It also is important during the time you are packing the mold, to observe whether or not the gate is sealed. This is an area that causes a lot of trouble with new tools. They are absolutely sure—based on the long hold time they have used in the process—that the gates are sealed,

or they know they have valve gates and shut them off so the gate has to be sealed.
Oftentimes reality is different. Looking at pressures in the mold and seeing whether or not they are maintained after hold pressure is removed is the simplest, most effective way to determine gate seal. While weight can be used in many situations, it is no substitute for seeing what is going on when the injection pressure drops.

It also is important to look at the balance of packing—not just of fill. Looking at the pressure gradient across the mold or across cavities provides an understanding of why some areas or parts are different. Shrinkage is inversely related to the pressure during packing—more pressure in the cavity means less shrinkage; less pressure in the cavity means more shrinkage.