3. Key performance parameters of the cutting head
Concentration: Refers to the volume percentage of diamonds within the working layer of the cutting head. International standards typically define 100% concentration as 4.4 carats (0.88 grams) of diamonds per cubic centimetre. Excessively high concentration compromises the matrix's retention of diamonds, causing premature diamond shedding before full utilisation. This reduces cutting efficiency and increases costs. Concentration that is too low results in insufficient effective cutting particles, leading to poor cutting efficiency, accelerated matrix wear, and reduced tool life. The principle for selecting diamond concentration in the working layer is to use lower concentrations for cutting hard, brittle materials and higher concentrations for cutting soft, ductile materials.
Grit size: Also referred to as mesh size, this denotes the size of diamond particles. Coarse grit or low mesh sizes, such as 30/40 or 40/50, deliver greater cutting force per particle and higher cutting efficiency, though resulting in rougher cut surfaces. Fine grit or high mesh sizes, such as 80/100 or 100/120, provide smoother cutting action and higher surface finish quality, albeit at reduced efficiency. The principle for selecting the diamond grit size in the working layer of a cutting head is as follows: coarse grit is used for rough cutting where efficiency is prioritised, while fine grit is employed for precision cutting where surface finish quality is paramount.
Bond hardness: Refers to the abrasion resistance of the bond material. An excessively hard bond results in slow wear, preventing dulled diamonds from shedding promptly. This causes the cutting edge to slip, impeding cutting efficiency and producing a polished surface. Conversely, an excessively soft bond leads to rapid wear, causing diamonds to shed prematurely before fully utilising their cutting capacity. This accelerates edge consumption and shortens service life. When cutting hard materials such as granite or hardened concrete, a soft matrix should be selected to facilitate rapid wear, allowing fresh, sharp diamonds to be exposed promptly. For cutting soft materials like marble, asphalt, or soft bricks, a hard matrix should be chosen to firmly retain the diamonds, preventing premature detachment and maximising their cutting capacity.
