Material

What type of material is being cut? These tips are not always 100 percent accurate, but they provide a good rule of thumb.

Short chipping material: This is usually the easiest way to control the chip, and the chipbreaker is the least important. However, a strong cutting edge will be required. The shortest chipping materials are cast irons, hardened steels and brass. With these operations, the groove width is usually not as important because the chips are easy to control.

Long chipping material: This is where the largest amount of materials will fall. The long chipping group could be sub-grouped into different categories. Long chipping materials include most carbon steels, alloy steels, stainless steels and exotics. The longer length will provide a smoother cut, but will create a larger watch spring chip. If the tensile strength is too low, this watch spring may become uncontrollable, and the chip may pigtail. The shorter length will produce a much tighter watch spring, but if the tensile strength is too high, chip forces may damage the main cutting edge.

If the groove width is wider than the insert width, multiple plunges can be performed to create the wider groove or you may plunge and turn the groove.

If you choose to perform multiple plunges, the easiest way is to take the first plunge and then step over 50 to 75 percent of the insert width and plunge again, repeating until the desired groove width is reached. This is the easiest to program. However, cuts using only 50 to 75 percent of the groove width can make chip control difficult. If a full cut is performed, you are collapsing the chip from both sides onto itself. When taking a partial cut, you are collapsing the chip from one direction only, and this can result in pigtails or unmanageable chips.

One simple method, using the multiple plunge process, is to take as many full cuts as possible, and then cut the remaining material on the center of the insert. This uses all of the advantages of a simple chip former.

For a plunge and turn operation, it’s best to use a chip former that tries to reduce the chip from the front and also provides an area on the side of the insert to control the chip. This requires more complex programming because when approaching the bottom of the groove, material should not be removed from both the front of the insert and the side of the insert at the same time. This will usually damage the insert and the toolholder.

“Impossible to break the chip” material: These materials are usually forgings, carbon and alloy steel of very low tensile strength carbon and alloy steels, as well as some tubing material.

In these materials, very aggressive chipbreakers are required, and in some instances, a programmed peck cycle is necessary. Never retract more than the feed rate per revolution; otherwise you can pinch a chip between the cutting edge and the material.

In addition, cutting an ID groove, face groove and/or form groove follows these same basic principles, but each provides its own characteristics. When choosing the geometry of the tool, it is important to choose a positive cutting geometry and understand the operation being performed.

If the groove width matches the insert width, the choices are much easier. You must now determine the aggressiveness of the chip formation in relation to the tensile strength of the material being cut. If you look at the two chip formers, you will see that the distance from the front edge to the back edge varies in length.

 Exercise 23. Translate the following article into English and explain your strategy, the main decisions you made in producing it.