Cutting processes will soon do without lubricating coolants.
Image: Fraunhofer IPT, Heidi Peters
Coming Clean: The “Dry” Factory
The use of dry cutting is boosting environmental protection and profitability in production. Bosch researchers are teaming up with partners from the automotive and tool industries to develop techniques and tools that will allow companies to stop using huge quantities of lubricating coolants for such jobs as drilling, milling, turning, and reaming.
Lubricating coolants have two primary functions, as the name suggests: They cool the tools and the workpiece during cutting and control the temperature of the entire machine. They also act as a lubricant in the process and remove chips.
The costs associated with wet cutting processes are enormous: In large series production, up to 200,000 liters of fluid are in circulation. After the cutting process is completed, the cooling lubricants must undergo expensive treatment. All that requires substantial amounts of space and money.
Up to 5,000 liters of cooling lubricant are lost each day in a typical production line: It remains on the workpieces, on the chips or in air filters.
That will no longer be the case in the future: Bosch researchers are conducting several projects that are intended to determine how cutting processes could be carried out dry – without cooling lubricants.
In situations where it is technically not possible to use dry cutting, a minimum quantity lubrication (MQL) is to be used. For each work hour and tool arbor, less than 100 milliliters of cooling lubricant will have to be employed.
The resulting benefits are obvious: The large facilities needed to reprocess and prepare the cooling lubricant would become obsolete, just as would the huge amount of the lubricant itself. This cuts investment and operating costs. The elimination of the lubricants will also be a major environmental benefit.
The process engineers are addressing three areas as they tackle this technological challenge:
– A new machine design is necessary because the lubricants will no longer carry away the chips. The machine interior and the cutting process must be designed in such a way that the chips flies onto a conveyor system.
– The tools must be able to endure increased thermal and tribological stresses: Without cooling lubricants, they penetrate the steel or aluminum. With an eye toward this problem, researchers are examining new, self-lubricating and extremely hard coatings.
– If it is impossible to use the dry procedure, a minimal amount of lubricant will be used. This will require the cooling lubricant to be applied to the exact spot where it is needed.
The engineers, working in a project sponsored by the German Federal Ministry of Education and Research (BMBF) and citing other studies, have shown where the limits of dry cutting lie and where a minimal amount of lubricant must be employed.
During the “dry” drilling of steel, the cutting edge’s temperature doubles compared with the wet process, reaching about 600 degrees Celsius. At this temperature, structural changes in the workpiece and tool are a definite possibility.
The use of a minimum quantity lubrication cuts the temperature to below 500 degrees Celsius. Aluminum, too, creates problems for the dry method, as it tends to stick to the cutting edge of the tool.
But for working with low-alloy steel, gray cast iron and brass, it is generally not necessary at all to use even a minimum quantity lubrication.
The costs associated with wet cutting processes are enormous: In large series production, up to 200,000 liters of fluid are in circulation. After the cutting process is completed, the cooling lubricants must undergo expensive treatment. All that requires substantial amounts of space and money.
Up to 5,000 liters of cooling lubricant are lost each day in a typical production line: It remains on the workpieces, on the chips or in air filters.
That will no longer be the case in the future: Bosch researchers are conducting several projects that are intended to determine how cutting processes could be carried out dry – without cooling lubricants.
In situations where it is technically not possible to use dry cutting, a minimum quantity lubrication (MQL) is to be used. For each work hour and tool arbor, less than 100 milliliters of cooling lubricant will have to be employed.
The resulting benefits are obvious: The large facilities needed to reprocess and prepare the cooling lubricant would become obsolete, just as would the huge amount of the lubricant itself. This cuts investment and operating costs. The elimination of the lubricants will also be a major environmental benefit.
The process engineers are addressing three areas as they tackle this technological challenge:
– A new machine design is necessary because the lubricants will no longer carry away the chips. The machine interior and the cutting process must be designed in such a way that the chips flies onto a conveyor system.
– The tools must be able to endure increased thermal and tribological stresses: Without cooling lubricants, they penetrate the steel or aluminum. With an eye toward this problem, researchers are examining new, self-lubricating and extremely hard coatings.
– If it is impossible to use the dry procedure, a minimal amount of lubricant will be used. This will require the cooling lubricant to be applied to the exact spot where it is needed.
The engineers, working in a project sponsored by the German Federal Ministry of Education and Research (BMBF) and citing other studies, have shown where the limits of dry cutting lie and where a minimal amount of lubricant must be employed.
During the “dry” drilling of steel, the cutting edge’s temperature doubles compared with the wet process, reaching about 600 degrees Celsius. At this temperature, structural changes in the workpiece and tool are a definite possibility.
The use of a minimum quantity lubrication cuts the temperature to below 500 degrees Celsius. Aluminum, too, creates problems for the dry method, as it tends to stick to the cutting edge of the tool.
But for working with low-alloy steel, gray cast iron and brass, it is generally not necessary at all to use even a minimum quantity lubrication.
