Diamond Wires for Cutting Without Damaging the Material

Different methods have been introduced to manipulate metals into various shapes and sizes. These methods involve large scale melting and cutting of metal slabs and thick sheets of alloys like mild steel, stainless steel, etc. Metal and hard non-metal material cutting is not as easy as it may seem. It is a tricky business, that involve detailed research about properties of material to be cut, like its melting point, brittle property, thermal conductivity, etc.

Since industrial revolution and evolution of hypothesis for research, various machines have been designed for industrial cutting. Most common cutting machines incorporate plasma cutting technology and laser cutting technology. These technologies ensure safe cutting, less waste material, accuracy and efficiency.

Diamond Wire Cutting is one of the latest techniques, which involve diamondwire cables, that rub against the material to be cut and produce friction. This process was invented in 1980s and was developed and further refined during the following decade.
Diamond wires are actually a form of wire saw which works in similar way as one does abrasion to saw teeth. Mostly, diamond is used as an abrasive to cut hardest rocks, huge stones and large reinforced concrete structures. The process involves use of wires or cables that are coated with diamond abrasive. Unlike common perception, diamond wire cutting is not only cheaper, it is one of the most effective ways of reducing overall cost of production. Unlike mechanical methods, that damage material surface, thousands of dollars can be saved via diamond wire cutting as it gives clean cutting and leaves no material wasted. A thin wire, that is coated with diamond beads has huge frictional capacity.

Diamonds for diamond wire

The wire saw method for diamond cutting is powered through hydraulic motor. When the wheel starts to rotate, diamond wire automatically starts to move along the circular path. It works like a pulley, in which diamond cable is set on a defined cutting path on required material slab or block. The material is cut through frictional force that produce heat and cuts through any material slowly and steadily. The reason why diamond is used as beads on these cables is because diamond is purest form of carbon, which is the hardest rock ever known. Only diamond can cut diamond and other materials with less constructive strength. Diamond wire cutting produce minimal sub-surface and surface damage as it is the most gradual and gentle method for material cutting. It is highly suitable for stiff, delicate and brittle specimens like glass. The fact that diamond wire cutting ensures minimum material damage can be confirmed by kerf loss, which is highly dependent on cable diameter. Usually it is 0.25mm. Diamond discs are not suitable for cutting delicate material where one cannot afford any kind of damage.

The option of different cutting pressures helps a lot in cutting of fragile materials with minimum loss or damage. Furthermore, with the advent of careful processing techniques, any fracture or damage on costly materials can be eliminated easily. Speed control of wire cutting and quick configuration from wire to disc also helps a lot in cutting expensive materials with less surface and internal damage.

diamonds by Jared Tarbell / CC BY

More about industrial cutting

Various technologies have been invented over the course of last century, to help in mechanization of industrial gadgets. One of the common functions incorporated in industrial sector is that of cutting and welding of metals. Industrial cutting has been highly revolutionized with the help of laser beam technology. Commercial lasers are used to cut large sheets of thick metals and brittle non-metal materials via a motion control system that follows a G-code, commanded by a CNC. A CNC, abbreviation of Computer Numerical Control, controls commands that are sent to cutting machine via computer aided design (CAD) and computer aided manufacturing (CAM).

Industrial Cutting

An advantage of industrial cutting via laser beam is that it requires lesser manpower and leaves high quality surface finish. Industrial cutting is largely used in variety of ways, especially in mining of coal, marble, diamond and other hard rocks. These cutting tools are used to cut large pieces of raw stones, which are further refined in close by laboratories. Use of wire saw is common for cutting large rocks.

Industrial cutting is not only limited to large scale mining and construction projects, it is also used in cutting large flat metal sheets and piping materials, etc. The concept of large scale industrial cutting started with the invention of cutting machines for drilling holes in diamond dies, back in 1965. This technology was further refined to be able to cut titanium, an important metal in aerospace engineering.

With the invention of CO2 lasers, the extents of industrial cutting was expanded to non-metal industries as well. CO2 lasers do not have enough energy to surpass thermal conductive property of metallic objects. These days, CO2 lasers are largely used in textile industries where they are used to cut fabric and other non-metal objects. It works on principles of infrared light, which has a wavelength of maximum 10.6 micrometers. It is generally used for boring, engraving and cutting of non-metals like wax, paper, wood and mild metals like steel, aluminium, etc. Different forms of CO2 lasers include transverse flow, slow axial flow, fast axial flow and slab.

In order to cut materials like sail cloth, PVC, webbing, canvas and vinyl, various CNC cutting systems have been introduced. There is a wide range of cutting solutions for industrial fabrics, tension structures, outdoor furniture and inflatable products. Neodymium yttrium-aluminium-garnet (Nd-YAG) and Neodymium (Nd) laser cutting industrial tools have been introduced for high energy cuttings.

Major cutting tool includes diamond wire cutting tool. It works like a pulley method. The hydraulic pump is provided power to set the wheel in motion. Cabled wire with diamond beads is wrapped around that wheel, which is set to motion. It moves the cable wire along the cutting path on the object to be cut. When diamond beads rub against the object, it produces immense heat via friction which cuts the material. An advantage of diamond cutting is that the cut is finer and uniform in comparison to other mechanical methods. Different methods for industrial cutting include vaporization, thermal stress cracking, reactive method, silicon wafers stealth dicing and melt and blow method.

Gas cutting by Lydur Skulason / CC BY

Laser Cutting

There has been a tremendous advancement in industrial sector since industrial revolution. Various new innovative ways have been devised to manufacture and create various products. With the help of machinery, mass production has been made possible. With the invention of laser cutting technology, it is now possible to cut any kind of material via laser. The term “laser” is in fact an abbreviation of Light Amplification by Stimulated Emission of Radiation. A “laser” is a gadget that works on the principle of optical amplification, which emits light via electromagnetic radiation.
These days, the use of laser technology is not only limited to large-scale industries. Now it is also used widely by artists, hobbyists, small business enterprises and even in schools for laser printing.

Laser cutting

Computer Numerical Control (CNC):

CNC is a programmed encoded machine tool that is operated via automatic command. These numeric control machines are mostly computers. Computer aided design and computer aided manufacturing (CAD) and (CAM) are readily used to create program file which extracts the command, which further redirects information to laser producing machine.

There are different applications where laser technology is widely incorporated, like bar-code scanners, optical disk drivers, cutting and welding on industrial level, fiber optics and lighting displays in entertainment industry.

The earliest production of laser cutting machine was meant to insert holes in diamond dies back in 1965. In 1967, oxygen jet cutting was introduced that worked on laser principles to cut metal quickly. Laser technology soon became common for titanium cutting. It was widely used by aeronautical engineers for aerospace applications. In textile industry, CO2 lasers were adapted to provide quick cutting for different non-metals.

Methods for Cutting:

There are different types of cutting techniques which can be done via laser cutting technology. Usually different methods are implied for different metals, because of varying chemical properties. Most commonly used techniques include:
Thermal Stress Cracking:
Thermal fracture is a major problem while cutting metal with brittle properties. In order to avoid stress cracking, a hot beam is projected on a surface to ensure thermal expansion. The outline of crack formed can be gilded with the help of beam movement along the path, the movement subjected to m/s order. Thermal stress cracking is commonly used for glass cutting and smoothing.

Vaporization:

In this type of laser cutting, boiling point of a metal is achieved by heating up a surface till it forms a key hole. The hole is deepened due to increased absorptivity as a result of vaporization. The boiling of material leads to further deepening of hole. The metal vapors erodes hot, molten wall which bows the ejecta out. All non-metals like thermostat plastic carbon are cut using vaporization method.

Reactive Method:

This method is also called “flame cutting” or “laser gas cutting”. Laser beam is the ignition source, which incorporates relatively less laser power to cut thick metallic plates, like steel or carbon steel.

Melt and Blow:

In this method, high pressure gas is used to “blow” away material at the cutting source, once the metal space is heated to a molten state. At first, the material is heated till its melting point, followed by gas blowing that cuts material without the need of raising temperature to gaseous state. This method is widely used for metal cutting.

Types of Lasers:

Generally, there are three major types of laser cutters: CO2 Laser, neodymium yttrium-aluminium-garnet lasers (Nd-YAG) and neodymium (Nd) lasers. CO2 laser is more suitable for boring, engraving and cutting whereas later two are commonly used for boring with low repetition and high power requirement. Nd-YAG is more common for engraving where high power is required.

Pros and Cons:

Laser cutting is advantageous in many ways in comparison to mechanical cutting. There are less chances of material contamination because unlike mechanical way, there is no cutting edge. Unlike mechanical process, which is not only handy, but there are high chances of material becoming weary, in laser cutting, the precision is finer. Heat affected zone in laser cutting is less which reduces chances of metal warping. Furthermore, laser cutting can cut almost any thick sheet of metal, unlike mechanical process. Laser cutting is much cheaper and more neat than plasma cutting as well.

The major set back to laser technology is high power of industrial consumption. This power consumption is largely dependent on operating parameters and output power. Moreover the amount of laser cutting, also known as heat input, also decides about power consumption. Material type, process and thickness can also fluctuate laser efficiency to a large level.

SP16_TEAMFacility_KL-2841 by UC Davis College of Engineering / CC BY

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