Injection Molded Plastics

Injection-molded plastic consists of a mold or cavity that is shaped like the intended product, and filled with molten resin. The mold is removed once the resin has hardened and cooled, revealing the product that has taken the mold cavity’s shape. Everyday household items such as plastic containers, gaming cartridges, buckets, and tool handles are manufactured using plastic injection molding, or custom injection molding process.

There is a wide range of materials, such as most polymers, that are used as a starter. An advantage of injection molding is that manufacturers have the freedom to decide on the exact material for the final product. This procedure, however, requires a lot of precision and calculation, as well as careful attention to the pressure and temperature in the mold and the chemical properties of the material that will fill it. Each and every one of these details could negatively affect the product’s quality turns out if miscalculated.

Upon cooling and hardening, elastomers retain their elasticity. Rubber bouncing balls are a well-known product made from injection-molded elastomers. Thermoplastics, on the other hand, harden completely after they have cooled in the injection mold.

Gas assist injection molding is another variation of plastic molding, which involves the use of an inert gas such as nitrogen to hollow out the mold and assist in filling the mold cavities with molten plastic. A second variation is known as reaction injection molding, which requires an additional step where a reaction injection molding machine adds a curing agent to the mold. The curing agent is necessary for the product to maintain its shape and strength upon removal from the mold.Read More…Request for Quote

Leading Manufacturers

GSH Industries, Inc.

Cleveland, OH | 440-238-3009


Holland, OH | 419-867-3900

MSI Mold

Shelby Township, MI | 248-275-1978

Molded Devices, Inc.

Riverside, CA | 951-509-6918

Technomag Inc.

Setauket, NY | 888-240-3606

HTI Plastics

Lincoln, NE | 800-824-0607

Diversified Plastics, Inc.

Minneapolis, MN | 866-900-2385

Injection molding machines consist of several components. The first is a hopper that holds the plastic materials before they are melted. The next component is a heating unit where the plastic material is transferred to be mixed and heated until molten. In its melted state, additional chemical agents such as dye can be added in order to achieve a certain final appearance and texture of the product. A screw, also known as an injector, uses mechanical or hydraulic pressure to force the melted plastic into the mold. The presence of air bubbles will be harmful to the product. However, most molds are capable of allowing the air bubbles to escape.

The cooling process—and thus, the overall manufacturing procedure—may be hastened by the use of cooling liquids around the molding chamber that removes heat from the plastic. The newly cooled and hardened plastic part is released after the two halves of the injection mold is pulled apart. Sometimes, a set of ejecting pins or rods has to be removed. The removal process can take anywhere from a few seconds to a few minutes. Numerous products such as vehicle bumpers and medical equipment can be made from injection molding. It is possible—even encouraged—to fabricate any sort of product if a plastic mold can be made for it.

One advantage of injection molding is how cost-effective it is compared to other production methods. The more parts that can be made from a mold, the more cost effective production will be. A mold for a particular product can be reused multiple times once it has been fabricated, and it can produce the same product with minimal differences. Because of how easily the mold can be reused, injection molding is an ideal procedure for high production runs.

The injection molding process involves little to no change in the process, and the plastic parts rarely need additional finishing once removed from the mold. The process also leaves minimal wastage due to all of the material being forced and enclosed into a mold cavity. The small amount of plastic scrap that the process leaves behind can easily be recycled. Since human interference is rarely necessary, labor costs and other risks for the injection process are significantly low.

As efficient as the injection molding process is, there are important things to consider. First, one needs to be mindful of the mold design, as the plastic material needs to be removed with minimal effort. For example, it would be more difficult to remove plastic from a complex, square, or rigidly designed mold, as the final product may develop stress marks and cracks upon extrication. Additionally, rods and pins are needed to successfully remove the plastic from the mold. Plastic injection molds can be expensive, so it is important to make sure that the plastic part can be easily removed.

Second, the final product may have joining lines or other forms of imperfections once extracted from the mold. Therefore, the product may require undergoing a finishing procedure. The amount of finishing a product may need depends on the quality of the mold and the material used.

Another possible procedure that may be implemented is custom injection molding. Custom injection molding is a process in which the mold is not a pre-made design, but is specifically formed according to the consumer’s requirements. Although the general injection molding process is cost-effective, it is even more costly to custom mold a product since it requires a specific mold to be developed. However, the cost may be balanced if a high enough quantity of the product is manufactured in a certain amount of time. The injection molding process can vary in a multitude of ways, and can be used for many industries such as consumer, household, automotive, and medical. Thus, it will be beneficial to take into consideration the industry and type of products for which it will be used.

Injection Molded Plastic Informational Video