Injection Molded Plastics & Injection Molded Plastics Manufacturers

Injection Molded Plastic is resin that has been heated until molten and then forced into a pre-made mold or cavity in the shape of the intended plastic product or object. When the melted plastic has cooled and hardened, the mold is removed to reveal a hard, plastic part in the shape of the mold cavity. Products made from plastic injection molding, or custom injection molding, include a wide range of everyday household items such as mop buckets, plastic containers, screw driver handles and even video game cartridges.

Injection molding can use a wide variety of starting materials, including most polymers. Plastic injection molding gives the injection moulders the freedom to choose exactly what the best material for the final molded plastic part would be and requires a lot of calculation as to composition of the resin as well as temperature and pressure in the mold. All these variables can affect the final quality of the plastic. Injection molding uses thermoplastics, called thermoplastics injection molding, thermoset materials or elastomers, depending upon the intended use of the final product. Thermoplastics and thermosets harden completely after cooling in the plastic injection mould; elastomers however, retain a sense of elasticity and so are used to produce items such as rubber bouncing balls. Other variations of plastic molding, or insert molding, include gas assist injection molding which uses an inert gas, such as nitrogen, to create a hollow portion in the mold, and to force the molten plastic into the mold cavities. Another is reaction injection molding; reaction injection molding machines require one further step which is the addition of a curing agent in the mold. This is required for the specific product material to maintain shape and strength once removed from the mold.

Some Leading Manufacturers

Britech Injection Molded Plastics

Stuart, FL | 772-286-9278

We have over 25 years of rapid injection molding experience. We specialize in custom injection molded thermoplastic parts using complex tooling and resins. Our injection molded plastics are used in many industries including automotive, military and government, aerospace, and more! We have established a reputation of superior customer service and quick turnaround with our worldwide customer base. If you are in the market for injection molded products, trust Britech Injection Molded Plastics!

Xcentric Mold & Engineering, Inc.

Clinton Township, MI | 586-598-4636

Xcentric Mold & Engineering, Inc. specializes in low-volume custom injection molding and CNC machined parts. We have advanced mold making systems and offer fast solutions with quick turn-around. Our state-of-the-art equipment can make molds that can produce an unlimited amount of quantities making us the best choice for both small and large quantities. We look forward to meeting all your injection molding needs! Call us today or visit our website for more information!


Holland, OH | 419-867-3900

In business since 2003, ICOMold has gained a reputation as a leader in low-cost, high-quality injection molded plastics. Headquartered in Holland, Ohio, we serve many industries and provide injection molded plastics to customers around the globe. Our online quote system provides fast quotes for your injection molded plastics projects.

GSH Industries, Inc.

Cleveland, OH | 440-238-3009

Here as GSH Industries we are known for quality work and excellent service! We have 15 injection molding machines ranging from 75 to 1,500 tons. We have the capabilities to make a wide variety of custom made prototypes. Our engineers and designers have many years of experience in the industry and will work with you to determine the best materials, design, and assembly methods for your project! Call us today to learn more!

Penguin, LLC

Sturgis, MI | 269-651-9488

Here at Penguin, we offer a variety of plastic molding services, including injection molding and blow molding. With presses from 260 tons to 1000 tons, we have the capabilities & resources to meet all of your injection molded plastic requirements. We work with you from start to finish to design, develop, manufacture, and deliver a plastic solution for your specific applications. Give us a call today to see how we can serve you!

Montrose Molders, Inc.

South Plainfield, NJ | 908-754-3030

Montrose Molders has been manufacturing molded plastic products since 1966. We utilize 51 different injection molding presses, ranging from 50 tons to 1000 tons, to manufacture all kinds of molded plastic parts and components. Over the course of nearly 50 years, we have continued to utilize the latest and most innovative technologies to bring you the very best! We can handle your molding project from concept to production, so give us a call!

The basic machinery used in the process of injection molding consists of a hopper – where the plastic pellets are placed prior to being heated. The plastic material is then fed into a heating unit where it is heated and mixed until molten, at which point dyes or other chemical agents can be added to change the final appearance and feel of the product. Next, an injector, or screw, forces the molten plastic into the mold cavity under hydraulic or mechanical pressure, to ensure that there are no air pockets. Most molds will allow air bubbles to escape to avoid damaging the final product. Cooling liquids are sometimes used around the mold chamber of the machine to extract heat from the plastic and speed up the cooling process, thus saving time in overall manufacturing. The two halves of the plastic injection mold are then pulled apart to release the plastic part. Ejecting pins or rods may have to be used to remove the plastic part from the mold. The entire process can take a matter of seconds or as many as a few minutes to get one complete plastic part. Injection molders are not limited by manufacturing capabilities when it comes to material choice, and are able to fabricate a wide range of product shapes and sizes. If a mold can be made for an object, plastic molding can be used to produce a product. Everything from car bumpers to intricate medical equipment can be made using the techniques of melting the appropriate material, forcing it into a pre-made cavity and allowing it to cool.

Compared to other forms of plastic parts production, injection molding is a cost effective manufacturing method. It can be used for high production runs, and in fact the more parts that are made from a mold, the more cost-effective it is. Once a mold has been made for a certain product, it can be used again and again to produce the same object with close tolerances. In injection molding, there is little or no change in the manufacturing process between cycles, and so often the plastic part extricated from the mold will need little finishing. Furthermore, because the molten plastic is forced only into the space of the cavity, there is very little material waste apart from joining lines and negligible other amounts. The production of minimal scrap saves further money and is a responsible manufacturing practice. Furthermore, what plastic is wasted and considered scrap can often be melted and recycled. Labor costs for the injection molding process are minimal as there is little need for human interference in the injection process.

There are important considerations to be made when discussing plastic injection molding however. Firstly, all the plastic material that is forced into the mold needs to be removed at some point, therefore mold design needs to be carefully considered. A complex rigid, square design might result in cracks or stress marks on the final product when trying to extricate it from the cavity. There also needs to be rods or pins in place to help remove the plastic part from the mold. Plastic injection molds are costly and so it is imperative to ensure that the plastic part can be removed from it once cooled. Another consideration concerning removal is the existence of joining lines, or imperfections in the final products that may require finishing services before being used. The finishing required will usually be minimal, but it is dependant on the quality of the starting material and mold. Finally, while injection molding plastic is a cost effective method of producing plastic goods, custom injection molding will be more costly due to the necessary production of a specific plastic injection mold for the custom product. If however, the quantity of product manufacturing is high, the cost of the plastic injection mold will balance out over time. With so much variance in injection molded plastics, it is helpful to consider the industries which make use of it such as automotive, medical, consumer and household goods.

GSH Industries, Inc.