Having established a need to improve mold changeover time, when deciding upon the clamping process, the molder is confronted by three technology choices.
• Manual-Mechanical - typically for smaller presses. Involves the mold being modified to accept some kind of clamping ring or spigot. Specially designed plates quick die clamp are mounted to both platens which through the use of a lever allow the user to locate and clamp the mold securely to the machine.
• Hydraulic/Pneumatic-Mechanical - For all sizes of press. Takes existing clamp technology (toe-clamps) and automates the process without the need for Operator intervention. For best results, Mold bases should be the same size to avoid the need to reposition the clamps.
• Magnetic - Typically for presses greater than 50 ton. Magnetic Plates are fixed to the machine platens and electronically switched to clamp the mold.
Over the past 15 years, the Molding industry has seen the "magnetic" option become the primary choice on the following provisos:
• Where the application is Thermoplastic Injection Molding and operating mold base temperatures rarely exceed 250 deg. F. • Where the daylight of the press allows for the thickness of (both) magnets. • Where the molds vary in size.
The first two points above address the magnet's primary weaknesses: Magnets are susceptible to high temperature, and although they have become thinner over the years, loss in machine daylight is unavoidable.
However, magnets have become much more affordable and when considering installation cost that includes the absence of mold modification, they are the most cost competitive option.