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Last updated: January 2026
This directory lists 41 gas assist molding companies across the United States, from specialty molders focused on large, complex parts to integrated manufacturers offering full assembly and finishing services.
Buyers typically engage gas assist molding companies to solve persistent challenges like minimizing sink marks and warpage in thick-walled sections, reducing part weight, and improving dimensional stability. This often involves optimizing gas channel design to ensure consistent internal pressure and reduce material stress, particularly for components where structural integrity or aesthetic appeal is paramount.
Suppliers in this space range from highly specialized shops with a few large tonnage presses dedicated to gas assist, to larger, diversified injection molders who offer it as one of many advanced processes. Some focus on specific markets like automotive or medical, while others serve a broader industrial base. The key differentiator is often their depth of expertise in mold design for gas assist and their ability to execute complex plunger displacement sequences.
To engage effectively, buyers should prepare detailed part CAD files, material specifications, and clear functional requirements including stress points and critical dimensions. Suppliers will expect to discuss anticipated production volumes, quality standards, and any post-molding processes required. Be ready to articulate specific performance goals that gas assist is intended to achieve, such as weight reduction targets or the elimination of specific cosmetic defects.
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41 companies nationwide
Based in Riverside, CA, Advanced Engineering & Molding is a custom plastic injection molding company. They specialize in gas assist molding, overmolding, and insert molding, offering comprehensive services from tooling design to final assembly. Serving various industries, they provide complete manufacturing solutions.
Based in Lenoir, NC, Bemis Contract Group specializes in custom plastic injection molding, including gas assist molding. They offer full-service capabilities for large parts, encompassing welding, decorating, and quality control. Their expertise serves markets such as recreational products, lawn & garden, and furniture manufacturing.
Based in Hutchins, TX, Cary Products is an ISO 9001:2015-certified plastic manufacturer specializing in custom injection molding and thermoforming services. They provide durable, cost-effective parts using advanced 3D design technology and extensive tooling capabilities. Serving automotive, HVAC, and medical sectors, they deliver tailored solutions.
Based in New Berlin, WI, CoreMT specializes in advanced injection molding solutions, including structural foam molding, gas assist molding, and overmolding. The company provides custom plastic manufacturing services for various industrial and commercial applications, utilizing modern technologies to produce complex, high-quality components.
Based in Freedom, PA, Crescent Industries is an experienced provider of custom injection molding, tooling, and post-molding services. With over 75 years of expertise, they specialize in plastic overmolding and offer design for manufacturing principles. The company serves the medical, military, and industrial/OEM markets, delivering high-precision plastic parts.
DPI Plastics provides custom plastic injection molding services, specializing in a wide range of processes including gas-assist molding, overmolding, and insert molding. Based in Ceredo, WV, the company offers comprehensive solutions from part design and engineering to tooling, assembly, and quality control for diverse industries.
Based in Corry, PA, Entech Plastics specializes in gas assist molding services. They inject nitrogen gas into the hot melt stream during the molding process, displacing resin in thick-walled sections to create a hollow core. This enables the production of lightweight, structurally sound plastic components.
Based in West Des Moines, IA, Engineered Plastic Components, Inc. provides injection and gas assist molding services. Capabilities include two-shot molding, assembly, sub-assembly, sonic welding, and hot plate operations. They utilize presses ranging from 25 to 4000 tons, serving various industrial clients across multiple US facilities.
Based in Grandville, MI, HL Advantage is a family-owned plastic injection molding company. They specialize in a diverse range of services, including gas assist molding, overmolding, insert molding, and assembly. The company provides high-quality plastic components and prototypes for various industrial applications.
Hoffer Plastics, based in South Elgin, IL, specializes in custom injection molding services. Their offerings include gas-assisted, multi-shot, and insert molding, alongside MuCell technologies. They provide comprehensive solutions from tooling and engineering to value-added assembly, serving diverse industries as a MedAccred accredited molder.
Intertech Plastics is a custom injection molding company based in Denver, CO, with over 40 years of experience. They provide advanced custom injection molding solutions with 50+ presses (30 to 1,500 tons) for medical, consumer goods, and industrial sectors, emphasizing precision and zero-defect results.
Based in Fenton, MO, Koller Craft specializes in custom plastic injection molding, offering advanced gas assist molding capabilities. With over 80 years of experience, the company provides high-quality molded parts for various industries, including automotive, medical, packaging, and consumer markets.
Based in San Jose, CA, KS Plastic Inc. is a plastic injection molding manufacturer specializing in Gas Assist Injection Molding. The company provides comprehensive services including standard injection molding, overmolding, insert molding, and micro molding for OEMs across diverse industries. They also offer tooling, CNC machining, and assembly solutions.
Mack Molding provides custom plastic injection molding services, specializing in gas assist molding for strong, lightweight, and complex parts. Their capabilities include precision molding for small to large parts, clean room environments, automated assembly, and Class A painting, utilizing presses from 28 to 4,000 tons.
Based in Washougal, Washington, PILLER AIMMCO is an integrated manufacturer providing custom injection molding services. They specialize in thin wall, low pressure, overmolding, and complex, tight-tolerance parts. With 45 presses and 24/7 production, they offer in-house mold design, tooling, and prototyping. Industries served include automotive, medical devices, aerospace, and consumer electronics.
Plastech Corporation is a contract injection molder specializing in gas-assist plastic molding. Based in Rush City, MN, the company offers a range of services from part design and mold to high-volume output. Serving various industries, Plastech focuses on custom project solutions.
Plastic Molding Technology offers over 50 years of expertise in plastic molding services. With multiple U.S.-based facilities, they provide comprehensive solutions for molding, assembly, and tool building. The company specializes in serving demanding industries such as aerospace and medical.
Based in Upland, CA, Precision Molded Plastics Inc. is a vertically integrated plastic injection molding company. They specialize in building custom molds and tooling, and manufacturing a wide range of plastic parts and products. Their comprehensive services cater to diverse industries.
PSI Molded Plastics is a custom injection molder offering Gas Assist Molding, Structural Foam, and small to large part injection molding. With manufacturing facilities in SC, IN, and NH, they provide comprehensive services, including finishing, assembly, and custom color matching, for industrial clients.
Based in Gainesville, TX, Reliant Worldwide Plastics is a custom plastic injection molding company. They specialize in gas-assist injection molding, insert molding, overmolding, and assembly. The company also offers plastic part design and engineering, providing comprehensive manufacturing solutions for various industries.
Romeo RIM specializes in structural foam molding and reaction injection molding (RIM) for large, complex plastic parts. This manufacturer provides comprehensive services including tooling, assembly, and finishing. Based in Bruce Township, MI, Romeo RIM focuses on delivering lightweight, durable, and structurally sound components for diverse industries.
Structural Foam Molding (SFM) specializes in providing gas-assisted injection molding services. They focus on producing lightweight, high-integrity parts that deliver enhanced performance and cost efficiency. Their advanced molding techniques serve industrial clients seeking durable and precision-engineered components.
Based in Gardena, CA, Techni-Mold & Engineering Inc specializes in custom plastic injection molding services. They offer gas assist molding, insert molding, overmolding, and in-house tooling development. Serving industries like medical, automotive, and electronics, the company provides comprehensive manufacturing solutions for complex components.
Plastic Industries, based in Athens, TN, specializes in custom plastic injection molding and Gas Assist Structural Foam Molding. Operating since 1955, they offer in-house tooling and warehousing, producing parts for industries such as medical, aerospace, and military. All facilities are ISO 9001 certified for quality assurance.
20/20 Custom Molded Plastics provides custom high and low-pressure injection molding solutions, including structural web and gas assist molding. They specialize in developing new and existing applications to achieve cost reduction and superior part performance. The company offers expertise in engineering, tooling, and quality assurance for large, structural components.
Based in New Albany, OH, AdvancTEK specializes in gas-assisted injection molding for custom plastic manufacturing. They solve complex challenges, reduce costs, and improve part quality across various sectors. With over 35 years of expertise, AdvancTEK serves industries such as battery & energy storage, medical, and telecommunications.
Based in Hartford, WI, CDM Tool & Manufacturing specializes in building custom gas assisted molds for complex plastic parts. Their precision CNC shop and design team offer comprehensive plastic injection mold manufacturing services, utilizing advanced machining capabilities for various industrial applications.
Based in Franklin Park, IL, Cortina Tool & Molding provides custom plastic injection molding services. They specialize in high-pressure foam molding, achieving superior surface finishes and eliminating sink marks in plastic parts. This American manufacturer offers cost-effective solutions from concept to production for diverse industrial and commercial clients.
Based in Butler, IN, DeKALB Plastics is a custom structural foam molder specializing in large, multi-nozzle plastic products. The company provides gas assist molding services, utilizing pressurized nitrogen gas to hollow strategically placed sections. They focus on optimizing designs and minimizing costs for industrial applications.
Based in DeForest, WI, EVCO Plastics is a global contract manufacturer specializing in plastic injection molding. The company operates multiple facilities across the United States, Mexico, and China, partnering with clients to develop projects from concept to completion and providing comprehensive manufacturing solutions.
Based in Hartland, WI, Fathom Manufacturing provides contract manufacturing with advanced engineering and deep industry expertise. Specializing in precision injection molding, they efficiently move products from concept to production. Fathom serves critical sectors including Aerospace & Defense, Medical, Automation & Robotics, Semiconductor, and Automotive & EV markets.
Based in Costa Mesa, CA, JG Plastics Group LLC specializes in constructing tooling for demanding, close-tolerance parts. Leveraging scientific molding principles and decades of mold making and injection molding experience, they offer comprehensive expertise in complex plastic manufacturing.
Based in Mount Pleasant, IA, Lomont Molding LLC is a plastic molding company. They directly provide Nitrogen Gas Molding, an injection molding process using pressurized nitrogen to create hollow, lightweight, and strong components. Their capabilities also include high-pressure injection molding, blow molding, structural foam, and over-molding.
Midwest Molding, Inc. manufactures high-quality, complex components and assemblies for the automotive, transportation, electronics, and consumer goods industries. Services include Reel to Reel Continuous Strip Molding, Two Shot Molding, Pre-Mold & Overmolding, Gas Assist Molding, and various assembly processes. They also provide engineering consultation.
Petersen Molding Corporation, based in Norwalk, CA, is a plastic injection molding manufacturer. The company specializes in producing custom plastic components, offering a comprehensive suite of services including advanced gas assist molding capabilities. They serve various industrial markets, focusing on precision and quality for their diverse client base.
Based in Corona, CA, PreProduction Plastics Inc. (PPI) is an ISO 9001:2015 and UL certified family-owned business. They directly provide comprehensive plastic molding services, including Gas Assist molding, Gas Counter Pressure, and standard injection molding. Capabilities extend to in-house tooling, engineering design, CNC machining, assembly, and finishing for diverse plastic products.
Based in Conroe, TX, Precision Interior Products LLC specializes in custom plastic injection molding, including conventional and gas assist injection molding. They provide comprehensive solutions from prototyping and tooling to overmolding, insert molding, and final assembly services for various industries.
PTA Plastics is an employee-owned custom plastic injection molder specializing in high-precision components for diverse applications. They provide comprehensive injection molding solutions, including DFM and in-house moldmaking capabilities. Certified to ISO 9001:2015 and ISO 13485:2016, the company leverages advanced technology and precision engineering to deliver high-quality plastic parts.
Thunderbird Molding provides high-precision custom plastic injection molding and contract manufacturing services from multiple US facilities. They offer comprehensive mold design, prototyping, engineering, production, and assembly. The company focuses on helping clients improve costs, reach performance potential, and accelerate time to market.
Based in Holyoke, MA, Universal Plastics is a custom plastics manufacturer specializing in gas assist injection molding. They produce large, complex plastic parts with superb cosmetic surface finishes. The company also provides thermoforming, standard injection molding, and comprehensive finishing and assembly services for diverse industrial applications.
All-Plastics, LLC is a custom plastic injection molding company based in Kerrville, TX. The company specializes in manufacturing various plastic components, offering comprehensive services from design to production. As a full-service plastics manufacturer, they directly provide diverse molding solutions for industrial and commercial clients.
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Prioritize suppliers who can demonstrate fine-tuned control over gas injection pressure profiles and plunger displacement sequences. For complex parts or those requiring very high cosmetic standards, look for systems capable of multi-stage gas injection and real-time pressure monitoring within the mold, which is crucial for uniform internal channeling and preventing issues like gas blow-through or inconsistent wall thickness.
A supplier's expertise in gas channel design is paramount, often more so than general molding experience. Poorly designed gas channels can lead to inconsistent gas penetration, residual stress, sink marks, or even gas breakthrough to the surface. Look for a partner who uses advanced simulation software for gas flow analysis and can provide examples of successful gas channel designs for parts similar to yours, demonstrating their ability to optimize for both structural integrity and aesthetics.
A frequent mistake is underestimating the specialized nature and cost of gas assist tooling. Unlike conventional molds, gas assist tooling requires precise gas entry points, often incorporating gas pins, and must withstand higher internal pressures. First-time buyers sometimes push for generic, cheaper tooling that isn't optimized for gas flow, leading to increased cycle times, higher scrap rates, and long-term quality issues. Always discuss tooling longevity, maintenance, and the supplier's specific experience with gas-assist mold builds.