When asked ‘How many clamps should I use?‘ one plant manager I know likes to respond with ‘As many as you can‘. In reality, each clamping system, mold base, and platen is different. When discussing standard adjustable height mold clamps, I prefer to use six clamps per half on smaller molds, and as many as a dozen for larger molds. In general, the spacing of the clamps are usually dictated by the platen hole location and rail size.

When tightening the bolts, I recommend using an alternating pattern which alternates back and forth as well as up and down. For example, when using a four clamp setup, starting with the top right hand corner, you would tighten in this order:

The intent is to balance the force being applied to the mold base to prevent any uneven stress on the mold base or platen.

Ultimately, the more clamps that you use, the less stress that is applied to any specific clamp point. This will increase the life of the clamps, and help prevent damage to the platen holes. 

-Andy