One of the most common questions we receive from customers is how much a custom plastic injection mold will cost. The truth is, there is no easy way to determine exactly what a mold will cost without the specific product details; the price of injection molding is based on a number of interplaying factors. However, we’ll break down each of those factors to give you a better idea of what influences the cost of an injection mold.

Many factors play a role in the ultimate cost of a plastic injection mold. Some of these factors include:

Mold Material

The first factor that influences injection mold cost is the material of the mold itself. Molds can be made of many materials to suit different needs, including standard and stainless steel, aluminum, and beryllium-copper alloys.

Every material has its own unique properties that make it more appropriate for certain types of applications. Steel, for instance, is more durable and long-lived, but also harder to machine. Aluminum can be easily machined to very tight tolerances but doesn’t last through as many injection cycles.

Mold and Cavity Complexity

The more complex the mold, the more machining, finishing, and maintenance are required. Because of this, the cost of a mold necessarily increases with its complexity. In many cases, it is more economical to design several simple molds that work together to create one piece, rather than designing a single, more complex mold.

Number of Cavities

Along with the complexity of mold cavities, you must also consider the number of cavities needed. At MDI, we recommend each mold be designed for a single part, rather than creating molds to produce multiple parts at once.

Mold Base

The mold base is the larger piece that holds the separate mold cavities and other parts together in a single unit. Most mold bases are designed from standard units and then machined to your particular specifications. The number of cavities, the material of the mold and the base, and the size of the base will all play a role in the ultimate cost of the mold.

Tolerances

No part can be reproduced absolutely perfectly, but with proper machining, they can come close. However, as tolerances become tighter, the costs rise. Parts with relatively loose tolerances, such as exterior plastics and single-piece parts, are cheaper to design and produce than parts with very tight tolerances.

Gate Type and Placement

Gates are the points at which plastic resin is injected into the mold. There are many different types of gates available, including edge gates, hot tip gates, and sub gates. Different types of gates are suited for different part designs. You will also need to consider the placement of the gate during the design phase, in order to reduce part stress and ensure fast, even injection.

Part Material (Resin)

The material you choose for your part manufacturing will affect the design of your mold. Different resins, such as acrylic, polycarbonate, polyurethane, or PVC, require different wall thicknesses and gate and ejector pin placement to ensure optimum performance. These design considerations have an effect on the ultimate cost of your mold.

Part Texturing

Texturing is an aspect of mold and cavity complexity. Plastic parts can be molded with a huge range of textures, but designing and machining the texture in the mold is an important consideration in the eventual cost.

Ejector Pin Number and Placement

Another design consideration for your injection mold is the ejector pins. Different pin sizes, numbers, and placements can impact your part in different ways. In general, your mold should be designed so the ejector pins minimize the stress your part encounters during ejection.

Manual Labor

Despite advances in computer drafting and automated CNC machining, manual labor still plays a role in your mold’s design. Your mold may need hand machining or finishing, or it could require several design iterations to ensure quality.

Manufacturing Location

A final consideration for the cost of your injection mold is where you choose to have it made. Molds made in China or Indonesia are often cheaper, but are also often made with lower quality materials and less precise machining. In contrast, having a mold manufactured within the United States ensures you get the highest quality materials and workmanship.

Why Choose Custom Plastic Injection Molds?

With all of these considerations, custom plastic injection molding might seem like a huge and complicated expense. However, custom injection molding does have many advantages that help offset these costs:

Part Accuracy

Only injection molding offers a high level of accurate reproducibility for large numbers of plastic parts. Other manufacturing methods can’t match injection molding for creating large numbers of parts quickly and with precision.

Durability

One well-made injection mold can create many thousands of parts over years of use. Other methods may be better suited for short production runs, but injection molding is the most cost-effective option for long runs.

Production Speed

Injection mold manufacturing is one of the fastest ways to reproduce large numbers of highly accurate parts. Other manufacturing methods can create parts with similar tolerances, but not at nearly the same rate as injection molding.

To get an accurate quote on the cost of your own custom injection mold, reach out to a professional manufacturer with the knowledge and skills to give you exactly what you need. And experienced project manager will ensure all your requirements and needs are incorporated into your design from the outset.