Sustainability in machining: What role does tool holding play?

Sustainability is a topic rightly becoming more important. Resources are limited and energy is increasingly expensive. When evaluating sustainability, consider the environment – the product life cycle and the entire process in which the product is integrated. In machining, the machine tool consumes most of the energy with its spindle and axis drives, peripherals, and auxiliary units such as cooling, lubrication, or compressed air supply. When purchasing new machines, the user can significantly reduce consumption by paying attention to energy-saving components.

Andreas Haimer, managing director and president of the HAIMER Group, explains: “In our own production, we’ve learned replacing an old machining center with a new one using the same machining process requires around 30% less energy. And, as a family business, we pay a lot of attention to sustainability. We source our steel for tools from Germany, have been using electricity exclusively from renewable energy sources for years, and are investing in solar energy systems and green infrastructure. In the last financial year, we invested more than one million euros and saved more than 250 tons of CO₂ per year.”

Savings can also be made in the machining process by using CAD/CAM-optimized machining strategies, such as trochoidal milling. One customer provided Haimer with data on how he reduced machining time 75% from 71 minutes to 18 minutes per part by trochoidal milling with HAIMER Power shrink-fit chucks and HAIMER MILL cutters compared to using a face mill cutter.

Sustainability of tool holding

In a machining process where a milling machine consumes an average of 30kW, plus the power of hydraulic and pneumatic devices, automation equipment, and robots, tool holding only plays a subordinate role, even if the clamping process with a shrink fit chuck consumes a marginal amount of energy.

Looking at other clamping systems, energy consumption during shrinking is higher in operational use than with a hydraulic or milling chuck, but if you look at the entire product life cycle of a tool holder, a different picture emerges.

Production of a hydraulic chuck requires significantly more effort and energy due to its more complicated structure. In addition to the high-precision machining of individual components, there’s also the soldering of the expansion sleeve, additional heat treatment to prevent the solder joint from breaking, and the effort required for cleaning, assembly, and filling with oil.

“From our experience, the energy required for production is around 3x as high as for the shrink fit chuck,” Haimer explains. “Our analyses have shown a hydraulic chuck requires approximately 25kWh more energy to manufacture than a shrink chuck. Conversely, a shrink fit chuck with an energy requirement of 0.026kWh per shrink-fit and cooling cycle can be shrunk almost 1,000x before it requires more energy than a hydraulic chuck.”

Life cycle and process reliability

In addition to the increased manufacturing costs, there’s also the different maintenance. HAIMER shrink chucks are maintenance-free and can be shrunk in and out unlimited times while hydraulic and milling chucks must be returned to the manufacturer every two to three years for regular maintenance. The contained hydraulic fluid or grease also makes environmentally friendly disposal more difficult than with shrink-fit chucks.

Energy consumption in perspective

Heating a shrink-fit chuck takes about five seconds with a current HAIMER shrink-fit machine. Users remove the worn cutting tool and shrink a new cutting tool in a single operation. The maximum output of a HAIMER Power Clamp shrink-fit machine is 13kW, but the average is 8kW, so the complete shrinking process consumes around 0.011kWh. Cooling consumes around 0.015kWh, making it 0.026kWh total for the entire process.

And how should the energy consumption be classified when considering the machining process, in which the power consumption of a milling machine with all auxiliary drives is around 30kW? Assuming a tool is in use for one hour and if 1% of the machining time can be saved, that would be 0.3kWh of energy saved; approximately 11x the amount of energy used for shrinking.

“Modern CAD/CAM milling strategies can save 75% of machining time. Machinists must focus on such improved processes if they want to be sustainable and productive. In a second step, they should select the most suitable and process-reliable tool holder for these strategies,” Haimer summarizes.

HAIMER USA
https://www.haimer.com/us
IMTS 2024 booth #431510