For today’s industrial cutting tool manufacturers there is a continuous and increasing demand for faster cycle times, better asset utilization, tighter tolerances and improved quality. Running a successful manufacturing facility takes more than acquiring the latest state- of-the-art equipment and the most advanced grinding technology. The grinding application can be optimized up to a certain point, where the product cycle time will be the same. However, automating the setup processes—such as truing and dressing cycles—can increase overall equipment effectiveness (OEE).
Shorter process times, reliability and longer product life are key requirements in the cutting tool industry and the efficient use of online dressing discs and spindle systems are critical for reaching high precision and flexible cycle times. For years, automation was synonymous with large-scale mass production plants (i.e., automotive factories). This left small machine shops to rely solely on experienced operators, manual adjustments and 100% post-production quality verification.
However, automation is now available to everyone and is being embraced by smaller shops that continue to adapt and understand the technology and are open to using it. If manufacturers can proficiently keep their processes running safely with minimum-to-no operator interaction, they can achieve vast benefits such as enhancing the effectiveness and life of their grinding wheels and online dressers.
To maximize productivity and the performance life of your superabrasive wheels, optimal dressing is critical. But what is the best way to achieve this? In the continuous search for product and process innovation, it has been determined that significant improvements and cost reductions can be achieved by leveraging existing dressing technologies, with minimum investment.
Generally, there are two types of dressing procedures. One that can either be performed offline (with the use of an optical grinder outside the machine) or one that can be performed online (inside the machine with an additional spindle).
With offline dressing, there is a lot of machine downtime and a higher degree of operator interaction. As an alternative, online dressing is achieved inside the machine, without the need of interrupting a production run. The major benefits of dressing online include, but are not limited to, the ability to increase machine capacity and reduce labor costs, while increasing part quality and process consistency.
For online dressing, dressing discs which have a thin diamond section that is traversed across the face of the grinding wheel are recommended. Different types of dressing discs include either synthetic, natural or CVD log diamonds.
Bonded Profiling Roller (BPR™) dressing discs from Norton | Saint-Gobain are an optimal tool of choice and consist of a single consumable layer of high-quality synthetic diamond secured with a brazed metal matrix. The single layer of consumable diamond eliminates the need for lapping, resulting in improved life. BPR technology is capable of dressing concave and convex profiles, offering constant, effective and reliable dressing diamond layer width throughout the dresser’s lifetime.
Understanding the dressing process and how it impacts the grinding application is key to making proper parameter adjustments for process optimization. Effects due to operational parameters must be optimized for the application.
In addition to dressing discs, it is vital to have the proper cutting media (diamond) to meet the dressing requirements. As previously mentioned, dressing discs are composed by synthetic, natural or CVD logs. Commonly, CVD diamonds are primarily used to dress conventional grinding wheels.
CVDs are synthetic diamonds that are manufactured using chemical vapor deposition (CVD) techniques. This technique produces long-shaped diamonds with a very uni- form cross sectional area. These synthetic diamonds provide superior edge reinforcement resulting in longer diamond roll life and a more consistent dressing process.
It has been demonstrated that by enhancing BPR technology capabilities with the use of CVD “logs” during online dressing, the following can be achieved:
- A more consistent and reliable process.
- Longer dresser and grinding wheel life. In the demonstration mentioned above, by reinforcing BPR dressing discs with CVD logs there was a 56% life improvement on the dresser where 91% of the total dresser’s infeed was taken from the fluting diamond wheel without sacrificing dressing quality.
- A continuous diamond layer offering a constant contact area and dressing conditions, providing consistency on the work piece and surface roughness on the dressing wheel after the dressing cycle.
- A more aggressive grinding behavior and higher material removal rate increasing productivity.
- Faster online dressing cycle times.
- Better product quality. Reinforced BPR uses less grinding force, which minimizes deflection, results in increased workpiece accuracy and eliminates tool breakages.
- Low and stable grinding power.
New Era of Tool Manufacturing
By using the techniques described in this article, superabrasive wheels can produce even greater results than ever before for cutting tool makers. Combined with automation, they are helping create a new, more efficient era of cutting tool manufacturing.