Like The Terminator movies, the machines are taking over in the stone industry. That is to say that technology, like in most production industries, has taken an increasingly larger share of work duties. Unlike The Terminator movies, the machines are seen as salvation not annihilation. They are increasing efficiency along with quality and have reduced much of the hard work that was done by hand in previous decades/centuries.
Automated Slab Polisher (ASP):
Watch the video of this ASP to see one type of machine used for polishing granite. The circular, spinning disc is what does the polishing. Rough grits are first used followed by increasingly finer grits until the desired finish is reached. (Note: if a honed finish is desired the polishing process is stopped halfway through and the higher grits left out.) This particular ASP is typical of a polisher that is used in fabrication shops which only need to polish a few slabs each day. Larger, more-assembly-line-like ASP’s are used in shops where slab polishing composes a larger percentage of their production. Still, these large- scale ASP’s work much the same way as seen in the video. All ASP’s are very finely tuned for polishing granite. A considerable amount of pressure is required for the overall outcome of the polish, but this pressure is calculated so as to not break the stone. Therefore, these machines aren’t really appropriate for other types of polishing; such as your car, your shoes, or your uncle’s bald head: only stone!
Computer Numeric Controlled (CNC) Machine:
For the stone-industry application, the CNC machine uses CAD/CAM programming to do many fabrication steps such as; routing edgework, coring holes, milling the thickness of the stone down, and cutting out sink openings. The CNC is extremely accurate, to 1/1000th of an inch. The CNC has many ‘tools’ that it uses. Each tool is used for a specific task and the operator selects the tools and programs the machine for the task at hand.
Automated Edging Machine (AEM):
This machine applies tooling to grind and polish a finished edge on a rough cut piece of stone. The AEM uses grinding disks to do the edgework as opposed to the CNC which uses a router type of tool. This limits the edge profiles that the AEM can do. AEM’s function by either moving the piece of granite past the grinding and polishing mechanisms or by moving the grinding and polishing mechanism along the stone. The following video shows an AEM that employs a rubber conveyor belt to move the stone.
This machine uses a steel diamond impregnated blade similar to that of a bridge saw for making straight cuts. It then uses tremendously pressurized water, 55,000 lbs. per square inch, to make advanced linear and nonlinear cuts. The pressurized water is so powerful it is capable of cutting almost any material including steel, rubber, and concrete.
In certain situations, reinforcement is beneficial for dimension stones because, hey, even something as tough as stone could use a little help every once in a while.
For softer, thinner pieces of stone (such as marble, limestone and some granites) with large surface areas, a polyester or epoxy adhesive is used to adhere fiberglass mesh to the nonpolished back side surface. This provides extra reinforcement to ensure against cracking.
To add extra support for the narrow strip of stone between the sink and the front edge of a countertop (the counter tops weakest area), a rod will provide the extra support. A shallow channel is cut into the back side of the narrow strip. A steel rod is epoxied into this channel, and then reinforced with fiberglass mesh.
Transportation of Granite
When pieces of stone are too big to lift by hand, slabs weigh over 700 lbs., machines must be employed. There are several different methods used in the warehouses and fabrication shops. Pneumatic vacuum lifters (see the CNC or AEM video) or rubber-clad clamps are used in conjunction with overhead cranes to lift and transport the pieces. Once the slabs have been cut down to manageable size, hand held gripper clamps are used. This is how the granite installers will bring the pieces into the customers’ home.
Application of Water
You’ve probably noticed lots of water spiraling off the tooling in the picture of the bridge saw, or the videos of the automated fabrication machines. There are several reasons for this. Because airborne stone dust poses long-term health risks, stone should always be cut, ground, and polished wet. Secondly, the water cools the blades and polishing pads which enables a smoother, faster cut and prolongs the life of the blade. All the water that we use is recycled through a filtration system and used over again.
What it Takes to Become a Countertop
Imagine yourself a customer interested in installing some nice granite countertops for your kitchen. As with any major purchase, the more you know about your product, the more comfortable you are when making a decision. So how does a chunk of rock become your countertops?
After the chunk of rock is quarried it is transported out of the quarry to the infamous gang saw. Here it is cut into approximately forty 1 1⁄4 inch 8 x 5 foot slabs, one of which is for your kitchen. Next and typically at the same location, the slabs are polished by a large-scale slab polisher (ASP) and placed in bundles of 6-8 slabs. Depending on the location, these bundles of slabs are crated up and sent on their way via rail, boat or truck to a fabrication shop near you.
At this point we are going to assume that the measure and templating already took place (we’ll look more in depth at this in an upcoming section). Now it’s your turn to see the granite slab before it becomes your kitchen. This ensures that you like the color and characteristics of the stone prior to us cutting it. After you approve your material it is taken to one of the bridge saws or another type of cutting machine. The templates from your kitchen measure are used to diagram on the slab where the cuts need to be made. After cutting, it’s off to the Automatic Edging Machine (AEM) where your selected edge profile is ground into the stone.
Chances are you have a sink or two in your kitchen. The Computer Numeric Controlled Machine (CNC) cuts and polishes the pieces with sink cutouts and performs any advance edgework. After the CNC, a customer’s countertops will be set up on steel tables by a fabricator. The fabricator does any edgework that the machines couldn’t. He may grind and polish radius corners, drills faucet holes, and finish anything and everything that the machines could not do. Finally the fabricator checks for chips, scratches, correct dimensions, and seam quality. The job is inspected one more time by a supervisor and the fabricator seals the tops. Your countertops are now ready for installation!
Technology’s Place in Fabrication
Stone is probably the last thing in the world that invokes images of cutting-edge technology. However, as you now may see, the applications of such technology (e.g. automated machining, saw jets, CNCs, synthetic diamonds, etc) are widely employed throughout the industry. In doing so, costs have been greatly reduced, efficiency improved, and quality heightened.
Because the granite countertop industry has been able to bring down its costs through technology and production efficiencies, more and more people have been able to enjoy the beauty of this natural product in their homes (as indicated by the rising popularity of granite and marble over the last twenty years). If the industry maintains its focus, natural stone’s upward trend should continue to rise.