Little knowledge about tool wear

Little knowledge about tool wear

1, whether the tool wear and tear, the amount of wear the most direct way to judge is to listen to the sound, if the cutting sound is very heavy or screaming, indicating the state of processing tool is not normal at this time can be a brief analysis, if the exclusion of the tool itself Quality problems, tool clamping problems, knife parameters, this time should be able to judge the tool wear and tear, the need to suspend processing, the replacement of tools.

2, through the processing of machine tool motion state to determine the wear and tear of the tool, if the processing parameters, cutting and other settings are reasonable, processing machine vibration, issued a "buzzing", then you can determine the tool reached a sharp wear state , Need to change the tool.

Often in the metalworking industry, all agree that too much money is spent on the wrong blade. Although I know this problem exists, but what is the solution? Most hardware companies just try to buy cheaper blades. That does have some help, but it is not a solution to this problem. So why not choose a more structured approach?

Some buyers usually spend a considerable amount of time negotiating lower prices. But the impact on the entire cost of production is negligible, let alone productivity.

Effective research

All factories have a scrap collection point. There is no more interest than researching scrap blades, which leads to the formation of a pragmatist view of how blades are used (abused), and this approach can be used to achieve cost reductions.

Considerations should be the following easily measurable factors:

How many different types of blades to use?

What is the average number of cutting edges that a blade has?

What percentage of the cutting edge is used relative to the length of the cutting edge?

What is the number of worn, worn or unused cutting edges?

This article is based on a study of a large customer of Seco tools. The results of this study represent the same research that is routinely conducted by our company.

Differences between blades

The first fact to be determined is that the blades used are very different. In our sample, there are 638 different inserts to maintain the operation of six CNC lathes. The good news is that each blade is a champion of each category. But the 638 blades are packaged in 10 pcs per pack, meaning 6,380 blades are stocked. All of this is just the maintenance of six lathes. The next truth is that the number of cutting edges per blade is relatively small. In many workshops, the car is still a triangle or diamond blade. The possibilities offered by the optimal combination of the number of cutting edges (triangular inserts) and the strength of the cutting edge (diamond inserts) are clearly not well understood in many shops.

Old school

In the 1970s, the best advice was to use a large, strong blade. The cemented carbide used in that era was hard, but the toughness was not good enough. The strength of the blade is guaranteed by its size (large blade = thick blade = high strength blade). A blade requires that its cutting edge length be at least three times greater than the depth of cut. Two things have changed at the same time. On the one hand, the average depth of cut for turning has been significantly reduced.

A study by Seco Tools shows that the average depth of cut for today's turning is about 2.5 to 3 mm On the other hand, today's fourth-generation cemented carbide, based on the TP2500, has good toughness and, at the same time, Hardness (wear resistance) higher. This means that with today's blades, the relationship between cutting edge length and depth of cut can change radically. The latest generation (with MF5 as an example) blade geometry is clearly suited to this new situation.

Destroy unused cutting edges

The situation is really clear when you look at the blades based on how they are worn in service. Correct cutting edge wear is flank-safe, predictable and controllable wear. Cutting edge should not be broken. The cutting edge is broken because of improper use or improper selection of the cutting edge. The cutting edge must be "worn" before it is dropped into the box with the worn cutting edge. The "new" cutting edges that have not been discarded for processing have always been striking.

In addition to a good cutting tool coated cutting fluid, there are cutting off the thermal current loop this new technology.

As we all know, the metal cutting process due to chip deformation and friction, the cutting area has a high temperature, at the same time as the tool and the workpiece material is different, forming the thermocouple poles produce thermoelectromotive force, resulting in DC thermal current. Thermal current is easy to strengthen the work surface of the oxidation process, accelerated tool wear. Under certain conditions, the contact area between the tool and the machine tool, the workpiece and the machine tool, as well as the contact area between the friction pairs of the machine itself, also generates a thermoelectromotive force - thermal current. The cutting process also produces thermal and magnetic effects and electromagnetic effects, contact surfaces in the high temperature will produce electron emission - discharge phenomenon.

In recent years, domestic and foreign scientific and technological personnel studies have shown that the thermal current generated during cutting and other factors caused by the thermal current, the two hot current are formed by the machine - tool - workpiece - machine system loop. In the meantime, there is also a local thermal current circulating in the tool-workpiece limited contact area, thus exacerbating the tool wear. Therefore, to improve tool cutting performance and improve tool life In addition to the basic approach above, but also to adopt a new approach - that is, to strengthen the tool wear and tear of the thermal current effect to combat, that is, to take off the thermal current loop.