User know-how

Why are tools made of different cutting materials?

Why are there different carbide grades?
Bending strength or wear resistance

For physical reasons, increasing wear resistance of the cutting material results in decreasing bending strength. With increasing hardness, the cutting materials get more brittle. Vice versa, less hard cutting materials have a higher bending strength.
 Both are features which have a more or less favourable influence depending on the application.

Which carbide grade is used for which application?

Polycrystalline diamond, one of the hardest and most wear resistant cutting materials, is at the same time one of the most brittle cutting materials. In case of impact the cutting material quickly breaks.
 High-speed steel (HS) is one of the softest cutting materials, more resistant to impacts but the cutting edges become blunt quickly. In tests with panel sizing saw blades an edge life of 500 km was reached with a diamond-tipped saw blade, which is equivalent to the distance between Berlin to Frankfurt. Under the same conditions a carbide-tipped saw blade (HW-tipped) reached only an edge life of 2.5 km, which is not even equivalent to the distance straight through Berlin.

The difference in tungsten carbides

Permanent development of the tungsten carbide cutting material allows an increasingly wider range of applications. This is why LEUCO offers HW cutting materials with user-oriented features. Whereas formerly soft wood was machined almost exclusively with HS tools, today the tough HW cutting material „HL Solid 20“is used for spruce, fir, pine, alder etc.. For cuts in particle boards, MDF boards or hard woods we recommend „HL Board 06“. In the case of highly abrasive workpiece materials such as highly compressed or cement-bound particle boards „HL Board 01“ is best for use.
 HW is industrially produced in a sensitive process. It consists of cobalt and tungsten carbide (WC). The physical law for cutting materials is also true within the HW cutting material group. A glance through the microscope shows the difference between the HW grades: The higher the tungsten carbide share, the harder, more brittle and more wear resistant is the HW material.

Quality for HW cutting materials

Depending on the manufacturer and the production site, even within a single HW grade there are quality differences not visible to the naked eye, only on the price label. The glance through the microscope shows the difference. Compression failures, lack or excess of carbon lead to increased porosity, slotted pores and a larger WC microstructure. The result is a deterioration of the mechanical features, an increase of the breaking risk and a decrease of hardness.

Summary

The machining quality is determined by several factors, e.g. the choice of the right tool, the cutting geometry etc. The cutting edge material considerably contributes to the optimization of edge life and cutting quality. The “ideal cutting material” would have to have bending strength and wear resistance in equal measure. However, in spite of intensive research this still is wishful thinking.

• What can be done, is to choose the right cutting material according to the respective demands (cutting quality, price-performance-ratio, machine downtimes etc.).

LEUCO not only offers tools but also a wide range of cutting materials for the most different applications.

Placement of cutting materials between two totally opposing demands "wear resistance" and "toughness".

Tungsten carbide grades - variety at LEUCO

Assembling of tungsten carbide - The ratio "Cobalt to "tungsten carbide" and the size of a special grain size varies according to the HW grade.

Important definitions in woodworking