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QUALITY CONTROL

Cylinder liners, bushings for various purposes, piston and sealing rings are made from hollow cylindrical billets of measured length obtained using the technology of continuous-cyclic freeze casting (CCLN) of special wear-resistant cast irons SCh – gray with lamellar and lamellar-vermicular (PVG) graphite, VChShG high-strength with nodular graphite, BVHCH – white high-chromium with trigonal carbides). The main distinguishing feature of this casting method is the ability to form hollow castings in a water-cooled metal mold without the use of a rod, which provides increased density, specified structure and hardness, absence of gas pockets, slag inclusions, shrinkage porosity and cracks. The distribution of structural components in castings is not reproduced by any of the known methods for producing cast billets of this type. The NTsLN method makes it possible to obtain in cast billets the required structure of a metal matrix in the range from pearlite to ferritic without additional heat treatment. The strength and wear-resistant properties of parts made from such castings are significantly superior to those obtained by centrifugal casting and casting into sandy-clay molds (SGF). In particular, punch bushings made of BVHCH for hollow silicate brick presses have a service life of 5-6 times higher than serial ones obtained by casting in a chill mold of cast iron of the same chemical composition and 15-18 times higher than cemented or borated steel ones. According to PO MMZ, the liners of the forced engines D245 and D260, made from billets obtained by freezing casting of gray cast iron, can withstand hydraulic pressure up to 40-43 MPa without destruction, while the best samples of serial liners, for which billets cast in PGF or by the method of centrifugal casting, are destroyed at a pressure of 28-32 MPa. The sleeves made from continuously cast billets also differ in a given distribution of structural components over the wall thickness, which, in addition to high strength characteristics, provides a simultaneous increase in wear resistance and cavitation resistance. We produce a wide range of piston and sealing rings from special alloyed SCH, PVG and VChShG. The rings are characterized by high elasticity and wear resistance. Ductile iron O-rings are not inferior to serial chrome-plated in terms of their tribological characteristics. The hardness of the rings made from SCh is 98-102 HRB, and from ductile iron – 102-110 HRB. The difference in hardness values ​​within one ring does not exceed 3 HRB units. The metal base of cast iron consists of highly dispersed pearlite with a small amount of ferrite in the form of isolated small inclusions. This feature of the structure gives the rings made of SCH a certain margin of plasticity, which significantly reduces the likelihood of their breakage when installed on a piston and makes them competitive with rings previously made from ductile iron. So, for example, according to the data of the MTZ Production Association, the installation on the hydraulic drive couplings of the front drive axle of the Belarus-1025 -1221 – 1522 tractors of O-rings from the midrange produced by NPP Technolit, instead of the previously used ones, made it possible to reduce oil leakage through the clutch with 2- 2.5 l / min up to 0.4-0.7, eliminate the intrashop defect and completely eliminate complaints about the FDA drive coupling. The specified rings have received technical specifications registered in the State Standard of the Republic of Belarus (TU RB 100316761.456-2000). We also produce similar sealing rings for transmissions of tractors K700, T150, Amkador, BelAZ, MZKT, etc. During the period of its production activity (since 1989), NPP Technolit has no complaints about the quality of the material used for the manufacture of products. Technolit pays attention to the quality of its products. The enterprises have implemented a multi-stage quality control system. Product control is carried out throughout the entire cycle of manufacturing parts: from the stage of obtaining a casting (blank) to packaging. The enterprise has all types of measuring tools, as well as modern measuring equipment from world companies: Mitutoyo, Mitsubish and others. Non-destructive testing laboratory: This laboratory controls the chemical composition, hardness, microstructure and other properties of materials and alloys. The following types of equipment are used for control: Spectrometer Hardness tester Microhardness tester Ultrasound

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