01 Turning and boring Rough turning: During rough turning, there is a large machining allowance, resulting in a large cutting depth and feed rate. The cutting resistance is high, resulting in a large amount of cutting heat. The tool wear is also severe. The main choice is to use water-based cutting fluids that mainly have cooling effects and have certain cleaning, lubrication, and rust prevention effects. The cutting heat should be taken away in a timely manner, reducing the cutting temperature, and thus improving the tool durability. Generally, extreme pressure emulsions are used for better results. In addition to good cooling performance, extreme pressure emulsion also has good extreme pressure lubrication, which can significantly extend the service life of cutting tools and improve cutting efficiency. When using water-based cutting fluid, attention should be paid to the maintenance of the machine tool guide surface. Before leaving work, the cutting fluid on the workbench should be wiped dry and coated with lubricating oil. Precision turning: During precision turning, the cutting allowance is small, the cutting depth is only 0.05-0.8mm, and the feed rate is small. It is required to ensure the accuracy and roughness of the workpiece. Due to the low cutting force and low temperature during precision turning, it is advisable to use high concentration (over 10%) emulsions and cutting fluids containing oily additives.
Boring: The boring mechanism is the same as turning, but it is internal hole machining. The cutting speed and cutting speed are not high, but the heat dissipation conditions are poor. Emulsion can be used as the cutting fluid, and the flow rate and pressure of the cutting fluid should be appropriately increased during use. 02 Milling Milling is intermittent cutting, with the cutting depth of each tooth constantly changing, which is prone to vibration and certain impact forces, so the milling conditions are worse than the turning conditions. When using high-speed cutting tools for high-speed flat milling or high-speed end milling, cutting fluids with good cooling performance and certain lubricating properties, such as extreme pressure emulsions, are required. When milling at low speeds, it is required to use cutting oils with good lubrication, such as precision cutting oils and non active extreme pressure oils. For stainless steel and heat-resistant alloy steel, cutting oils with sulfur and chlorine extreme pressure additives can be used. 03 Thread processing When cutting threads, the tool and cutting material form a wedge-shaped contact, and the three sides of the blade are surrounded by the cutting material. The high cutting torque makes it difficult to remove chips, and the heat cannot be taken away by the cutting fluid in a timely manner. The tool is prone to wear, and chip fragments are crowded and prone to vibration. Especially when turning and tapping threads, the cutting conditions are more stringent, and sometimes there may be blade breakage and tap breakage. It is required that the cutting fluid has both a lower friction coefficient and a higher extreme pressure to reduce the friction resistance of the tool and extend its service life. Generally, a composite cutting fluid containing both oiliness and extreme pressure agents should be selected. In addition, the permeability of the cutting fluid during thread tapping is very important. Whether the cutting fluid can penetrate into the blade in a timely manner has a significant impact on the durability of the tap. The permeability of the cutting fluid is related to viscosity, and oil with low viscosity has better permeability. If necessary, a small amount of diesel or kerosene can be added to improve the permeability effect. In some situations, such as blind hole threading, it is difficult for the cutting fluid to enter the hole. In this case, using a cutting fluid with high viscosity and strong adhesion can have a better effect.
04 Reaming
Reaming machining is the precision machining of holes, which requires high precision. Reaming belongs to low-speed and small feed cutting, which mainly involves extrusion cutting between the tool and the hole wall. Chip fragments are easily left in the tool groove or adhered to the edge of the tool, affecting the squeezing effect of the edge band, damaging machining accuracy and surface roughness, increasing cutting torque, and also producing chip deposits, increasing tool wear. Reaming is basically a boundary lubrication state, and generally uses high concentration extreme pressure emulsions or extreme pressure cutting oils with good lubrication performance, You can achieve good results. For deep hole reaming, using cutting oil with good lubrication performance can meet the process requirements.
05 Broaching
A broach is a machining tool that juxtaposes numerous cutting teeth along the axis direction according to the blade and tooth lift. The characteristic of broaching machining is that it can accurately process workpieces with complex shapes. Because broaches are expensive tools, tool durability has a significant impact on production costs. In addition, broaching is a precision machining that requires strict surface roughness of the workpiece. When broaching, the cutting resistance is high, it is difficult to remove chips, the cooling conditions are poor, and it is easy to scratch the surface of the workpiece. Therefore, it is required that the cutting fluid has good lubrication and chip removal performance. There are specialized sulfur-containing extreme pressure additives for broaching oil in China.
06 Borehole
Drilling with a general Fried Dough Twists drill is rough machining. It is difficult to remove chips when drilling. It is difficult to derive the cutting heat, which often causes annealing of the blade, affecting the service life and processing efficiency of the drill. Choosing cutting fluids with good performance can prolong the lifespan of drill bits by several times or even more, and significantly improve productivity. Generally, extreme pressure emulsion or extreme pressure synthetic cutting fluid is selected. Extreme pressure synthetic cutting fluid has low surface tension, good permeability, and can cool the drill bit in a timely manner, which is very effective in extending tool life and improving machining efficiency. For difficult to cut materials such as stainless steel and heat-resistant alloys, low viscosity extreme pressure cutting oil can be selected.
07 Deep hole drill
Deep hole drilling (gun drilling) is a deep hole processing technology developed in recent years. Traditional deep hole processing (which also requires a ratio of depth to aperture greater than 5) requires multiple processes such as drilling, boring, rough reaming, and grinding to produce holes with high accuracy and low surface roughness. The new process uses specially designed cutting tools and a high-pressure cooling and lubrication system, which can simplify the above multiple processes into a continuous cutting process to complete high-precision and low surface roughness hole machining of considerable depth. This process has high efficiency and significant economic benefits.
A high-performance deep hole drilling cutting fluid is one of the key technologies in deep hole drilling, and the deep hole drilling cutting fluid must have the following properties.
Good cooling effect, eliminating heat generated due to deformation and friction, and inhibiting the formation of chip deposits.
Good high-temperature lubrication, reducing friction and wear of the cutting edge and support, ensuring that the tool maintains good lubrication at high temperatures in the cutting area.
Good permeability and chip removal enable the cutting fluid to penetrate the cutting edge in a timely manner and ensure the smooth discharge of chips. Therefore, deep hole drilling cutting fluid requires high extreme pressure and low viscosity.
08 Gear processing
For high-speed gear cutting, using oil-based cutting fluids can generate significant oil fumes, pollute the environment, and due to insufficient cooling, it can often cause surface burns on the workpiece, affect machining quality, and exacerbate tool wear. In this case, it is best to choose water-based cutting fluids with strong extreme pressure properties, such as water-based synthetic cutting fluids containing sulfur and phosphorus extreme pressure additives or high concentration extreme pressure emulsions, to overcome oil pollution during high-speed cutting, The processing quality and tool wear are better than oil-based cutting fluids. However, for existing gear hobbing and slotting machines, measures must be taken to prevent water from entering the rotating parts to prevent machine failures.
Shaving machining requires high surface quality. In order to prevent tool sticking, cutting oil containing active extreme pressure additives can be used. However, because shaving machining produces small chips, it is best to use low viscosity cutting oil to make the chips easy to wash away. If the chips are not separated smoothly, it will worsen the quality of the processed surface.
09 Grinding
Grinding can achieve high dimensional accuracy and low surface roughness. During grinding, the grinding speed is high and the heat generation is high. The grinding temperature can reach as high as 800-1000 ℃ or even higher, which can easily cause surface burns of the workpiece and surface cracks and deformation of the workpiece due to thermal stress. The grinding wheel is worn and passivated, and the abrasive particles fall off. In addition, the grinding debris and grinding wheel powder are prone to splashing and falling onto the surface of the part, affecting the machining accuracy and surface roughness, processing toughness, and plastic materials, Grinding debris embedded in the gaps on the working surface of the grinding wheel or fused with processing metal on the surface of the grinding wheel can cause the grinding wheel to lose its grinding ability. Therefore, in order to reduce the grinding temperature, wash away the grinding debris and grinding wheel particles, improve the grinding ratio and surface quality of the workpiece, it is necessary to use cutting fluids with good cooling and cleaning performance, as well as certain lubrication and rust resistance.
High speed grinding: Grinding with a grinding wheel linear speed exceeding 50m/s is usually referred to as high-speed grinding. When the linear speed of the grinding wheel increases, the grinding temperature significantly increases. According to experimental measurements, the grinding temperature (average operating temperature) at a grinding wheel linear speed of 60m/s is about 50% to 70% higher than that at 30m/s; When the linear speed of the grinding wheel is 80m/s, the grinding temperature is 15% to 20% higher than that at 60m/s. After the linear speed of the grinding wheel increases, the number of abrasive particles participating in grinding per unit time increases, the friction effect intensifies, and the energy consumption also increases, causing an increase in the surface temperature of the workpiece, increasing the possibility of surface burns and cracks. This requires the use of cooling fluids with efficient cooling performance to solve. Therefore, in high-speed grinding, ordinary cutting fluids should not be used, but high-speed grinding fluids with good permeability and cooling performance should be used, To meet the requirements of high-speed grinding process with a linear speed of 60m/s.
Power grinding: This is an advanced and efficient grinding process. For example, during power input high-speed power grinding, a grinding wheel with a linear speed of 60m/s enters radially at a feed rate of about 3.5-6mm/minute, and the power division rate can reach up to 20-40mm/s. At this time, the friction between the grinding wheel particles and the workpiece is very intense. Even under high pressure and high flow conditions, the measured surface temperature range of the workpiece in the friction zone can reach 700-1000 ℃. If the cooling conditions are not good, The grinding process cannot be carried out. When using high-performance synthetic strong grinding fluid and emulsion in power input strong grinding, the total grinding amount is increased by 35%, the grinding ratio is increased by 30% to 50%, the normal grinding time is extended by about 40%, and the power loss is reduced by about 40%. Therefore, the performance of the coolant has a significant impact on the grinding efficiency during strong grinding.
Diamond grinding wheel grinding: This is suitable for grinding materials with high hardness such as hard alloys, ceramics, glass, etc. It can be used for rough and fine grinding, and the ground surface generally does not produce cracks or notches, resulting in lower surface roughness. To prevent excessive heat generation during grinding and premature wear of the grinding wheel, in order to achieve lower surface roughness, continuous and sufficient cooling is required. Due to the high hardness of the workpiece in this type of grinding, the grinding fluid should mainly have cooling and cleaning properties, maintain the sharpness of the grinding wheel, and the friction coefficient of the grinding fluid should not be too low. Otherwise, it will cause poor grinding efficiency, surface burns, and other adverse effects. A chemical synthetic fluid mainly composed of inorganic salts can be used as the grinding fluid. A small amount of polyethylene glycol can be added as a lubricant during precision grinding, which can improve the surface processing quality of the workpiece. For parts with high machining accuracy, low viscosity oil-based cutting fluids with good lubrication performance can be used.
Grinding of threads, gears, and screws: This type of grinding places special emphasis on the quality and dimensional accuracy of the machined surface after grinding. It is generally recommended to use grinding oils containing extreme pressure additives. This type of oil-based grinding fluid can reduce grinding heat due to its good lubrication performance, and the extreme pressure additives can react with the workpiece material to generate low shear strength iron sulfide film and iron chloride film, which can reduce wear of abrasive particles and cutting edge tips, Ensure smooth grinding. In order to achieve good cooling and cleaning performance, cutting fluid should ensure fire safety and choose grinding oil with low viscosity and high flash point.
