Plastic Injection Molding

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front panel and chamber of an injection molding machine

Expertise with Complex Products

Cadrex has been a leader among plastic injection molding companies for over 50 years. Our early engineering involvement allows us to mitigate product design issues and costs during the new product introduction (NPI) process while decreasing time to market.

Our experience tackling complex product design, temperamental specialty materials, and intricate tool builds makes us an ideal plastic injection molding manufacturing partner for your next program. With our state-of-the-art plastic injection molding machines in Mexico and across the United States, Cadrex is the premier plastic injection molding manufacturer in North America. You can count on a dedicated team of experts to work with you throughout the product lifecycle, assisting with initial parts discussions and the production launch.

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Injection Molding Capabilities

  • 36 Injection Molding Machines

    Plastic injection molding machines are categorized by tonnage, or the amount of force it takes to hold the mold shut. Horizontal molding, performed on a machine that opens and closes on a horizontal path, is the most common type of molding where parts drop into a box or onto a conveyer belt. In contrast, vertical molding is ideal for overmolding or insert molding because gravity helps the part being overmolded stay in position.

  • Engineering & Commodity Grade Resins

    Commodity grade resins are often less expensive and easier to process than other plastics. They are the most common type of plastic molding material, can be easily mass produced, and are used for a wide variety of consumer goods. Engineering grade resins are plastics that are designed to withstand specific conditions, giving them qualities like high heat resistance, chemical resistance, or strength. Companies that produce materials for injection molding will design custom resins that are formulated to meet specific application requirements.

  • Structural Foam Molding

    In structural foam molding, a foaming agent is mixed with resin, the mixture is injected into a mold and heated into a gas, and the gas forms a thick skin on the inside wall of the mold. The process uses less material and creates lighter parts than other molding processes. Learn more about structural foam molding.

  • Insert Molding

    Insert molding involves placing preformed parts or metal inserts into a mold, where molten plastic flows and hardens around the object. Insert molding services often eliminate the need for post-production assembly and ensure a tight bond between the plastic part and its inserts. Learn more about insert molding.

  • Post-mold Machining

    Post-mold machining is work performed on injection molded parts to give them their final shape, improve their appearance, and provide additional properties (like enhanced strength or durability). Our expanded precision machining capabilities provide the potential to complete or assist in the production of a part when paired with plastic injection molding.

  • Conveyor Paint Line, Pad Printing, & Silk Screening

    Cadrex offers a myriad of mechanical assembly and finishing solutions, including conveyor paint line systems, pad printing, and silk screening. Products move through a conveyor paint line for finishing applications, like coat paint, powder coating, or wet spray. Pad printing is the process of transferring a 2-D image onto a 3-D object or part. Silk screening is a method of transferring ink or dye onto a base material or fabric around a stencil.

Increased Efficiency

Injection Molding Automation

Cadrex's plastic molding operations incorporate multiple forms of automation and robotics, including custom fixtures to increase efficiency, quality, and ergonomics. Depending on our customers' program requirements, we have the expertise to incorporate pick-and-place automation or a robotic operator for faster and more consistent cycle times, better labor utilization, and lights-out manufacturing.

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A pick and place crane system for an injection molding machine

How it Works

Plastic injection molding is the process of injecting plastic material into the mold cavity of a metal tool, which then cools and ejects a plastic part from the machine. Most plastic products we see and use daily are made using this manufacturing process.

Plastic injection molders, or machine operators, load resin, a generic term for plastic material, into a plastic injection molding machine in the form of a pellet. A screw, called the reciprocating screw, rotates the plastic into a heated barrel. Friction and the heated barrel melt the plastic, which accumulates in front of the screw. The screw then pushes the molten plastic through a nozzle into the mold, where cooling channels help it cool and harden. The mold opens after a predetermined cycle time, and the machine ejects the plastic part and repeats the process.

Uses of Plastic Injection Molding

Products made from plastic injection molding are found everywhere from the car in your garage to the kitchenware in your cabinets and bottles of water in your refrigerator. The manufacturing process allows for high production rates and repeatability at a low cost per part. Therefore, it is often the best choice for packaging, plastic parts, and disposable medical devices. The flexibility and properties of plastic make this a solution when creating mechanical parts, casings for electronics, and construction materials.

Common Injection Molding Materials

Engineering Grade

Acetal (POM), PBT/PET (GF & Non GF), PC/ABS, PC/PET, Polyamide (Nylon 6 & 6/6) (GF & Non GF), Polybutylene Terephthalate (PBT), Polycarbonate (PC), Polyether Ether Ketone (PEEK) (GF & Non GF), Polyether Imide (PEI) (Ultem), Polyethylene Terephthalate (PET), Polyphenylene Ether (mPPE), Polyphenylene Sulfide (PPS), Polyphthalamide (PPA) (GF & Non GF)

Commodity Grade

Acrylic (PMMA), Acrylonitrile Butadiene Styrene (ABS), Polyethylene (PE) (HDPE) (LDPE), Polypropylene (PP), Polystyrene (PS) (HIPS), Styrene Acrylonitrile (SAN)

Injection Molding Design Guide

Learn more about the injection molding process including terms, definitions, and industry best practices. 

Read Design Guide

Closeup of an injection molding tool

Tooling Design & Build

Our highly talented injection molding tooling engineers can design simple and highly complex single-cavity, multi-cavity, and family tools. Actions can be built into your tool depending on the complexity of your injection molded part to ensure you get the look and function needed.

Our plastics operation utilizes domestic and international suppliers for the tool build, which our in-house engineers closely monitor. We constantly communicate with our suppliers to keep your tools on schedule and monitor quality. Maintenance and repairs are taken care of by our in-house tool room.

Metal & Plastic Overmolding

Structural Foam Molding

Related Links

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