Our injection molding is the preferred way to fabricate complex, thin-walled components for use in many different industries, and techniques such as overmolding and insert molding.

This allows clients a wide range of customization options when designing components.


As a division of PTR Group, PTR Tool & Plastics utilizes injection molding to create reliable, complex parts and components from polymer substrates for many industries. 

Our injection molding capabilities are taken to the next level with robotics, in-mold decoration, and insert-molding. We are thoroughly equipped to handle any project with our 22 molding machines ranging from 50 to 550 tons. We can run molds up to 42″ x 42″ (166.8mm x 166.8mm) with shot sizes ranging from .71 oz to 54.3 oz. We offer support services and program management to give you predictable performance, accurate timing, and reliable delivery. We manage the process, program, and push the envelope to ensure that your job is complete and on-spec in every way.

How We Design Injection Molding Parts

Injection molding is a popular way to create large volumes of complex plastic components with little variation between each part. Injection molding can be as simple or as complex as the project requires. We design parts in several steps to ensure dimensional accuracy and repeatability. We always verify that each part is designed with uniform wall thickness to avoid physical reactions.

Overview of Injection Molding Process

Design a Prototype Mold

Design a prototype mold with a CNC machine or 3D printing. Digital molds can be tested to ensure the correct substrate was selected.

Inject Molten Plastic

Use an injection molding machine to inject molten plastic into the mold.

Mold Complete

Once it cools, it solidifies into the exact shape of the mold

Our injection molding process ensures high levels of surface and dimensional accuracy for smooth finishes.
When the substrate is a thermoplastic, scrap material can be gathered and remelted for successive injection rounds. Components can also be produced quickly without requiring a costly amount of manual labor or human oversight.

Injection Molding Design Considerations

Our injection mold design considerations are vital ways to efficiently produce long-lasting components. Finding the right design service will ensure that all your components are built using reliable, repeatable processes.

  • Adding an insert into the part design for product assembly
  • Hollowing out thick portions of a part with built-in ribs to avoid over-thickness while still preserving its structural stability and strength
  • Incorporating the right degree of draft angles into the design for easy part ejection
  • Incorporating complex additions such as text, joints, and hinges


Our overmolding is an injection molding process that layers one material over another during the fabrication process. Many types of plastic or rubber can be added on top of the metal substrates to create more comfortable, colorful, or ergonomic components. Depending on the compatibility of the two materials, plastics and rubbers can also overmolded an initial plastic substrate. Some of our overmolding projects use more than two materials, especially if the layers are connected through mechanical interlocks rather than simply curing together.

Insert Molding

At PTR Group, we use insert molding as another type of injection molding that uses multiple materials. In this process, we place a preformed insert into the mold before closing it. Then, we inject melted substrate into the mold, where it hardens around the insert. We frequently use this technique to create threaded and electrical parts. Insert molding is often the faster molding process, and overmolding creates long-lasting and safe components when completed correctly.

Request additional information about our injection molding services.