Blade Performance - Important Factors

In a previous blog, I discussed “Blade Steel Basics”. While blade steel is a very important factor in determining blade performance, there are several other factors that will influence blade performance….. The heat treat, blade geometry, and sharpening are also important factors that determine blade performance. In this blog I will discuss those factors.

HEAT TREAT

Heat Treatment is the process of hardening and tempering the blade steel through heat. The steel is heated up hot, quenched, and tempered. This provides the desired properties at the end which include high hardness in combination with sufficient toughness. A well done and consistent heat treat goes a long way towards the performance of a knife. High hardness (60 HRC+) increases the edge retention of the steel at the cost of brittleness. Low hardness increases toughness at the cost of edge strength. A good performing blade is the combination of the quality of the steel, and the quality of the heat treat process. You have to have both to obtain a good performing blade. I like to think of the steel as the “heart” of the blade and the heat treat as the “spirit” of the blade.

BLADE GEOMETRY

There are several factors that go into blade geometry, blade type/style, grind, blade thickness, and bevel (edge) angle. All of these factors will play an important role in blade performance, and will determine which task(s) the blade is best suited for. Example: Cutting, slicing, and piercing/stabbing. There are literally dozens of different blade types out there. For this blog I will concentrate on the most popular types that you will find on production knives currently being made today. Many of these blade types come in modified variations from knife makers and manufacturers to add something new to the market, and to come up with their own designs or look, but even modified variations will originate from a standard blade type.

The Drop Point knife blade features a slight curve and a convex curve on the back of the knife. It is probably the most common blade type used for knives, since the shape of the blade can be used for many different applications/tasks. The drop point blade style is very versatile and strong making it perfect for slicing and cutting, but it is not meant for piercing/stabbing. The drop point blade style is a great all around EDC blade shape.

The Tanto Point knife blade features a chisel edge. The strongest feature of the tanto point blade is it’s tip strength. It evolved from the Japanese sword, specifically, the samurai warriors discovered that the physics of the tanto blade could penetrate just about anything, including body armor, which made it very effective during battle. The tanto point knife has no belly, so it is not recommended for slicing or chopping. With a massive potential for penetration and insane durability, the tanto blade style is a popular choice for modern tactical knives.

The Clip Point knife blade is similar to the drop point blade with one distinction. Instead of a convex curve, the clip point blade features a concave curve to the tip. This type of blade takes a portion out of the back of the blade, which creates a second curved edge and a thinner tip. The clip point blade offers more control, and with it’s thin sharp point can be used for small or hard to reach places, but it usually does not perform well for more heavy duty tasks, such as chopping and cutting thick materials. The clip point style blade offers versatility and control, and excels at detail work towards the blade tip.
The Wharncliffe knife blade features a thick blade, a straight edge, and a dull back with a gradual curve. It originated from the use by sailors. The straight edge and dull spine makes the wharncliffe blade easier and safer to use in unstable conditions. The thick blade lends strength and stability, and the dull spine allows you the ability to apply pressure for extra force and control. The straight edge is very effective for slicing, and the edge is strong enough to handle light chopping. Note: The blade point cannot pierce or stab. The Wharncliffe blade style excels in EDC tasks with a thin tip and long, straight edge.

The Spear Point knife blade features a symmetrical curve on both sides of a center spine. It is used for daggers and small knives that are used for thrusting and throwing. The blade is typically sharpened on both sides (double edged). Spear Point knives are known for one main thing…..stabbing. Besides the stabbing and piercing capabilities of a spear point blade, the spear point blade is still flexible and balanced enough for slicing and general EDC tasks.

SHARPENING

Sharpening is a big part of the overall blade geometry. The bevel (Edge) angle is one factor that determines blade performance. Typical edge angles are about 20° (40° inclusive). Inclusive edge means that each side of the blade is sharpened to 20 degrees. The edge angle for very sharp knives can be as little as 10 degrees (20° inclusive). Knives that require a tougher edge may be sharpened at 25° or more. Most blade steels are more stable at high acute angles.