An effective method for prolonging the service life of a cutting tool

As component makers continue to improve productivity, customers often demand lower prices for finished components each year, challenging component makers' margins. In order to survive and develop, component manufacturers must spare no effort to reduce production costs, including improving employee productivity, extending cutting tool life, improving consumables management, reducing energy consumption and so on. While working on these improvements, our management team found an effective way to extend tool life, improve part quality and reduce manufacturing costs.

The initial breakthrough came from research into tapping and thread quality. A customer complained of fine metal particles sticking to the threaded hole walls of an automobile part. To solve this problem, various methods were tried, such as increasing the coolant pressure from 3 bar (44psi) to 10 bar (145psi) during tapping, using wear-resistant coated taps, and improving the lubrication of the cutting fluid. Unfortunately, the results were not satisfactory.

By magnifying the cutting edge of tap under a microscope, it is found that there are some small particles adhered to it. The analysis concluded that these metal particles were from the aluminum alloy workpiece material and, although they were very small, they still prevented the taps from cutting tool threads effectively. The idea of increasing the coolant pressure to remove these metal particles proved incorrect.

Subsequently, a mechanical method of cleaning the taps with a brush with nylon bristles was proposed, and this must be done on each tapping cycle. To avoid the time-consuming interruption of tapping cycles caused by cleaning taps on the machining center, nylon brushes were mounted on the fixture and machining was programmed to clean the cutting tool edge against the fixed nylon brush once before each tapping cycle began.

As a result, the operator reported that the inspection results of the thread workpiece after processing showed that the thread quality was significantly improved, the thread surface was clean, without defects and tiny burrs. Thread quality remains acceptable even after the specified cutting tool life (defined by the company for each tool used to facilitate inventory management) is exceeded. For this reason, the company reformulated a new tap life parameters. For example, when tapping with Emuge M10×1-6H taps at 600rpm spindle speed and 1mm/r feed rate, the specified tool life before the introduction of the clean cutting edge method is 6000 holes; After introducing the method of cleaning the cutting edge, the tap life has reached more than 13000 holes. Based on this calculation, the annual tool cost savings from cleaning the cutting edge is approximately $650.

After its success with taps, the method was extended to all cutting tool. The results were encouraging, although the life-extending effects of different knives were not uniform. By cleaning the cutting edge at the beginning or end of each machining cycle, the tool life can be improved by 2-4 times. The indexable ceramic milling blades were also tested over 6 months. Advantages of clean cutting edge include improved part quality, extended tool life, reduced tool inventory, and increased machine processing time due to reduced tool change frequency. The company has saved about $12,600 a year in production costs by taking this step.

To further extend tool life, technicians have tried cleaning the cutting tool edges with brushes containing abrasives, such as alumina or silicon carbide abrasives, but this method has not been successful, and in all cases tool life has been reduced.

At present, technicians are installing a rotary annular brush in the position of the automatic tool changing manipulator in the machining center, which will help to shorten the processing cycle time.