G D GOENKA UNIVERSITY

MANUFACTURING PROCESS &

METTULURGY

STUDY PROJECT TOPIC:

CUTTING TOOLS USED FOR CUTTING OF

STONE

SUBMITTED TO: SUBMITTED BY:

HARDEEP SINGH PRAVESH TANEJA

(ASSISTANT PROFESSOR) 130020201057

INTRODUCTION

AN AMAZING INVENTION

Diamond coated wires comprise diamond beads threaded on a high tensile steel

supporting cable. The diamond beads are made by fixing a diamond layer around a

cylindrical steel support.

Nearly 30 years ago, Diamant Boart invented the first diamond wire for the

extraction of marble in quarries. From the entry into service of the first wires at

Carrara, success was immediate, in a few months all the quarries abandoned their

helical wire sawing installations to make way for the new diamond wire cutting

equipment.

During the 1980s, Diamant Boart were the first to introduce a diamond wire into

granite quarries. It was an immediate success, to the point that, today most granite

quarries have adopted this new procedure. Later on Diamant Boart began to

develop wires for squaring the blocks and then cutting them into thick slabs.

Marble and granite producers very quickly discovered the advantages of these new

products.

The recent launch of multiwire machines is the opportunity for Diamant Boart to

put on the market a new diamond wire specifically designed for these machines

and which is of the high quality that is required for this application.

We focus all our energy on improving your work situation. Consequently our

objectives are high accessibility; prompt service, exact deliveries and perfect

cutting results.

Diamond Wires

WIRES FOR MARBLE QUARRIES

Two types of diamond beads – two uses suitable for the extraction of marble.

The electrolytic wire was the first cable placed on the market. Its beads are made

from an annular steel support onto which the diamond grains are electrolytically

deposited; they are remarkably robust and sharp.

The electrolytic wire is perfectly suitable for sawing marbles; it is especially

appreciated for small cuts and for cutting blocks (small radii of curvature).

Compared to the sintered wire, the electrolytic wire offers the double advantage of

needing only 25 horsepower and reduced water spraying (from 10l/min to

20l/min). It is also used when the customer wants a high cutting speed.

The diamond-sintered wire is designed to cut all types of rock (including the

hardest and the most abrasive) and to increase the number of m2 sawn (some are

described as “long life” wires). The active part of the beads is a ring of sintered

diamond, whose composition is like the segments used in blades and discs.

Technological advantage: the sawing speed of a wire is practically constant

throughout its lifetime. The sintered wire requires a minimum power of 40 hp and

normal water spraying, between 20 to 50l/min according to the cut dimensions.

TWO TYPES OF WIRE FOR MARBLE EXTRACTION.

1. ASYMMETRICAL FITTING

The spring inserted between the bush crimped on the cable and the bead dampens

the shocks experienced by the latter and reduces their impact on the supporting

cable. For this reason, the cable must turn in the direction of rotation indicated by

the arrow.

2. SYMMETRIC FITTING.

A spring fitted on both sides of the bush protects the assembly from shocks. This

cable can turn in both directions without danger.

PERFORMANCE

3. HIGH SPEED WIRE

Increasing the sawing speed provides the marble producer with an appreciable

benefit resulting from reductions in energy and water consumption and operator

costs.

As an example the table below shows that an increase in speed from 11 to 16 m2/h

can bring a benefit in the case of extraction of compact marble (reference: standard

sawing cost = 100).

To increase the wire sawing speed, Diamant Boart is working on the optimum

combination of the best performing diamonds and the most suitable metallic bonds

for a material type. This therefore updates solutions for each use.

COMPARISON OF SAWING COSTS PER M2 SAWN

WIRES FOR GRANITE QUARRIES

Except for small cuts made in marble quarries, all other applications of diamond

wires use beads with diamond concretions.

For granite quarries, the cables are in general fitted by injection of a vulcanised

rubber, whereas cable used in granite and marble sawing works are more often

injected with plastic. The more difficult to implement and costly rubber injection is

preferred for cables used in granite quarries, for the following reasons :

The vulcanised rubber adheres better to the beads and support cable, which

protects it better from the action of abrasive pastes, in particular when the

cable takes up small radii of curvature (beginning and end of quarry cuts),

The vulcanised rubber easily withstands increases in temperature caused by

badly controlled water spraying, which often happens in a quarry, whereas

plastic softens and looses its strength properties,

The flexibility of a cable fitted with rubber is greater, which reduces the risk

of irregular wearing of the beads (ovalisation phenomenon).

WIRES FOR STATIONARY MACHINES

1. Squaring and cutting of blocks using diamond wire.

Diamond wire is now generally used in most workshops.

There are many reasons for this:

The wire allows significantly greater sawing heights than large discs,

The wire saw in width is thinner and more precise than the large disc

(deviation < 1 mm),

The investment in a wire machine is relatively low,

By virtue of its greater and greater reliability, wire sawing technology is

more and more automated and thus becomes just as productive as competing

techniques,

Noise nuisance generated by diamond wire sawing is significantly less than

that produced by other sawing techniques.

Recommendations

For optimum use of diamond wire, Diamant Boart supply detailed operating

instructions. These are the essential elements:

– the rotation of the wire about itself should be regularly checked

(clothes peg or paint line method),

– the bead wear profile should be regularly inspected (avoid ovalisation

and coning of the beads),

– the connections should be changed whenever excessively high wear of

the adjacent beads is noted and whenever it is necessary to apply

pretorsion to the cable,

– the cable tension is set to 250–300 kg for 4 and 5 mm diameter

supporting cables

– adjust the linear speed of the wire to the material being sawn :–

granite class 1 – 2 : 25–30 m/sec– granite class 3 – 4 : 22–26 m/sec–

granite class 5 : 20–22 m/sec– marble : 30–35 m/sec– abrasive rocks :

30–35 m/sec

– water spraying of the diamond wire is an essential criterion for good

sawing : depending on the blocks the water flow rate to be provided

is between 15 and 25 l/min.

– during the sharpening of a new wire, the linear speed must be reduced

by 2 to 3 m/sec relative to the speeds given above.

WIRES FOR PROFILING MACHINES

Profiling – a complementary application for stationary machines.

The introduction of new numerically controlled machines allows the shaping of

complex forms in large production runs for gravestones and building. The use of

diamond wire for shaping makes possible the optimum use of excellent quality

materials that are discarded from the production of slabs and paving stones.

The low cost of the cuts, the profiling precision and the surface quality

indisputably make diamond wire very competitive. The diamond wire used in

profiling machines is similar to that found in stationary machines, but it is

generally of a smaller diameter (8.3 mm). Performance is slightly inferior to that of

cables for stationary machines.

Recommendations.

For operating parameters refer to the recommendations given in the chapter on

stationary machines. The parameters are nevertheless adjusted to the particular

requirements of the (desired) cut.

WIRES FOR MULTIWIRE MACHINES

To saw granite into thin slabs, the classical procedure using a grit-set frame is often

chosen for two main reasons, namely a very competitive cost and a well

understood procedure.

However, the drawbacks remain obvious : limited productivity (7 cm/hour) and

thus poor flexibility, water recycling, labor costs and increase in the sawing costs

per m2 for thick slabs and of course a large installation area.

These disadvantages associated with the grit-set frame have led to many attempts

to derive a diamond based alternative. By far the most successful is the multiwire

sawing machine.

ADVANTAGES

With the new wires customers gain a decrease in the sawing costs and an improved

productivity. Moreover, to avoid the long and costly remounting operations the 7.3

mm is “one use”.

RECOMMENDATIONS

For optimum use the following is necessary.

The blocks have to be squared at the top and the bottom before sawing.

The minimum block length has to be 2.5 m or more.

The blocks have to be installed and cemented on three wooden support.

CHARACTERISTICS

The standard wires for multiwires machines are injected with transparent plastic

and they contain 36 beads/m. In general, they are not sharpened.

WHAT TYPE OF CONNECTION?

The most common way of closing a diamond wire is to crimp to the ends tubes or

steel parts to be screwed up. Diamant Boart offer a complete range of standard

connections with the equipment needed to crimp them to the cables.

DIAMOND BLADES

Fast cutting diamond blades are available in diameters 115 to 3500 mm.

Different materials represent different challenges and Diamant Boart’s vast range

of specified bonds along with a choice of standard noise reduced steel centers

provide perfect solutions.

We particularly recommend that the blade to be used should suit the material to be

cut. Each material or group of material has its own particular hardness and abrasive

properties.

The type of blade is determined by these two factors. Therefore it is easy to foresee

that a change of material can be fatal to the tool life. A blade intended to cut

marble, for example, will be completely worn after sawing a few square meters of

soft sandstone, which is softer but more abrasive than marble.

Especially developed to cut all kind of granite, marble and other stones our blades

will respond to all and even more than you demand. The correct identification of

the material to cut is the most important factors for choosing a tool.

THE BLADE AND THE CORE

The blade

Description. A diamond blade consists of two parts :

the diamond segments and the blade center

The core

Different kinds of core. The standard core. The steel center is a high-grade heat-treated, tempered steel

disc; to meet highest demands on stability and wear resistance. The steel center

width prevents wobbling of the blades.

The silent core. The silent core is constituted from 2 sheets of steel separated by a

sheet of copper to enable an improvement of 6-9 dBA in noise level.

THE SEGMENTS

The segments contain a mixture of diamonds and metal powder. During the

manufacturing process, the metal powder and diamond mixture is compressed in

order to obtain a solid metal alloy which holds the diamonds. The segment is

slightly wider than the core, to allow the attacking edge to penetrate the material

without the steel rubbing against it.

ATTACHING DIAMOND SEGMENTS TO THE STEEL CORE

The diamond segment can be attached to the steel centre using two basic methods.

Brazing. The segments are attached to the core by brazing with silver solder.

Used on standard blades for wet cutting

Do not use for dry cutting !

Laser-welding. Segments are welded to the centre using a laser beam.

Strongest bond possible between steel centre and segment

Suitable for wet and dry cutting applications. The laser-welding

process is the latest state of the art method to attach diamond

segments to the blade centre. This process assures a maximum

degree of safety.

FINISHING OPERATIONS

After the assembling process, each individual segment undergoes double-sided

cross-bend tests to ensure that they are solidly fused to the centre.

Tension must be put on each blade to assure that it runs straight and true even

under tough cutting conditions.

Each blade is tensioned by hand; a process performed by specialists who are

skillfull experts in their craft.

Each blade is sharpened, at the factory to make sure that the blade will cut freely,

the very first time your customer will put it to use.

The last steps - finishing, painting, printing and packing - are performed with the

same amount of care and concern for quality as you already have seen in the

manufacturing process.

BLADES VARIABLES

SEGMENT HARDNESS

Softer bonds tend to cut faster but have a shorter life

Harder bonds tend to cut slower but have a

longer life.

SEGMENT SIDE CLEARANCE

The balanced ratio between widths of segment and steel centre assures sufficient

discharge of material and even wear of segments and prevents jamming of the

blade in the material.

Thinner blade segments tend to cut faster but give shorter life.

Thicker blade segments tend to cut slower but give longer life.

The reason is very simple : thinner blade segments have less surface area in contact

with the material and offer less resistance as they grind through the material.

CUTTING VARIABLES

1. CUTTING SPEED

It is important to adjust the feed speed so that it corresponds the recommended

cutting speed expressed in cm2/min.

2. CUTTING DEPTH Depth of cut and feed speed should be combined so as to respect the recommended

cutting speeds (cm2/min) for the particular type of material.

3. FORWARD FEED This one depends on the already chosen cutting depth (high speed combined with a

shallow cutting depth sharpen the tool).

MACHINE VARIABLES

1. Watering

The water pressure is of little importance compared to the quantity. Therefore,

abundant watering is recommended.

2. Power. Should be determined by the blade diameter and type of material cut.

3. Peripheral speed. The peripheral speed should be selected according to hardness and abrasiveness of

the material to be cut; together with the feed speed it affects the cutting speed and

the tool life. It is therefore important to suit the peripheral speed to the material to

be sawn.

GANG SAW BLADES

For the precision cutting of natural stone, the gang saw blades of variable

dimensions and characteristics are cater for all types of marbles and other material

plants (except granite)for exactly-dimensioned blocks and slabs.

The blade life and quality of the cut largely depend on the care and precision with

which the set of blades has been fitted to the frame.

Time devoted to correct mounting of the blades will pay later when the sawing

takes place.

Diamant Boart introduced the first diamond gang saw blade in 1955 and the thin

gang saw blades in 2002. The great advantage of those thin gang saw blades is the

real saving achieved on the total sawing cost by obtaining additional m2 per block.

Further development will be introduced on the market.

Hammer and Chisel

HAMMERS

With the advent of iron - and later steel - the efficiency of carving marble and stones of similar

hardness improved, and the most common types of hammers and chisels for carving by hand

have since remained almost unchanged.

There have been some improvements such as tungsten carbide inserts for chisel tips that allow

carving of harder stones like granite, but high carbon tool steel is still preferred by many carvers

for working in more responsive marble and similar types of stone.

Aside from the shape of the striking end, the Hammer Head chisel differs from the Mallet

Headed type in that the cutting edge of the tool only is hardened and tempered, while the shank

of the tool is left unhardened. This is to allow the shank a certain amount of

resilience when working hard stone under the blows of a hardened steel Hammer - i.e., the

shank will bend rather than break . . . when between the rock and the hard place!

CARVING CHISELS

Many sculptors might use chisels like those above for all their work when stone carving, managing quite well with the wide selection available in those basic types of chisel. However, for those sculptors working in large blocks of stone or who often get stone cut-to-order for commission work there are a couple of additional types of chisel that might be used. During the initial stages of working on a dimensionally-cut block sometimes very large amounts of waste need to be removed before carving, as such, begins.

One of these specialized chisels is the Tracer or Line Tracer, which looks like a very stout and

oversized Flat Chisel. It is used to 'trace' a line across or around a cut block of stone to create a

weakened area, allowing a controlled fracture of the block. It is repeatedly placed perpendicular

to the surface of the stone along adjoining segments of the intended split line and at each

placement struck a blow with a heavy hammer.

The Pitching Tool - aka, the Pitcher or Hand Set - is also used to remove a great deal of waste

material at the initial stages of carving, but only if the carving block has flat-sawn faces. The

'working-edge' of the Pitching Tool is a broad flat face that usually is ground to an angle just

slightly-off the perpendicular.

A small version of the Pitching Tool that has the cutting face offset from the centre axis of the

shank is called a Chipper. This offset is to allow clearance when doing a 'finishing' pitch

following the work of the larger Pitching Tool.

1. HAND CARVING CHISELS:

THE POINT

The Point or the Punch is used after any initial work with the tracer or the pitching tool. The

Point and the Punch are used to rough-out the form. The Point differs from the Punch in that the

latter tapers to a small cutting edge where the former tapers to a single point.

The manner in which the chisel is gripped varies according to regional traditions, personal

preferences, or to the type of work being done.

2. HAND CARVING CHISELS:

The Tooth Chisel or Claw is used after the coarse carving with the Point.Following the roughing-

out, the Toothed Chisels are used to further define the surfaces of the form. Beginning with

varieties that have a few large teeth — such as the two-toothed Calcagno pictured at the far left

above — and following successively with versions that have both more numerous and finer

teeth, the Tooth Chisel is used to refine the form and make the surface contours more uniform

and regular.

The toothed chisel, with its row of pointed teeth, acts like a rake to even out the surface

irregularities left by the point. During use the chisel’s teeth should all be in contact with the stone

in order to prevent breakage.

A couple of manufacturers make Skutch Holders in three sizes which allows for a quick change

between replaceable inserts of either coarse or fine cutting teeth, or a plain flat cutting edge.

6. TRADITIONAL PROCESSES:

HAND CARVING CHISELS

The Flat Chisel is primarily used to follow and refine the work of the toothed chisel. It is used to

flatten surfaces, to crisp-up edges and intersections of planes, and to incise lettering.

The Cape Chisel — also called a Splitter — has a narrow blade (1/8-inch to 3/8-inch wide) that

swells and thickens in the opposite dimension about one inch away from the cutting end of the

chisel. This extra steel strengthens the cutting end of the relatively narrow tool and allows it to

be struck with fairly powerful blows without damaging the tool. It is used for cutting narrow

grooves or hollows into the surface.

The Bolster or Drove, a Flat Chisel that is two-inches wide or more, is used when working broad,

flat areas.

The Rondel, Round, or Bullnose Chisel is used in much the same manner as the Flat Chisel

except it is used for flattening concave surfaces and working into intersections of curved

planes. The curved corners of theRondel allow curved hollows to be worked without marring the

adjacent surfaces.

The Gouge is used in much the same manner as theRondel, though allowing a greater control

over the uniformity of the cut. The Gouge is used primarily when working softer stones or when

doing architectural carving of mouldings, when its contoured cutting edge can be more

effectively used to achieve uniformity.

SURFACING TOOLS:-

The Pick is used to chip away at the surface of the stone, either

to make it more uniform or to shape it in a rough manner much

as the Point Chisel might be used.

The Pick can remove material more quickly than the Point, but

the degree of control it affords the carver is somewhat less.

For this reason the use of the

Pick is usually limited to the initial roughing-out stages of

the carving, although it can be used to provide an irregular

texture to areas that are deliberately left to appear as

only roughly worked from the 'natural' contours of the stone.

One tool made specifically for sculptors combines the Pick with another surfacingtool,the Bush

Hammer. The Bush Hammer, sometimes called a Facing

Hammer, is used to pulverize the surface of the

stone, evening-out

The Bush Hammer has several rows of pyramidal teeth on its

faces, which crush the surface of the stone and leave a distinctive

texture. In use the tool serves to even-out the contrast of high

and low points, softening the surface contours making them more

uniform.

Because tool steel is about the same hardness as granite — about

6.5 to 7 on the Mohs’ scale of hardness — granite and similar

stones cannot be practically carved with common steel carving chisels.

When the hardest carving chisels were made

only from tool steel, the pulverizing action

of the Bush Hammer was the primary means

of shaping granite or hard stone.

The type of monolithic form that the nature

of this tool permitted the carver to work into

granite was generally more dense and

compact in overall design than similar

subjects worked into marble or softer

The advent of synthetic tungsten-carbide

tipped chisels that allow these hard stones to

be worked in much the same manner as

marble often now tends to limit the use of

the Bush Hammer as simply a means of

applying surface texture.

Two examples of the Crandall, a tool in the

Bush Hammer family which has removable

teeth that are held in place by a simple

wedge.

The Crandall was most often used to

surface sandstones that tended to simply flake away if struck with the common type of Bush

Hammer.

An example of one type of Bush

Hammer thathas interchangeable faces,

thus allowing one tool to span a wide

range from coarse to fine textures.

Bush Chisels, Frosting Tools, or Matting

Tools are used when a greater degree of control

is needed than the Bush Hammer allows, such

as when working near edges or intersecting

surfaces

Though deceptively similar to the Bush Hammer in

appearance, both the Toothed Stone

Axe and theToothed

StoneHammer are lessused for

workingthe face of thestone and

moreused for chippingaway at the

edges.

These examples of Bush

Chisel are all made for use in a pneumatic Carving Hammer. Though long versions are made for

use in an air hammer, the short versions are much easier to use when a high degree of control is

not necessary. This is because the chisel is not held in the hand as the longer versions must be,

but instead are just loosely held in the socket of the hammer slightly above the surface to be

worked. This allows the chisel to 'dance' randomly as the hammer is moved across the surface.

One manufacturer makes several other types of surfacing

tools in a short version so they may be used in the same

manner; the Three Blade Bushing Chisel, the Criss-

Cross Chisel, and the Cup Chisel.

SAFETY REGULATIONS REGARDING THE USE

OF DIAMOND TOOLS

GENERAL SAFETY RULES

Incorrectly used diamond tools can be dangerous.

- Follow the instructions of the supplier of the diamond tool and the manufacturer

of the machine.

- Make sure the diamond tool is suited to the use to which it is to be put. Examine

all tools before fitting to ensure that they are free from damage or faults.

- Follow the recommended procedures for the handling and storage of diamond

tools.

- Know the risks of using diamond tools and take the relevant precautions :

- Bodily contact with the diamond tool when operating.

- Injuries caused by the breaking of a diamond tool during use.

- Milling debris, sparks, smoke and dust generated by abrasion.

- Noise.

- Vibration.

- Never use a machine that is not in good condition or has faulty parts.