Adhesives for Diamond Cutting Tools
Diamond Adhesive Bonding for Cutting Tools
As most of us already know, diamond is the hardest material known to mankind. Most of us will have been told by an enthusiastic school teacher, “The only way to cut a diamond is to use another diamond.” As well as its coveted beauty which makes it one of the most valuable and sought-after gems, diamonds also have a great number of industrial uses.
What is a diamond tool?
Diamond grains are fixed on the functional part of the tool by a bonding material or some other method. Typical tools where diamonds are affixed to the machining parts include diamond cutting tools, twist drill bits, grinding tools, saw blades, drawing dies and diamond polishing pads. These can range in size from small, handheld cutting tools up to massive boring drills used in the mining industry.
Methods for Bonding Diamonds
There are several methods bonding diamonds to substrates, including sintering, brazing, electroplating (by chemical vapour deposition method), cemented carbide liners or by adhesive bonding. Adhesives offer an effective yet low-cost method of bonding and are ideal for bonding diamonds to a variety of different materials as desired (rather than have to incorporate various other joining procedures to work around different substrates).
It is important to select an adhesive with the right characteristics to achieve optimum diamond bonding performance. Key features essential to successful diamond adhesive bonding include:
- Extremely high shear strength
- High peel strength
- Good resistance to cleavage stress
- Must have impact and vibration resistance
- Must be toughened to absorb differential thermal expansion and contraction between dissimilar substrates without cracking off
- Resistant to high temperature (heat is generated by friction of machining tools) – must maintain a high adhesion strength at elevated temperatures
- Abrasion resistant – will not be worn away
- Resistant to water, chemicals, slurry and cutting oils
It is a “tool” order (!) to find an adhesive that ticks all the boxes. Generally heat-cure single part epoxies with a specialist toughening matrix are the preferred choice for adhesive bonding of cutting tools, both for bonding diamond grains but also tungsten carbide wear tips.
For further information regarding diamond adhesive bonding of cutting tools, please contact Permabond’s technical team via our enquiries page here.