Tool Tipping Materials (continued)

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List of materials

Steel

Tool Steel (High-speed steel)

Cutting / hardfacing alloys with WC (Talonite +WC)

Tungsten carbides – standard & premium WC grades

Cermets

Ceramics

Cubic Boron Nitride

Diamond

Materials listed Best to Worst:

Materials listed from Highest to Lowest in Expense:

Tungsten carbide        Typical values

This is a complex issue. 

1.  Successful cutting in terms of wear and breakage is perhaps one-third material used, one-third operator skill and one third equipment condition. 

2.  There are over 5,000 grades of tungsten carbide so this is over simplified. 

3.  Tungsten carbide can overlap hardfacing alloys in values.  Tungsten carbides and cermets can overlap.  There are many ways to make and use diamonds.  Anyone disagreeing with this chart might indeed be right.  Each application is unique.  You need to experiment with different grades and different materials from different sources until you find the best for you. 

Gross Physical Breakage  (listed from hardest to break to easiest to break)

Steel                                         Hardest to break                                                           

Talonite (Stellites®)                                                                  

Tungsten carbide                                               

Cermets                                    

Ceramics

Diamond                                   Easiest to break

There can be considerable overlap here.   Cermets are generally easier to break than tungsten carbide but some cermets are much tougher than some tungsten carbides.  Some tungsten carbides also outperform Talonite depending on the respective materials and the testing.

 Wear 

As rule of thumb, hard materials wear better but break easier.  Tungsten carbide wears better than Talonite and cermets wear better than tungsten carbide. 

Chemical wear

Solid diamond (perfect diamond coatings)            Most chemically resistant - Best for wear

Ceramics

Cermets

Talonite (Stellites®)       

Tungsten carbide

Diamond (polycrystalline diamond in a matrix - PCD)

Special steels

Steel (ordinary)                                                           

The situation is not nearly this clear.  To a great extent it depends on what steel, tungsten carbide, etc and what chemical in what conditions.  

Microfracturing 

Solid diamond (perfect diamond coatings)                                    Most likely to fracture

Ceramics

Cermets

Tungsten carbide - Just the exposed WC grains and not the whole part

Diamond (polycrystalline diamond in a matrix - PCD) - just the exposed grains 

(Probably no microfracturing)     

Talonite (Stellites®) - 

Special steels

Steel     (ordinary grades) 

It is possible but pretty unlikely to have Microfracturing in the last three.  These materials all take a very sharp edge and that edge is susceptible to nicking but that is a slightly different condition although it has similar effects. 

Stellite(R) is harder to break than tungsten carbide.   Tungsten carbide wears better than Talonite.  If you are cutting high acid materials such as green cedar then the tungsten carbide grains still wear better than Talonite but the cedar acids dissolve the tungsten carbide binder so the tungsten carbide grains fall out and the tip gets dull.   You can use a cermet tip, which is more acid resistant than Talonite or standard tungsten carbide.  This is great on relatively clear green lumber for example.  If you get some very knotty boards or start mixing dry lumber with the green then the constant change in impacts can cause micro-fractures to form in the edges of the cermets and they will get dull faster than tungsten carbide. 

Using the materials

Talonite and the similar Stellite® alloys have advantages over tungsten carbide in high acid applications where the problem is not wear but is actually chemical erosion.  Talonite can be welded on with automatic machines, which can be a significant labor saver.  It is also much easier to run an automatic tipper than to braze tungsten carbide with a torch.    Some people just never quite catch onto consistent torch brazing although most people pick it up readily. 

Talonite has the advantages over tungsten carbide of being harder to break, possibly having less drag (lower coefficient of friction) and Talonite can be ground with less expensive wheels.  Tungsten carbide requires diamond wheels and Talonite can be ground with CBN (cubic boron nitride) wheels. 

Cutting speeds in sfm (Surface Feet/Minute)

Which Material Takes and Keeps the Sharpest Edge?

Sharpness is critical and obvious in terms of the quality of the finished product.  It is less obvious but still important other ways because sharper tips use up to 20% less energy and will successfully handle higher feeds and speeds up to as much as 30 to 35%. 

Cermets will take and hold a sharper edge than tungsten carbides and they will keep this edge if used in proper applications such as clear cedar, paper covered materials and other consistent applications.  If they are used in rougher sawing applications they will lose their edge due to Microfracturing. 

Quite often all the materials are sharpened to the same configurations.  This is a mistake.  Talonite, steel and cermets can be run with steeper angles but they are generally run the same way tungsten carbides are run.