Diamond cutting discs, or as they are called, diamond wheels, have a number of advantages over conventional abrasive counterparts. They have significantly higher rates for the resource, accuracy of cutting and productivity. Next, we'll look at how to choose a diamond disc for a Bulgarian, what kind of discs exist and what is their advantage.
- 1 Introduction to diamond cutting discs
- 2 Principle of work of a detachable diamond disk
- 3 Design of detachable diamond discs
- 4 Varieties of diamond discs
- 5 How to choose a diamond disc for a Bulgarian
- 6 Problems arising in the course of work and solutions
Introduction to diamond cutting discs
Circles with diamond cutting edges for waterless cutting were first created in the design bureaus of the Japanese company Sankyo Diamond Tools, the structural division of the Hitachi corporation.
A lot of technologies were used for the first time, so the circles were not reliable enough and quickly failed. For example, diamonds and the cutting part were attached to the steel base by high-temperature soldering. In the process of work, when a large frictional force occurs, the metal heats up, the solder melts and the working part simply falls off. With water cooling, such circles worked more or less tolerably, but with dry friction, their resource was small.
The fact is that the diamond does not cut the material, but it rubs it into the dust, large friction forces are accompanied by rapid heating - the heat does not have time to retract along the body of the circle, in addition, despite the presence of special slots, the circle deforms when heated. The shape changes are insignificant and do not threaten destruction, but the strength of the connection is adversely affected.
Sankyo Diamond engineers also offered other solutions - sintering the working part and the base under great pressure. Such a connection is more durable and withstands significantly higher temperatures. Thus, it was possible to create segmented and solid discs that are resistant to heat and deformation. The technology is still used.
The second solution is laser welding at the molecular level. According to this technology only circles of a segmented type are produced. For strength and reliability, both types of discs are almost identical, although many professionals believe that the laser welding method is better.
Principle of work of a detachable diamond disk
Most diamond discs are used on angle grinders with a speed of up to 12,000 rpm. The maximum number of revolutions that the best wheels can withstand is 13,900 rpm, but there are not too many tools that can develop them when cutting.
With the surface to be treated, only the diamond itself contacts - it protrudes above the surface of the rim and, when rotating, it rubs the material into fine dust. The multi-layer structure of the cutting edge ensures a constant readiness of the disc to work - the diamonds that have worn out or come out of the socket are replaced by others that are in the lower layer of the rim.
Excess heat is transferred to the disk body, but, nevertheless, it heats up to sufficiently high temperatures, which requires compliance with certain safety rules for dry cutting.
The longevity of the circle and the effectiveness of its application depend on the diameters of the diamonds. The large ones ensure the efficiency of the work, but wear out quickly, the small ones are cut very accurately, but more slowly, their service life is 25 to 30% longer than the tool with large fractions of the crystals.
Design of detachable diamond discs
Structurally, the diamond disc is a steel circle with a cutting part and slots all over the area that contribute to the removal of heat and reduce strain stresses. Diamonds are interspersed throughout the rim of the disk. They are inserted into the rim from alloys of nickel, zinc, cobalt and tin. With a linear speed of up to 80 m / s and enormous frictional forces, the fastening must be exceptionally strong, which is achieved by using special technologies.
To ensure the holding of the cutting part under heavy loads, they can be fixed by laser welding, sintering, galvanizing or soldering. Soldering is only used in discs for cutting with water-cooled machines.
Depending on the method of fixing the diamond, the purpose of the disc is determined. Galvanically fastened diamonds are designed to work with soft natural stone types, processed by laser welding and sintering, especially segmented - for all types of solid materials in a dry and "wet" way.
The holes and slots are strictly symmetrical, and the mass of diamonds is also balanced in diametrically opposite directions. This eliminates the vibration and "beating" of the disc and ensures uniform cutting. But you can use circles for dry cutting only to perform a straight cut - for a curved path the disk can not only lose diamonds, but also collapse. This kind of tools is very sensitive to lateral loads.
1. Damping slots. 2. Cutting layer. 3. Landing hole. 4. Steel disc.
Varieties of diamond discs
Diamond cutting discs have certain differences in design and manufacturing technology.
Types of diamond disks in structure
By structure, dry cutting discs are divided into:
Solid diamond wheels. Equipped with a continuous cutting tape running along a circle, into which are interspersed artificial diamonds in several rows. For cutting ceramics and other materials, where the accuracy of the cut is the main parameter, it is preferable to have a solid edge.
Segmented diamond discs. Segmented are separated by radial slots into several working sections of the same size, they are more resistant to mechanical and thermal stresses and are used more often than solid ones, although they are somewhat more expensive. They are more productive than solid, but the cutting after them is not as accurate. It is best to use them for rough cutting of concrete structures.
Diamond wheels turbo. Turbodisk are distinguished by the presence of oblique (and not only) notches on the sides of the rim. It slightly increases the mechanical strength of the wheel and significantly enhances the heat removal rate, which makes it possible to accelerate the cutting from 50 to 100%. Like segment discs, "turbo" is suitable for rapid cutting of any mineral materials of a wide range of hardness - from sandstone to concrete and granite.
Diamond disks are turbo-segmented. Even more productive are circles, divided into segments with a side incision "turbo". They are characterized by high performance and versatility.
Difference between disks by the location of diamonds
Artificial diamonds are fixed in the working rim in a certain order. There are circles with a uniform distribution, when in any of the selected units of length or segment there is the same number of crystals.
But there are also circles in which diamonds are placed with a certain period (the so-called sandwich). They are more productive, providing less force to the tool, more efficient cooling and even distribution of effort.
Diamond discs for dry and wet cutting
By the method of cutting, diamond disks are divided into circles for dry and wet cutting. The first provide an accurate cut and more "clean" work, but require the use of devices for dust suction - when cutting, very small particles of solid materials are formed, which irritate the eyes and the respiratory tract. Circles with water cooling work with a constant inflow of fluid that binds and flushes the dust, but they can not always be used. This is due to some cumbersome hydraulic system and the formation of streaks.
Circles for dry cutting can be used in water-cooled machines, but the wheels for "wet" cutting without cooling can not be used - they overheat and quickly break down.
How to choose a diamond disc for a Bulgarian
When selecting a diamond disk, you must pay attention to the type of material for which the disk is intended, its size, landing diameter and disk rotation speed.
The material to be worked on
Most diamond circles are designed to work with non-metallic materials. Most often they are used for cutting concrete, ceramics, glass, bricks and asphalt. But there are a number of disks created for cutting metals of different hardness. When buying, remember that different types of diamond discs are designed to work with different materials. There are disks designed for working with concrete, ceramic tiles, marble, granite, sandstone, stone and asphalt.
There is a certain rule of choosing a disc - for soft materials, wheels with hard strapping of diamonds are chosen, and for hard materials - with soft straps. This is determined by the degree of wear of artificial diamonds located on the rim of the circle.
When cutting solid materials, they are abraded faster and the next come out in their place from a sufficiently soft cutting strip. Soft materials on the diamond affect little, it should be in its place for the longest time, which provides a solid substance into which the mineral is embedded.
In addition, various artificial diamonds are used for different circles.
Two types of diamonds are produced in an industrial way:
- Single-crystal, representing a single spatial structure of regular shape;
- Polycrystalline, consisting of several strongly interconnected single crystals of a smaller size.
The first are very strong and are used for cutting hard materials and metals, the latter can break down when in contact with them, so they are used on cheaper tools for relatively soft materials.
Dimensions of diamond discs
The maximum depth of cut and, in some cases, the speed of work, depends on the size of the disk. The main diameters are 115, 125, 180 and 230 mm, which corresponds to abrasive wheels for the most commonly used brands. Diamond discs with a diameter of 150, 300 or more millimeters can be found on sale. Large diameters are installed on powerful cutting machines - gasoline cutters, stationary cutting machines, etc.
The most common disk holes can be - 22.2 mm or 25.4 mm. Buy a disc of only the size for which your tool is intended.
Never place a large disc on a caliper, which is designed to work with a smaller disc, after removing the protective cover. This is very dangerous, because when you destroy a metal disk, you can cause deadly damage to your health. If you have such ideas, then find on the Internet a photo of the consequences of working with a diamond disc without a protective cover and you will forever want to work without protection.
Rotational speed of the disk
Also on the discs, the maximum speed and linear speed are indicated. If the capabilities of your tool exceed the characteristics of the disc, then you can not put it - the centrifugal forces simply tear it apart.
Problems arising in the course of work and solutions
1. As already mentioned, diamond discs are designed exclusively for straight cuts. Cutting speed and feed force must be adjusted so that the working area does not overheat. At rim temperature above 700 0Since artificial diamonds are graphitized and lose a significant percentage of strength.
Increase the resource of the disk can be a simple way - periodically extract it from the cut without turning off the engine of the wheelchair. The oncoming airflow cools the disc and removes thermal stresses between the central part and the working area.
Another way to increase the life of the disk is not to perform too deep cutting in one pass. It is better to go through the same path several times. This will slightly increase the running time, but the tool life will double.
2. One of the main problems encountered in the work is the rapid wear of the work area. First of all, this is due to incorrect selection of the tool, too high feeding speed (clamping) or with the state of the drive of the ears. If beating occurs in it, the lifetime of the disc is sharply reduced, in some cases, with especially large oscillation amplitudes, it can collapse, which is very dangerous.
If the side of the disc wears out below the cutting edge, the feeder vertical is broken or a drive defect is created that creates lateral runout.
3. If you quickly blunt the segments, you need to replace the disk - it is not suitable for this material. If the disk is selected correctly, but still this picture is observed - it is necessary to cool the disk more often. It overheats due to too much load. The same causes lead to a discolouration of the disc's base - a bluish tide appears on the steel circle.
4. If a disc has cracks, replace it immediately. The disc crackles when the material is not in compliance or the work is too intensive. Often these defects appear after jamming in a cut, or a skew at work. To avoid trouble, inspect the disc before work and periodically during operation, stopping the instrument.
5. It is not allowed to work with a diamond disc if the EWM or other tool is defective - there are lateral and radial beats, uneven rotation, uncontrolled increase or decrease in the speed of rotation. In this case, the tool must be returned for repair or a new one.
To increase the resource of a diamond disk, you must follow a number of simple rules:
- use circles of large diameter, thus reducing the load on the crystals;
- Ushm or another tool should be chosen as much as possible, this ensures the stability of the revolutions;
- correctly choose the disc according to the material;
- do not exceed permissible revolutions.
When working with diamond discs, gloves, goggles and respirators are always used.