An abrasive wheel is a tool that is used during a metal cutting operation such as grinding. This operation allows you to smooth out the roughness of the surfaces of the part, as well as to increase their quality. Often grinding is the finishing of products, so a lot of stringent requirements are imposed on the tool (abrasive wheel). The further product quality and product life will depend on whether the circle is correctly selected.
Application area
As already known, abrasive grinding wheels belong to cutting tools that are used during finishing various surfaces of parts (holes, ends, threads, etc.). They are mainly used in mechanical engineering and machine tool industry in the processing of metal products, which are subject to high technological requirements.
But besides this, circles, like the grinding operation itself, are used in the fields of optics and jewelry.
Types of abrasive wheels
Depending on the material used to create the tool, there are several types of abrasive wheels. Namely: grinding, diamond and elborovye.
In addition, abrasive wheels are divided into:
- Bilateral flat circles of a conic profile (2P). As a rule, they are used during grinding of gears and simple threads.
- Flat circles of a direct profile (PP). They are used during internal or centerless grinding, as well as when grinding the ends of parts and sharpening some tools of other machines (for example, a cutter or drill).
- Flat circles having a recess (PV and PVD). A similar circle is used during round grinding, as well as for cutting the ends of parts. In addition, it is often used during centerless grinding as a host.
- Cylindrical and conical circles (CC and CC). Quite often used for sharpening various tools. Therefore, it is also called a grinding grinding wheel.
- Dish circles (T). Used only for sharpening tools with multiple cutting blades. For example, with the help of plate circles, the blades of cutters, cutters, taps are processed.
Marking
Abrasive wheels have their own classification, and it depends on the main parameters of the tools. These include:
- tool dimensions;
- accuracy class;
- type of material;
- grain;
- types of ligaments;
- hardness coefficient;
- type of form;
- maximum speed during processing;
- percentage of binder, material used and pore (structure).
The main parameters are listed above, thanks to which it is possible to easily decipher one or another abrasive wheel before choosing it for a specific operation.
Marking circle selection
For example, the machinist has an abrasive wheel 1250208025AF60K6V35. From the number “1” at first it immediately becomes clear that this is a flat grinding wheel with a direct profile, which is used for sharpening tools and machining ends. Further decryption will be:
- 250 - maximum outer diameter, mm;
- 20 - circle height, mm;
- 80 - diameter of the mounting hole, mm;
- 25A - tool material (electrocorundum);
- F60 - graininess;
- K is the degree of hardness;
- 6 - structure;
- V - type of ligament (ceramic);
- 35 - maximum speed during processing, m / s.
Similar marking is applied to any grinding wheels. The only exceptions are those that are individually labeled. Usually individually marked are circles of foreign manufacture. In this case, in order to choose the necessary circle, you need to consult with the seller or read the characteristics on the instrument packaging, if any.
Edit circles
Like any other tool, the abrasive wheel wears out over time and loses its primary technological properties. In this case, so as not to buy a new tool, and there is editing circles.
Editing is carried out by two main methods:
- With the help of diamonds.
- Without diamonds (so-called diamond-free dressing).
Editing abrasive wheels with diamonds is as follows:
- The editing tool is placed in a special tool (most often a holder).
- The wheel to be edited is set so that the tool, which is in free rotation, can touch the surface of the abrasive.
It is recommended that the axis of the ruling circle be located at an angle (5-6 degrees vertically for internal and 10-15 degrees horizontally for external grinding). In this case, the maximum effect of editing is achieved.
Editing tools
As tools for diamond dressing are used:
- diamond wheels
- diamond pencils (rods);
- diamond plates and rollers.
Since diamond dressing in most cases is an expensive operation and may not always be economically feasible, in the field of mechanical engineering it is replaced by diamond-free dressing. To implement it, use the following tools:
- grinding wheel abrasive (or disk) made of silicon carbide, electrocorundum or fused alumina;
- hard metal alloy wheels;
- disks with a metal bunch;
- rollers and discs made of high-speed steels (for example, P18).
After editing with diamond substitutes, the purity of the processing of circles can reach 7, 8 or 9th grade. This, in fact, is quite acceptable for tools that are used for roughing parts. If a circle requires a higher accuracy class, for example 6 - for finishing parts, then only diamond tools should be used as dressing.