Overheating Of Diamond Tools

Overheating is the most common culprit for ruined diamond tools. The intense heat can cause deformation, glazing, cracking, and graphitization of the blade. A diamond tool is made of diamond particles sintered together with specific metal alloys. Overheating can cause the metal component of the tool to become malleable and prone to deformation.

The excessive heat can also cause a reaction often referred to as glazing in which the metal component melts and ends up covering the diamond particles. The diamond particles have to be exposed in order for the tool to cut through materials. The glazing reaction causes the tool to become inefficient or totally incapable of cutting the material.

Cracked blade is another effect of overheating. The metal component in diamond tools can be made of two or more metal alloys. The different metal alloys, when exposed to heat, expand at different rates and can lead to the formation of cracks.

Graphitization is what happens when the diamond particles is exposed to so much heat and carbon-containing material. The  molecular structure of the diamond rearranges and transform into soft and brittle graphite.

Diamond tools can be very expensive. It is unlike a magnet tool that can be affordably replaced. Knowing how to prevent overheating from happening can help protect the diamond tools. A proper cooling system, using the correct speed configuration and type of tool for a certain material can help prevent overheating and increase the life of the tools.

Non-Ferrous Cutting Applications

The development of new work piece materials resulted to new range of products that perform in various demanding conditions. The aerospace industry is the leading industry in material development as scientists and engineers in this sector are always trying to find stronger and lighter materials to be used on airplanes. The search for better materials has resulted to many nonferrous materials that are now being used in different industries.

Diamond tools are the most preferred machine tools for many nonferrous  applications. Its hardness gives it an extremely efficient cutting ability and makes it very resistant to wear and allows the tool to produce consistent results over a long period of time. Its long service life reduces downtime due to parts replacements or repairs, boosting the productivity of the operation. Diamond is the most effective tool for applications involving high speeds, high volumes, or materials such as aluminum or graphite.

There are two main types of diamond tools. The poly-crystalline diamond offers hardness, strength, and abrasion resistance of natural diamond without its weakness to fracturing. This type of tools are manufactured using synthetic diamond particles that are created using a high pressure and high temperature process. The diamond particles are integrally bonded to a cemented tungsten carbide substrate for mechanical strength and resistance to shock or impact.

The second type of diamond tools are those that use chemical vapor deposited diamond. This technology is relatively new. Instead of using diamond particles that are held together by a binder, the cutting tip or edge is made of one solid diamond. The absence of a chemical binder results to lower heat and more efficient cutting.

Dulling Of Diamond Tools

It is normal for any cutting tool to become dull after a good amount of use. How long the tool is able to retain its sharpness and cutting power depends on the material used. The harder the material the better the tool is at retaining its sharpness. Diamond is one of the hardest substances known to man. That is why it makes the perfect material for cutting tools. Diamond tools are used for materials that are impossible or too time-consuming for traditional cutting tools. However, these tools can be very expensive. And although the diamond is very hard, diamond tools are not immune to premature dulling. The reason for this has to do with how the tools themselves are made.

Tools like diamond grinding wheels are made of very small diamond particles held together by a bonding agent. In a normal use, the worn and dulled outer diamond particles fall off to reveal the sharp particles underneath. This process happens repeatedly throughout the life of the tool, until the tool is completely worn out.

Although the diamond particles themselves are very strong and able to retain their sharpness, the bonding agent that holds them together is vulnerable to thermal and physical damages. Using the grinding wheels at speed well-above what is recommended by the manufacturer can produce excessive heat that can cause the bonding agent to become so malleable that it forms a layer over the outer diamond particles, dulling the tool.

Magnet Tool And Maintenance

A magnet tool represents an investment for a workshop. Although it might not be as expensive as diamond tools, a magnet tool must be properly taken care of to protect the investment and yourself. The last thing you want when moving a heavy work piece is for the magnet to fail. There are things that can be done to increase the life magnet tools.

Like any material, magnets are not immune to harsh environmental conditions.  They are vulnerable to temperature and moisture. A magnet can lose its magnetic charge when exposed to a certain temperature. The temperature at which magnets can become demagnetized is known as Curie temperature. The curie temperature varies depending on the type of a magnet. The common ferrite magnets become demagnetized when exposed to temperatures over 460° Celsius. Avoid storing a magnet tool in places that have the tendency of becoming very hot.

Most magnets are made of materials that can corrode when it comes contact with water. Water vapor in humid air can cause magnets to corrode. Ensure that the storage area for the magnet tools has the suitable humidity.

Aside from temperature, there are other causes of demagnetization. Placing two different magnets near each other can cause the weaker magnet to lose its magnetic charge. There are special magnet keepers that are ideal for storing magnets. These magnet keepers help protect magnets from conditions that can have adverse effect on its performance. 

Grinding Wheels

Grinding wheels are made up of thousands of minute abrasive grains that are bonded together. Every abrasive grain acts as a cutting edge.  The abrasive grains are made of very hard materials. The diamond grinding wheels features the hardest material known to man. The grain cuts a small chip to leave a smooth and perfect surface as it passes over the work piece. As each abrasive grain becomes dull, it breaks away from the bonding material to expose sharper grains.

The abrasive grains used for grinding wheels are differentiated between natural and manufactured. These days, the natural abrasives have largely been replaced by manufactured abrasives. The diamond tools are the last of the grinding wheels that use natural material. And even then, the natural diamonds are starting to get replaced by synthetic diamonds.

Manufactured abrasives are easier and more affordable to produce than natural abrasive materials that need to be mined and then processed. Manufactured abrasives also offer more consistent cutting quality due to the controlled conditions of the manufacturing process. The most widely used abrasives for grinding wheels are aluminum oxide, cubic boron nitride, diamond, and cubic boron nitride.

There are few remaining grinding wheels that use natural abrasives today. Most of these tools are able to subsist because of traditions. An example is in sword making wherein the inconsistency of natural abrasives give the blade a unique and attractive patterns.  

Graphite and Electrodes

Electrical discharge machining or EDM is a process used for cutting intricate shapes, cavities and contours in pre-hardened steel. There is no heat treatment required. Compared to other machining methods, EDM involves less processes as there is no need to soften and then re-harden the steel. One of the key components for EDM are the electrodes. Rapid recurring current discharges between two electrodes remove the material from the work piece.

There are different types of electrodes used for EDM. Graphite electrodes is one of the most widely used. There are several reasons why graphite is preferred by many. It is fast and easy to produce. It is also resistant to thermal shock. Thermal shock happens when different parts of an object to expand by different amounts. This differential expansion can causes stress on the material. At some point, this stress can exceed the strength of the material, causing a crack to form.

Graphite electrode does not melt. It goes directly from solid to gaseous state. Graphite removes material better than copper or copper-tungsten while wearing slower. The wear rate tends to diminish as the discharge increases, unlike copper, whose wear increases at higher currents. This makes graphite more suited for machining of large electrodes since working with a high current intensity provides decreased roughing time.

Although graphite is prone to abnormal discharge, this can be eliminated through quality flushing, and lowering the intensity of discharge during negative polarity machining. However, since graphite is a ceramic, it is sensitive to mechanical shock. It must be handled and machined with care.