DIN EN 14081-2:2013-03

Machine grading is in common use in a number of countries. Two basic systems, referred to as "output controlled" and "machine controlled", are used. Both systems require a visual override inspection to cater for strength-reducing characteristics that are not automatically sensed by the machine. The output-controlled system is suitable for use where the grading machines are situated in sawmills grading limited sizes, species and grades in repeated production runs of around one working shift or more. This enables the system to be controlled by testing timber specimens from the daily output. These tests are used together with statistical procedures to monitor and adjust the machine settings to maintain the required strength properties for each strength class. With this system it is permissible for machine approval requirements to be less demanding and for machines of the same type to have non-identical performance. The machine controlled system was developed in Europe. Because of the large number of sizes, species and grades used it was not possible to carry out quality control tests on timber specimens drawn from production. The system relies therefore on the machines being strictly assessed and controlled. Furthermore, considerable effort is required to derive the machines settings, which remain constant for all machines of the same type. This document (EN 14081-2:2010+A1:2012) has been prepared by Technical Committee CEN/TC 124 "Timber structures", the secretariat of which is held by AFNOR. The responsible German committee is Working Committee NA 005-04-01 AA "Holzbau" (Spiegelausschuss von CEN/TC 124, CEN/TC 250/SC 5) ("Timber structures") (Mirror Committee of CEN/TC 124, CEN/TC 250/SC 5) at DIN, the German Institute for Standardization e. V. The following changes have been made with respect to DIN EN 14081-2:2010-11: a) The dates of DIN EN 14081-1 have been deleted in clauses 2 and 3.