Unit 9 Synthetic Diamond Products
Text I
Vocabulary Notes
hardness – твердість
tool hardness
diamond hardness
to attract the attention of – привернути увагу
to attract the attention of scientists, man, people
load – навантаження
great load
enormous load
growing load
to be in great demand – користуватися великим попитом
precision technique – прецизійна техніка
precision technique development
component (syn. part) – деталь
machine component
instrument component
brittle – крихкий
brittle metal
brittle material
cemented carbide – твердий сплав
semiconductor – напівпровідник
sharpening – заточка
tool sharpening
blade sharpening
lapping – притирання, доведення
metal-cutting tool lapping
carbide-tipped (syn. cemented-carbide) – твердосплавний
carbide tipped tool (instrument)
grinding – шліфування
surface grinding – пласке шліфування
cylindrical grinding – кругле шліфування
thread grinding – різьбошліфування
form grinding – профільне шліфування
blade surface grinding
tool grinding
thread grinding quality
internal – внутрішній
internal surface
internal component
polishing – полірування
part polishing
surface polishing
of low machinability – важкооброблюваний
Read and translate text I
Diamond is one of the most wonderful minerals. Its exceptional hardness has attracted the attention of man from ancient times.
Nowadays in the age of space flights, supersonic speeds and enormous loads, the age of production automation and wide application of extra-hard and superstrength materials, diamonds are in great demand.
The successful development of modern precision techniques, the high requirements made to the machining accuracy and surface finish of machine and instrument components, the continuously growing speeds and loads, and wider application of cemented carbides, difficult to machine steels and artificial materials in industry would be impossible without the extensive use of diamonds.
Synthetic diamonds find especially efficient application in machining the hardest, most brittle and most difficult-to-machine materials, such as cemented carbides, semiconductors, glass, ceramics, granite, marble, etc.
Application
Diamond tools made of diamond powders are nowadays employed in the following main fields (classified into types of materials to be machined).
Cemented Carbides. Sharpening and lapping cemented-carbide metal-cutting tools of all types; lapping carbide-tipped measuring tools; grinding (cylindrical and surface) cemented-carbide blades; centreless grinding, thread and form grinding, etc.
Steels, Cast Irons, Non-Ferrous Metals and their alloys. Grinding various surfaces of metal-cutting and other tools made of high-speed and other tool steels; sharpening and lapping surgical instruments; grinding and lapping measuring tools; honing components and workpieces when accuracy and surface finish of machining internal cylindrical surfaces are required.
Electrical and Radio Engineering Materials. Cutting, grinding and polishing all types of parts made of porcelain, quartz, ferrites, radioceramics, germanium, silicon and other materials with low machineability.
Text II
Give a short summary of the text in Ukrainian.
New Synthetic Diamonds
Scientists from the Institute of High-Pressure Physics of the Russian Academy of Sciences have developed another two synthetic diamonds - niborit and almet.
In due course, a whole galaxy of men-made materials appeared, such as elbor, geksanite, and komposit, which have been widely used in practice.
Niborit and almet, which set a new record in durability, open a qualitatively new stage in the synthesis of extrahard materials. Niborit is obtained in a usual steel chamber under а pressure of only about 500 tons.
Almet (abbr. for diamond + metal) like niborit, is used for cutting hard alloys and glass-fibre-reinforced plastics. Its wear-resistance is 5-8 times more durable than tungsten-bearing compounds. Man-made diamonds become man's reliable helpers in his work.
Text III
Vocabulary Notes
straight (diamond) wheel – (алмазний) плаский круг прямого профілю
straight wheel application
straight wheel surface
taper – конічний
taper surface
taper tool shank
flat – плаский
flat surface
flat component
straight three-sided wheel – плаский трибічний круг прямого профілю
straight three-sided wheel use
straight three-sided wheel work
recess – виїмка, уступ
workpiece recess
drill recess
setting – установка
wheel (tool) setting
during one setting
flaring cup wheel – чашковий круг
flaring cup wheel application
broach – протяжка
reamer – розвертка
gun drill – гарматне свердло
reamer quality
broach lapping
reamer sharpening
gun drill sharpening
gun drill work
multi-edge tool – багатолезовий інструмент
multi-edge tool lapping
multi-edge tool sharpening
flute (syn. notch) – канавка
helical flute – спіральна канавка
drill flute
drill helical flute
relief surface – задня поверхня
top face – передня поверхня
multi-edge cutting tool top face
multi-edge cutting tool relief surface
dish (diamond) wheel – (алмазний) тарілчастий круг
dish wheel surface
dish wheel application
profile grinding (diamond) wheel – (алмазний) профільний шліфувальний круг
profile grinding wheel work
profile grinding wheel surface
form tool – фасонний інструмент
form tool grinding
form tool lapping
form tool quality
die – штамп
die component
die work
cut-off (diamond) wheel – (алмазний) відрізний круг
cut-off wheel application
cut-off wheel surface
cylindrical mounted diamond point – алмазна циліндрова головка
cylindrical mounted diamond point use
cylindrical mounted diamond point surface
form (diamond) wheel – (алмазний) фасонний круг
form (diamond) wheel application
form (diamond) wheel surface
chip-breaking – стружколамний
chip-breaking notch
contoured (syn. form) – фасонний
contoured surface
(diamond) honing stick – (алмазний) хонінговальний брусок
honing stick quality
honing stick use
precise – точний (прецизійний)
precise work
precise tool
precise hole
Read and translate text III
There are different types of synthetic diamond wheels produced by industry.
They are:
straight wheels used for grinding cylindrical, taper, and flat surfaces on internal, cylindrical and surface grinding machines;
straight three-sided wheels used for machining cylindrical surfaces, faces and recesses of workpieces during one setting;
flaring cup wheels used for sharpening and lapping cutting tools and for machining flat surfaces;
flaring cup wheels used for sharpening and lapping broaches, reamers, gun drills, etc.;
flaring cup wheels used for sharpening and lapping multi-edge tools with helical flutes on relief surfaces;
dish wheels applied for sharpening and lapping top faces of multi-edge cutting tools;
dish wheels used for sharpening and lapping top faces of large size cutting tools;
dish wheels used for sharpening and lapping top faces of multi-edge cutting tools with helical flutes.
profile grinding wheels used for grinding and lapping form tools and cemented-carbide components of dies on profile grinding machines and for grinding threads on thread-grinding machines;
cut-off wheels employed for cutting various hard and brittle materials (glass, quartz, etc.);
cylindrical mounted diamond points used for internal grinding of small holes;
form wheels for machining chip-breaking notches on cutting tools and for grinding contoured surfaces;
honing sticks used for machining highly precise holes in cast-iron and steel workpieces.
Text IV
Vocabulary notes
effective operation – ефективність
effective operation of the lathe
effective operation of the diamond wheel
to ensure – забезпечити
to ensure effective work
to ensure effective operation
to ensure the relation speed
to ensure high surface finish
service – служба, експлуатація
lathe service wheel service
sequence – послідовність
cycle sequence
sequence of operations
tip – ріжуча кромка, пластинка
tip sharpening
tip grinding
cemented-carbide tip treatment
chamfer – фаска
diamond wheel chamfer
chamfer lapping
proper – правильний, належний
proper work
proper operation
proper rotation speed
runout – биття (шпинделя)
axial backlash – осьове биття шпинделя
to dress – правити (алмазний круг)
dressing – правка (алмазного круга)
to dress the wheel
wheel dressing
proper wheel dressing
dressing tool
metal-bond diamond wheel – алмазний круг на металевій зв’язці
metal-bond diamond wheel operation
metal-bond diamond wheel dressing
metal-bond diamond wheel effective operation
resinoid-bond wheel – круг на органічній зв’язці
resinoid-bond wheel operation
resinoid-bond wheel cooling
cooling – охолодження
diamond wheel cooling
abrasive wheel cooling
stick – брусок
silicon carbide stick
hard stick
coarse-grained – грубозернистий
coarse-grained material
coarse-grained diamond wheel
dry – сухий
dry cleaning
dry operation
Read and translate text IV
Recommendations for Operation of Diamond Wheels
Effective operation of diamond wheels is ensured only by their rational service. Diamond sharpening of cutting tools should be performed in the following sequence: sharpening the tool shank by ordinary abrasive wheels, sharpening cemented-carbide tip by diamond wheels and diamond lapping of it on chamfers.
Proper operation of diamond wheels is available on machines, whose radial runout on spindles is within 0.006-0.008 mm, and axial backlash – 0.005-0.006 mm.
Diamond wheels should be dressed only in special cases, as their proper operation does not require dressing.
Metal-bond wheels are to be dressed with cooling. Dressing is performed by wheels or sticks made of green or black silicon carbide of medium hardness. Organic (resinoid)-bond diamond wheels are dressed by wheels or sticks made either of green or black silicon carbide, or white or standard aluminium oxide. Coarse-grained diamond wheels are to be dressed by dressing tools of high hardness.
Use lubricating cooling fluids to decrease diamond wheel wearing out, to ensure higher surface finish and to increase machining efficiency.
Resinoid-bond wheels can operate dry, while metal-bond wheels cannot work without cooling.
Text V
Vocabulary Notes
circumferential sрееd – окружна швидкість
sharpening – заточка
tool sharpening
tool tip sharpening
cutter sharpening
lapping – притирання, доведення
machine parts lapping
machine tools lapping
cylindrical grinding – кругле шліфування (шліфування циліндрових та конічних поверхонь)
cylindrical grinding of conical work
cylindrical grinding of cylindrical pieces
surface grinding – пласке шліфування
surface grinding of flat surfaces
longitudinal feed – подовжня подача
longitudinal feed of the tool
longitudinal feed of the workpiece
depth – глибина
cutting depth drilling depth reaming depth
cross feed – поперечна подача
table cross feed
cross feed speed
Read and translate text V
Recommended Cutting Procedures
Circumferential speed must be 20-30 m/sec for sharpening, lapping and for cylindrical and surface grinding; for internal grinding the speed must be 10-25 m/sec.
Longitudinal feed must be 1-2 m/min for sharpening; 0,5-1,0 m/min for lapping, 0,5-2,0 m/min for cylindrical-, 5-15 m/min for surface- and 0,5-1,0 for internal grinding.
Cutting depth must be 0,01-0,02 mm for sharpening, 0,005-0,01 mm for lapping, 0,0025-0,02 mm for cylindrical-, 0,01-0,03 mm for surface- and 0,0025-0,015 mm for internal grinding. Workplace rotation speed must be 40-120 m/min for cylindrical grinding and 10-25 m/min for internal grinding.
Table cross feed must be 0,5-1,0 mm/stroke for surface grinding.
Additional Reading
Translate texts I-IV. Pay attention to the underlined words.
I. Grinding. Grinding means the use of a rotating grinding abrasive wheel to remove metal. A grinding wheel consists of abrasive grains held together by some form of a bond.
Abrasives. There are two kinds of abrasives - natural and artificial. Before, grinding operations were performed by the use of natural stones known as grindstones, which were composed of small particles of hard quartz - like material closely bound together by a natural bond.
Such minerals as corundum or aluminum oxide when crushed or broken into small particles and bonded together also formed grinding wheels used in the past.
But grindstones and other natural abrasives are not uniform and could not be used for high speed grinding.
II. A surface finishing process, that is removal of irregularities from machined surfaces may be performed either by employing hardened steel tools in such operations as filing, scraping and burnishing or by employing abrasives for surface grinding, honing, superfinishing and polishing. Grinding is the process of removing metal very accurately by means of solid or sectional abrasive wheels rotating at a comparatively high speed.
Grinding is performed on machine tools known as grinding machines which use rotating grinding or abrasive wheels for producing cylindrical, conical or flat surfaces.
Grinding wheels consist of abrasive grains held together by some bond such as clay, shellac or rubber. The hardness of the abrasive, the shape of the grain, the structure of the bond are very important in grinding operations.
Grinding wheels are dressed or trued to remove metal particles of abrasive and to restore their original shape and accuracy.
III. A tool known as a hone is employed for honing - a finishing process which gives metal a very fine finish. Hones of special shapes used for finishing internal surfaces of cylindrical work may contain several abrasive blocks, which can be moved out from the axis thus giving the tool any desired diameter.
A bonded abrasive stone held in contact with the work under low pressure is used in superfinishing - a finishing process which gives metal an extremely smooth surface. The work rotates against the stone at low speed and the stone is rotating at a random motion.
IV. Cutter Grinding. The diamond abrasive wheel is used for grinding milling cutters, flutes in tungsten carbide reamers, etc., with flaring cup and straight cup wheels. This type of grinding, in toolrooms and workshops, is normally done dry.
But flood coolant systems have been introduced on to the tool and cutter grinding machines.
The grinding of small flutes is done dry. But in most cases, after the initial "touch" between work and wheel, it is necessary to see the work more than once and grinding is performed wet.
At all times it is better, in the interests of wheel economy, to grind wet.
The economy here is in wheel wear, not time. When grinding wet the job takes a little longer time than grinding dry.
Give the main idea of texts V-VIII.
V. Surface grinding should always be done wet. A supply of coolant is very necessary to ensure that the extremely high grinding point temperatures do not cause the wheel to heat up.
This is illustrated when using a resin bond wheel, 150 mm. in diameter with a face width of 8 mm., on a machine that has a 2 kW motor driving the grinding wheel spindle, with normal feeds and speeds. If the coolant supply is insufficient the heat generated at the grinding point will cause the wheel to heat up.
For surface grinding the peripheral speed of the wheel should be between 2 and 30 metres per second (4 750 to 5 900 ft. per min.).
VI. Diamond tops Stone. Thin flexible strips of diamond shim stock are said to bе more effective than the polishing stone. Made of thin nickel steel, plated on one side with diamond grain, the 0,10-in. thick strips are 1/2 in. wide × 2 in. long, and available in four grits: coarse 80/100, medium 100/120, fine 200/240, and extra-fine 270/315.
VII. Wheels Cut with Aluminum. Abrasive wheels with an improved aluminum oxide as the cutting agent provide long life on present grinding equipment. The wheels have special hubs which eliminate vibration at speeds of up to 20.000 rpm. wheel sizes range from 2 to 3 in. diameter and from 1/2 to 1 in. wide. A 1/4-in. arbor hole or a 1/2-20 threaded shaft adapts the wheels to standard hand-held grinding tools. Abrasive grades range from 60 to 240 and are coded.
VIII. Wheel Replaces Brush. A strip cup wheel for hand-held grinders is said to be ideal for cleaning such as oxide and rust removal and cleaning concrete molds and forms. The 6-in. × 1-in. cup wheel is made from non-metallic web impregnated with abrasive minerals. It can be used in applications where wire brushes would normally be used. Maximum operating speed is 6.000 rpm.