One of the most popular methods to mold plastics that are used to form 3D shapes. It is based on the method of molten die casting and consists of the clamping unit and the injection unit.

Rib refer to thin bladed features on a part that are used for strengthening wall sections and bosses.  It helps to eliminate sink marks and minimize warp.

An undercut is any indentation or protrusion that prohibits an ejection of a part from a one-piece mold. Undercuts add cost to tooling and molding, which is recommended to eliminate or minimize as possible.

Insert molding involves molding plastic around a core or “insert”. Most often, the insert is a metal object, such as a pin, blade, threaded rod, electrical contact, wire, and others.

Warp (warpage) is also know as bending. It refers to area of a injection molded part that distorts or bends during cooling or molding.

Weld lines are also known as “stitch lines” or “knit lines”. These are imperfections in the part where separated flows of cooling material meet and rejoin, often resulting in a visible line.

Injection and extrusion molding are two popular plastic molding methods in the industrial and manufacturing sector that are used to make products with varying shapes and sizes. Depending on the product and the customer, both processes have their individual strengths. Midstate Mold & Engineering is strictly a plastic injection molding manufacturing company, but it is always helpful to our customers to know the difference between each process.

Marks left by ejector pins. Ejector pins are long pins that are used in the injection molds to push the final molded product out of the mold. The marks can not be removed due to process of injection molding.

Co-molding is one of overmolding. It refers two plastic materials to bond, which usually are a hard material like ABS and a soft material like TPE. Co-molding provides aesthetically pleasing color contrasts.

The plastic resin is put into the hopper, which then releases the plastic pellets from the feed section into the compression section, where the frictional heat is created. The plastic is pushed through a protracted chamber using a reciprocated screw. The melted fluid-like plastic, known as melt, is forced through the nozzle into a closed, cooled/hot mold. The melt can be easily molded into the desired shape and size of the mold.

Core out refers to is a technique where you remove material from a plastic part, leaving distinct walls and ribs which provide enough strength and mating surfaces for other parts in the assembly.

Gate is also known as gate location. It refers to where the plastic enters into the cavity of the mold. It plays a role of the link between the part and the runner system.

The machine motor, extrusion machine, turns a screw that feeds plastic through a heater. The granules in the plastic melt into liquid, which is pushed through a 2D die opening tool. This forces the material into a tube shape based on the specific shape on the die. The material forms a solid tube shape after cooling. This product is now ready to be cut into required sizes.

When the mold is completely filled and being pressurized, part of the cooling process is performed here. Finally, the ejection cylinder unclamps the mold and starts pushing the part out of the mold onto a conveyor.

Now that you know the differences and benefits between the two methods of plastics and molding, you can make an informed choice to select the best technique. Plastic injection molding is one of the preferred methods for manufacturing parts because of its multiple advantages over other methods of plastic molding—it is simpler, more reliable, and extremely efficient. Contact our experts today so we can get started on designing and fabricating your next part.

Flashing is also known as flash. It refers to plastics that leaks into a fine gap in the parting lines of the mold to create an undesired thin layer.

Also known as “draft angles”. Refers to portion of injection molding part that has some taper to make it easier to remove from the mold. Generally all plastic components should be designed with draft where possible.

A parting line is the “line” or “seam” of separation on the part where the two halves of the mold meet, and it can not be avoided.

This technique extrudes, or forces out, materials through a die to create shapes using constant cross sections like window sections, drinking straws, pipes, and seals. This method is used to form 2D shapes.