Конструкциялық материалдар және термоөңдеу Конструкционные материалы и термообработка Constructional materials and heat treatment Учебное пособие для специальности: 5В071200– «Машиностроение»

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monocorundum containing 97-98% for Al2O3. Electro corundum grinding 
circles are applied to processing of materials with a high resistance on a gap. 
Carbide of silicon has grains firmer and fragile, than electrocorundum grains. 
Depending on SiС contents it is divided into two kinds: black carbide of silicon 
(BC) containing 95-97% for SiС and green carbide of silicon (GC) with the 
contents more than 97% for SiС. Circles from black carbide of silicon apply to 
processing of materials with a low resistance on a gap and viscous metals and 
alloys. Circles from green carbide of silicon are used mainly for sharpening of 
the hard-alloy and mineral ceramic cutting tool. 
Powder of boron carbide of gray-black color is applied during the lapping and 
honing works, to operational development of hard-alloy tool and grinding of 
very firm materials (ruby, quartz, corundum, etc.). 
Abrasive powders (chrome oxide, Vienna lime, bergmeal) are used for 
production of grinding and polishing pastes. 
Granularity of abrasive materials. 
Depending on the size of grains grinding materials are shared on four groups: 
grinding grain (2000-160 microns), grinding powders (125-40 microns), micro 
grinding powders (63-14 microns), and thin micro grinding powders (10-3 
microns). 
Set of abrasive grains of grinding material in the established interval of the 
sizes is called fraction. The fraction prevailing on weight, volume or number of 
grains is called the main. The characteristic of concrete set of the abrasive 
grains, expressed by the sizes of main fraction grains, is called granularity. 
Depending on group of materials the following designations of granularity are 
accepted: 
-grinding grains and grinding powders - 0,1 sizes of the party of sieve cell on 
which grains of the main fraction (for example, 40 corresponds to grain of 400 
microns) are left when sifting. 
- micro grinding powders - on the top limit of the size of grains of the main 
fraction with index "M" addition (for example, M40-grain of 40 microns). 
- diamond grinding powders - in fraction, where numerator - the size of the party 
of the top sieve cell, denominator - the bottom sieve (for example, 400/250-main 
fraction from 400 to 250 microns)., 
- diamond micropowders and submicro powders - in fraction, where numerator - 
the greatest size of the main fraction, and denominator - its smallest size (for 
example, 40/28). 
- grinding grains and grinding powders of elbora - depending on a control 
method. At sieve control - fraction to similarly diamond grinding powders. 
At designation of diamond grinding powders we specify brand of a grinding 
material, granularity and the standard. For example, grinding powder AC6 
160/125. 

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Bonds of abrasive tools. 
The substance or set of the substances applied to fixing of grinding grains and 
a filler, is called as a bond. The bond influences geometry of a relief of a 
working circle surface, its wear, parameters of the processed surface roughness. 
Ceramic bonds (K1, K2, K3, K4, K5, K6, K8, K10) are applied to all main 
types of grinding, except slotting narrow grooves, roughing works. K2, K3 - are 
brands for the tool from silicon carbide. K2 - for the fine-grained tool. K1, K5, 
K8 - for the tool from electrocorundum. K1- for grinding and sharpening by a 
diamond circle of hard-alloy cutting tool in common with steel holder or case. 
Bakelite bonds (B, B1, B2, B3, B4, B156, BP2, BU) are applied to production 
of circles with the strengthened elements, intended for grinding at speeds of 60-
100 m/s. for roughing grinding, flat grinding by a circle end face, pieces, slotting 
grooves, sharpenings of cutting tools, grindings of faltering surfaces, for 
production of fine-grained circles for finishing grinding, diamond and elbor 
circles, honing whetstones. 
Vulcanite (B, B1, B2, B3, B5), glyptal (Gp) and polyvinyl formal bonds are 
applied to production of leading circles at centerless grinding, flexible circles 
when polishing and finishing (B5), circles for pieces, slotting and grindings of 
grooves, to profile grinding. 
Metal bonds are applied to production of diamond circles of the increased 
wear resistance when processing firm alloys, to the circles used at 
electrochemical abrasive processing. 
Organic bonds with a metal filler (B156, BP2, TO) are applied to production 
of diamond circles used at sharpening of hard-alloy cutting tool, for grinding of 
hard-alloy or ceramic details, profile grinding. 
Organic bonds with mineral filler (B1, O1) are applied to the diamond circles 
used at fair sharpening of the hard-alloy cutting tool, fair grinding of hard-alloy 
details. 
Hardness and structure of the abrasive tool. 
Hardness of abrasive tool - is the size characterizing its property to resist to 
violation of coupling between grains and a bond at saving of characteristics of 
the tool within established norms. The following scale of hardness is 
established: BM1, ВМ2 - very soft, M1, М2, M3 - soft, CM1, CM2 - medium-
soft, S1, S2 - average, CT1, CT2, CT3 - solid medium, T1, T2 - firm, ВТ - very 
firm, ЧТ - extremely firm. 
Soft and medium-soft circles (М2 - CM2) are used for flat grinding by circles 
on bakelite basis, grindings by the periphery by ceramic circles, grindings of 
details from the firm alloys tempered by steel, non-ferrous metals and their 
alloys. 

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Medium-soft and average bonds (CM2-C2) are used for fair grinding of 
carvings with a big stride. Averages and medium-hard circles (C2-CT2) are used 
for grinding and thread grinding of blanks from not tempered steel, cast iron, 
viscous materials, honing. 
Medium-hard and firm circles (CT2-T2) are used for grinding of roughing and 
preliminary, profile and faltering surfaces, blanks of small diameter, centerless, 
honing of tempered details. 
Very firm and extremely firm circles are used for grinding of balls of bearings, 
editing of grinding circles. 
The structure of abrasive tool defines a ratio of volumes of grinding material, 
bond and time. We distinguish 16 numbers of structures. Abrasive tools 
granularity 125-80 make structure No. 3 and 4, granularity 50-40 No. 5 and 6, 
granularity 25-12 No. 6 and 7. 
High numbers of structures correspond to high porosity. Time and capillaries 
are reported among themselves at the expense of use of burning-out steam 
generators. In the characteristic of such circles the steam generator is surely 
specified. 
Diamonds and diamond cutters. 
Diamonds should be carried to special group of abrasive materials. In the 
industry diamonds are used either in the form of powders, or in the form of 
small crystals, and applied both natural (A), and artificial (synthetic) diamonds 
(АС) consisting for 95,5% of crystallized carbon. 
Diamond is considered the firmest material, has a high red hardness and wear 
resistance, well resists to a sticking of processed material and shaving to a 
cutting edge. Shortcoming is its considerable fragility. 
About 70% of technical diamonds are applied to production of diamond circles 
and diamond fine-grained powders. Diamond circles and powders are applied 
during the grinding, tool-grinding and honing works at production of tools and 
details from firm alloys. About 20% of diamonds are used for editing of 
grinding circles from corundum and silicon carbides in the form of separate 
diamonds or diamond pencils. Crystals of diamonds are applied to equipment of 
cutting tool (cutters, drills, etc.). The mass of the crystals going on equipment of 
the cutting tool, reaches 0,2-0,75 carats (1 carat=0,2g). 
The scope of diamonds extends every year. Special value the diamonds get 
for processing of such firm materials, as germanium, silicon, corundum, 
semiconductor materials, special types of ceramics, heat resisting, stainless 
steels, etc. Application of diamonds opens ample opportunities for technical 
progress, increase of labor productivity and decrease in product cost. When 
using the tools equipped with diamonds, quality of the processed surfaces of 
details sharply increases. Cutting speed when processing any materials makes 
not less than 100 m/min. There are cases when processing by diamond cutters 

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the speed of cutting reached more than 3000 m/min. When processing by the 
diamond tool purity of the processed surfaces sharply increases, the sizes of the 
processed surfaces of details differ big stability as diamonds possess high 
dimensional firmness owing to small wear in the course of processing. 
For increase of accuracy and purity of the processed surface we apply thin 
turning (boring) by diamond cutters which possess big wear resistance, the 
hardness and the smallest coefficient of friction. Diamond cutters are applied 
when processing materials with the increased abrasive ability: plastic, insulating 
materials, semiconductor materials, and also bronze, brass, aluminum and easy 
alloys. When processing plastic by diamond cutters, their firmness is higher than 
firmness of hard-alloy times in hundreds. 
Owing to fragility of diamond, corners of cutting of cutter are led up to 90º, 
and sometimes forward corner is done even negative. Crystals of diamonds are 
fixed in by holder mechanically, soldering or filled in with solder. 

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