How To Judge Whether The Tool Is Worn?

Method for judging tool wear

1. For the tool wear, the wear quantity size, listening is the most direct judgment method. If voice screaming is heavy or sharp, cutting tool machining status is not normal, this time can briefly analyze. Excluding the tool itself quality problem, the cutting tool clamping problem, problem of parameters with the knife, should able to judge the tool wear is at this time, need to suspend processing, replace the tool. 2. Through the machining machine tool, the motion states to judge the wear of the tool. If the machining parameters, cutting parameters and other settings are reasonable, machining machine vibration is very large, issued a "buzz", this can be determined that the tool has reached a state of rapid wear, the need to replace the tool. It is generally accepted in the hardware industry that too much money is spent on the wrong blades. Knowing that the problem exists, what is the solution? Most hardware companies are simply trying to buy cheaper blades. That does help, but it's not the solution to the problem. So why not opt for a more structured approach? Some buyers often spend considerable time negotiating lower prices. But the effect on overall production costs, let alone productivity, is negligible.

Pragmatic research

All factories have a collection point for waste blades. Nothing is more interesting than studying waste blades, which leads to a pragmatic view of how a blade is used (abused) and can be used to achieve cost reduction. Considerations should include the following easily measurable factors: How many different types of blades are used? What is the average number of cutting edges a blade has? What percentage of the cutting edge is used relative to the length of the cutting edge? How many cutting edges are worn, broken or unused? The content of this paper is based on the research of a large customer of mountain high cutting tools. The results of this study represent the kind of work that our company routinely does.  

Difference of blade

The first fact to be determined is that the blades used vary widely. In our sample, 638 different blades were used to run six CNC lathes. The good news is that every blade is a champion in every category. But 638 blades are packed in boxes of 10, meaning 6,380 blades are in stock. And all this is just to keep six lathes running. The next fact is that the number of cutting edges per blade is relatively small. In many workshops, the blades are still triangular or diamond. The possibilities offered by convex triangular blades with the best combination of cutting edges (triangular blades) and cutting edge strength (diamond blades) are clearly not well understood in many workshops.

Old school

In the 1970s, the best advice was to use large, strong blades. The hard cemented carbide used in that era was not strong enough. The strength of the blade is ensured by its size (large blade = thick blade = strong blade). A blade is required to have a cutting edge length at least three times the cutting depth. Two things have changed at the same time. On the one hand, the average cutting depth for turning has been significantly reduced. On the other hand, today's fourth-generation cemented carbide (TP2500, for example) has good toughness and higher hardness (wear resistance). This means that for today's blades, the relationship between cutting edge length and cutting depth can be radically changed. The latest generation (in MF5's case) of blade geometry clearly fits this new situation.

Break an unused cutting edge

When you look at the blades in terms of the way they wear in use, the situation really becomes clear. The correct form of cutting edge wear is safe, predictable and controllable wear on the back face. The cutting edge should not break. The cutting edge was 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 containing the worn cutting edge. The "new" cutting edges that are discarded before they are used for machining are always conspicuous. In addition to a good tool coated with a good cutting fluid, there is a new process of cutting off the thermal current loop. As is known to all, the metal cutting process due to chip deformation and friction, so that the cutting area produced high temperature, at the same time, because the tool and workpiece materials are different, formed a thermocouple of the poles and generate thermoelectric emf, produced a thermal current. Thermal currents can easily strengthen the oxidation process of the working surface of the tool and accelerate the wear of the tool. Under certain conditions, the contact area between the tool and the machine tool, the workpiece, and the machine tool, and the contact area between the friction pair of the machine tool itself will also generate thermoelectric EMFs -- thermal current. The cutting process also produces a thermomagnetic effect and electromagnetic effect, in the high-temperature contact area surface will also produce an electron emission - discharge phenomenon. In recent years, researchers at home and abroad have shown that the thermal current generated in the cutting process and other factors caused by the thermal current, the two thermal current are through the machine tool - tool-workpiece - machine tool system to form a loop. At the same time, local thermal current circulates in the limited contact area between the tool and the workpiece, thus exacerbating tool wear. Therefore, in addition to the above basic ways to improve the cutting performance and durability of the tool, a new way can be adopted -- namely, to combat the thermal current effect of strengthening the wear of the tool, namely, to cut off the thermal current loop.