The haunched mortise and tenon joint has a long track record in furniture construction. For windows, this new composition gives a highly stable corner joint which can be milled efficiently and cost-effectively at most CNC machining centres. The tenons at rails or stiles are cut out and rounded with a solid tungsten carbide roughing/finishing router cutter and interlock perfectly with the haunched mortises, machined with the same tool at the counterpart. This results in a very accurate and extremely strong corner joint.
Tests carried out by OERTLI at the EPH test lab in Dresden as early as 2012 are approving, that depending on the dimensions, this corner joint has strength of up to 180 kg. This means that it is even sturdier than a conventional tenon connection. Advantages: straightforward machining, less tools as well as the fact of saving another work step for driving in single dowels. Just a perfect corner joint for high Quality, efficient and economical CNC window manufacturing.