Diamonds & Water: A Good Marriage

   Fifty years ago, it wasn’t uncommon to have marble in an upper-scale home – but it was unlikely to have much granite. One of the main reasons was the difficulty of cutting and polishing granite; things have changed from the days of hammer and chisel.
   With the advent and technology of new-generation diamond tooling, it’s now possible for anyone to afford granite. This is great for both the consumer and the fabricator. Diamond tooling allows faster fabrication speeds, higher-quality edge detail, and, in some markets, more-competitive prices. But this is where the cream rises to the top.
   In a competitive market, maintaining your tooling, and having diamonds that are sharp, are very important. This is how you can maintain an additional edge (and the pun’s intended); if those diamonds cut faster, are more-accurate, and cut with less dust than your competitor’s diamonds, you win.
   How can you do that? Easy: properly place the water on the leading edge of the diamond as it enters the stone. It sounds simple, but you’d be surprised of how many people neglect to do that.
   Keeping the diamonds cool is critical to tool life. If you heat the diamonds to the point of being white-hot, and then apply water, you risk exploding them. They’ll come out of their mounting metal bond and drastically shorten the life of the tool. (At times, this actually can be advantageous if your diamonds are glazed over, and you need to sharpen your tool to expose new diamonds.)
   Water also lubricates the cutting process. This will allow you to use less horsepower, and less amperage, to remove the same amount of material than if you were to cut without water.
   It also improves the finish in the material you’re cutting. You’ll have less chipping on the edges, because – without proper amounts of water – the diamonds heat the stone to the point that it literally explodes the edges.
   The Occupational Safety and Hazards Administration (OSHA) is fond of water because it really helps keep the dust out of the air, and it also helps in noise abatement. We all know water is good … but only if you put it on a blade or cutting tool at the proper time. It does no good to bring in the water after-the-fact.
   If you’re running a router and spraying water on your tool on the backside after it leaves the cutting process, all you’re doing is washing the stone. There’s not much value to the water placement, and you are probably loading your diamond bit with stone and heating up your work.
   It’s imperative that you place enough water on the leading edge of your tool as it enters the stone so that your diamonds don’t overheat and load with debris. If possible, always place as much water as possible to the leading edge of where the diamonds make contact with stone, so the water gets carried into the stone while the cut is made, not after the fact.
   If you put the water on the tool too early, at too high of pressure, and at too high of an angle, the water will bounce off the tool and won’t be carried through to where the water is needed. If the water is placed on the tool too early, then it’s spun off before it reaches the stone.
   Ideally if you can point the water directly into the tool path as you’re cutting, you’ll get optimal life from your diamonds. Of course, this is easiest on a hand router, but when you are running a CNC, it’s critical to take the time needed to point the water jets on the tool to get optimum tool life. If you don't, you may lose up to 50 percent of the life of your diamonds.
   Don't get skimpy on the amount of water that you’re using on your diamonds. Follow the factory-recommended amount, or contact your tooling supplier or machine manufacturer to find out the amount of water needed for the particular tool or cutting operation.
   It’s not a wise idea to reduce the amount of water you apply to diamonds. It will not improve anything. The only time you’d reduce the water consumption is when you’re buffing and you want to increase the amount of heat in your stone to get your final polish. Then – and only then – would you want to reduce your water consumption.
   Water is extremely necessary to remove the debris from in-between the diamond-tooling surface as it rotates past the material you are cutting. If debris or stone dust wedges in the spaces between the diamonds, then they fail to remove material; they just rub on the surface of the stone and heat it.
   When this happens, the water enters the fissures of the heated stone, turns to steam, and rapidly expands. Literally what you have are millions of tiny explosions, chipping the surface. The cooler your tool runs, the less chipping you will have.
   Some of the new saws today are programmable to cut in both directions. The water is usually fed to the leading edge of the blade; again, it’s important to have water right at the contact point where diamonds meet stone. Make sure the water forks are adjusted so that the flow of water is not bouncing off the blade, but being carried through the cut … where the action is.
   This is where the water is needed, and lots of it. I have seen too many times where the operator reduced the amount of water to the blade, causing the stone to chip because it got too hot from the blade and fractured the edge.
   On the return cut with bi-directional saws, the water must be carried through the cut before it makes contact where the actual cutting is taking place. If you don't have enough water here, it can be hazardous; you may be dry-cutting at the point of contact and be treated to a ring of fire traveling around the rim of the blade as it’s cutting. This will increase the amp draw for the arbor; if your stone is small enough, you may actually lift the material right off the table.
   I would suggest that, when changing your blades, you inspect your water forks. Look for holes that may be clogged with foreign debris, especially if you’re recycling your water.
   Make sure that the water flow is placed in the correct location on the saw blade so it’s not bouncing off the blade, but being carried through so that the point of contact (where diamonds meet stone) also has water. Last, but not least, make sure you’re putting enough water on the blade to cool the diamonds and remove the material from the cut.
   It is essential to have the water contact the diamond tool as close as possible to where it meets the stone. It’s no joke about exploding edges ; diamonds and stone heat up to 1,000°F, and water applied too late is worse than a cold drink thrown on a griddle. The heat also fractures the diamonds, causing premature tool failure and decreasing profitability. (Not for the tooling suppliers, of course, but they don’t want to see their own tools fail, either.)
   So how can you tell if you have enough water on your tool? Examine it during use; you should not be able to see any buildup of material in the tool itself. If you do, you’re building up stone dust and you’ll need to increase water volume to wash it away. If you don’t turn up the water, the tool will rub the stone edge with the dust rather than the diamonds, heating up the work that may cause steam fractures and chipping.
   Let's review: What is the purpose of water?
   • To keep the diamonds cool
   • To wash away the slurry
   • To keep the shop dust free
   • To lubricate and make the job freer-cutting, which requires less horsepower and smaller machines.
   By keeping these things in mind, you’ll significantly increase the life of your diamonds, improve quality of the cut, and improve your bottom line.
   Bill O'Connor is a stone-industry consultant with over 30 years of manufacturing and engineering experience; he’s been in more than 1,000 stone shops installing/repairing machinery and advising on shop plans and expansion. O’Connor can be contacted at www.granitemachine.com; he also frequents Stoneadvice.com as “The Consultant.”

This article first appeared in the March 2007 print edition of Stone Business. ©2007 Western Business Media Inc.