The following article was originally published in Gear Solutions. Click here to read more.

Example of poor sharpening. Note the too-shallow depth of grind over several resharpenings, which has resulted in “root steps” and an incorrect tooth profile.

Cutting tool management is a critical aspect of gear manufacturing operations, and expert resharpening services are worth their weight in accumulated chips.

On a per-unit basis, the overall cost of cutting tools in a gear cutting process boils down to only a few percentage points. As a result, this overshadows the cutting tool’s obvious direct impact on the cutting process and cut gear. Consequently, some gear manufacturing operations focus elsewhere to find productivity gains, better quality, or lower costs, but cutting tool management remains critical for all gear manufacturers. While there are many aspects of choosing a cutting tool for each application, choosing an expert hob sharpening service is an easy step toward improved gear production.

Whether an “expert sharpening service” is internal or external to a gear manufacturer, the concepts presented here still apply. “Sharpening” and “resharpening” are used interchangeably.

Disclaimer: Koepfer America sells Helios hobs and offers Helios gear tool sharpening services. The opinions presented here draw from this technical sales experience, which dates back to 1988 and includes projects from numerous gear manufacturers of all types and sizes.

Seeking Knowledge

For the foreseeable future, gear manufacturers must find detailed, nuanced advice via other manufacturers and knowledgeable suppliers. It may be a cliché to label a supplier, a “partner,” so perhaps a “resource” would be more palatable and accurate today. Such suppliers of products and services act as on-call advisors, easily reachable at the end of a video call, phone call, text, or email.

A gear manufacturer’s sharpening service must serve as such a resource. At its core, sharpening is simply grinding away stock material from a cutting tool, but an expert sharpening service offers a well of knowledge. Not only can the service offer information on resharpening, recoating, and inspection, but their experience potentially includes a full gamut of tool types, tool materials, coatings, and the application of all to a variety of gear types and workpiece materials.

Consequently, this expert sharpening service doubles as an information assistant. The sharpening service has transformed into a technical resource for production engineers, operators, shop supervisors, and nearly anyone who touches the gear manufacturing process. It is no longer a “black box” where tools are simply sent and returned in better condition.

Example of poor grinding quality. Note the axial “streaks” along each tooth face due to a wavy surface, resulting in inaccurate tooth profiles. (Courtesy: Koepfer)

Quality is Key

An expert sharpening service utilizes a state-of-the-art dedicated CNC gear tool sharpening machine. This is a machine tool grinder specifically designed to sharpen hobs, milling cutters, and shaper cutters. It uses the latest specifications of CBN (cubic boron nitride) and diamond grinding wheels, which lead to lower costs, better productivity, and high-quality ground surfaces. This latter quality is necessary for optimal recoating quality. Lastly, a dedicated gear tool grinding machine includes on-board dressing of dressable tools, such as vitrified wheels. This capability offers accurate and correct grinding of complex geometries, such as spiral-gash tools, conical hobs, or high-helix worm gear hobs.

Along with dedicated machine tools, expert sharpening services are performed by gear tool specialists. With the variety of tool materials and coatings available in the industry today, a sharpening expert can advise on an optimal reconditioning solution for each gear cutting application. Additionally, these experts apply their experience to determine a microscopically minimal amount of stock removal during grinding. This extends tool life by offering additional resharpenings compared to less sophisticated methods.

Recruiting Reliability

Resharpening is an inherent part of any gear hobbing or shaping application today. The goal of resharpening is to return a tool to its original geometric quality without damaging the tool during the multiple steps required. These typically include handling, stripping, grinding, inspection, edge preparation, and recoating. Each of these steps has the chance to damage a tool, so using an experienced service will help reduce the risk of inadvertent damage and increase consistent and reliable quality.

Today’s expert sharpening services also offer reliable and transparent information. This may come in several forms. As mentioned above, the service as an information assistant is accessible for communication on-demand. Additionally, the service may be accessible 24/7 online through a web portal to offer status updates, issues, questions and answers, and more. Such a service may send automatic updates via email or text, and for the internet of things (IoT), the service may offer an application programming interface (API) to allow any device or other service to automatically query for specific real-time information.

Active Resource

Most gear cutting tool resharpening services are arguably “expert.” If I could leave only one closing statement, it would be to check if your expert suppliers are active resources of knowledge. As competitive capabilities between manufacturers near parity, accessing and applying valuable information will become a more important differentiating edge. All gear manufacturers should take the moment to reevaluate the “expert” in their resharpening services.