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Views: 0 Author: Site Editor Publish Time: 2024-08-16 Origin: Site
MAXNOVO MACHINE Tips : Cutting Oil and Coolant Oil is widely used in machining processes. Cutting oils is regarded to be an essential machining partner in these days. Understanding the specific of your machinery and the performance of cutting oils is important to help you to choose the right types of cutting oil. Can you use WD-40
as a cutting oil ? Let us explore the importance of cutting oil, how to choose the right types for your metalworking machines and CNC machines.
Table of Content
1. Functions of Cutting Oil in Machining Process
1.1 Lubrication
1.2 Cooling
1.3 Cutting Chip Removal
1.4 Prevention of Welding
1.5 Prevention of Corrosion
1.6 Improvement of Tool-life
1.7 Enhancement of Surface Finish
2. Types of Cutting Oil
2.1 Water-soluble Cutting Oil
2.2 Oil-based Cutting Oil
2.3 Be Careful with fire in use of Oil-based Cutting Oil
3. Select the Right Cutting Oil for Your Machining Operation
3.1 Cutting Tool Type
3.2 Work-piece Material
3.3 Machining Operation
3.4 CNC Machining
3.5 Can you use WD-40 as a Cutting Oil
4. How to Check The Quality of Cutting Oil
4.1 Appearance
4.2 Smell
4.3 Concentration and PH
4.4 Cleaning Coolant Tank
5. Conclusion
Do you know why we have to use cutting oil ? We need to understand its roles before learning how to select one from several types. Cutting oil actually has seven roles when it is used in machining operations.
1.1 Lubrication
It goes through into the interface between a cutting tool and a workpiece to reduce friction. There are several benefits as follows to reducing the friction:
Life extending effect due to less abrasion
Smooth finishing of a machining surface
Suppression of a rise in temperature
1.2 Cooling
During Metal and CNC Machining Processes, the temperature of a contact area of a tool and a machining surface increases up to 600 degrees Celsius because of the friction. Metal changes shapes and the machining accuracy goes down, but if we use cutting oil, we are able to prevent the heat escalation.
Moreover, if we keep the contact area in a low temperature, we can reprogram its machining conditions to finish a work earlier. In other words, cooling is considered a great way to reduce cycle time.
1.3 Cutting Chip Removal
If we keep machining while chips are piled up, it would be the cause of defective products. Applying cutting oil makes chips ease to be removed while machining. Moreover, a cutting oil plays a role not only to remove chips, but also to prevents fine swarf generated from lifting into the air in a working chamber.
1.4 Prevention of Welding
A part of a work-piece or chips melts and melds onto a tool while machining. This process builds a deformed tool so called “a built-up edge (BUE)”, and affects to the debasement of machining accuracy. Cutting oil gets through into the interface between a workpiece and a tool to prevent from generating BUE. This is also considered to be a benefit of cooling in a way, because cooling can prevent work materials from welding.
1.5 Prevention of Corrosion
Rust and corrosion inhibitors present in cutting oils prevent the corrosion the machine parts and the machined surface. Mineral oils cutting fluids prevent oxidation by forming a very thin protective layer over exposed surfaces.
1.6 Improvement of Tool-life
By dissipating heat, reducing friction and abrasion, and preventing corrosion and rust, cutting oil greatly reduces tool wear, subsequently improving tool life.
1.7 Enhancement of Surface Finish
By preventing thermal expansion and property changes in a work-piece, cutting oil contribute to a good surface finish of machined work-pieces.
Let us get straight to the point. Cutting oils are mainly divided into two types: water-soluble cutting oil and oil-based cutting oil, and they are separated into more small groups.
Many CNC Machines (such as CNC Lathe Machine) move very fast and easily gets exposed to the heat escalation. Therefore, in order to prioritize cooling of a machine, water-soluble cutting oils are often selected.
Oil-based cutting oils are mainly used for hard-to-cut materials to prolong the life of tools. For your further interest, those who work on copper alloys machining tend to choose dry machining without using a cutting oil to avoid from adhering oil to a workpiece or chips.
2.1 Water-soluble Cutting Oil
This type is often called “coolant” on the field and mainly used for cooling. It is diluted with water and has a low risk of ignition. Therefore, water-soluble cutting oils are relatively comfortable to use for machining 24/7 without operators. However, since the water-soluble type has a tendency to deteriorate easily, careful management would be required.
They are divided into three groups by International Industrial Standard.
A1 | Milky white (Emulsion) |
A2 | Translucent or transparent (Soluble) |
A3 | Transparence (Solution) |
Tips : Please note some of cutting oils may affect negatively to Metal working Machine and CNC Machine, for instance, paint peeling, cracks in resin products, the expansion of rubber products, the corrosion of copper and aluminum materials. Do not use a synth-tech or chlorine-containing cutting oil as it may cause machines failure.
As a result, our MAXNOVO MACHINE experts recommend customers to choose Type A1 (Emulsion) cutting oil for use with our high precision machines.
2.2 Oil-based Cutting Oil
This type is aimed at lubrication and welding prevention mainly, introduced in machining that is required the high accuracy of work in the most of cases. On the other hand, it should be handled with careful management because it could cause a fire due to ignition by heat. Therefore, if you use an oil-based cutting oil, you would be required to add the following devices on a lathe depending on a situation.
Automatic fire-extinguisher system
A mist collector with an automatic fire extinguishing device interlocking a fire damper
An automatic liquid temperature regulator
An air blow device or a coolant blow device
As a result, our outstanding technical engineers recommend customers to add automatic fire-extinguisher device and fire damper in use of an oil-based cutting oil on machines (such as Lathe, Milling Machine, CNC Lathe, Machining Center, Drilling Machine, Grinding Machine and etc).
2.3 Be Careful with fire in use of oil-based Cutting Oil
As we already know, we need to pay full attention to using an oil-based cutting oil because it is at risk for fire. Bellowing are some useful precautions.
2.31 Heat generation caused by abnormalities
It would catch fire due to abnormalities caused by the damage of tools, friction, or heavy-duty operations. In order to avoid these conditions, equipping detective devices to sense abnormalities is preferrable.
2.32 Unsuccessful approach to a machining point
If cutting oil fails to touch a machining point, it could not cool down the contact area and may result in catching fire. Please try to adjust the outlet location of the cutting oil to gain a sufficient reach to the point.
2.33 Setting of Cutting Conditions
You might think of programming strict cutting conditions to increase machining efficiency, but this brings the increase of machining resistance that heats chips tremendously, and then the heated chips could become an ignition agent to catch fire. Please avoid from setting too strict conditions and leave some room for it.
2.34 Control the quantity of Cutting Oil
When the quantity of cutting oil is shortening, outlet pressure also gets lowered. That means a machine is not able to preserve sufficient performance to make the cutting oil reach a machining point. This might result in catching fire. Observing the oil’s quantity habitually is necessary, but we also recommend you to equip with a liquid level detector.
The selection of cutting oil depends on a number of factors including cutting tool type, work-piece material, and machining operation.
3.1 Cutting Tool Type
Carbide tools can get very hot. This makes them more susceptible to thermal shocking, the phenomenon in which different parts of the cutting tool expand by different amounts. Synthetic cutting oil with very high cooling capabilities is recommended for this tool type.
High-speed steels also get hot, but not as hot as carbide tools. Soluble oils and semi-synthetic fluids are suitable.
3.2 Work-piece Material
Metals are the most common workpiece materials which require cutting fluids. The following are some of the most machined metals and their suitable cutting oil.
Steel –– Mineral oils containing lubricant additives
Alloy steels –– Sulphur brass oil or mineral oil
Aluminium –– Soluble oils or mineral oils without active sulphur
Copper –– Soluble Oils
Stainless steels –– Mineral oils containing excellent Extreme pressure additives
Cast iron –– None
3.3 Machining Operation
Relatively easy machining operations such as turning, milling, forming, and drilling take place at relatively high speeds. At such speeds, a high level of cooling is required. Only modest lubrication and extreme pressure properties are required. As such, synthetic fluids are best suited for such operations. Although soluble oils may be used.
On the other hand, difficult machining operations such as broaching and thread cutting require good lubrication. These operations take place at low speeds and high pressures, therefore cutting oil with excellent lubrication and extreme pressure properties are required. Mineral oils containing extreme pressure additives are the best choice.
3.4 CNC Machining
The functions of cutting oil mentioned above also apply to CNC machining processes. However, there are various machining processes with various methods of application.
CNC Milling: In CNC milling operations, your work-piece stays stationary while the cutting tool moves. In this operation, cutting oil is best applied by flooding.
CNC Drilling: The main purpose of cutting fluids in CNC drilling is chip removal and cooling. Lubrication is not really necessary as the possibility of built-up edges forming
is low. Jet application of the cutting oil is recommended.
CNC Turning: This process occurs at very high speeds therefore cooling is crucial. Considering that the work-piece rotates. Jet application of the cutting oil is suitable.
3.5 Can You Use WD-40 as a Cutting Oil ?
WD-40 is multi-purpose Cutting Oil has a mineral, oil-based formula with anti-wear additives and a unique liquid-foam consistency to help reduce tip welding and wear on tools. The WD-40 suitable for use on most kinds of metals. It is designed to prevent pitting and metal seizures, ease mechanical processing of metals, reducing frictional heat accumulation and frictional forces. As a result, in a pinch, a fit of laziness or other inconvenient reasons, you could have a try to use WD-40 as a cutting oil.
Cutting oils deteriorate soon affected by the interfusion of chips and foreign materials. Especially, we need to pay attention to water-soluble cutting oils because this type gets colonized by bacteria after diluted with water, and becomes the cause of the decomposition and deterioration of the cutting oils. Let us show you some methods in the quality control of cutting oils, and essential points to be checked.
4.1 Appearance
Daily observation on the appearance is needed. If you find floated oil, please remove it.
4.2 Smell
The more bacteria increase, the more awful smell arises. Using those contaminated cutting oils would be the cause of corrosion. Those are often seen with water-soluble cutting oils diluted with water.
4.3 Concentration and PH (alkalescent)
If concentration and pH are not adequate, it would cause corrosion or decomposition that gives damages on wipers and packings in a machine, and could finally result in a decline in function.
4.4 Cleaning Coolant Tank
It is important to pour cutting oil after cleaning up a tank. Once a new cutting oil was mixed with the one used in a former machining, the concentration would be changed and lost the component balance of the cutting oil. Moreover, if chips or foreign materials are left in the coolant tank, metallic composition would be melted and mixed into the cutting oil.
Cutting oil is regarded to be an essential machining partner in these days. However, if we select wrong type of cutting oil for machining, it negatively affects to the performance of machines, which comes to a decrease in machining accuracy and accelerates the aging of tools. The important thing is we need to understand the features and machining conditions of your machines, we also need to understand the performance of cutting oils for smooth works. Meanwhile, the maintenance also is very important.
We, MAXNOVO MACHINE, are happy to support customers to select the high precision machines to meet their machining requirements. If you have any requirements about machine tools, Please feel free to contact our machinery expert (www.maxnovocnc.com) at any time.
