'Zero radius' laser forming of tungsten carbide/superabrasive cutting edges and teeth

"We will use innovative additive manufacturing to radically update the process for forming hard teeth on saw blades. The most commonly used tooth tip material is tungsten carbide. In a typical tipped blade less than 1% of the high value wear material is used. The rest is machined off during the manufacturing process or left on the base and discarded when the sharp edges are worn.

State-of-the-art tungsten carbide tipped (TCT) teeth are currently formed by welding pre-formed tungsten carbide inserts to steel strip and then grinding these to a sharp edge. The need to manipulate individual inserts means that fine-toothed metal-cutting blades ( \>6 Teeth Per Inch) cannot currently be manufactured. The grinding process is environmentally wasteful - of materials, energy and coolant.

Our new process uses micro laser metal deposition (micro-LMD) of the tip material to form the hard cutting edge, thus avoiding the need to manipulate and weld TCT inserts. In LMD, a jet of powder (eg tungsten carbide) is directed at a surface while being simultaneously melted into the surface by a focused laser beam. We have obtained two patents on tooth-making via LMD. With our subcontractor ManuDirect we have experimented with micro-LMD in a test rig and have been able to achieve hard surfaces on teeth and proved their ability to cut.

The edges of these teeth are still rounded; we are not yet able to form a sharp 'zero radius' cutting edge. However, once we are able to do so, we will have created a near-net-shape tooth, reducing or eliminating the need for subsequent grinding, or even permitting laser sharpening.

Our process should also be applicable to all types of blade and other metal-ceramic combination. However as tungsten carbide is the most widely used abrasive it is our initial focus. The greatest opportunity will be in fine-toothed metal-cutting blades ( \>6 TPI) where there is currently no possibility of using TCT inserts and conventional bimetal blades blunt easily. In addition, we see an opportunity for a wood cutting saw blade that sits in the gap between bimetal and TCT in terms of cost and performance.

The lead partner is a manufacturer and exporter of abrasive saw blades and will exploit the process through its customer base. The consortium includes a powder supplier, the UK's leading university in this area and a subcontractor that is expert in micro-LMD equipment."