Every injection mold has to have a door or opening through which molten plastic is injected into the mold cavity. The type and size of the door has a very important role in the injection molding process and should not be overlooked.
In the custom injection molding business, margins are tight. This requires the mold maker to make a very precise determination of the size and type of gate for the injection mold. The wrong door can spell disaster, or at least reworking the mold, which can quickly eat up profits.
There must be a gazillion plastic parts in the world: phones phones, computers, hula hoops, keyboards, televisions, toy guns, goggles, etc, etc
Gates vary in size and shape depending on the type of which is molded plastic and the size and shape of the well. Obviously, the larger pieces require larger doors, or even more doors.
Common types of doors
 • Tab doors.
 • tunnel doors (also known as submarine doors)
 • Doors banana
 • Smiley doors
 • Heat the tip of doors
Other types of doors, especially in extreme heat applications, but is an issue in itself.
The door of the card is the simplest of all. It’s the kind of door you see when you buy a plastic product that requires breaking the corridor, or trees like piece of plastic attached to the part. Usually, a flat, sheet-like connector that allows that plastic flow in the piece.
A tunnel, or underwater gate, is more complicated and requires a much higher degree of ability to add the mold. This type of door is a cone that is added below the surface of the workpiece, thus the name: submarine gate. It also looks like a tunnel. This is used when there can be little evidence of the door on the left. This is known as a vestige of the door.
It is also used in high production molds where everything is automated and the door should be released in order to be separated and packaged.
The door is smiling so called because when viewed, it resembles a smile, something like that. This is more difficult to machine and is used to add a right of the door at the bottom of a piece of plastic. It’s like a tunnel door, except the bottom is cut off or truncated. This allows the door right at the bottom of the plastic piece. Smiley doors also used in high production applications where the part that released the door for purposes of automation.
The door of the banana is new, but very useful. These doors are used when there is no trace of the door in the plastic. It’s like a tunnel door, but curved, like a banana, so you can get below the part and allow the plastic to be injected into a hidden area of the piece.
Conclusion
The size, type and placement of the door used in plastic injection molds making have a dramatic impact on the quality of the plastic piece, and the speed with which it occurs. Gates play an important role in automating of custom injection molding.
Reinbold Shredder
Comments on this entry are closed.