Top row; left to right:
A triple pencil - 4 cm portable router bit (metal bond);
triple pencil - 4 cm portable router bit (resin bond);
cove DuPont - 3 cm portable router bit (metal bond);
cove DuPont - 3 cm portable router bit (resin bond);
Bottom row; left to right:
CNC vulcanized rubber bit;
CNC segmented bullnose bit;
bevel - 2 cm portable router bit.
You have been in solid surface fabrication for years and now your customers are asking for granite and marble. You try to talk them out of it and resist but finally you surrender. If this is your story, you should know that you are not alone. Granite has actually done the same thing to the glass industry.
Fabricators in the glass industry, who were fabricating things like conference tables and lobby reception podiums from glass, were also drawn into the stone industry when granite went up in popularity. They too were facing the tough challenge to equip their shop with the appropriate tools to work with stone. The biggest dilemma in this transition is that the existing tools you use are not effective on the new material and you find yourself in the painful trial and error tool qualification process again. Well, let's talk about what you need to know about the diamond tools that are used for these natural beauties.
You know they say that granite and marble are just like ice cream. Here is why:
- • Both granite and ice cream come in lots of "flavors" and colors, but they both have a few basic ingredients.
- • For both ice cream and granite you can have all the basic ingredients together, but not mixed properly, and you end up with something that's only a cold dairy treat (like a milkshake) or just a plain old rock (like sandstone).
- • For both granite and ice cream, appearances can be deceiving.
Even if I couldn't put a smile on your face with this unorthodox comparison, I still have a point to make. Granite and marble, when it comes to grinding, honing and shaping, will follow a common rule of thumb — Use a hard tool on soft material and a soft tool on hard material.
You have been using carbide bits on wood, countertops and Romanesque china molding for years. That is an indication that you have already applied the grinding principles to work. Because of the constituents of these natural stones that mainly consist of quartz, conventional abrasive tools like silicon carbide or aluminum oxide, are not very effective. This is mainly because those little deceptive quartz pieces are really hard-headed and refuse to confine to the shape of the tool. Usually what really happens is that the tool can't hold its shape and gives up somewhere in the middle of the job where it is not supposed to. We have all been there.
Contrary to conventional abrasives and carbide bits, diamond tools are the perfect match for granite and marble. A matrix of material that is usually called bond, such as sintered powder metal, brazed materials or electroplated material, is encapsulating the diamond particles in place. A portion of the diamond sticks out of the surface and removes material until it gets dull or worn out. Ultimately the worn diamond particle will be pulled out by excessive grinding forces and new diamonds will start to rise from the surface to replace those being lost. This phenomenon is called micro milling.
The reason harder tooling is more suitable for softer materials and vice versa is because softer materials do not need new diamonds exposed as quickly as harder materials. Softer tools allow the diamonds to be exposed more quickly, making them function better on harder materials, and harder tools allow the diamonds to be exposed more slowly, which is more cost-effective for softer materials, such as marble, that do not wear down the diamonds as quickly.
Different Granite/Marble Tooling Types
Multilayer Sintered Diamond Tooling: These types of tools are made in a process called sintering. In the sintering process, fine-size powders like copper, tin, bronze, aluminum oxide, silicon carbide and diamond are mixed together and agglomerated with a bonding agent to form uniform and mono-size particles and then pressed under pressure and temperatures up to 1,500 F to form a solid medium, technically called a matrix, to hold the diamond in place. Sintered tools are very effective on hard stones like granite. The matrix, once it loses its shape, can be retrued or refurbished. I would consider buying a new tool if the new tool costs less than $450, and I wouldn't refurbish exotic profiles like triple-pencil and cove-DuPont tooling, as there is a chance the profiles won't match the originals. Cobalt was widely used in the manufacturing of sintered granite/marble tooling until it was classified as a hazardous material and was banned from this segment of the market.
Brazed Diamond Tooling: These types of tools are made in a process called brazing. Brazing is a heating process in which two or more like or unlike materials are joined together by means of another metal alloy with a lower melting point. Brazed joints can be made exceptionally strong, sometimes stronger than the two metals being joined. When diamond is placed in such a strong bond, the result is a tool with excellent grinding characteristics. Unlike sintered tooling, brazed tools have a single layer of diamond and as long as it stays in place, the tool will hold the form and grind properly. Once the diamond is pulled out or dulled, you will face problems.
Electroplated Diamond Tooling: These types of tooling are made in a process called electroplating. In this process, nickel ions with positive electric charge leave the anode (an electrode through which electrical current flows) and travel toward a negatively charged grinding tool with diamond held on it. Because of the fact that nickel starts forming matrix around the diamond, the whole structure is strong and makes these tools a perfect candidate for soft stones like marble. Most electroplated tooling could be refurbished in a process called reverse plating, and it is often very cost-effective for the owner to reuse the tool. Electroplated tools are single-layer diamond tools like brazed tools.