|There is more to a mold than two halves. While there’s too much to cover in this course, it is beneficial to learn a few basic things. Let’s look at a basic two-plate mold.
Both the top clamping plate, at the figure’s far right and the “A” plate mount to the stationary platen on the mold machine.
In the center of the top clamping plate is the sprue bushing. The sprue bushing connects the nozzle on the heating cylinder to the mold. This allows the molten plastic to enter the mold.
The “A” plate contains the cavity of the mold. The cavity is a depression that forms the outside of a part. This essentially constitutes one half of the mold.
The “B” plate contains the core of the mold. The core is a protrusion that forms the inside of the part, making up the second half of the mold. This half attaches to the moving platen that pulls the part out of the cavity.
Once the moving platen has separated the mold halves, the part ejects from the mold. The ejector housing, at the figure’s far left, contains a moving plate, the ejector plate.
Attached to the ejector plate are pins. The ejector pins, also known as knockout pins, push the part off the mold core.
Once the part ejects, the moving platen closes the mold, ready to form a new part. The time it takes to make one entire part is known as a cycle. The cycle time is very important in the design of a part. A shorter cycle time means that more parts can be made on a given day, resulting in a higher production rate.