Choosing a Hardwood Lumber Grade for Furniture Manufacture

A study was conducted to determine yields of furniture parts from yellow-poplar lumber in a furniture plant with a cut-off saw, a face planer, a single surfacer, and a double-edge jointer connected by conveyors and operated by two men. Material costs were based on the usable portion of lumber which results in finished cuttings. Labor rates are arbitrary, and other rates could be applied. The yields per Mbm by grade were: FAS 795, Saps -692, No. 1 Common – 555, and No. 2A Common – 350. Prime cost per foot for 1-inch yellow-poplar cut to 3-inch widths varied from $0.2670 for 72-inch-long parts to $0.2996 for 12-inch parts made from No. 2A lumber. Costs for the same parts from higher grades were more, running up to $0.3397 for 12-inch parts from FAS lumber. The greatest element of cost was the direct material cost. It is evident that as long as the cutting sizes be obtained from each of the grades, No. 2A Common will yield required cuttings at the lowest unit cost, No. 1 Common is the next in cost, followed by Firsts and Seconds, and Saps. This is in direct contrast to the normal buying policy of the study plant, which had purchased No. 1 Common and better lumber with a high percentage of Saps and Firsts and Seconds. Because of the number of defects allowed in lower lumber grades, and the small clear-faced cuttings permissible in them, it is difficult to obtain a high yield of long cuttings. It is necessary, therefore, to know approximately what yields can be expected in each cutting length from each grade. Yields by cutting length in this plant resulted in the following: 1) That the Saps grade, as used in plant A, is more costly than other grades when a minimum cutting length is below 28 inches; that it is less costly than No. 2A Common above 28 inches; that it is less costly than No. 1 Common when minimum lengths are above 38 inches; and that it is never as cheap as Firsts and Seconds. 2) That when utilization can be obtained in lengths below 24 inches, No. 2A Common is the most economical and No. 1 Common next. 3) That when 27-inch and longer lengths are required, the Firsts and Seconds grade is the most economical. 4) That a mixture of grades might yield cuttings at a lower overall cost than any single grade. For instance, the Firsts and Seconds grade might be used to cut bill calling for predominantly long cuttings, and a lower grade used for bills calling for short ones.

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