When shops implement ceramic cutting tools, they enter a brand-new paradigm as they turn many of the traditional conventions of machining upside down. From the lack of coolant to the need for sparks during the cut, working with solid ceramic tools gives shops new approaches to difficult materials – and some new challenges to overcome as they take advantage of those new capabilities.
If you haven’t actually seen solid ceramic tools in action, watching them looks startlingly like a fast-forwarded video rather than a real-time cut. These tools achieve much higher speeds than carbide, running at 15,000 rpm to 20,000 rpm and yielding 1,500 to 2,000 surface feet per minute. The material removal rates for high-temperature alloys such as Inconel, as well as for hardened steels and stainless steels, look like the results that shops would expect to achieve with aluminum.
Phase-toughened solid ceramics develop an internal grain structure that yields a tough tool with greater ability to withstand machining forces than normal ceramics can offer. To obtain ideal results and avoid potential problems at the high speeds these tools require, shops should test and verify their machining programs before they start to cut. Nonetheless, solid ceramic tools can run unattended along with carbide tools in an automated tool changer. Ceramic tools touch off the same way that carbide tools do, provided that the auto touch off system uses pressure instead of conductive energy. Ideally, automated sequences run ceramic tools before those that require coolant so no residual liquid remains inside the machine when ceramics load in. A pressurized air blast can blow away coolant if a ceramic tool must run after carbide, and water-based coolant minimizes fire risk from hot chips during a cut with ceramics.
To rough parts in some of the most difficult materials on the production line, solid ceramic tools can provide outstanding results with much higher material removal rates than other types of tools. With ongoing advances in metallurgy and increasing reliance on high-temperature alloys for the aerospace industry, ceramic tools outlast carbide in demanding roughing tasks. In hardened steels for the mold and die industry, ceramic tools work well on machine tools with sufficiently fast spindles.
Ceramic tools also excel in machining 3D-printed materials. The output of additive manufacturing yields more-abrasive results with greater potential for interruptions because of the nature of powder-based production, a situation that’s not ideal for carbide tools. Ceramic tools also easily remove the honeycomb-like scaffolding from 3D-printed parts – a highly interrupted material in which carbide can’t develop a consistent cut.
Technically speaking, ceramic tools don’t actually cut. Instead, they build up heat so workpiece materials can plasticize and be pushed away. The heat that’s integral to the process also forms one of the central challenges of working with these tools: Finding the right toolholding to ensure rigidity, and banish runout and vibration. For these applications, mechanical toolholding offers some real advantages. Because ceramic tools suffer from thermal shock in the presence of coolant, they run with coolant turned off to avoid degraded performance and premature tool failure, and toolholding must help dissipate heat. Higher feed rates thicken chips to help pull heat away, but not all toolholding systems cope equally well with solid ceramics.
Ceramic tools do their best work for customers who look for ways to reduce production costs with new and innovative materials and processes. In all of these applications, one essential requirement stands out: Secure toolholding that can withstand the heat and high speeds of ceramic cutting. The REGO-FIX powRgrip system provides an ideal solution to the task, with the low runout, high tool security and excellent rigidity that ceramic tools need.