Ceramic machining has been around for decades, yet some manufacturers still aren’t aware of the applications for this type of tooling. Within manufacturing, ceramic cutting tools can be used in different turning and milling operations.
“Heat-resistant super alloys, hard materials, chemically stable, abrasive materials — all lend themselves to ceramics,” says Denny Carpenter, senior sales and service engineer at Greenleaf Corporation.
It’s not just materials manufacturers should look at, though. Using ceramic cutting tools in machining operations can have several advantages. Learn more about ceramic machining and its benefits.
Ceramics Vs. Other Tooling Types
The properties of ceramic tools are substantially different than other types of cutting tools. Ceramic cutting tools are significantly more resistant to the high temperatures generated during the machining process because they remain stable and inert, while carbide and high-speed steel soften and oxidize.
“Ceramic materials are not as strong as other tooling materials, like carbide, so they require different conditions in their application,” Carpenter explains. “Whereas carbide can muscle through material with proper chip forms and speed/feed combinations, the primary shear zone in ceramic machining contains a lot more heat, plasticizing the material immediately in front of the cutting edge to allow it to cut.”
The “primary shear zone” is a small area in front of the insert or solid endmill where the material is forced through a great deal of deformation to separate from the workpiece and form a chip. The compressive strain and subsequent failure of adjacent grains in shear creates a lot of heat, resulting in plasticization or softening of the machined layer of material. The state of the primary shear zone is one of the biggest differences between a carbide operation and a ceramic operation.
Additionally, there are a lot of differences in how the cut looks and sounds (sparks, very hot chips, ribbon-like chips, the characteristic sound of milling HRSA, etc.) when machining with ceramic tooling over other types of tools. It’s important for manufacturers and machinists to familiarize themselves with these differences to ensure they’re properly using ceramic tooling.
Some of the main differences between ceramic and carbide tools, like hardness, strength, and chemical stability at high temperatures, enable manufacturers to run ceramic tools at higher speeds, giving them an advantage. With ceramic cutting tools, they can turn and mill much faster, making their operations more efficient.
Ceramic Machining Benefits
The heat-resistant properties of ceramic tools allow them to machine at higher speeds. This translates to the biggest benefit of ceramic machining: cycle time reduction. Ceramics run faster in machines because of the need to create heat in the shear zone. This results in higher feed rates leading to significantly higher metal removal rates.
“The most expensive thing in machining today is time,” Carpenter says. “You have to pay for the machine, the machinist, and everything that gets lumped in there. So, that burden rate is the most expensive part.”
Reducing the time it takes to manufacture a part is key to saving costs. With ceramics, machinists can often run a part at up to 10 times higher cutting speed, resulting in faster throughput.
“All of this is done in pursuit of time reduction. If manufacturers can reduce their cycle times, they’re saving money. That’s where ceramics comes in: saving manufacturers money and improving throughput,” explains Carpenter.
These benefits are the main reasons manufacturers choose to machine with ceramic tools. The substantial amount of time saved more than makes up for the cost for manufacturers to switch to ceramic tooling.
Ceramic Tooling Applications
Ceramic cutting tools can be used in various turning and milling applications, particularly on hard materials that generate high heat. Some of these materials are only compatible with ceramics tooling. The hard, abrasive nature of these materials creates a lot of heat during operations, enough to soften or even melt other types of cutting tools, such as carbide.
“I’ve had quite a few manufacturing customers find that ceramic runs so much faster than carbide. On one job we were able to reduce the cycle time from four days to four hours just by switching the tooling to ceramics,” describes Carpenter.
Carpenter also highlights Greenleaf’s ceramic wear components as an additional application for this type of tooling. Wear ceramics offer more resistance to heat and corrosion compared to using steel or carbide in the same application.
“Ceramics are capable of lasting so much longer even than hardened steel; they’re much more impervious to the effects of their surrounding conditions,” says Carpenter. “This drives cost savings. Ceramics can outlast steel by a few months to a few years because of that ability to wear longer. That may not sound like much, unless you're in a production area where minutes can be thousands of dollars, and hours can be millions of dollars. If you can reduce that cycling of replacement, it’s big money saved.”
Considerations When Machining with Ceramics
Carpenter knows that carbide tools still have their place in machine shops, but he sees more manufacturers moving to ceramics. However, it’s not necessarily a one-to-one swap; processes and programming are different when using ceramics.
To properly make the switch to ceramic tooling and improve operations, manufacturers have to rethink what the process is and learn the proper techniques for machining with ceramics. Running machines at higher speeds requires manufacturers to look at operations in a different way.
In machining, ceramics need different clearance angles, lead angles, and rake angles. These differences require manufactures to get new holders to achieve optimal performance. For milling, manufacturers would need a cutter designed for high velocity milling with ceramics. Machines and setups need to be rigid, and capable of accelerated feed rates.
“Ceramics work wonderfully, but you have to set yourself up for success,” stresses Carpenter. “Most modern machine tools are very capable of machining with ceramic cutting tools. Older machines can often take advantage of ceramic productivity if the parts are within parameters of the ceramic operating ranges. But it’s extremely important for manufacturers to understand that ceramic tooling has to be handled differently.”
Making the Switch to Ceramic Machining
Manufacturers should consider switching to ceramic tooling when they need to save time, cut manufacturing costs, or increase throughput. Today, the costliest aspect of manufacturing is time. With ceramic tooling, manufacturers can decrease cycle times and improve throughput, helping them save money in this high-cost area.
Though ceramics have many benefits over other types of tooling, there are some considerations manufacturers must take into account when switching their operations to ceramics.
“They have to be prepared to rethink the process,” Carpenter says. “Can adjusting tool paths to accommodate ceramics, adjusting approaches, and using ceramic tooling save on your most costly item? Do you have the equipment necessary to run at elevated speeds and feeds? Often, the answer to both is yes.”
Using ceramic tooling requires manufacturers to approach their machining processes with a different way of thinking. Understanding the best applications and techniques for ceramic tooling allows them to get the most benefit when switching to this tool type.
If you’re a manufacturer interested in making the switch to ceramic tooling, Carpenter encourages reaching out to the experts at Greenleaf. They have developed several innovative ceramic tooling options, and offer guidance and support to customers to ensure they get the best performance from their tooling. And if you want to see a variety of tooling options in person, explore the Manufacturing Technology Series of events.
Biography
Denny Carpenter, Greenleaf Corporation
Senior Sales and Service Engineer
Project Lead
Denny Carpenter has been with Greenleaf Corporation for 22 years, and currently works as a Senior Sales and Service Engineer and Project Lead. In addition to his tenure at Greenleaf, Carpenter has a total of 46 years of manufacturing experience. This experience includes positions as a tool maker and machinist, programmer, and a manufacturing engineer.
In his current position, Carpenter specializes is several different elements of tooling, including design, applications, appropriate tool and grade selection, and programming guidelines. He enjoys teaching and training people in methods and processes of manufacturing, with an emphasis on productivity and quality improvements.