Knowing what the sheet looks like is everything. At a glance the Process Tech can tell if it is to hot or to cold. He/she can also tell if there is a bubble forming under the rolls that the sheet passes over. He/she should also be able to correct such problems by warming up the rolls or cooling them off.
If the sheet is wrinkling he/should know if one roll is going to slow. Speeding up a roller and the subsequent rollers, should help alleviate such a problem.
Heat control is the main part of a proper form. If you are to cold you will wind up with to thin of a wall in certain areas of the form. The trick is to get the sheet to a near liquid state before it gets to the mold. Failure to do so results in improper form.
If the product is improperly trimmed you could lose rows of product. If the shrinkage factor is not right, you could battle this part of the process for days, weeks, or even months.