Computer processing power is increasing all the time. It is faster, more reliable, easier to use and less expensive. And with machine operators holding more computing power in their hands to make a phone call than the Americans had available to them to land a man on the Moon, the technology is no longer daunting. Add new materials such as Dekton and Lapitec to the mix and it is not surprising that, as the economy improves, more companies are taking a second look at the technology they use.

In January, Intermac, well known for its Master CNC workcentres, invited customers to it headquarters in Daventry, Northamptonshire, where it has a large demonstration area, to see its Primus waterjet cutter.

Intermac sells to the glass industry as well as to the stone industry, and its parent, Biesse, also supplies CNC machinery, including waterjet cutters, to the timber processing trade, so it was not just, not even mostly, stone companies that went to see the waterjet cutter in action. But there were people from the stone industry who took the opportunity of going to Daventry to see the Primus going through its paces.

Flow UK, the British arm of the American waterjet manufacturer, has also had open days at its premises in Hinckley, Leicestershire, where stone companies have gone along to look at its waterjets and last year the company exhibited alongside the Waters Group at the Natural Stone Show in London.

Waters Group, the stone machinery, tools and accessories company, sells Flow waterjet cutters to the stone industry in the UK and before the end of last year had installed two at stone processing businesses in the UK.

Not too many stone processing companies have invested in waterjet cutting yet, but the number that has is growing – and includes some of the biggest (and most publicity shy) names in the sector. One of the companies that bought a Flow waterjet last year from Waters Group and does not mind being mentioned is Midland Stone Centre in Rothwell, Northamptonshire. There will be more from the Midland Stone Centre in a future edition of Natural Stone Specialist.

Cutting stone in a straight line with a waterjet might never be as quick as cutting stone in a straight line using a bridge saw and it is certainly more expensive, but you can cut shapes using a waterjet that would leave a bridge saw standing.

Waterjets can also cut through most materials without having to change the tool that is doing the cutting. That trait is starting to look increasingly attractive to stone processors as they take on board a wider range of materials.

The worktop market has spread out from granite for the kitchen into marbles and limestones for the bathroom and other rooms of the house. There is also plenty of stone used in the commercial market.

The stone industry has already encompassed engineered quartz and is rapidly assimilating ceramics and the new superhard materials of Dekton from Cosentino and Lapitec from Breton.

Just out of interest, Nicola Waters, the MD of Waters Group, says these new products are taking off well and Waters Group has had a lot of requests from customers for recommendations for tooling to work them. “As we work with ADI, Konig and SKE we are perfectly positioned to advise and supply, which is always a pleasure,” she says. “The tooling is on back order with our manufacturers as demand has been so high.”

Even without the new materials, marble and granite are best worked with a different set of tools for each, and then there is limestone, travertine, sandstone, onyx… 

A range of tools is needed if they are to be sawn and shaped efficiently on conventional bridge saws and CNC workcentres. A machine that can go straight from one material to another without having to stop to change the tools; that can cut almost square inside corners; that can (as long as it has five axes) cut particularly accurate mitres; that can produce almost any shape it is possible to achieve within the tolerances of the material being cut; that does not create dust; that is quiet in operation; that can cut cleanly enough not always to need secondary finishing of the edges; that leaves minimal waste; that has no thermal impact on the material being cut… a machine that can do all that is worth taking a closer look at. At least, quite a few stone processors have decided it is as they start to make up for their understandably low level of investment during the past five or six years.

Perhaps an even better solution is to combine a circular saw with a waterjet, as Breton has done with its Combicut, so that simple lines can be cut using the disc, while mitres and more complex work can be performed by the waterjet. Both the saw and the waterjet work on five axes and in setting up the program, the saw cuts and the waterjet cuts are shown in different colours on the screen to distinguish between them.

Just one Combicut has so far been installed in the UK and that was as part of a production line. However, Carl Sharkey, who heads Breton UK, says there have been a lot of enquiries since the launch of Dekton, and not just for the CombiCut, but also for the stand alone Practica waterjets made by the Italian Waterjet Corp. Breton is selling Practicas having decided to use the expertise of a company already well established in the market rather than try to develop a new range of its own machines.

Of the waterjet manufacturers, Flow has been around longer than most and so the machines have had longest to evolve. Gary Davis is the Flow Sales Manager covering the UK. He says that along with technical advances (such as eliminating the splay of the cut towards the bottom of it on thick materials like stone), the most noticeable change over the years has been a fall in the price of the machines. A Flow waterjet costs no more now than it did 10 years ago, in spite of the level of inflation there has been in that time. And you get a lot more machine for your pound these days, he says.

With each improvement to the machines, sales have increased and economies of scale have kicked in, making them better value for money. The correction of the splay of the cut, which is now an accepted feature of waterjet cutting, was introduced by Flow in 2001. The next big development after that was the introduction of what Flow calls hyperjet technology, which ramped up the pressure to 600MPa (6,000Bar). The higher the pressure the faster a clean cut can be produced.

The 600MPa cutter was introduced 10 years ago, but it is only as the price has come down that it has started to become more widely used in some parts of the world – notably in Italy and the Middle East, where mass production benefits from faster machines.

In the UK, few products are made in such quantities and 380MPa waterjets that cost around £40,000 less than the 600MPa machines are most popular. When you are cutting a small number of a lot of different shapes in various materials, it is the speed at which the change from one job to another can be made that improves productivity rather than the speed of the cut.

Following the increase in pressure has come the tilting head in what Flow calls Dynamic XD technology. This allows bevels to be cut and has helped make the machines more interesting to stone processors, especially as bevels cut by waterjet are particularly clean and can be joined together straight from the waterjet without further attention.

Compared with Flow, Intermac, the Italian company, is a newcomer to the waterjet cutter market, introducing its first machine six years ago. It has proved to be a best seller in stone, glass and wood in Italy and other parts of the world.

Inevitably, as stone processors in the UK and Ireland have seen the benefit of the technology, interest has also grown in the British isles – hence the stone companies that attended the Intermac open days in January.

Intermac played a major role in making CNC workcentres mainstream in the natural stone worktop sector in the second half of the 1990s and could well play a leading role now in getting waterjet cutting accepted.

The Intermac waterjets go under the name of Primus and the machine being put through its paces in January was a Primus 322 that was on its way to a glass company, although for the benefit of the stone companies that went along to see it at Daventry it was cutting engineered stone as well as glass. A benefit of Intermac waterjet cutting is that it uses software already familiar to anyone who has used an Intermac CNC workcentre.

The maximum water pressure used by any Primus is 420 MPa, although they are supplied with different power ratings from 22kW to 75kW. The more powerful they are, the higher the flow rate of the water / abrasive mix (from 2litres a minute to 7.8) and the faster the cut. There are machines with two bridges and two cutting heads per bridge, working with two tables. In the UK companies tend to go for machines with one bridge, one head and a power rating of between 37 and 54kW.

Waterjet cutting is more expensive than operating a bridge saw and the biggest single expensive is the garnet powder that is mixed with the water. Garnet is used rather than sand because sand is silica and breathing silica dust can damage your lungs, as any mason cutting granite, engineered quartz or sandstone ought to be aware. Garnet is also a good abrasive because it has a lot of sharp edges.

Garnet is sold in various qualities but costs about £300 a tonne. Different prices relate to the quality of grading. Cheaper garnet is less well graded and you will use more of it to achieve the required cut.

A waterjet cutter consumes garnet at a rate of about 30kg an hour, which remains constant whether it is cutting 5mm thick ceramic or 100mm thick granite.

Although about 40% of the garnet will not actually cut the material being worked, it is not practical to recycle it, not least because 60% of it did come into contact with the material being cut and has been degraded. Also, it is mixed with the material that has been cut. And in any case in order to flow into the jet of water it has to be bone dry.

The cost of disposing of the waste garnet and the material it has cut can come as a surprise to some operators, although stone companies are more used to disposing of such sludge.

Of course, the garnet takes its toll on the tungsten carbide ‘focussing tube’ that delivers the cutting jet. It is a wear part that has to be replaced every 80-200 hours, depending on the pressure and flow.

The water itself is also abrasive. It could be used on its own for cutting (in fact it is for softer materials such as rubber). The water is concentrated into a jet through an orifice of zircon before it is mixed with the abrasive. The disc containing the orifice needs replacing every 50 hours or so.

While waterjet cutting is attracting most attention at the moment, some companies are also taking a second look at robot arms.

Working in conjunction with a rotating table holding the workpiece, all operated by the same software, mean a block of stone can be worked all round at any angle.

Robot arms did not have the happiest of introductions to the stone industry in the UK, which has created a barrier to further investment in them. Even the engineering involved in the arm itself is looked on with some suspicion because so many articulations all with bearings to wear, and such long lengths of unsupported metal raise questions about accuracy when a heavy spindle carrying heavy tools is being used to work a hard material.

The more metal there is, the less likely it is to bend and vibrate, but it also requires more effort to move it around.

And the engineering is only part of the difficulty. Getting the software to work in six simultaneously interpolated axes requires a considerable amount of processing power.

For different reasons, with both waterjets and robot arms versatility does come at the expense of speed of operation. You might think that would favour small markets for stone such as the UK, but it is in other, high production markets that most robots have been sold with their capabilities being used primarily for sculpting in both architectural and monumental applications.

French machinery manufacturer Thibaut, represented in the UK by Waters Group, has produced a robot specifically for the stone industry using its T’Cad T’Cam operating system that will be familiar to anyone who already has a Thibaut three, four or five axes workcentre.

Called the Transformer, the Thibaut robot has a spindle rotating at up to 10,000rpm and a reach of up to 3.1m. It has a 21-space tool magazine plus a saw disc holder.

T & D Robotics in Italy, meanwhile, has worked hard on developing a robotic system for the worktop market. Robots have generally proved to be too slow for making relatively simple worktops that CNC saws, workcentres and edge polishers can produce without much bother. But T&D has developed its Lapisystem Top that in a relatively small amount of space can cut worktops to size from the slab (or load pre-cut pieces directly from a pallet), process them as required and load them back on to a pallet. T&D says in this way 20 kitchen worktops can be produced and loaded on to pallets ready to be shipped in 24 hours with just one operator working a normal shift.

On the other hand, you do not have to buy a whole package from one company. There are companies that will help you buy a suitable robot (or other piece of computer-controlled machinery) and program it to meet your requirements.

Alphacam is one such company (you can read how it helped Toffolo Stirling in the panel on the left). From the Vero Software stable, Alphacam Stone has been specially developed to address the requirements of machining stone.

Another company that can help is CNC Robotics, in Liverpool, which works with a software developer called Delcam in Birmingham. Delcam is a computer-aided manufacturing (CAM) specialist, and has just been bought by another company, Autodesk, which is a computer-aided design (CAD) specialist. The aim is to integrate the CAD with the CAM, although Delcam will remain an autonomous entity.

You might have seen CNC Robotics and Delcam at the Natural Stone Show at ExCeL London last year.

If you are thinking of getting a robot, especially if you intend to buy a second-hand one (and Delcam does not think that is a bad idea as good, used robot arms can be acquired for tens of thousands of pounds) it is a good idea to talk to a company such as CNC Robotics to make sure what you intend to buy is up to the job. Peter Dickens of Delcam says: “If the robot arm isn’t accurate enough the best software in the world won’t make it work properly.”

He says a pick and place robot design for stacking pallets might not have been made accurately enough in the first place to enable it to cope with precision masonry work.

He points out that there is also always a compromise with robotics between speed and accuracy and it is up to the operator to decide where that line should be drawn.

However, Jason Barker of CNC Robotics says with electrical PC controls taking over from mechanical controls, speed and accuracy are improving all the time. “Robots are like cars,” says Jason. “Seven years ago they weren’t bad, but now they are a million times better. The technology in a car today didn’t exist seven years ago and the same is true of robots.

“If you are thinking of spending a lot of money like this, the first thing you want to do is: a) see a demonstration, b) see a demonstration and c) see a demonstration. The problem companies in the UK have is that no-one is doing demos for stone machinery. We do live demos but we’re not set up to do stone machining demonstrations because the vast majority of enquiries we get don’t involve stone. I’m sure for a UK stone company to see a live demonstration of a robot – a modern robot – it would be more than a day trip.”

A final point: Delcam’s Peter Dickens says learning to use Delcam’s PowerMill software involves some training. “It’s not something you can pick up in an afternoon but it doesn’t require years of study, either. We give a week’s training on PowerMill software.”

Another company with hi-tech robotics solutions exhibiting at the Natural Stone Show last year was MasterCam, which produces the RobotMaster CAD/CAM that is in use in 20 installations in the UK, including the factories of stone companies Johnsons Wellfield Quarries, which extracts and processes the famous Crosland Hill Yorkstone from Huddersfield, and Rainbow CNC, a processor of architectural stone in Park Royal, London.

They have used RobotMaster in conjunction with Stäubli machining robots that offer high speed machining with a spindle directly integrated into the robot arm. The drive to the spindle and all associated services – such as cooling and lubrication – are placed inside the robot arm and connected to the various supplies through the robot foot.

This offers protection class IP65 (against dust) for the complete arm and IP67 (against water) for the ‘wrist’. Any machining robot working in the stone sector will need to offer these classes of protection – and, of course, they do. RobotMaster can just as easily be used with ABB, Fanuc, Kuka, Mitsubisha or Motoman robotics.

In Stäubli’s case, its VAL HSM software controls the robot arm while the RobotMaster software is used to import and translate CAD / CAM data and apply and optimise six-axes robotic tool paths into Stäubli’s VAL3 language that can then be used to control the processing.

RobotMaster says its software means the robot arm can be programmed as simply as a CNC workcentre, automatically generating the toolpaths, optimising them for the specific robot model chosen and detecting and avoiding any potential collisions.

Toffolo Stirling steps up with Alphacam Stone

State-of-the-art Alphacam Stone CAD/CAM technology has helped Toffolo Stirling produce a stunning limestone spiral staircase for a private house.

Just one program created in the Alphacam Stone software drove Toffolo Stirling’s 24-tool-station Brembana Speed-3 CNC workcentre, controlling toolpaths for both the machining and sawing of the 16 hefty Jura blue-grey limestone risers.

At a depth of 175mm, this was the thickest material Toffolo had ever machined. The company is more used to working with 20-30mm thicknesses, occasionally going to 50mm or 60mm.

Managing Director Kenny Turnbull says new tooling was needed for the contract – and taking the vacuums and tooling length into account, The Brembana was working right up to its limits.

Kenny: “We had to create special blocks and worked with the material on a jig made from a slab of quartz to give us the height we needed. This project, for contractors Stephen Gardiner Construction Ltd, was new and innovative for us, but Alphacam ensured we could complete it accurately and quickly.”

He says Alphacam Stone not only speeded up the programming, but also gave Toffolo Stirling the confidence of a collision-free machining operation and that each step would be totally accurate.

“The risers had to be high precision so they would fit together perfectly. We installed the staircase in less than two days, but if there’d been discrepancies either at the workshop or when we got on site it would have taken considerably longer.”

As well as manufacturing, supplying and installing the 2.5m high staircase, Toffolo Stirling built the engineering brick surround which the stone keys into. The company also worked on the kitchen, several bathrooms and fireplaces for the exclusive property at Comrie, in Perthshire.

Denholm Partnership Architects originally drew the staircase in Autocad and sent the work to Toffolo Stirling as a DWG file.

Kenny: “We split out the elements and, in consultation with the architects, amended some of the sizes to make it work better and integrate into the surrounding brickwork, without compromising the architect’s design.”

Once Toffolo Stirling’s drawing office had finished its work, the Autocad drawing was placed on the server and the CNC programmer downloaded it, applied and programmed the different tools, and Alphacam automatically created the optimum toolpaths.

This was sent to the Brembana via a serial cable and the operator set the machine, making sure all the tools were in the correct stations.

“Programming the work in Alphacam Stone took around two hours and gave us a total of around 64hours machining time. Each step was on the Brembana for around four hours and our masons hand finished them.”

Kenny is impressed with Alphacam. He says it cuts down programming time considerably compared with the software that came with the CNC machine and has enabled Toffolo Stirling to take on work that would not be profitable without it. “Almost everything we do is a one-off, so saving time on programming is a major advantage. We’re writing programs constantly, maybe doing 20 or more a day, so even taking just 10 minutes off each one is a huge benefit.”

And Kenny Turnbull has found another use for Alphacam’s powerful simulation function. As well as running programs through the simulator before starting to cut the stone to ensure they are collision-free, he uses it as a sales tool. “We can show customers exactly how we’re going to manufacture their order.”

He says Alphacam has proved to be a major technological asset. “The biggest benefit to us is the speed. If a company sets up a machine to produce hundreds or thousands of identical parts, the programming time probably isn’t too important. But to us, working mainly on bespoke one-off items, shaving off just a few minutes on each is absolutely vital.

“And because there are never any glitches with this software, it gives us confidence to take on more complex work, knowing we can deliver on time. Although we’re not working to engineering tolerances, we digitise the templates and need to be sure that the finished product is exactly as the template.”

Based in Stirling and part of the Stirling Stone Group, Toffolo Stirling works from a 700m2 factory set in a 2.5acre yard. It uses a wide selection of granites and marbles. While regularly working on standard kitchen worksurfaces, it focuses on one-off bathrooms, flooring, kitchens and other stone elements for large, high quality, new build housing, and restoration projects, along with shopfittings, hotels and commercial properties.