Grooving is a crucial step in the turning process, and its chip formation and chip discharge characteristics make it distinctive in almost every aspect.
Innovative insert designs and coatings can improve groove efficiency and outcome, but there are several machining techniques that must be mastered to carry out this process effectively.
This article presents 10 key considerations for using a channel tool.
1. Understand the type of groove
It is crucial to understand the three main types of grooves, which are: outer groove, inner groove, and front groove.
External grooves are the simplest to process, as the force of gravity and the use of coolant can aid in chip removal. The operator can directly observe the machining of the external grooves, making it relatively easy to monitor the quality of the machining process. However, it is essential to avoid possible design or workpiece clamping problems. For optimal cutting results, it is best to keep the tip of the grooving tool slightly below the center line.
The inner bore flute resembles the outer diameter flute, except that coolant application and chip removal can be more challenging. Best results can be achieved when the tip position is slightly above the center line for internal canals.
For end face grooving, the tool must have the ability to move in the axial direction and the tool flank radius must correspond to the radius of the machined surface. The position of the cutting edge of the grooving tool should be slightly above the center line.
External groove
Inner hole groove
Front slot
2. Machine tool processing and applications
In the grooving process, the design type and technical specifications of the machine tool are also critical factors to be considered. Some of the key performance requirements for machine tools include:
Have enough power to ensure that the tool operates within the correct speed range without braking or vibrating;
Possessing high rigidity to complete the necessary cut without vibration;
Have high enough pressure and coolant flow to facilitate chip removal;
Have a high level of precision.
Furthermore, to produce the desired groove shape and size, it is crucial to properly adjust and calibrate the machine tool.
3. Understand the material characteristics of the workpiece
Being familiar with the material properties of the part, such as tensile strength, hardening characteristics, and toughness, is vital to understanding the impact of the part on the tool. When machining different part materials, varying combinations of cutting speed, feed rate and tool characteristics are required. Different part materials may also require specific tool geometries to manage chipping or require the use of specific coatings to increase tool longevity.
4. Choose the right tool
Proper selection and use of tools will determine the cost-effectiveness of machining.
The grooving tool can machine part geometry in two ways:
The first is to process the entire shape of the groove by making a single cut;
The second is to grind the final size of the groove by cutting in several stages.
Once the tool geometry has been chosen, it may be beneficial to consider a tool coating that improves chip removal performance.
5. Form Tools
When machining in large quantities, it may be advantageous to consider the use of forming tools.
The forming tool can cut all or most groove shapes in a single operation, freeing up tool position and reducing processing cycle time.
One disadvantage of non-bladed tools is that if one of the teeth breaks or wears faster than the other teeth, the entire tool must be replaced.
It is important to control the chips generated by the tool and the machine power required to cut the shape. This must be taken into consideration.
6. Choose a single-point multitool
The use of multifunctional tools can generate tool paths in both axial and radial directions.
With this type of tool, not only the groove can be machined, but also the diameter can be turned, the radius and angle can be interpolated, and multidirectional turning can be performed.
Once the blade starts cutting, it moves axially from one end of the workpiece to the other, maintaining contact with the workpiece.
By using a multitool, you can spend more time cutting the workpiece instead of changing tools or making empty stroke movements.
Multifunctional tools also help to speed up the machining process of the entire part.
7. Use the correct processing sequence
Rational planning of the ideal machining sequence involves taking into account several factors, such as the change in the strength of the part before and after machining the groove, as the strength of the part decreases after the groove is machined first.
This may cause the operator to use a lower than ideal feed rate and cutting speed to avoid chatter. However, reducing cutting parameters can lead to longer machining times, shorter tool life and unstable cutting performance.
Another factor to consider is whether the subsequent process will push the burrs into the previously machined grooves.
As a general guideline, it is advisable to start with the furthest point from the tool holder after turning the outside diameter (OD) and inside diameter (ID) has been completed, followed by machining the grooves and other structural features.
8. The role of feed rate and cutting speed
Feed rate and cutting speed are crucial factors in grooving. Inadequate feed and cutting speeds can result in chatter, reduced tool life and prolonged machining cycle times.
Several factors, including workpiece material, tool geometry, coolant type and concentration, insert coating, and machine performance, can affect feed and cutting speed.
To resolve problems caused by incorrect cutting and feed speeds, secondary machining is often required.
Although there is a wealth of information available about the “ideal” feed and cutting speeds for various tools, the most relevant and practical information is typically provided by the tool manufacturer.
9. Blade coating selection
Coating a carbide blade can significantly increase its service life.
By providing a lubricating layer between the tool and the chip, the coating also reduces machining time and improves the surface finish of the part.
Some of the coatings commonly used today include TiAlN, TiN and TiCN. For optimal performance, it is essential to match the coating to the material being machined.
10. Cutting fluid
Proper application of cutting fluid involves supplying sufficient fluid to the cutting point where the grooved insert contacts the workpiece.
Cutting fluid has two purposes: to cool the cutting area and to assist in chip removal.
Increasing the cutting fluid pressure at the cutting point is highly effective in improving chip evacuation when machining slots with a blind hole ID.
For grooving challenging materials, such as those with high toughness or viscosity, high-pressure cooling offers significant benefits.
The concentration of water-soluble oil-based coolant is also crucial for trenching difficult materials.
While the typical coolant concentration range is between 3% and 5%, you can also test increasing the concentration (up to 30%) to increase coolant lubricity and provide a protective layer for the blade tip.
Lastly, you can watch a channel tools demo video by following the link below:
