Injection Molding Cost
Manage Your Injection Molding Costs with Fathom

Injection molding is highly repeatable and allows for identical parts to be produced quickly and in large volumes, but there are many factors that can affect the final cost of the project.

The more complex the part design, the more costly the tooling. Simple designs with fewer features don’t require as much labor and fabrication time, reducing their cost. Complex part designs that require undercuts, surface finishes or intricate cooling channels, for example, contribute to higher injection molding costs. Multi-cavity tools and family molds are also more complex and cost more to produce than single-cavity tools.

Mold material can also influence the cost. Molds can be made using hardened steel, aluminum or 3D printing. For production parts, Fathom prefers steel tools because they last longer and don’t require as much maintenance as the other two types of tooling. We also offer aluminum molds, hand molds, MUD molds, and unit molds for prototype and low-volume parts.

Our U.S. tooling is produced using automated CNC machining and EDM cutting, which keeps our tool quality consistently high, shortens our lead times and keeps our tooling cost-competitive.

The labor required to set up a mold to run on an injection molding press can also contribute to higher costs. This includes configuring and optimizing the locations of runners, plus pre-production runs and quality checks. For large production runs, these injection molding costs can be amortized over a larger number of parts. For short production runs, they will have a bigger impact on the per-part cost.

The cost of materials for custom injection molding largely depends on the polymers chosen and the size of your production run. Common materials used for injection molding include polypropylene, polyethylene and acrylonitrile butadiene styrene (ABS). All three of these materials are popular due to their durability and affordability.

In addition to tooling, materials and setup, injection molding costs can be affected by a part’s size, design and quantity ordered.

As the size and complexity of a part increases, injection molding costs usually increase, too. Complex parts may require more sophisticated gating, runner and cooling systems to ensure consistent fills and to prevent warping during cooling. Larger parts may also require a larger press, which also results in higher injection molding costs. And of course, larger parts require more material, which also has an incremental effect on the overall cost per part.

The complexity of a part also impacts its cost. Parts with intricate details are often harder to mold than simple parts. Here are several examples:

• Bosses, which are structures within a part that will contain inserts, must be designed so that they don’t cause sink marks or unsightly seams as the parts cool.
• Parts with thick walls may also cause sink marks or warping due to uneven cooling.
• Parts with surface textures may require additional draft so they can be ejected from the mold without damage.
• Undercuts may require tooling with slide actions so the parts can be ejected from the mold.

Injection molding costs can be reduced by simplifying part geometry and avoiding these potential problem areas. Fathom’s injection molding experts can perform a DFM analysis of your part designs to identify any issues before tooling is made.

Injection molding is a popular manufacturing method for medium- to high-volume production runs. Longer production runs usually have a lower cost per part, because tooling, setup and material costs can be amortized over a larger number of parts.

Knowing injection molding specifications and tolerances will ensure that parts fit correctly during assembly. Tolerances also influence how a part should be designed for optimum functionality.

After the injection molding process, some parts may require a surface finish. This step can add a rough or smooth texture to a part. Industrial, mechanical, or construction parts may require a rough finish. Items such as toys or medical supplies may need a smooth or glossy finish. Below is a list of surface finishes offered by Fathom.

• Flat screen enclosures
• Remote controls
• Printers
• Electrical circuit boards
• Cell phones
• Toothbrushes
• Cosmetic packaging
• Helmets
• Jewel boxes
• Padding
• Syringes
• Knobs
• Intake manifolds
• Beakers
• Test tubes
• Medical implants
• Fixtures
• Vents

Fathom has 2 U.S.-based locations that offer injection molding. In addition, we offer a lower-cost overseas option via ICOMold by Fathom.