Achieving Quality Edging Results

There are six primary "secrets" to consider if you're having problems in achieving quality edging results at a reasonable cost per linear foot. These secrets are based on experiences of many years serving the stone processing industry.

Achieving Quality Edging Results
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Why is it that some stone fabricating shops consistently deliver defect-free products with smooth, perfectly shaped edges, while so many others struggle to achieve the same level of quality and consistency, even when they use state-of-the-art processing machines? There can be several reasons, but in virtually every case, the answers are fairly straightforward and simple.
The most cost-effective method in the marble and granite industry to produce consistent, finished edges — rounded or more intricate compound/complex profiles like triple pencil or ogee — is to use automated edge polishing machines. The accuracy, repeatability and speed of a sophisticated, time-tested edging machine that has a production rate of up to 100 linear ft. per hour will out-perform manual laborers, provided the machine is operated and maintained properly.
There are six primary "secrets" to consider if you're having problems in achieving quality edging results at a reasonable cost per linear foot. These secrets are based on our experience after many years serving the stone processing industry.
1. Use Only Skilled, Trained Operators
The best way to assure your equipment produces top-quality results is to have only trained, skilled personnel running the machines. As with more technical equipment, the problem is seldom with the machine; it's generally the operator. Don't assume you can grab anybody in the shop, put them on the machine, and get the same results as with a skilled operator — it's not going to happen.
In edge polishing it's extremely important that the operator knows how to process each of the materials he encounters. Different materials may have different requirements, such as different feed rates or processing pressures — all in order to achieve the desired results. In fact, a skilled operator can tell by the sound of the polishing action whether the machine and its components are functioning correctly and if you'll get a perfect or flawed edge.
When a machine is first delivered, it is desirable to have as many people as possible trained in its operation and maintenance, including the owner and/or shop foreman. What often happens is one person is trained and, if he leaves the company, a second person is assigned the job who may know about 80 percent of what the first operator did. Then he leaves and a third person who knows even less takes over, lowering the skill level even more. The answer is to invest in timely training seminars by the manufacturer to ensure you always have trained operators on hand.
2. Practice Scheduled Maintenance
To minimize downtime and repair costs, and to maximize your equipment's longevity, schedule regular maintenance, including keeping the machines clean, a sure indicator of proper maintenance. Remember, a clean machine works better and lasts longer.
Normal maintenance as recommended by the manufacturer can increase each machine's life cycle up to 50 percent; and meticulous care can more than double each machine's expected longevity. Under normal conditions, and even with regular, routine maintenance, a machine should probably be extensively refurbished every seven to 10 years. These estimates are based on years of experience as a machine tool supplier and rebuilder.
Stone processing machines operate in a demanding, harsh environment with lots of water, moisture and abrasive dust, and they process one of the hardest materials in the universe. So the equipment is subject to extreme wear and tear. Yet too many shop operators ignore basic maintenance requirements — regular lubrication, keeping oil reservoirs filled, regular washing and checking moving parts for functionality and wear and tear, especially rollers and belts.
Belt slippage can be a common problem, usually traced to one of the following conditions: The operator is not maintaining the proper pressure on the pressure bar or other device being used to maintain belt tension; the rollers are worn out; the belt is incorrectly positioned; and/or the belt might be so dirty that it can no longer carry the piece. There have even been situations in which the operator oiled the belt to make it look nice and shiny. As a result, of course, the slippery belt was incapable of moving a workpiece through the machine.
Too often shop operators resist any scheduled maintenance that limits production time. If the machine breaks down, they just want it fixed with no additional time spent to perform routine maintenance on the machine that could prevent future breakdowns.
If shop personnel don't have time for maintenance, a factory representative or some other service should be contracted to perform routine maintenance on a monthly basis. The manufacturer's maintenance agreement is one of the best investments a fabricator can make.
3. Use Recycled Water
An extremely important factor in producing world-class results is the quantity and quality of the water used in processing each workpiece. Using fresh water and not recirculating it is an unnecessary and expensive luxury that fabricators cannot afford. If you're using recycled water, but it contains abrasive remnants of previously processed material, you're going to get a dull finish scored with swirl patterns. This harms both job quality and customer satisfaction. Fabricators need to invest in a good water reclamation system and make certain it is properly maintained. It pays for itself in a couple years.
4. Follow Manufacturers' Instructions
FOLLOW THE MANUFACTURERS' INSTRUCTIONS. This applies to both edge polishing machine operation and the tools and consumables recommended at the specified speeds and pressures. The manufacturer that built the machine invested countless hours and resources in R&D, testing and performance analyses to determine what tooling packages, polishing bricks and diamond pads, as well as which combination of operations, will maximize each machine's output to assure it reaches its maximum life span.
The No. 1 consideration in equipping your edge polishing machine is to use the abrasives recommended by the manufacturer. There are dozens of companies selling abrasives of all different types, but the reality is that the factory recommended products were selected because they have proven to be optimum in terms of finish and life cycle duration.
Another manufacturer suggestion that is often ignored is to use the proper sequence of tooling to achieve the desired finish edge shape and avoid using the machine's shaping wheels and mandrels to remove bulk material prior to shaping. For example, if the machine has pre-bevellers, be sure to use them because they can remove up to 80 percent of excess material. This not only saves wear and tear on your shaping tooling, but it also eliminates the all-too common complaint of tools being squared off prematurely. In this case, not only does the No. 1 tool not conform any longer, but the No. 2 tool then has to compensate with increased grinding to achieve the proper shape, shortening its life as well. The result is a set of tools wearing out much faster — as much as twice the normal rate. By using the pre-bevellers correctly, the machine can process a piece much more quickly because it only has to take off a millimeter of material to achieve the final rounded shape, rather than hogging a complete square corner with the more expensive shaping tools.
5. Purchase Manufacturer Recommended Tooling — Not Cheap Substitutes
"You get what you pay for." The old adage warning against being "penny wise and pound foolish" is especially true in the stone processing industry. In too many cases, saving a little money upfront can cost much more in the long run. If you want your edge polishing machines to operate correctly, eliminate problems and minimize manpower costs, equip the machine with the proper bricks and diamond tooling, once again following the manufacturer's recommendations. Using cheap substitutions usually costs more per lineal foot in the long run because of more frequent tooling replacement, higher operating speeds and pressures with more wear and tear on the machine and manual touch-ups to correct flaws. Some replacements may be effective, but it's a hit or miss proposition. The real key to high quality polishing is not how much you can save on the polishing pad or brick, but how much labor can be saved by utilizing the machine as it was designed and with the factory-authorized tooling that guarantees the desired finish.
Saving 10 cents per linear foot by buying cheap, nonfactory recommended pads defeats the purpose of buying the machine in the first place. Cheaper pads may have synthetic or low-quality diamonds, lower concentrations of diamonds or diamonds with imperfectly formed faces, meaning fewer cutting surfaces than those in more expensive pads.
In addition, low-cost pads generally require much higher application pressures — 8 or 9 bar compared to 2.5 for high-quality diamond pads — and the higher pressures exert more wear and tear on the machine as well as cause the pads to wear out three times as fast.
It makes little sense to buy a $50,000 to $100,000 machine and then negate its productivity potential by equipping it with cheap pads that cost the owner more money in the long run from increased frequency of repairs and downtime, not to mention the lower rate of productivity and quality issues.
These same basic principles hold true for hand polishing operations. Cheap polishing pads wear out faster, give lower quality results and if the manual polisher does strive to deliver a first-class finish, it will take longer to achieve desired results. If you're paying on the basis of piecework, you very likely will wind up with some poorly executed edges because your polishers most likely won't spend the time required to deliver quality results.
When buying a machine or its tooling package, consider two things. First, determine if the price of the machine includes any tooling. Most manufacturers don't include that first tool, which reduces the cost of their total package. Second, many will claim you only need a minimum number of tools to achieve desired results for any given job, rather than a larger package recommended by a competitor. The fact is that to achieve a uniform, high-gloss finish, you have to use the proper sequence of polishing pads. This may require seven pads rather than four, but if you skip pads of the required abrasive concentration, you will likely wind up with scratches in the finished surface.
6. Beware
One last note of caution: Beware of "sabotage" in the form of employees willfully producing less than desirable results with your machines in order to generate more hand polishing work for themselves and others. If you have an inordinate number of edging machines pushed into a corner or against a wall and a fairly high number of people performing hand polishing and edging, driving up your costs per linear foot, there may be an issue. If you do have machines and they are not being utilized to their maximum potential because your employees claim the equipment performance is subpar, call in a factory expert for an analysis — you may learn a valuable lesson.
Purchasing an edge polishing machine is one of the most important and expensive investments stone fabricators can make to stay competitive and produce high-quality countertops, islands and vanities. These purchases of state-of-the-art machines can dramatically upgrade your shop's capabilities and help distance you from your competitors. Consequently, it's in your best interest to keep your machines in optimum condition. Keep them well maintained and running all day, and surround yourself by highly skilled personnel who understand machine and tooling operation and maintenance.
Phil Mularoni is president and Steve Collick is East Coast regional sales manager for Marmo Machinery USA, 23455 Telegraph Road, Southfield, MI 48034, 248-355-3128, www.marmousa.com.
author: By Phil Mularoni and Steve Collick




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