Boy is jck26 right. If you haven’t changed carbide grades in five year you are way behind. Here's an article I just wrote about it. The focus is cutting tools for wood but it will give an idea as to what is available in advanced grades.
You can braze the chip back in successfully with proper surface preparation of the carbide. If it is a great big chunk it might work.
Also go to:
and scroll down until you find the article on crack initiation and propagation. This will give some pictures to explain NickE’s comments.
Tom
New Carbide Grades Cut Faster and Last Longer
There are a couple new grades of carbide that are doing extremely well in custom tool shops.
Most production tools are made using standard carbide grade such as C-3 and C-4. These are grade designations from World War II and they are proven, reliable performers. Today’s “C” grade carbide is much better made than the 1940’s version but still essentially the same tungsten carbide grains in a cobalt matrix.
The new grades are being used in applications where fast feeding, clean cuts and long tool life are paramount. Since a 10” x 60 tooth or 10” x 80 tooth can run between $80 and $90 there needs to be a compelling reason to use them.
One of the big advantages is a dramatic reduction in the size of the carbide grains. Advanced carbide grains are now well below, one millionth of an inch in size. This means that they pack much tighter and more evenly than the much larger grains of the older grades. Because the particles are much smaller you can get a much sharper edge and keep it longer. What has been a surprise with these nano-grain carbides is that they are both tougher and longer wearing than conventional carbides.
The chemistry of advanced grades is considerably different. The standard was tungsten carbide grains cemented with a cobalt binder. This was the first one used because it was the first one that worked. Advanced grades vary somewhere from the traditional formula all the way up to titanium Carbonitride with a Nickel / Chrome binder. The advanced materials provide sensational wear properties especially in areas of chemical attack such as green lumber and MDF as well as other man made materials.
Advanced grades also use special chemistries.
Straight tungsten carbide grades have the highest resistance to abrasion (flank wear) of any carbide grades and have the greatest strength. Titanium Carbide gives "lubricity" to the carbide so that the chip slides across the face of the cutter with less heat and friction. Titanium carbide, Tantalum Carbide and Tantalum Niobium Carbide (TaNbC) additives are frequently used to maintain structure edge strength at cutting temperatures. In addition, Tantalum carbide and Vanadium carbide are used as additives to make finer carbide crystals and improve the property of the material.
This advanced technology is being used primarily in two ways. First is an extremely tough carbide. Since a great deal of carbide wear is actually micro-chipping it also gives much, longer life. This would be used for saw mills, pallet operations, old flooring and similar. The second use is in a fast cutting, long life grade such as Cermet II where the primary use is man made materials, such as MDF mills, and general cutting, such as cabinet shops.
How long the advanced grades last depends on the use but they are lasting about fifty percent longer in fiberglass up to eleven times as long in green wood in a sawmill. As a rule of thumb they are lasting about 5 to seven times as long in man made materials.
Because the cutting edges grind smoother and sharper, they also cut faster. This testing was done in a free fall test. Think of a chop type saw allowed to cut its way through the material with no additional weight on it. In a test of four major saw blades and an advanced, Cermet II grade the cermet II cut though in an average of 2.4 seconds. The others ranged from 2.7 seconds to 8.3 seconds. (This was the average of ten of each brand of blades.)
What is even more important is what happened after cutting a mile of MDF. The cermet II cut in an average of 3.4 seconds while the others ranged from 7.3 to 48.4 seconds.
The Cermet II blade took about 40% longer to cut while the standard blades took up to five times as long to cut.
Thomas J. Walz
Carbide Processors, Inc.