May 26, 2017
All factories have a collection point for scrap blades. There is no such thing as more interesting than the study of scrap blades,which leads to the formation of a pragmatic view of how carbide blades are used (and misused) and can be used to reduce costs.
The considerations should be the following easy to measure factors:
How many different types of blades are used?
What is the average number of cutting edges that a blade has?
What percentage of the cutting edges used in relation to the length of the cutting edge?
What are the number of worn, damaged or unused cutting edges?
The content of this article is based on the study of a large customer of a mountain tool. The results of this study represent a similar study conducted by our company.
The first fact to be determined is that the carbide blades used are very different. In our sample, there are 638 different blades to maintain the operation of six CNC lathes. The good side is that each blade is the champion of every category. But the 638 blades are packed in 10 boxes each, meaning 6380 stock blades. All this is just to keep the six lathes running. The next fact is that each blade has a relatively small number of cutting edges. In many workshops, the blade is still triangular or diamond. The possibility of the best combination of the number of cutting edges (triangular blades) and the cutting edge strength (diamond blade) provided by the convex triangular blade is clearly not enough to be recognized in many workshops.
In 1970s, the best advice would be to use a large, robust blade. The hard alloy used in that period was tough but not good enough. The strength of tungsten carbide blades is guaranteed by their size (large blade = thick blade = high strength blade). A blade requires that its cutting edge be at least three times longer than the cutting depth. Two things have changed at the same time. On the one hand, the average cutting depth for turning has been obviously reduced.
A study carried out by seco showed that the average cutting depth of turning about 2.5~3mm. on the other hand, the fourth generation of hard alloy today (such as TP2500) has very good toughness, but also its hardness (higher wear resistance). This means that for today's cemented carbide blades, the relationship between the length of the cutting edge and the depth of the cut can be radically changed. The geometry of the blade of the latest generation (for example, MF5) is clearly suited to the new situation.
Unused cutting edge
The situation becomes really clear when you look at the blade according to the way they wear in use. The correct form of cutting edge wear is the safety, predictable and controlled wear of the flank.The cutting edge should not break. The cutting edge is broken because of incorrect use or improper selection of the cutting edge. The cutting edge must be "worn" before being thrown into the box that holds the worn cutting edge. The new cutting edge, which has not yet been discarded for processing, is always striking.
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