Global supply chain uncertainty and shifting cost structures are changing the landscape of modern manufacturing. Speed-to-market, flexibility, and proximity to production partners are no longer luxuries—they’re requirements for staying competitive.
In this environment, plastic injection molding stands out as a reliable, scalable method for producing high-precision plastic parts. Thanks to its efficiency and repeatability, injection molding is used across industries like automotive, medical, consumer products, and electronics to produce functional components.
Choosing the right plastic injection molding company can impact everything from part quality to production lead time and cost. Not all providers offer the same services, so it’s important to evaluate them based on experience, equipment, support, and quality.
In this article, you’ll learn everything about the best plastic injection molding companies in the United States, including what they offer, how they compare, and which might be the right fit for your specific project.
How Does Plastic Injection Molding Work?
Plastic injection molding is a manufacturing process that involves melting thermoplastics and injecting them under high pressure into a mold. Once inside the mold cavity, the material cools and solidifies into the final part shape.
At the core of the process is the injection molding machine, which typically includes a feed hopper, a reciprocating screw, and a heated barrel. Plastic granules or powder are fed into the hopper, where they’re moved forward by the screw. The frictional action of the screw, combined with controlled external heat, melts the plastic to the appropriate processing temperature.
Once molten, the plastic is injected into a precisely machined mold. As the material cools, it takes the shape of the mold cavity, capturing fine details and maintaining tight tolerances. After cooling, the mold opens and the finished part is ejected.
Advanced techniques like multi-material molding and insert molding can also be used. These allow for the integration of different materials or combining plastic with non-plastic components in a single cycle, useful for products that require built-in reinforcements, electrical contacts, or soft-touch surfaces.
While the basic principles are straightforward, plastic injection molding is a technically demanding process that requires careful control over temperature, pressure, timing, and tooling. When properly executed, it enables high-speed, high-precision production at scale, making it one of the most effective solutions for complex manufacturing needs.
Best Custom Plastic Injection Molding Companies & Services in the US
Finding the right custom plastic injection molding partner can significantly impact your product’s cost, quality, and speed to market. Here’s a list of the best plastic injection molding companies in the US.
1. Quickparts
Year founded: 1990
Headquarters: Seattle, Washington, USA
Quickparts delivers end-to-end plastic injection molding services designed for speed, scalability, and precision, whether you need rapid prototypes or full production runs.
With decades of experience and in-house manufacturing across U.S. and European facilities, Quickparts combines global reach with the efficiency of a localized supply chain. This means faster timelines, better quality control, and real-time visibility into your project.
Quickparts’ injection molding capabilities cover the full product lifecycle: from initial design review and fast-turn tooling to complex, multi-material production at scale. Their engineers work directly with your team to optimize part design, select the right thermoplastic materials (including customer-supplied options), and reduce risk early on.
They specialize in tight-tolerance, high-performance parts for industries like aerospace, medical, and industrial equipment, offering advanced processes like insert molding, overmolding, hot runner systems, and multi-cavity tooling. It also offers a design-for-manufacturing (DFM) review as standard, helping to catch geometry, tolerance, or material issues before tooling begins.. It is ISO 9001:2015 certified and ITAR registered through the Directorate of Defense Trade Controls (DDTC).
Injection molding solutions:
- Quick molded parts: Provide rapid part turnaround with short tool life for fast design validation.
- Prototyping: Use production-grade materials to test fit and function before scaling up.
- Production: Support high-volume runs with durable tooling for consistent, repeatable results.
- Overmolding: Create multi-material components with distinct properties in a single mold cycle.
- Stack molding: Produce multi-level parts efficiently using vertically stacked mold faces.
- Hot runner molding: Reduce cycle times and material waste by keeping plastic in the runner system molten.
- Insert molding: Integrate metal or other inserts into plastic parts for added strength or function.
- Highly intricate tooling: Manufacture complex parts with fine detail and tight tolerances.
- Multi-cavitation tooling: Increase efficiency by producing multiple identical parts per injection cycle.
Other manufacturing and production services:
- CNC machining: Produce precision plastic or metal parts using 3‑ to 5‑axis CNC tools with tolerances as tight as ±0.001
- Stereolithography (SLA): Create detailed, high-resolution prototypes and models using photopolymer resins, ideal for fit, form, and functional testing.
- Selective laser sintering (SLS): Build durable and functional nylon parts without support structures, suitable for complex geometries and fast-turn prototyping.
- Cast urethane: Replicate production-grade parts in low volumes using silicone molds and urethane materials that mimic injection-molded properties and aesthetics. This is a great solution for low volume manufacturing of molded parts.
- Investment casting patterns: 3D print patterns for metal casting applications, like aerospace and industrial tooling. Quickparts Quickcast patterns are lighter, stronger, and more dimensionally stable than wax patterns and other 3D printed solutions.
- Direct metal printing (DMP): Produce complex metal parts directly from CAD with high density and strength using powder-bed fusion technologies.
- Sheet metal fabrication: Cut, bend, and assemble sheet metal into custom enclosures, chassis, or brackets with tight tolerances and professional finishes.
- Die casting: Produce high-volume metal parts with excellent dimensional accuracy and repeatability using zinc and aluminum die casting methods.
- Rapid prototyping: Accelerate early-stage design testing with on-demand parts and prototypes produced via additive and subtractive manufacturing methods.
2. American Tool & Mold
Year founded: 1978
Location: Clearwater, Florida, USA
American Tool & Mold builds custom injection molds for complex, high-volume applications across medical, aerospace, electronics, and consumer product industries. Their services include in-house design, engineering, and manufacturing, with full control over tooling from concept to delivery.
They specialize in multi-cavity, stack, thin-wall, two-shot, and hot runner molds. Projects are supported with mold flow analysis, DFM, and FMEA to ensure production readiness. The company is ISO 9001:2015 and ISO 13485:2016 certified, and ITAR registered.
Injection molding solutions:
- Stack molding: Increase part output by molding on multiple levels within a single cycle.
- Hot runner molding: Reduce material waste and cycle times by eliminating cold runners.
- Two-shot molding: Mold two different materials or colors into a single part during one cycle.
- Unscrewing molds: Mold threaded or undercut parts that require rotational ejection.
- Thin-wall tooling: Produce lightweight parts commonly used in packaging and consumer goods.
Other manufacturing and production services:
- Mold design and engineering: Apply DFM, mold flow analysis, and FMEA during tool development.
- In-house machining: Build mold components using high-speed machining centers, EDM, and automated pallet changers.
- Mold lifecycle services: Maintain, refurbish, and manage tooling throughout its production lifespan.
- Secondary tooling features: Incorporate components like collapsible cores, mechanical slides, and in-mold labeling.
3. Berry Global
Year founded: 1967
Location: Evansville, Indiana
Berry Global manufactures injection-molded caps, closures, and dispensers for diverse markets, including beverage, medical, home care, and industrial applications. The company provides mold tooling and also offers customers compression, cube, insert, or multi-component injection molding services via in-house mold manufacturing or external delivery.
Berry Global operates hundreds of manufacturing lines that include multiple molding technologies and provides end-to-end packaging solutions, including in-mold labeling and high-impact decorating services. They also offer on-site and process services, including evaluation, troubleshooting, and performance validation, to support trials and manufacturing launches.
Injection molding solutions:
- Mold tooling and design: Build molds in-house or deliver molds for compression, cube, insert, or multi-component injection molding processes.
- Insert molding: Enable integration of plastic parts with other materials or components in injection runs.
- Multi-component injection molding: Combine different plastic components or materials in a single molding cycle.
Other manufacturing and production services:
- Decorating and in-mold labeling: Use photo‑realistic printing, pad printing, and flexographic decorating on molded packaging parts.
- Resin reprocessing: Invest in systems to reprocess post-consumer and post-industrial waste into usable plastic pellets.
- On-site technical services: Conduct line evaluations, troubleshooting, performance validation, and training in support of customer operations.
4. Extreme Molding
Year founded: 2002
Location: Menands, New York, USA,
Extreme Molding specializes in silicone injection molding using high-performance materials like liquid silicone rubber (LSR), heat‑cured rubber (HCR), and moldable RTV silicones for consumer and life science markets such as women’s and infant healthcare, pet products, and promotional items.
They operate a full-service manufacturing facility that handles molding, CAD drawing, color matching, secondary operations, packaging, and fulfillment. The company produces FDA-compliant, food-grade, and Class VI silicone components and also offers overmolding, compression, and transfer molding capabilities.
Injection molding solutions:
- Silicone injection molding: Mold custom parts from LSR, HCR, and RTV silicones for consumer and medical applications.
- Overmolding: Mold silicone over plastic or electronics to create integrated, multi-material components.
- Compression and transfer molding: Use these methods for parts not suited to standard injection molding.
Other manufacturing and production services:
- CAD drawing services: Create or review CAD files for manufacturability and mold readiness.
- Color matching: Match silicone parts to specific color requirements.
- Value‑added secondary operations: Perform tasks like adhesive application, ultrasonic insertion, and final inspection.
- Packaging and fulfillment: Handle product packaging, inspection, and direct shipping from their facility.
5. GSH Industries
Year founded: 1986
Location: Strongsville, Ohio, United States
GSH Industries manufactures custom plastic injection molded parts along with extruded plastic, aluminum, and rubber profiles and tubing. They serve markets including automotive, construction, medical, appliance, packaging, and signage. Their process covers design assistance from CAD drawing through die making, molding, and finished product shipment.
Injection molding solutions:
- Injection molding: Produce custom plastic parts using presses from 75 to 1,500 tons for both prototypes and production assemblies.
- Insert molding: Integrate plastic molded parts into assemblies using ultrasonic welding and other secondary joining methods.
- Decorated assemblies: Mold parts that include aesthetic or functional decorations and finishing directly in the injection process.
Other manufacturing and production services:
- Extrude plastic, rubber, and aluminum profiles: Produce custom extruded shapes for various markets.
- Design and engineering: Guide customers from CAD drawing to die making and finished production.
- Fabrication and assembly: Provide secondary operations including tubing fabrication, welding, turning, and trimming.
6. Ironwood Plastics
Year founded: 1979
Location: Ironwood, Michigan
Ironwood Plastics manufactures custom plastic components using precision injection molding, insert molding, overmolding, and reel-to-reel molding processes. They produce high-performance, close-tolerance molded parts for industries including automotive, industrial, medical, electronics, and defense. Their capabilities support molding with engineered resins and the integration of metal or electronic inserts in complex assemblies.
Injection molding solutions:
- Insert molding: Mold plastic over embedded components including metal, sensors, or wiring harnesses.
- Reel-to-reel molding: Mold parts around continuous inserts fed through automated reel systems.
- Overmolding: Mold one material over another to produce layered or multi-functional parts.
Other manufacturing and production services:
- Tool design and build: Create custom tooling and molds in-house for production programs.
- Pad printing and sonic welding: Apply markings and join plastic components through secondary operations.
- Tape-and-reel packaging: Package molded parts using reel-fed systems for automated assembly applications.
7. Murray Plastics
Year founded: 1998
Location: Gainesville, Georgia, USA
Murray Plastics manufactures custom plastic injection molded parts and builds prototype and production molds using a range of thermoplastics, including ABS, polycarbonate, nylon, polystyrene, and HDPE/LDPE. They serve industries such as electronics, packaging, appliance, and industrial markets by supporting clients from design through mold building and finished part delivery. The company offers design services from CAD drawings, prototyping, and tool building to full production and distribution directly to end customers.
Injection molding solutions:
- Custom injection molding: Produce molded parts from ABS, nylon, polycarbonate, polystyrene, and HDPE/LDPE using presses sized for prototypes and production runs.
- Insert molding: Embed plastic parts with components such as electronics or metal inserts during molding.
- Overmolding and two‑shot molding: Combine multiple materials or features in a single part using sequential molding steps.
Other manufacturing and production services:
- Prototype and tool building: Create prototype or full production molds in-house and modify or repair existing molds.
- Secondary assembly and finishing: Apply pad printing, hot stamping, ultrasonic welding, adhesive assembly, thermal insertion, barcode labeling, and part decoration.
- Packaging, inventory, and logistics: Manage finished part storage and direct shipment to end customers.
8. Nicolet Plastics
Year founded: 1986
Location: Mountain and Jackson, Wisconsin, USA
Nicolet Plastics manufactures custom injection-molded parts for markets including medical devices, sporting goods, consumer products, and industrial applications.
Their Mountain facility handles low- to medium-volume work, while their Jackson facility supports medium- to high-volume molding and secondary services. The company provides design support, mold making, and production for tight-tolerance and multi-material parts using a wide range of injection presses and auxiliary equipment.
Injection molding solutions:
- Insert molding: Mold plastic around electronic components, metal inserts, or sub-assemblies.
- Overmolding: Mold layered plastic parts with combined material properties and aesthetics.
- Tight-tolerance molding: Produce components for industries requiring dimensional precision, including medical and electronics.
Other manufacturing and production services:
- Design and engineering support: Assist with part design, DFM, and mold readiness reviews.
- Pad printing, heat staking, and welding: Apply finishes and assemble components using thermal and vibration-based bonding methods.
- Warehousing, assembly, and fulfillment: Package and ship finished parts or assemblies through integrated logistics services.
9. Plastek Industries
Year founded: 1956
Location: Erie, Pennsylvania, USA
Plastek Group designs and manufactures custom and stock plastic packaging products, including caps, jars, containers, and applicators, for industries such as personal care, cosmetics, home care, pharmaceutical, food and beverage, medical, aerospace, and industrial applications.
They provide end-to-end manufacturing from package design and mold toolmaking to injection molding, decorating, assembly, and packaging using hot-runner, high-cavitation, stack, and multi-shot molding machines.
Injection molding solutions:
- Custom injection molding: Mold rigid packaging parts using high-performance materials such as HDPE, PP, LDPE, and PCR.
- Multi-shot and stack molding: Produce multi-component parts and high-output runs using stack tools and electric or all-electric molding machines.
Other manufacturing and production services:
- Package design and development: Create packaging concepts using CAD, Moldflow simulation, rapid prototyping, and part testing.
- Decorating and assembly operations: Apply pad printing, silkscreen, hot stamping, label wrapping, and in-mold labeling; also assemble multi-part packaging using sonic welding and robotic lines.
- Injection blow and stretch blow molding: Produce jars, bottles, and containers using blow molding techniques integrated within packaging assembly lines.
10. Seaway Plastics Engineering
Year founded: 1973
Location: Port Richey, Florida, USA
Seaway Plastics Engineering provides custom plastic and silicone injection molding for highly regulated industries including medical, aerospace, defense, consumer goods, and precision industrial sectors. Their offerings cover product development, prototyping, tooling design/build, injection molding, and full product assembly across multiple U.S. facilities. They support a wide range of materials, including medical-grade thermoplastics and LSR silicone, delivering FDA-registered, ISO 13485 and ITAR/NADCAP-compliant production.
Injection molding solutions:
- Two‑shot and overmolding: Mold multi-material or multi-color parts in a single molding cycle.
- Cleanroom injection molding: Operate ISO Class 7 and 8 cleanrooms for medical and clean assembly requirements.
- EMI/RFI shielding: Apply in-house electromagnetic shielding to injection-molded parts for electronic and aerospace applications.
Other manufacturing and production services:
- Mold design and engineering: Provide DFM, mold flow analysis, FMEA, and tooling guidance from product concept to launch.
- Post-molding operations: Execute pad printing, sonic welding, heat staking, painting, shielding, assembly, and packaging in-house.
- Kitting and distribution: Provide packaging, warehousing, inventory management, and logistics support for finished parts.
11. Valencia Plastics
Year founded: 2000
Location: Valencia, California, USA
Valencia Plastics operates a full-service facility delivering custom injection and blow molding solutions for industries including medical, aerospace, consumer goods, food and beverage, and military applications.
The company offers in-house mold design, tooling, engineering support via CAD and CAM, and secondary services such as pad printing, sonic welding, in‑mold labeling, assembly, packaging, and fulfillment.
Injection molding solutions:
- Insert molding and overmolding: Create multi-component parts through sequential or combined molding techniques.
- High‑cavitation and multi-component tooling: Build molds with hot runner systems and multi-cavity tooling that can produce multiple parts per cycle, including family molds.
Other manufacturing and production services:
- Mold making and engineering: Provide in-house CAD/CAM design, mold tooling, and inventor assistance throughout project development.
- Secondary operations: Apply pad printing, heat staking, sonic welding, hot stamping, in‑mold labeling, and screen printing on molded parts.
- Packaging and fulfillment: Manage part assembly, warehousing, custom packaging, and global distribution from their facility.
- Blow molding: Produce plastic containers using blow molding techniques, in addition to injection molding capabilities.
12. Xometry
Year founded: 2013
Location: North Bethesda / Gaithersburg, Maryland, USA
Xometry is an online on-demand manufacturing marketplace connecting customers to external suppliers for CNC machining, injection molding, sheet metal, and 3D printing. They do not operate injection molding in-house; instead, they manage tool and part production through a vetted network of external manufacturing partners worldwide. Their offerings include prototype molding, bridge tooling, production molding, overmolding, insert molding, compression molding, and LSR silicone services, delivered via their supplier network.
Injection molding solutions:
- Prototype molding: Deliver molded parts using aluminum or soft steel tooling for low-volume validation runs.
- Bridge tooling and production molding: Scale from prototypes to full-volume parts using production-grade steel tooling via external suppliers.
Other manufacturing and production services:
- CNC machining: Provides parts from local and global CNC suppliers via instant quoting and ordering.
- 3D printing: Offers dozens of polymer and metal additive processes for prototyping and production through partner networks.
- Sheet metal, die casting, and urethane casting: Has a broad range of manufacturing processes through networked suppliers.
- Assembly and secondary services: Coordinates secondary operations, kitting, and turnkey solutions via their supplier base.
Partner with the Best Plastic Injection Molder in the US
Finding a supplier that manages both prototyping and production under one roof helps reduce delays, rework, and communication gaps. It’s also important to choose a partner that offers tooling flexibility, material support, and clear engineering input early in the process.
Quickparts is built to help you move faster, lower your risk, and scale with confidence. From design validation to full-scale production, Quickparts offers manufacturing agility that adapts to your timeline and complexity, without compromising quality.
You get direct access to engineering support early in the process, so issues are caught before they become costly. With fully in-house production, you’re not just getting parts, you’re getting control, visibility, and consistent results across every phase.
Need a quote? Upload your CAD files through the QuickQuote platform and get fast, transparent pricing along with DFM input and material recommendations, so you can make informed decisions before tooling even begins.
Ready to create your prototype or start production?
Get your free quote with Quickparts today!
Plastic Injection Molder FAQs
What is the best plastic for injection molding?
There isn’t one single plastic that’s best for every injection molding project. The right material depends on what your part needs to do, whether it must handle heat, resist impact, withstand chemicals, or meet FDA or medical standards.
That’s why Quickparts gives you access to hundreds of commercially available thermoplastics, including options tailored for medical, industrial, consumer, and aerospace applications. Whether you need a commodity-grade material or a high-performance engineering resin, their team will help you select the right plastic based on performance, moldability, and cost.
Which injection moulding machine is best?
The best machine depends on what kind of part you’re trying to make. Important factors include the size of the part, the type of plastic you’re using, the shape or complexity of the part, and the quantity of parts required. Machines are rated by tonnage, which is the amount of clamping force they apply to keep the mold closed during injection. Small parts need less tonnage, while large parts or molds with many cavities need more.
With Quickparts, you don’t have to figure that out yourself. Their team selects the ideal press, from 40T to 1300T, for your project and handles everything from setup to production, so you can focus on your design while they deliver the results.
Should you use aluminum or steel tooling for plastic injection molding?
The right tooling material depends on your production volume, part complexity, and lead time requirements. Aluminum molds are faster to produce and more cost-effective for prototyping or low-volume runs. They’re easier to machine and modify, making them suitable for early design iterations and small-scale production.
Steel molds are more durable and better suited for high-volume manufacturing. They support tighter tolerances, more complex geometries, and longer tool life. Quickparts offers both aluminum and steel tooling, allowing customers to balance speed, durability, and cost across different stages of development
What type of tooling is best for low-volume molding? What about high-volume molding?
Aluminum tooling is typically used for low-volume molding because it machines quickly and allows faster turnaround for prototyping or bridge production. It’s ideal when short runs or early-stage design changes are expected, and tool longevity is less critical.
Steel tooling is preferred for high-volume molding due to its strength and wear resistance. It holds tighter tolerances over longer production cycles, making it suitable for high-use molds where consistency and repeatability are required.
What are the benefits of domestic vs overseas molding?
Domestic molding typically offers shorter lead times, easier communication, and better visibility into quality control. It’s a practical choice for projects that require fast iterations, close collaboration, or strict IP protection.
Overseas molding can reduce unit costs, especially at high volumes, but may involve longer shipping timelines and added complexity around logistics or compliance. Quickparts offers both domestic production and a vetted overseas supplier network, allowing customers to choose based on cost, lead time, and project complexity.
What is the strongest injection-molded plastic?
Strongest can mean different things depending on the application. If you need impact resistance, polycarbonate is commonly used in safety equipment and housings. For heat and chemical resistance, PEEK offers high strength at elevated temperatures and is often used in aerospace and medical parts. Nylon is widely used in automotive and industrial applications because of its mechanical durability and wear resistance.
Some plastics are also available with fillers like glass or carbon fibers to boost strength. These reinforced materials are more rigid and suitable for structural parts, though they can increase tool wear and processing difficulty. Choosing the strongest plastic depends on what kind of strength is most important for your part.
