Mold cam bar

A knockout system is required to eject the part from the mold (see Chapter 7 Mold Design"). On most machines there is an adjustable stationary ejector plate containing ejector bars which go through the movable platen. As the mold closes, the ejector bars go through the holes in the back platen of the mold, contact, and stop the mold knockout plate. The rest of the mold continues to close to a predetermined distance and stops. A superior method to activate the knockout system is by use of hydraulic cylinders. This permits advancing or retracting the knockout system with any speed or force. This can be particularly useful in cam and insert molding. 

All so often we assume the mold opening time and mold closing time repeats. You should really know your clamp opening time and your total mold closing time. In closing, it is a good practice to close fast until you are approximately 0.5-0.1 in. of final close. Of course, this depends if your mold has moving cams or cylinders, stretch bars, movable blow pins, etc. All of these movements should be timed so you know if they repeat within a time. 

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