At the outset, let us know the difference between conventional abrasives and super abrasives. Conventional abrasives are grinding wheels with silicon carbide, aluminum oxide or even ceramic grains, whereas super abrasives are those with diamond or Cubic Boron Nitride (CBN) grains.
The super abrasives got the name because they are the hardest grinding materials known to man. They are capable of machining materials that are challenging or considered impossible to grind with the conventional abrasive wheels, which are made of silicon carbide or aluminum oxide. The crystal structure of Diamond and CBN are similar, with the difference being that diamond consists pure carbon while CBN is a combination of boron and nitrogen.
Besides the diamond grinding wheels and CBN grinding wheels another important product is the diamond countersink bit. Although it is not mentioned about much, the countersink bit is a very important tool and we shall check out its different aspects here.Countersink bits cut conical holes, enlarging and beveling a drilled hole in the material so as to fit the screws flush with the surface such that the finish is neat and smooth. Diamond Countersink bits are designed for the countersinking process in a variety of materials like Glass, Quartz, Carbon, Boron, Composites, Graphite Epoxy, Fiberglass and Marble.
The Proper Method to use the Diamond Countersink Bit
While using the diamond countersink bit, you need to ensure that the bit is fixed in the chuck properly so that it runs true. You can check the trueness by lowering the bit onto a piece of scrap material fixed firmly in place. Lower the bit such that it barely comes in contact with the surface of the material. Run the machine at a very low speed. If the bit produces a defined point or dot on the surface and does not wobble around, you can be sure that is truly centered.
If the bit does wobble during the trial, you may want to re-insert the bit into the chuck and repeat the process again till you get the perfect dot.
Why are Diamond countersink bits used?
As already learnt, Diamond is the hardest material. When diamond is used on cutting tools, it removes material on a micro level. The hard Diamond surface works on all and sundry types of material with a hardness of 40 and upwards on the Rockwell scale. These Diamond countersink bits (and also other diamond tools/ grinding wheels/ diamond drill bits) machines even the hardest material that conventional, high speed steel or carbide tools cannot. Diamond Countersink Bits and Drill Bits drill hard materials quicker, yield smoother surface finish and gives reliable performance. Thus, Diamond tools/drill bits are the best alternative to carbide & other types of drills when it comes to machining hard material.
Difficulties with Conventional Diamond Tools
The dissemination between Diamond or CBN particles on the tool usually regulates the work load each particle will perform. As such, if the distribution of these particles is uneven or sparse, it could lead to the failure of the bond structure prematurely. On the other hand, if the particles are too close, some of them become redundant and provides very little assistance in machining, resulting in some particles getting worn out while some others remain unused. Excess particles tend to increase the manufacturing cost and thereby the cost of end product for the customer.
With the conventional diamond tool, after a few initial uses, reduction in speed occurs. It would take longer periods of time to finish machining a part that was much easier to do not too long ago! Constant dressing of the tools become mandatory and could cause overheating. Overheating in turn leads to gradual loss of the tensile properties of the tool. This negates the efficiency of the tool, thereby increasing costs and affecting production adversely.
Conventional Diamond Tools have had these problems of ineffectiveness over the last few decades. But with modern precision technologies, Diamond and CBN Abrasive Tools have come of age and are the bestsellers when machining of harder materials is the need. Diamond and CBN abrasive tools are the main super abrasives and their effectiveness in machining of harder materials has now been proven beyond any reservation.