Precision molding 3 questions you need to ask

Precision molding is a production process that uses more precise techniques and processes to make molds and parts than typical injection molding. If you want to ensure there are no air leaks between two molded parts or there are no visible seal gap lines, you need precision molding.
The difference between a typical injection molded part and a precision molded part is the tolerance or range of acceptable dimensional variation: while most injection molded parts have tolerances of +/- .005", precision molded parts have tolerances of +/- .002" and +/- .001" (or less in some cases).

If your project requires high-precision parts that require precision molding, before you look for the proper manufacturer to produce them, precision molding supplier Shengqi tells you that the following 3 questions you need to figure out can save you a lot of time and money.

1. Are you sure which areas of the mold need precision?
Because precision molding is more expensive than typical injection molding, determine which areas of the part require tight tolerances and whether those tolerances can be achieved with injection molding before moving forward. For example, a surgical handle may only require precision for the part attached to the pin, not the entire handle.
Get a handle on your project needs first and identify the parts and components that require high precision, which will effectively ensure that you do not waste money where it is not necessary.

2. Have you chosen a plastic material with low shrinkage?
The plastic material you choose for your part can greatly impact whether you can perform precision molding. For example, polypropylene has a shrinkage range of +/- .014" to +/- .022", with an average of +/- .018". This is an extensive shrinkage range, making it difficult to achieve specific tolerances. If you are molding toothbrushes (usually polypropylene), dealing with shrinkage is not a big issue because it works fine whether the toothbrush is slightly larger or smaller than its counterpart. Acrylonitrile butadiene styrene (ABS) - another common thermoplastic polymer - has a much narrower average shrinkage of +/- 0.006. This gives you a better chance of achieving tighter tolerances. However, it won't achieve the +/- .001" or +/- .002" tolerances required for precision parts.

One way to achieve high tolerances with plastic materials is to add glass or other filler resins (such as carbon fiber or mica) to the material. This can minimize shrinkage and warpage by providing more structure to the material. For example, suppose you include long glass fibers in a polymer material. In that case, the part will shrink more perpendicular to those fibers.

3. Can the mold maker choose a high-precision mold?
To manufacture high-precision parts, you first need high-precision tooling. Accurate tooling ensures accuracy and consistency in each part. Therefore, if you are after high-precision of parts, choosing a mold maker who understands the slow and steady process of making high-precision tools is essential. Sometimes we may choose a mold maker that makes fast molds for the sake of being fast, but this may not be the best choice for you if you are looking for precision because the goal of fast molds is to complete the mold quickly but not necessarily accurately.

Shengqi is a professional mold and parts manufacturer with many years of experience in precision molding. We are happy to answer any questions you may have about precision molding. You can contact us regarding these questions, or if you have a project that requires precision molding services, feel free to contact us. We will be sure to provide you with satisfactory service.

Reprinted from precision molding supplier Shengqi - “Precision molding 3 questions you need to ask”