Insert molding service

Create strong, durable parts with thermoplastic
injection molding around pre-placed inserts.

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What is insert molding?

Insert molding involves the injection of plastic around a pre-placed insert to shape a strong, durable, and permanent bond between the molded plastic and an insert. During production, an insert is placed inside an empty mold cavity which is then filled with molten thermoplastic and cooled to form a solid part. Cost-effective, precise, and consistent, insert molding is suitable for low to high volume production.


Ordering insert molded parts with Fast Radius is simple. Upload your CAD file to our Cloud Manufacturing Platform™, work with our experts to optimize your design and choose your production material, and then manufacture your products with the click of a button. We also offer heat-staked inserts as a post-processing option for other thermoplastic manufacturing projects.


For more on-demand manufacturing options, browse our injection molding capabilities, including our overmolding services.

Design considerations

Fast Radius injection molding services enable you to manufacture parts to meet a variety of functional needs. Unlock the potential of your insert molding project with the following injection molding design considerations: 

Substrate wall thickness
  • The thickness of the substrate’s wall determines how effectively the overmold material flows in, on, and around the substrate. Due to temperature differences between substrate and overmold materials, having an inconsistent wall thickness can lead to warping, increase flash, and render fills incomplete.
  • Ensure that the wall thickness of the substrate and thickness of the overmold are even and consistent from the beginning of the process. Wall thicknesses ranging from 0.060″ to 0.120” (1.5 mm-3 mm) will ensure good bonding in most overmolding applications.

Insert molding general process information

Maximum part size​

  • 800 x 800 x 400 mm
  • 31.5 x 31.5 x 15.7 in
Minimum part size
  • 5 x 5 x 5 mm
  • 0.2 x 0.2 x 0.2 in


  • Best achievable tolerance: ±0.001″ (0.025mm)
  • Standard: ±0.005″ (0.127mm)
  • For larger part tolerances please contact a Fast Radius engineer
Lead time
  • As low as 2 weeks for T1 samples
  • After T1 sample approval, lead time for <10,000 parts is as low as 1 week

Tool validation

  • Standard process is to produce a small set of T1 samples for approval before initiating full production

Maximum press size

  • 800T

Minimum order size

  • 100 parts and $5000

Set-up fee

  • $500 per mold per order (applies to sample runs
    after initial T1 samples or engineering changes)

Insert molding tooling information

Rapid tooling

  • Molds with steel cavity and core with a shot life of 5,000-10,000 shots
  • Typically machined in 2 weeks
Production tooling
  • Steel tool with shot life up to 1M shots
  • Ability to integrate side-pulls or cam-actions
  • Typically machined in 3 weeks
Multi-cavity or family molds
  • Multiple identical cavities or family of parts machined into a single tool
  • Allows for more parts to be produced per shot, minimizing unit costs


  • Inserts are placed into the mold and molding occurs around them to extend tool life for critical features
  • Allows for inserts such as helicoils to be molded in your design

Thermoplastic injection molding materials

Most common materials

Acrylonitrile Butadiene Styrene (ABS)

Polyethylene (PE)

Polypropylene (PP)

Polycarbonate (PC)

Other supported materials

Nylon (PA 6, PA66, PA12)

Polycarbonate/Acrylonitrile Butadiene Styrene (PC/ABS)

Polyurethane (PU)

Polymethyl Methacrylate (PMMA/Acrylic)

High Density Polyethylene (HDPE)

Low Density Polyethylene (LDPE)

Polystyrene (PS)


POM (Acetal/Delrin)

Polyethylene Terephthalate (PET)

Thermoplastic Elastomer (TPE)

Thermoplastic Vulcanizate (TPV)

Polyetherimide (PEI)

Polysulfone (PSU)

Inquire for additional options

Additives and fiber

UV absorbers

Flame retardants



Glass fibers

Insert materials



Stainless steel

Aluminum 6061

Aluminum 7075


Polypropylene (PP)

Polyamide (Nylon)

Acrylonitrile Butadiene
Styrene (ABS)

Injection molding finishing and

We can apply a range of injection molding finishing and post-processing options to insert molded parts:

Insert molding colors, finishing,


Pantone color matching

RAL color matching

Finishing and post-processing options

Standard SPI finishes (A2-D3)

Mold-tech textures also

Pad printing

Inserts (e.g. heat stake inserts)

Light assembly

Protective packaging / film

Get an instant quote for your insert molding project

Use our quoting platform for quick quotes on injection molded parts.

Why choose insert molding?

Versatile and cost-effective, insert molding offers the following key benefits
and challenges:


  • Precision production at low or high volume
  • High quality, permanent bonds
  • Strong, durable final products with reduced assembly and labor costs
  • Multi material production possibilities
  • Different inserts offer different mechanical qualities and 
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  • Requirement to use suitable resins to prevent plastic cracking around insert
  • Slight increase in molding costs due to increased cycle time required for each part to add the inserts
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Insert molding applications

From functional prototypes to full production runs, insert molding’s key industrial applications include:

Consumer-facing products

Insert molded parts can be created from a variety of high quality materials with finishing options that are ideal for consumer-facing products.

car key remote

Low volume production

Insert molding offers consistency and cost-effectiveness and is an ideal process for low-volume manufacturing projects.

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Handheld devices

Insert molding is used widely in the production of handheld devices, such as scissors, screwdrivers, remote control coverings, case assemblies, knobs, and dials. Insert molding is also used in the manufacture of medical implants.
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Aerospace and automotive

Strong and durable, insert molded parts are used in a variety of aerospace and automotive contexts, where they are manufactured to meet precise industry standards and certification requirements.

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Explore insert molding news
and industry updates

Find industry news, resources, insight into the insert molding process, and more, on the
Fast Radius blog:

Critical design and production guidelines for insert molding

Heat vs. ultrasonic insert molding

Plastic injection molding: From material options to when to use it

Fast Radius manufacturing solutions

Fast Radius manufacturing solutions, including insert molding, are used by businesses across the world. Learn more about our manufacturing capabilities:

CNC Machining

Automated CNC turning and 3-axis and 5-axis milling, using rotating drills, end mills, and lathes.

3D Printing

Fast, scalable, and cost-effective 3D printing technology for a variety of industrial applications.

Urethane Casting

Versatile mold-casting for the production of robust urethane components, customizable with colors and textures.

Injection Molding

Cost-effective plastic injection molding for precision, durable parts and low to high-volume production runs.

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