Torque Values For The Clamp Bolts…

I got a multi-part question the other day regarding a couple aspects of mold clamping…

Do you have a suggested torque specification for 5/8-11 and 3/4-10 bolts? I know you are suppose to refer to the manufacturers torque specification, but does that apply to a clamp bolt and clamp? The clamp is a lever and flexes a little like a spring, so would that require the same torque as a bolt holding two flanges together? Also, would you recommend or discourage using a lubricant on the clamp bolts?
My Response
I will address this question in a few parts…
Regarding Torque Ratings: Many bolt manufacturers will provide recommended torque values. You must remember that these bolts are not manufactured or designed specifically for injection molders. The same bolt you are using to hold your mold in place may also be used to secure the rafters in a stadium. The torque rating is based on what the bolt can safely sustain… not necessarily how it should be used. Since the machine platen is typically cast, the threads are significantly weaker than the threads on the bolt.
Regarding Torque Recommendations: Most injection molders using similar bolts use a torque value around 50-60 ft-lbs. For more on this, please read our past blog: Proper Torque Value for Clamping Mold to Platen
Regarding Lubrication: You should not need lubrication to remove the bolts from the platen unless you are using a small amount of anti-seize. If you are having problems removing the bolts from the platen, it is likely that your die setters are using too much torque on the bolts or your platen threads may already be damaged, burred, rusted, or dirty. If this is the case, you will need to repair or re-tap the platen holes to ensure proper mold clamping. Lastly, always ensure the platen is smooth, flat, and clean each time you change molds.
Additional Thoughts
Your technicians will get much more support through the use of more clamps rather than using more torque. For more on this topic, I recommend reviewing the following post: How Many Clamps To Use?

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