Stone processing – equipment

Recommendation points

• Stone cutting – cutting machine
• How to choose a cutting machine
• Diamond disc in stone processing
• How to choose diamond discs

In this article: types of cutting machines; structural elements of the cutting machine; how to choose a cutting machine; methods of applying diamond dust to the disc; methods of fastening segments to a steel base; how to choose diamond discs

Natural stone was one of the first building materials for mankind. Someone will object, they say, the huts were built of wood, but it was the caves that were the first home for the ancient people. And the stone buildings of the ancient and middle ages have survived to this day – the majestic pyramids of Egypt, the trapezoidal temples of South America, the castles of Europe … The strength of natural stone, its beauty and durability attract architects of the present time, especially since the construction equipment for stone processing is being improved from year to year.

Stone cutting – cutting machine

Modern cutting machines can be divided into three types according to the scope of application – industrial, construction and jewelry, the first two types are the most common. The basic design of the cutting machine: frame (bed); the motor is usually electric; transmission; cutting tool. In addition to the main elements, the cutting machine must be equipped with means for feeding stone to the cutting tool, as well as devices for controlled cutting.

The bed of a stone cutting machine is made of steel or cast iron, this is an important element of a stone cutting machine, because the performance of the device depends on its reliability, ability to damp vibration of the electric motor and the correct location of the cutting equipment on it.

The electric motor of the cutting machine, which drives the cutting tool, is most often designed for 380 V, less often for 220 V. Of course, machines designed for a current consumption of 380 V have more power and are equipped with cutting discs of a significant diameter. According to the method of fixing the engine, there are two types of stone-cutting machines – with a fixedly fixed electric motor, with a motor on a bed with rails. In the first case, the stone to be processed is fed to the cutting tool, in the second – a frame equipped with rails with an engine and a cutting tool installed on it is fed to the stone.

Stone cutting machines can be equipped with several types of transmissions – chain, belt, gear, with direct drive from an electric motor, etc. The type of transmission directly depends on the power of the engine and the tasks that the manufacturer has laid down in this model of the machine..

Industrial and construction machines for cutting stone, in turn, are divided into three types – cant-milling (cutting), calibration and stone splitting. With the help of cutting machines, stone blocks and slabs are cut into fragments of the required size. There are stone cutting machines for sawing and for edging stone.

Stone cutting machine Cedima CTS-425

The cut stone slabs are leveled on sizing machines equipped with rotating heads to roughly align the stone slabs. After leaving the sizing machine, the slabs are subjected to grinding and polishing..

Stone splitting machines are designed for the production of split stone products – curbs, paving stones, wall stones and tiles. They are equipped with metal blades that break stone slabs into fragments of specified sizes.

How to choose a cutting machine

First of all, find out if this model of the machine is universal or has a narrow specialization – some cutting machines are designed by manufacturers to cut certain materials.

Study the technical data of the machine, paying attention not to the average but to the maximum allowable load. Find out how accurately and efficiently the cut is made, how many permissible cutting angles this machine allows, how long and deep the cut can be made, whether it is possible to change the cutting depth during operation, what is the capacity of the coolant container that lowers the temperature of the blade during cutting. The saw blade must have a protective cover.

Make sure that there is no damage to the planer table – its surface must be perfectly level and the support legs are stable.

On the Russian market there are stone cutting machines, drilling machines, tile cutters and other equipment, both domestic and foreign manufacturers from Europe and Asia – the average cost of a professional cutting machine is about 80,000 rubles.

Diamond disc in stone processing

Diamonds, as the hardest minerals on our planet, were used in stone processing thousands of years ago – the ancient Egyptians were the first to use diamonds in stone processing and similar in hardness corundum and topaz were the ancient Egyptians. The discovery of a method for producing artificial diamonds in 1956 by General Electrik made it possible to use these minerals in construction work – after some 15 years, diamond cutting tools appeared at almost every construction site.

The diamond blade consists of a steel body and a segmented edge with diamonds on it. There are several methods for the production of segments with diamonds attached to them – the galvanic method, the silver brazing method, hot pressing and the sintering method..

The first method, galvanic, is much simpler and cheaper than others – segments are placed in an electrolyte containing industrial diamonds, and an electric current is supplied. The advantages of diamond discs produced using this technology are low cost, high productivity (greater protrusion of diamond grains). Minus – low resource. Cutting tools made with this technology are suitable for cutting soft materials such as marble..

The sintering method or cold pressing consists in mixing powdered metal (an alloy of copper and tin, with the addition of iron, cobalt, and other metals) with diamonds, placing them in molds and applying high pressure to them without heating. The costs of such production are low, hence the low cost of cutting tools made by the sintering method, but the resource of such diamond discs is extremely small.

Hot pressing is similar to the sintering method with the difference that the segments are heated in an oven before high pressure is applied to them. This method is most common among cutting tool manufacturers – a significantly longer resource is achieved than discs made by sintering, galvanizing and silver brazing methods, but the cutting ability of such diamond discs is much lower. The reasons for the lower productivity in a low concentration of diamonds and their low strength of fixing in a bond, in comparison with the methods of silver brazing and electroplating.

Cutting tools made using the silver soldering method have a greater resource and productivity than those of the galvanic method – diamond powder protrudes more on them and has a stronger bond.

Segments made according to one of the above methods are fixed along the perimeter of a circle made of tool steel in one of three ways – laser welding, brazing using high-temperature solder, and “baking” under the influence of high temperatures. The best and most expensive way to connect the segments to the body is “baking”, during which a layer of diamonds is built up on the body of the cutting tool. Laser welding provides a slightly lower strength than “baking”, and is also expensive. The method of soldering segments to the body, which is widespread due to its low cost, provides the lowest joint strength when compared with the two described methods – it is less resistant to heat during friction during cutting.

After connecting the segments with a round steel body, they are turned with a ceramic sharpener until diamond particles appear on the surface and the disc itself acquires the necessary cutting properties.

Depending on the method of fixing the segments on a given diamond disc, cutting with it is performed dry or wet. Discs with segments fixed to them by the method of silver soldering must be moistened with water during cutting, otherwise the segments will warm up and fall behind the body. Diamond blades with laser welded or baked-on segments with the main body of the blade can withstand high friction temperatures and can be used for cutting materials without moisture (depending on the hardness of the material).

How to choose diamond discs

Before visiting the market, you need to decide for yourself the following questions: what material is supposed to be cut and to what depth; what is the diameter of the disc the cutting machine is designed for, what is the bore; the drive power of the machine and the number of revolutions generated by it; what type of cutting the machine is designed for – dry or wet, what type of cutting will be used on a given material. Answers to the above questions must be reported to the seller.

The depth of cut will depend on the radius of the blade, if this machine is not designed for the depth of cut you need – do not use it, because this will change the linear speed and the cutting blade will be exposed to improper wear, which can cause malfunctions, overheating and overloading of the machine drive.

The disc must have a bore commensurate with the machine shaft – no, even the slightest, clearance is unacceptable. Manufacturers produce discs of the following diameters:

• from 115 to 230 mm with a bore of 22.2 mm in diameter, for angle grinders (grinder), for dry cutting;
• from 150 to 350 mm, bore diameter 25.4 mm, for a panel cut-off machine, for wet cutting;
• from 300 to 400 mm, bore 25.4 mm, for asphalt and manual cutting machines, for dry and wet cutting;
• from 500 mm, bore 25.4 mm, for specialized cutting machines, for wet cutting.

The cleanliness of cutting and the speed of rotation of the diamond blade largely depend on the shape of the segments-teeth, in turn depending on the material for which it is intended to be cut. For example, cutting asphalt is performed with discs with a significant distance between the teeth, because cleanliness of the cut is not important here – good removal of asphalt chips is required. But when cutting glass or clinker tiles, the cleanliness of the cut is of great importance, therefore, diamond-coated discs designed for these materials do not have teeth..

The opinion about the influence of the height of the segments-teeth of the disc on its service life is fundamentally wrong – the service life of a diamond disc depends on the way in which the segments are fixed on the disc, on the composition of the bonding segment, as well as on the amount of diamond chips and its concentration. Large toothed discs are designed for cutting stone – the size of the segments protects their bonding with the disc body and prevents them from getting stuck in the stone.

For cutting various types of stone, universal discs are suitable, for cutting a specific stone – specialized discs. When choosing a brand of a diamond disc, it is required to divide the rocks of the stone into three groups according to abrasiveness and hardness:

• soft rocks (for example, clinker and marble). Cutting is carried out with one brand of disc with a soft bond, because these rocks are of low abrasiveness, they wedge the disc well – discs with the application of diamond chips by the galvanic method directly to the steel body are suitable;
• hard stone (for example, reinforced concrete and granite). Discs are required, the strength of the binder in the segments of which is low or medium level. these stones are hard and have low abrasiveness – discs with average characteristics are selected, for example, universal;
• stone rocks that are a soft abrasive (for example, chamotte, silicate, asphalt). The high abrasiveness of these materials will require diamond discs with tooth segments with an extra hard bond.

The described conditions for the selection of a disc apply to any stone cutting equipment, such as a table saw or cutting machine.

Important: if cracks appear on the disc during operation, it is prohibited to use it for further cutting!

The cost of discs varies from 400 to 35,000 rubles, depending on the technology of their production, the density of the diamond dust, the diameter, the material that they can cut, and the resource of production. Chinese-made diamond discs, for example, are more suitable for small-volume work, because have low cost and durability.

Products of domestic and European manufacturers are of higher quality, but they will cost more and, therefore, such discs are worth buying if there is a sufficient front of work..