 The Basics
Here we will explain the basic mechanics of sharpening. The importance of the type of steel and significance of carbides & vanadium content will become apparent. These mechanics apply to all shears currently on the market, and the impact of DHMS will be detailed.
 Shear blades have two sides, side 1 and side 2, where they come together forms the cutting edge, see illustration to right. Performance of the cutting edge depends on many factors, such as; steel, angle between the sides, sharpness, burr (also known as roll over), straightness, type of manufacturing process behind the blade and finish. With a subject that has become so misunderstood it is necessary to address each area, at least minimally.
Angle Between Sides, Sharpness & Burr
The following illustrations, figures 1 & 2, show the cutting edge. Where sides 1 & 2 of the blade connect they form the cutting edge – depending on how evenly and precisely this connection is made determines the blade’s sharpness. The angle between the sides can be a factor of the blade thickness and its performance – the angle must be large enough to fit the blade thickness. The smaller the angle the easier it cuts through the hair, but thinner can mean more fragile for cast and forged shears. The Kagawa LanceMARK Blade is thinner, stronger and more flexible because the SCV steel is more advanced. The differences can be seen in the illustrations below. Figure 1 shows a blade profile typical for a cast or forged shear where figure 2 shows the LanceMARK Blade found on all Kagawa shears.
Blades often have a slight curve on the top, sometimes referred to as clam shelling or Japanese Style shear. The shape actually has nothing to do with neither a country of origin nor a sea creature; it was developed by manufacturers of cast and forged shears to make their blades thicker and stronger. Kagawa's LanceMARK Blades, made from super strong SCV surgical steel, are thinner and lack this bulbous form. The resulting thinner profile is more efficient in cutting, and lessens stress on hair (helping to eliminate damage).
During manufacturing, and even sharpening, the point where Sides 1 & 2 connects, the cutting edge, displays a unique characteristic known as the “burr”. The burr is a small & thin flap of steel that grows on the edge as the edge becomes sharp. The sharpening process causes the steel to become progressively thinner at the edge, at a certain point the steel opposite the removal process becomes so thin it is pushed away – this is the burr. Sharpening systems using motorized grinding cause excessive heating and pressure, at this point, leading to the development of an exaggerated burr. Many times those persons providing sharpening services are not properly trained and tend to leave this burr on the blade as a cutting edge. Since it is only rolled steel, it will quickly break off, resulting in a dull shear. Properly trained technicians use burr development as a sign the sides have come together at their finest point. They will then remove the burr and prepare the edge.
The small circles in the above illustrations represent carbides – carbides give steel its' strength. Figure 3 shows a blade with side 1 and side 2 connected by a radius point. The carbides are solidly attached to the base metal creating a strong but dull edge. In figure 4, the metal removal process begins, as steel is removed the carbides at the cutting edge will begin to lose their solid connection point and be forced to roll away or break off. Figure 5 shows the formation of a burr, the carbides on the cutting edge have lost their hold and been forced off, leaving the weaker base metal to roll downward. Figure 6 shows a fully formed burr, few if any carbides remain on the cutting edge.
DHMS sharpening is controlled by microscope and removes only a small amount steel from both sides of the cutting edge. This process minimizes burr development, and in many cases eliminates it altogether. DHMS also removes the steel in a specific pattern, Cryo425, which is certified to eliminate hair damage. The micro sized carbides in SCV steel are less then 1/50th the size of the carbides found on other steels, yielding a cutting edge that is heavily populated with carbide rich surgical steel that will remain sharp many times longer and resist nicks over 4 times better.
Next Chapter: The Cryo425 Edge |
