Injection Molding Costs: The Best Way to Save Money in Manufacturing

Initially, injection molding costs can run higher than other manufacturing methods. This is mainly due to the upfront cost of creating a high-quality molding tool that will produce large quantities of molds. Once this molding tool has been made, the cost of manufacturing parts become very low to produce.

By investing up front, you can create a molding tool that will create hundreds of thousands of parts for you. At a fraction of the cost compared to other methods.

This article will explain all the different variables that go into injection molding manufacturing costs.

Molding Tool Costs

Creating and designing an injection molding tool takes a lot of time and careful planning. It is the highest cost when dealing with injection molding. That is because a mold tool is a highly intricate piece that takes a lot of manpower as well as special machinery to make.

The cost of a molding tool is affected by the size of the part needed, the material of the tool itself, the intricacy of the part, as well as the number of cavities the part will have. A large and more complex molds take more time, material, and larger machines to make.

The type of metal used in the molding tool will determine how long it will last in production. A stronger metal will cost more to make but will last longer in production and cost less over time.

Resin and Material Costs

Choosing the material of your part plays a large role in production costs. Depending on the function of your part, cosmetic or structural will determine the quality of plastic needed. Also determining how thick the plastic walls of the part will need to be. Then, will affect how much raw material is used.

Material costs for injection parts made of plastics can cost as little as $.80 per pound, and increase up to $100 per pound. This depends largely on the quality of the plastic. Lower end plastics like polypropylene, polyethylene, and polystyrene cost significantly less than more complex resins, such as polyetheretherketone (PEEK), or liquid crystal polymer (LCP).

A simple equation for figuring material costs is—$ Material Part Cost = $ Plastic Material Price x Part Weight lbs.

Cycle Time and Mold Cavities

“Cycle time” represents the amount of time a machine takes to finish an injection molding cycle. A “machine rate” is calculated by figuring out the hourly costs to run and operate mold injection machinery, and added with the desired profit margin.

Here are a couple of important equations to know for figuring out the non-material cost of an injection mold part. The # of units produced per hour = (3600 sec/cycle time sec) x number of mold cavities, and $ Non-Material Part Cost = $ Machine Rate per hour / # of units produced per hour.

Summary of Injection Molding Costs

Now you can see why injection molding costs are initially higher than other manufacturing methods. Though higher upfront costs, injection molding methods give you the ability to mass-produce intricate parts, at a very low cost over time.

Use this article to grow and expand your business.

If you’d like a more detailed look into injection molding, read our Breaking the Mold article. The more education you receive the better prepared you’ll be.

About the author