5 reasons why coolants and lubricants are used in cutting
The use of coolants and lubricants in metal cutting is extremely important. Why this is so and the advantages of cooling and lubricating are explained in this article.
If you do a lot of drilling, or if you want good quality when drilling a hole, you must not only choose the right tool, but also think about cooling and lubrication. If you do not use the right cooling lubricant, you may have bad results.
But before we go into the applications and the right cooling lubricant, let's take a look at what happens during cutting.
How does friction between two materials happen?
Why do we need to cool and lubricate at all? Let's assume you are drilling with a HSS-Co 5 twist drill in stainless steel. The rotary movement of the twist drill and the resulting friction with the workpiece generates heat. In some cases, application temperatures of up to 1,200 °C can occur. In this case, cooling is of great importance, e.g. to prevent high heating (annealing) of the twist drill.
However, there are other reasons why you should use coolants and lubricants.
The purposes of coolants and lubricants
Cooling and lubrication in metalworking has different purposes and is therefore extremely important:
- Reduction of friction between drill and workpiece
This leads to a reduction of the wear of the drill and thus increases the service life of the tool - Heat removal
Heat should be dissipated as quickly as possible and thus the tool and workpiece do not overheat - Removal of chips and wear parts
Facilitates the pick-up and removal of the chips - Cleaning and corrosion protection of the workpiece
The workpiece is protected - Improvement of the surface of the workpiece
The quality of the workpiece is maintained
Which cooling lubricant for which application
But which coolant do you use for your application? First of all, you have to look at what type of cutting method you are dealing with.
The selection of the right cooling lubricant then depends on the cutting speed, the workpiece to be cut and the required cooling and lubrication effect.
There are different cutting concentrates to be used depending on the application. Coolants and lubricants are available as cutting paste, cutting spray and universal cutting oil concentrate.
The selection of the cooling lubricant depends on:
- the drilling process (drilling, countersinking, thread cutting) and its requirements for cooling, flushing and lubrication
- the cutting ability of the workpiece
- the cutting speed
- the required dimensional accuracy and surface quality and
- the thermal sensitivity of the cutting material.
Taking this into account, the following applications for coolants and lubricants result:
| Type of cutting | Cutting speed | Cooling effect | Lubricating effect | Coolants and lubricants |
|---|---|---|---|---|
| Pre-drilling | very high | very high | very low | Water mixable cooling lubricants such as cutting spray |
| Drilling | very high | very high | very low | Water mixable cooling lubricants such as cutting spray |
| Countersinking | medium | medium | high | Non-water mixable cooling lubricants such as cutting oil, cutting paste |
| Thread cutting | very low | very low | very high | Non-water mixable cooling lubricants such as cutting oil, cutting paste |
Conclusion and summary
Cooling is important and should, if possible, be done when cutting steel and metals.
The 5 reasons for using cooling and lubrication are obvious:
- Reduction of friction between drill and workpiece
- Heat removal
- Removal of chips and wear parts
- Cleaning and corrosion protection of the workpiece
- Improvement of the surface of the workpiece
By choosing the right coolant and lubricant for each application, you can work towards this and achieve a good drilling result.
Did you know that you can drill in aluminium with the right cooling using a TiN coated twist drill?
If you have questions, please do not hesitate to contact us.
You can find our coolants and lubricants here Products > Coolants and lubricants.