Manufacture parts with multi-shot thermoplastic injections for enhanced consistency, strength, and durability in high volume projects.
What is overmolding?
Overmolding is an injection molding process in which multiple shots of thermoplastic are injected separately to create a single part. The first thermoplastic injection into a tool or cavity forms a substrate, before an overmolding material is injected into, onto, or around it. The thermoplastic layers bond as they cool to produce a unified and highly durable final product. The bond between substrates depends on the properties of the relevant overmolding materials. Learn more about the bonding process with our material compatibility chart.
Overmolding is ideal for high-volume production runs. Kickstarting your injection molding project is simple. Upload your CAD file to the Fast Radius Cloud Manufacturing Platform™, optimize your design and choose your desired thermoplastic, and then greenlight production with the click of a button.
Unlock the potential of your overmolding project with the following injection molding design considerations, including tooling details, available materials and colors, and finishing and post-processing options.
|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.
|Maximum part size
|800 x 800 x 400 mm
31.5 x 31.5 x 15.7 in
|Minimum part size
|1 x 1 x 1 mm
0.04 x 0.04 x 0.04 in
|Best achievable tolerance: ±0.001″ (0.025mm)
Standard: ±0.005″ (0.127mm)
For larger part tolerances please contact a Fast Radius engineer
|As low as 2 weeks for T1 samples
After T1 sample approval, lead time for < 10,000 parts is as low as 1 week
|Standard process is to produce a small set of T1 samples for approval before initiating full production
|Maximum press size
|Minimum order size
|100 parts and $5000
|$500 per mold per order (applies to sample runs after initial T1 samples or engineering changes)
|Molds with steel cavity and core with a shot life of 5,000-10,000 shots
Typically machined in 2 weeks
|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
|Premade parts are placed into the mold and molded over
Allows for multi-material injection molding
|Most common materials
|Other supported materials
|Additives and fiber
|Acrylonitrile Butadiene Styrene (ABS)
|Nylon (PA 6, PA66, PA 12)
|Polycarbonate/Acrylonitrile Butadiene Styrene
|Polymethyl Methacrylate (PMMA/Acrylic)
|High Density Polyethylene (HDPE)
|Low Density Polyethylene (LDPE)
|Polyvinyl chloride (PVC)
|Polyethylene Terephthalate (PET)
|Thermoplastic Elastomer (TPE)
|Thermoplastic Vulcanizate (TPV)
|Inquire for additional options
|Finishing and post-processing options
|Pantone color matching
|Standard SPI finishes (A2-D3)
|RAL color matching
|Mold-tech textures also available
|Inserts (e.g. heat stake inserts)
|Protective packaging / film
Get an instant quote for your overmolding project
Use our quoting platform for quick quotes on injection molded parts.
Why choose overmolding?
Overmolding produces strong, long-lasting parts for improved component reliability.
Explore the key benefits and challenges of the process:
- Strong, durable parts
- High consistency and precision
- Customization potential
- Cosmetic finishing options
- Create safe, comfortable parts for customer end-use
- Requirement to check compatibility between thermoplastic materials
- Precision set-up required to prevent fractures.
- Requires 2 mold cavities to produce the substrate and the overmold
- Upfront design and tooling costs
Overmolding is used to produce customized parts and components for a variety of applications:
The overmolding process is useful for the manufacture of niche, durable parts, including gaskets, filters, and brackets. Overmolding is also suitable for functional prototyping.
Overmolding produces consistent parts quickly with low tooling costs, and is ideal for projects with high volume production requirements.
The overmolding process is capable of creating specialized parts with complex dimensions, making it particularly useful for manufacturing medical devices and instruments, and high-end consumer-grade products.
Overmolding offers a range of customisation and finishing options, and can be used to add grips, buttons, knobs, and other ergonomic features to pre-existing parts while minimizing additional labour.
Fast Radius manufacturing solutions
Fast Radius manufacturing solutions, including overmolding, are used by businesses across the world. Learn more about our manufacturing capabilities: