Determining the impact of sorting capacity on rip-first rough mill yield

Abstract

The problem of increasing gang-rip-first rough mill yield often amounts to little more than optimizing the fit of needed parts into strips. However, it is rare when a part or combination of parts fits precisely in the area between two defects. Intuition tells us that the more lengths we have to choose from, the greater the chance of completely filling such an area. Because of the many interrelated processing dependencies in a rough mill, it is difficult to estimate the potential yield increase due to cutting more lengths simultaneously by conventional methods. Using the ROMI-RIP simulator, we analyzed the impact of sorting capacity (i.e., the number of lengths and widths cut simultaneously) on yield for various lumber grade mixes and typical industrial cutting bill combinations. Using an analysis of variance, significant yield increases were observed as a result of increasing sorting capacities. However, a plateau is reached around 18 to 20 part sizes, where additional sorting capacity increases result in negligible yield gains. Knowing the necessary number of lengths for maximum yield provides the opportunity for rough mill operators to determine the most economical sorting capacity for a rough mill.

Citation

Thomas, Edward; Brown, John. 2003. Determining the impact of sorting capacity on rip-first rough mill yield. Forest Products Journal. 53(7/8): 54-60.