Burrs are a special type of cutting tools. JSC SIZ “Tvintos” provides 2 types of burrs: high precision burrs and normal precision burrs.
High precision burrs are manufactured with particularly high demands to quality specifications such as durability, dimensional accuracy and low chatter.
Manufacturing of high precision burrs includes manufacturing of carbide blanks and steel shanks. An entire production cycle of powder metallurgy is carried out to get carbide burr blanks. The cycle consists of several operations. The main operations are mixture preparation, pressing, and sintering. Sizes of burr blanks and microstructure of the material they made of are controlled. Because the measurement of density and magnetic characteristics of hard metals are non-destructive tests, these tests are widely used to estimate the mechanical properties of the material.
Turning and following heat treatment are carried out to manufacture steel shanks. The quality control of the shanks consists of measurements of sizes and hardness after heat treatment.
Tested blanks and shanks are brazed to get burr blanks. Brazed blanks go to the operation of grinding shanks and the last operation of grooving. Grooving is one of the most complicated operations. It is carried out using modern CNC grinding and sharpening machines. Hard metals are hard-to-machine materials. The only type of tool used to machine cemented carbides is diamond grinding wheels.
Quality control of high precision burrs includes the control of shanks and working parts, measurement of chatter, and sample control of joint strength.
Advantages of high precision burrs are:
- high wear resistance of working parts;
- low chatter;
- low friction during machining;
- various cutting edge geometries;
- high quality of machined surfaces.
High durability of the burrs is achieved using up-to-date technologies and materials to manufacture carbide blanks. Fine-grained cemented carbides are used to manufacture carbide blanks for high precision burrs. The cemented carbides are alloyed with special additives to get higher mechanical properties of the material.
Alloyed steels with a low coefficient of thermal expansion are used as a material to manufacture shanks. Due to the low coefficient of thermal expansion of the steels the difference in thermal expansion between a shank and a carbide blank in the brazing process is not critically high. That is one of the conditions to get a high-strength brazing joint and consequently to prevent tool breakage.
We produce burrs with low chatter due to using special brazing devices and modern CNC grinding and sharpening machines in the operation of grooving.
Precision grooving using CNC machines makes it possible to manufacture tools with a wide range of cutting edge geometries. The geometry of cutting edge is designed for each material to be machined basing on the material properties and controlled continually.
High precision burrs are widely used due to the advantages noted above. New requirements for precision and quality of tools make high precision burrs increasingly demanded.
