Cutting/Yield Explanation

About This Helpful Hint

This “Helpful Hint” is intended to explain the yield policy for full width untrimmed rolls.

Fall Off

The first factor is rather simple. It represents the loss incurred from a liquid being turned into a “sponge like foam”. We refer to this loss as “fall off”. Fall off will occur on both ends (cross machine direction) of the material. The amount of fall off will change with the thickness. The thinner the product the less fall off. The thicker the product the more fall off.

Coning

The second factor is called “Coning”. The loss incurred with coning is a little harder to understand. There are several different examples of coning. It can occur when product without exposed adhesive is stood on end. This type of coning occurs primarily during transit. Material must be wrapped as tightly as possible to prevent this from occurring. This must be corrected before cutting otherwise you can experience loss of yield. A simple corrective action can be to turn the log over and stand it on the other end, or push the core back in line with the material.

Walking

Another type of coning is caused by a “walking condition”. We have taken positive steps to reduce this condition. Part of our continuous improvement was to purchase “edge guiding equipment” in our manufacturing process to reduce the loss incurred with this type of coning. A common misunderstanding about yield is to think that the loss is double the amount coned. This is not true. Let’s assume you receive a log cast at 56 inches wide with 1-inch of coning. Looking at this you might first think you have loss at both ends. In reality, you only have loss at one end or the other.

As you can see from the drawing, the “fall off” problem is not addressed in this example. At any given time though, there is 55 inches of cast material. Please notice there is only 1-inch of loss on any given layer. On thinner material the fall off will not be this noticeable, however thicker products have the larger fall off. You can reference Gaska Tape’s “PVC Foam Manufacturing Tolerances” publication for yield specifications. Please feel free to contact us if you have any comments or questions.