8 Questions to consider when choosing an injection mold

2023-05-09
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8 Questions to consider when choosing an injection mold

Injection molding is one of the most common methods of making products in production. The first step is to select the options that are appropriate for your project. Here are eight questions from real customers that will help make choosing your injection molding easier.

What is the scope of the project?

This is probably the most important factor in deciding which processing method to use.

If the part is for pre-production, the answer is simple: aluminum. This is common when projects require the use of final production injection molded materials to make parts. Aluminum offers lower costs and faster delivery times. If the part is used in production, there are several things to consider. What is the EAU on a component? How long will the project run?

How does part size affect?

Part size plays an important role in determining the mold. Larger parts will need to be built in a separate die, but smaller parts that fit the size parameters may require (more efficient) and cheaper alternatives. Insert molds are very popular for smaller components. Instead of paying full price for a stand-alone mold, build an insert mold that fits the basic unit of our press (standard MUD).

For example, you have a small 3 "x 2" x 1/2 "case that needs to be produced by injection molding. Instead of building a complete stand-alone die for such a small part, we build an insert die out of aluminum or steel to fit the existing base on our press. This is an extremely economical way to produce smaller parts with minimal waste.

How is part volume affected?

Part volume can affect the mold, especially when the volume reaches higher levels. The standard is a single cavity die, producing several hundred or several thousand parts per year, but as part production grows, you may consider adding multiple cavities to the die to produce parts more economically. Single-cavity molds are a good place to start when the number and longevity of projects is unknown or there is no reliable prediction. You can always consider building multi-cavity molds later. The upfront cost of a multi-cavity mold is slightly higher, but it can significantly reduce your per-piece price.

Does the material of the part affect it?

Yes, it does. Part materials have a direct effect on the mold for several reasons. Mild injection-molded resins such as polypropylene are easier to form on the mold and therefore help extend life. Glass filled nylon and other coarser injection molding resins are more likely to wear the mold. This can be a key deciding factor when you have a part life of 8,000-12,000 pieces and you are choosing between aluminum or steel molds.

Does part geometry matter?

Yes, it does. We thoroughly evaluate each part before making an offer. We look at the parts characteristics that will affect the mold. Does it have a base cut? Core? We also focus on surface finish requirements. Will it feel grainy? Polishing? The texture? These will affect the decision on the type of mold to be used.

What is the life expectancy of the mold?

Aluminum molds have a service life of 2,000-10,000 parts, depending on the type of aluminum used, part material, and geometry.

Depending on the material and geometry of the part, the service life of the steel die can reach more than 100,000 parts. The mold may need to be reworked after a period of production.

What is the timeline for building the mold?

This varies on a section-by-section basis, but a good rule of thumb is:

Aluminum molds can be made in 4-6 weeks for small parts and 6-10 weeks for large parts, while steel molds can be made in 6-8 weeks for small parts and 8-12 weeks for large parts.