Ten points to use grooving tools

1) Understand the groove type

It is important to understand the three main types of trenches: outer circular trenches, inner trench trenches, and end trenches. The outer groove is the easiest to machine because gravity and coolant can help with chip removal. Furthermore, the outer circular groove machining is visible to the operator, and the machining quality can be checked directly and relatively easily. However, some potential obstacles in the design or clamping of the workpiece must also be avoided. In general, the cutting effect is best when the tip of the grooving tool is held slightly below the centerline. The inner hole grooving is similar to the outer diameter grooving, except that the application of the coolant and the chip removal are more challenging. For the inner hole grooving, the best performance is obtained when the tool tip is positioned slightly above the centerline. To machine the end face grooves, the tool must be able to move in the axial direction and the radius of the tool's flank must match the radius being machined. The end face grooving tool has the best machining result when the tool tip position is slightly higher than the center line.

2) Processing machine tools and applications

In the grooving process, the design and technical conditions of the machine tool are also essential elements to be considered. Some of the main performance requirements for machine tools include: large enough power to ensure that the tool operates in the correct speed range without stalling or shaking; high enough rigidity to complete the required machining without flutter; High enough coolant pressure and flow to aid chip evacuation; high enough accuracy. In addition, in order to machine the correct groove shape and size, it is also important to properly calibrate the machine.

3) Understand the material properties of the workpiece

Familiarity with some of the properties of the workpiece material (such as tensile strength, work hardening characteristics, and toughness) is critical to understanding how the workpiece affects the tool. When machining different workpiece materials, different combinations of cutting speed, feed rate and tool characteristics are required. Different workpiece materials may also require specific tool geometries to control the chip or use a specific coating to extend tool life.

4) Correct selection of tools

Proper selection and use of the tool will determine the cost-effectiveness of the process. The grooving tool can machine the workpiece geometry in two ways: one is to machine the entire groove shape by one cutting; the other is to finish the groove final size by multiple cutting steps. After selecting the tool geometry, consider a tool coating that improves chip removal performance.

5) Forming tool

Forming tools should be considered when processing in large quantities. The forming tool can machine all or most of the groove shape by one cut, freeing the tool position and shortening the machining cycle time. One disadvantage of non-blade forming tools is that if one of the teeth is broken or worn faster than the other teeth, the entire tool must be replaced. An important factor to consider is the control of the chip generated by the tool and the machine power required for the forming cut.

6) Select single point multi-function tool

Multi-tools can be used to generate tool paths in both axial and radial directions. In this way, the tool not only can machine the groove, but also can cut the diameter, interpolate the radius, and machine the angle. The tool can also perform multi-directional turning. Once the blade enters the cutting, it moves axially from one end of the workpiece to the other while maintaining contact with the workpiece. The use of multi-tools allows more time to be used for cutting workpieces than for tool change or idle travel. Multi-tools also help reduce the entire machining process.

7) Adopt the correct processing sequence

Reasonable planning of the optimal machining sequence requires consideration of various factors, such as the change in workpiece strength before and after the groove machining, because the strength of the workpiece is reduced after the groove is first machined. This may cause the operator to use less than optimal feed and cutting speed in the next process to reduce chatter, while reducing cutting parameters may result in extended machining times, reduced tool life and unstable cutting performance. Another factor to consider is whether the next step will push the burr into the groove being machined. As a rule of thumb, after completing the outer and inner diameter turning, it is first possible to start machining from the point farthest from the tool chuck and then machine the grooves and other structural features.

8) The effect of feed rate and cutting speed

Feed rates and cutting speeds play a key role in groove processing. Incorrect feed and cutting speeds can cause chatter, reduce tool life and increase cycle time. Factors affecting feed and cutting speed include workpiece material, tool geometry, type and concentration of coolant, blade coating and machine tool performance. In order to correct problems caused by unreasonable feed rates and cutting speeds, secondary processing is often required. For many different tools, although many sources of information for “optimized” feed rates and cutting speeds can be listed, the latest and most useful information is usually from tool manufacturers.

9) Select blade coating

The coating can significantly increase the life of the carbide insert. Since the coating provides a lubricating layer between the tool and the chip, it also reduces machining time and improves the surface finish of the workpiece. Currently commonly used coatings include TiAlN, TiN, TiCN, and the like. For optimum performance, the coating must match the material being processed.

10) Cutting fluid

The correct application of the cutting fluid means that sufficient cutting fluid is provided for the cutting point where the grooving blade contacts the workpiece. The cutting fluid plays a dual role in cooling the cutting zone and helping to remove chips. Increasing the cutting fluid pressure at the cutting point is very effective in improving chip evacuation when machining blind hole inner diameter grooves. For trench processing of difficult materials such as high toughness and high viscosity materials, high pressure cooling has significant advantages.

The concentration of water-soluble oil-based coolant is also critical for trench processing of difficult-to-machine materials. Although the typical coolant concentration range is 3%-5%, in order to improve the lubricity of the coolant and provide a protective layer for the tool tip, it is also possible to test the effect of increasing the coolant concentration (up to 30%).