The first thing to understand is the characteristics of oil-based and water-based cutting fluids. Generally speaking, oil-based cutting fluids have good lubrication properties, while water-based cutting fluids have good cooling properties. Emulsions have certain lubricity and anti-rust properties, as well as certain cooling and cleaning properties, but they are prone to the generation of microorganisms. Decomposition occurs.
The selection of cutting fluid is mainly considered from the following aspects:
Process lubricants used in the cutting, forming, handling and protection of metals and their alloys are collectively called metalworking fluids, also known as cutting fluids. In the process of metal processing, in order to reduce the cutting force during cutting and take away the heat generated in the cutting zone in time to reduce the cutting temperature and improve the durability of the tool, thereby increasing production efficiency and improving the surface roughness of the workpiece to be processed, to achieve the best economic effect.
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1. Selection based on workpiece material
Cutting processing - the machinability of the workpiece material has important implications for the selection of cutting fluid: the machinability of the workpiece material is of great significance to the selection of cutting fluid. The specific conditions and requirements of cutting processing are different, and the difficulty of cutting processing is different. During rough machining, slow tool wear and high machining productivity are required; during finishing, the workpiece is required to have high precision and small surface roughness.
For materials that are difficult to machine, a cutting fluid with high activity and containing anti-wear and extreme pressure additives should be used; for materials that are easy to machine, a cutting fluid without extreme pressure additives should be used.
When cutting non-ferrous metals and light metals, the cutting force and cutting temperature are not high, so mineral oil and high-concentration emulsion can be used. When cutting alloy steel, if the cutting volume is low and the surface roughness requirements are small (such as broaching and thread cutting), a cutting fluid with excellent lubrication properties is required. Extreme pressure cutting oil and high-concentration emulsion can be used. When cutting brittle materials such as cast iron and bronze, chipping chips are often formed during cutting, which easily flow everywhere with the cutting fluid and flow into the machine tool guide rails, causing component damage. Low-concentration emulsions with good cooling and cleaning properties can be used.
2. Select according to workpiece method
In rough machining at higher cutting speeds (such as turning, milling, drilling), the cutting fluid is required to have good cooling performance. In this case, water-based cutting fluid and low-concentration emulsion should be used. In some precision and high-intensity machining (such as broaching, tapping, deep hole drilling, gear machining), the cutting fluid needs to have excellent lubrication properties, and extreme pressure cutting oil and high-concentration emulsion can be used.
3. Select according to tool material
1. Tool steel cutting tools
The heat-resistant temperature of this type of tool is 200-300oC, and the heat resistance is poor. It will lose hardness at high temperatures. Therefore, it is required to use a cutting fluid with good cooling performance, preferably a low-concentration emulsion.
2. High speed steel cutting tools
During high-speed rough cutting, the cutting volume is large and a large amount of cutting heat is generated. In order to avoid workpiece burns and affect the processing quality, water-based cutting fluid with good cooling properties should be used; if high-speed steel tools are used for medium and low-speed finishing, it is To reduce the friction and adhesion between the tool and the workpiece, inhibit the formation of cutting nodules, and improve machining accuracy, oil-based cutting fluid or high-concentration emulsion is generally used.
3. Carbide cutting tools
This type of tool has a higher melting point and hardness, better chemical and thermal stability, and much better cutting and wear resistance than high-speed steel tools. Oil-based cutting fluids can be used in general machining. If it is heavy cutting, the cutting temperature is very high and it is easy to wear the tool very quickly. At this time, a cooling lubricant with sufficient flow should be used, preferably 3%-5% emulsion (spray cooling is used for better results).
4. Ceramic cutting tools, diamond cutting tools, cubic boron nitride cutting tools
These tools have high hardness and wear resistance, and cutting fluids are generally not used during cutting. Water-based cutting fluids can sometimes be used.
4. Choose according to machine tool requirements!
When selecting cutting fluid, you must consider whether the machine tool structure is suitable. Generally, the type of cutting fluid specified in the machine tool manual should be followed. Do not change it easily without special reasons to avoid damage to the machine tool.
5. Choose based on economic benefits
When selecting cutting fluid, a comprehensive economic analysis must be conducted to correctly evaluate the economic benefits of the cutting fluid. The costs generally include: the cost of purchasing cutting fluid, cutting fluid management costs, cutting tool consumption costs, improvement of production efficiency, cutting fluid life cycle, cutting fluid disposal costs and many other aspects.
In the total cost of processing products, the cost of purchasing cutting fluid only accounts for a small part. If the cutting fluid is correctly selected, the product quality and operating environment will be improved, the processing efficiency will be increased, the durability of the tool will be extended, and the cutting fluid will be reduced. The cost of supplementation and management...thus bringing significant economic benefits. If used improperly, it will have the opposite effect. So a comprehensive economic analysis is needed.
6. Other considerations
If you choose oil-based cutting fluid, you need to emphasize fire safety; if you choose water-based cutting fluid, you should consider the discharge of the cutting fluid, and the company should have waste liquid treatment facilities and take corresponding measures.
In addition, regulations such as the Safety and Health Law, Fire Protection Law, and Sewage Discharge Law must be followed.
