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Current Online Topic: MULTICAVITY CLAMP FORCE

Multicavity Clamp Force
IMM 09/01

I would like to find out what is the most accurate way to calculate the clamp force required to keep multicavity tools closed. Are there any other factors besides the projected area of the parts and the runners that need to be considered?
Although the projected area is probably the number one factor here, the material you are processing is also critical in this formula. The rule of thumb is to multiply the projected area by between 1.5 and 3 for thermoplastics, and between 3 and 5 for most thermoplastic elastomers, acetals and nylons. The 3 to 5 range should also be used for thermosets. Fillers in any material tend to cause increased injection pressures and will require more clamp force. If your materials have a high filler content you should stay toward the high side of the range. For example, if you are running a glass-filled nylon and the projected area is 25 sq in, you would multiply 25 by 5, which equals 125 tons. - C. Soulsby, Van Dorn Demag Corp., Strongsville, OH (440) 876-6446, christophersoulsby@vandorndemag.com.