The effect of the thickness and geometry of a knife’s edge on its functionality

All types of knives have different characteristics in terms of their optimum parameters, although in many areas the issues related to them coincide irrespective of the intended use or material used. A good example are the side effects of the sharpening process that are associated with the change in the thickness and geometry of the sharpened edge. Even though the kind of steel used for the manufacturing knives usually allows great grinding possibilities, an issue may arise in the form of limitations resulting from the deterioration of the tool’s characteristics.

Why is there a change in the thickness and geometry of the cutting edge?

Knives are used for various tasks, and depending on the nature of the task, they may have different geometries. Utility knives may be intended for daily tasks, such as cutting and slicing, and have a dissimilar geometry to industrial knives utilised for various processing tasks, such as plastic forming, material cutting, trimming, and machining, or being used to loosen chips during rolling, boring, chiselling, or planing. A common feature of all tools with a blade used for the mechanical separation of a material is the fact, however, that they are subject to gradual wear, with a rate depending on the nature of the tasks, load exerted during the tasks, and the characteristics of the steel. In this case, the abrasion resistance of a given steel grade is of particular importance. Resharpening is required to deal with the loss of an appropriate angle between the surfaces forming the blade, such as for turning tools, or the rake face and tool flank, while the loss of the curvature of the cutting edge, such as when nicks occur or uneven wear, then the entire blade requires resharpening. Although the best parameters for this process differ for individual types of industrial and utility tools, as the process is carried out repeatedly, the material is collected in such an amount that the characteristics of the blade’s wedge change. For utility knives, it means that the material just above the sharpening edge is going to become thicker over time. This phenomenon may also appear on some industrial knives, depending on the shape of their operating parts. This will have an impact on the possibility of further use of specific tools, including in terms of their strength.

What are the consequences of the change in the thickness and geometry of the knife’s edge?

The effect of the change in the thickness and geometry of the sharpening edge on the operating parameters of industrial knives depends on the case and the optimum blade shape. These characteristics are usually clearly defined, and when the dimensions that prevent further carrying out of the tasks have been reached, the existing cutting knife must be replaced with a new one. For utility knives, this phenomenon usually translates into the degree of difficulty in obtaining satisfactory sharpness and into the impressions related to the use of the knife. This arises from the fact that the thicker the edge during grinding, the greater amount of material removed. In terms of the comfort of use, a thicker edge may lead to problems relating to slicing softer items and to the penetration of the blade into harder ones. It is important to remember that the scale of the consequences resulting from subsequent sharpening processes is largely dependent on the original shape of the knife, as those tools with a narrower and longer wedge tend to experience issues later than those tools with a wider and shorter wedge.