Index of efficiency for strength-grading machines for solid wood

Abstract

The settings of strength-grading machine for structural pieces of wood are checked according to the EN 14081 standard. However, different machines have different performances depending on the accuracy of the estimation of the board’s properties, and there is no easy way to compare the efficiency of these machines especially if the machine does not use the same sampling. In this paper, we introduce an index called index of efficiency for grading machines. This parameter is in the range of 0–100% and allows to compare performances of different machines for a given set of grades. The computation of this index is based on the cost matrix method of the EN 14081 and requires to have the size matrix of a setting to be computed.