Torque Values For Larger Molds…

I received a few follow-up questions from a previous post, so I will address the most common one…


I was wondering if you have a chart showing proper torque spec for mold c

lamps and bolts for 250 up to 1100 Ton machines? 

My Response

Sorry, but I do not have such a chart, but I suggest that you look at the torque value based on bolt diameter. Platens accommodating bolts around 5/8″ diameter typically handle torque values around 50-60 ft-lbs… while larger platen threads above 1″ diameter can usually handle torque values around 80-120 ft-lbs.

Unfortunately, all platens are not manufactured equally. Machine age, manufacturer, steel type, and thread quality will factor into how much torque the threads can actually bear. In many cases, newer manufacturers will actually provide maximum allowances verbally, but will not publish these values since they don’t want to be liable for any platen damage.

As a general rule of thumb, it is best to torque the bolts based on their diameter (and machine in some cases). Always use more clamps when a larger mold is present. Personally, I like to use as many clamps as possible to ensure the mold base stays in place, and to ensure no bolts loosen during production. Clamps are inexpensive compared to one damaged mold, and inconsequential when compared to an injured employee.

Many molders will not go above 100 ft-lbs as it is easy to injure yourself when removing an over-tightened bolt. 

Additional Thoughts
Unfortunately, most molders do not torque the bolts on their molding machines. They will usually tighten the bolt manually, applying pressure based on the size of the tool. For instance, they will crank down on the bolts if it is a large 1 ton mold, but apply less pressure if the mold is smaller. 

Arm, back, and rotator-cuff injuries are not uncommon for these molders.


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