PTR is thoroughly equipped to handle your component projects with 22 molding machines ranging from 50 to 550 tons.

We at PTR Tool & Plastics use injection molding to create reliable, complex parts and components from polymer substrates in many industries. Our injection molding capabilities are taken to the next level with use of robotics, in-mold decoration, and insert-molding.

Behind the scenes, we offer support services and program management to give you predictable performance, accurate timing and reliable delivery. We manage the process, we manage the program and we push the envelope to ensure that your job is complete and on-spec in every way.

Your part size and shape options are vast. 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.

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. To begin, we design and fabricate a mold to our client’s specifications. Then, we use an injection molding machine to inject molten plastic substrate into the mold. Once the material cools, it solidifies into the exact shape of the mold interior.

Injection-molded parts can be as simple or as complex as the project requires. This process also 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, even for production runs numbering thousands of pieces.

Injection molding uses many automated processes to complete tasks. Before the initial run, a prototype part and mold will be designed via computer numerical control (CNC) machining or 3D printing. Digital models can also be tested to ensure that the correct substrate is selected.

We design parts in several steps to ensure dimensional accuracy and replicability. We also verify that each part is designed with uniform wall thickness to avoid physical reactions such as warping. This injection mold design consideration is an important way to create smooth planes, interlocking connection points, and corners and edges, which gives injection-molded pieces their distinct rounded forms.

Other design considerations include:

  • 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

All these 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.


Overmolding is an injection molding process that layers one material over another during fabrication. 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 overmold an initial plastic substrate. Some overmolding projects use more than two materials, especially if the layers are connected through mechanical interlocks rather than simply curing together.

Insert Molding

Insert molding is 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.

Create High-Quality Molds with PTR Tool & Plastics

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 allow clients a wide range of customization options when designing components.

To request a quote for injection molding and project management services, contact us here.