10/15/2026
INJECTION MOLDING 101: UNDERSTANDING THE MOLD
Ever wonder what goes into making a plastic part? It all starts with the mold.
An injection mold is a precision-engineered tool designed to shape molten plastic into a specific part. Each component plays an important role in producing consistent, high-quality products.
Core: Forms the interior surfaces, recesses, and features of a molded part.
Cavity: Forms the exterior surfaces and overall shape of the part. Together, the core and cavity create the geometry of the finished component.
Inserts: Provide specialized features, detailed geometries, wear-resistant surfaces, or replaceable sections that can simplify mold maintenance and modifications.
Sprue, Runners and Gates: Direct molten plastic from the injection molding machine into the mold cavity. The gate controls where plastic enters the part.
Cooling Channels: Circulate coolant through the mold to control temperature, help the plastic solidify, and support efficient cycle times.
Ejector System: Uses ejector pins or other mechanisms to release the finished part from the mold after it has cooled sufficiently.
Vents: Allow trapped air and gases to escape as plastic fills the cavity, helping prevent defects and incomplete filling.
Why does mold design matter?
Proper mold design directly impacts injection molded part quality, dimensional accuracy, repeatability, cycle time, and overall manufacturing cost. Getting the details right from the beginning can make a significant difference throughout the life of a project.
At JATCO, Incorporated, our team understands critical relationships between product design, mold engineering, and molding performance. We work with customers to help turn ideas into reliable, manufacturable plastic components.
Have a plastic part or project in mind? Let's talk soon! www.jatco.com. You can also contact Steven Ames, Director of Sales, 209-985-2329 or [email protected].