagine, a single cavity mold can only produce one part per cycle. These molds are, thus, cost-effective when your part volume is low since they are less expensive to build. They also have a shorter lead time. On the negative side, the piece-part-cost is higher in injection molding production. Then we have multi-cavity molds that can manufacture more parts per cycle, so they have larger capacity and lead to lower piece-per-costs.
Two/Three Plate Molds
These are essentially cold runner tools; the addition of a 3rd plate to the runner system allows you to pinpoint the injection point into nearly any location on the tool. If a hot runner system is too expensive for you, this is a great option. But keep in mind that this type of injection molding is much more difficult to automate.
Hot Runner Molds
These molds utilize a temperature-controlled manifold to eliminate or significantly reduce runner scrap from the cycle. Injection points can be directly into the part or outside the part. This can really improve cycle times; a runner system (or a sprue) is usually a deciding factor on the mold cycle. Plus, it leads to less waste of expensive material.
A temperature controller for the press is necessary for hot runner molds to run, and the controller must be sized properly to match the manifold inside the mold. In some cases it may seem expensive to maintain the mold on a hot runner tool but it almost always pays for itself in the long run through cycle time and material savings, especially in application that require high annual volumes or expensive engineering-grade resins.
Cold Runner Molds
A cold runner mold utilizes runners and sprues to gate into the component. So, as such, it is not as complicated as other methods. But it may lead to slower running cycles and larger volume of wasted material. In most cases, you can re-ground and re-process a percentage of this wasted material for future use.
Let Us Help You Determine the Right Injection Molding Process for You
At Uniflex Inc., we offer in-house tooling solutions so it takes a few days – not weeks – to make the molds you need. We also specialize in running low and medium volume jobs, with a wide range of materials to choose from. If you’re not sure where to get started with injection molding, just give us a call at 248-486-6000 or contact us online and we will be happy to assist.