How to choose cutting fluid according to machining

2022-09-19
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How to choose cutting fluid according to the machining method

for different cutting types, the cutting characteristics of metals are different, and the more difficult cutting requires higher cutting fluid. The degree of difficulty in the cutting process is arranged in the order from difficult to easy as follows: internal broaching - External broaching - tapping - thread machining - gear hobbing - deep hole drilling - boring - cutting threads with forming tools - cutting threads with high speed and low feed - Milling - Drilling - planing - turning (single edge tools) - sawing and grinding

the above arrangement order is not absolute, because changes in tool geometry and workpiece material will also change the difficulty of processing

this paper briefly describes how to select cutting fluid for some commonly used machining methods

1 turning and boring

rough turning: during rough turning, the machining allowance is large, so the cutting depth and feed rate are large, the cutting resistance is large, a large amount of cutting heat is generated, and the tool wear is also serious. It is mainly necessary to choose water-based cutting fluid with cooling effect and certain cleaning, lubrication and rust prevention effects, so as to take away the cutting heat in time, reduce the cutting temperature, and improve the tool durability, Generally, extreme pressure emulsion is better. In addition to good cooling performance, EP emulsion also has good EP lubricity, which can significantly prolong the service life of the tool and improve the cutting efficiency. When using water-based cutting fluid, pay attention to the maintenance of the machine tool guide rail surface. Before going off work, wipe the cutting fluid on the workbench dry and apply lubricating oil

finish turning: during finish 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 small cutting force and low temperature during finish turning, it is appropriate to use emulsion with high concentration (more than 10%) and cutting fluid with oily additives. For turning with high accuracy requirements, such as fine turning threads, rapeseed oil, soybean oil and other products should be used as lubricants to meet the accuracy requirements. As mentioned above, due to poor stability and easy oxidation of vegetable oil, some factories use 15% JQ-1 precision cutting lubricant +85% l-an32 full loss system oil as precision cutting oil, which has a good effect

boring: the boring mechanism is the same as turning, but it is inner hole processing, and the cutting speed and cutting speed are not large, but the heat dissipation conditions are poor. Emulsion can be used as cutting fluid, and the flow and pressure of cutting fluid should be appropriately increased when using

2 milling

milling is intermittent cutting, and the cutting depth of each cutter tooth changes from time to time, which is easy to produce vibration and certain impact force, so the milling condition is worse than the turning condition. When using high-speed tools for high-speed flat milling or high-speed end milling, cutting fluid with good cooling and certain lubricating performance, such as extreme pressure emulsion, is required. In low-speed milling, it is required to use cutting oil with good lubricity, such as precision cutting oil and inactive extreme pressure oil. For stainless steel and heat-resistant alloy steel, cutting oil with sulfur-containing and chlorine extreme pressure additives can be used

3 thread machining

when cutting threads, the tool is in wedge contact with the cutting material, and the three sides of the blade are surrounded by the cutting material. The cutting torque is large, and it is difficult to remove chips. The heat cannot be taken away by the chips in time. The tool is easy to wear, and the chip fragments are jammed and prone to vibration. In particular, when turning and tapping threads, the cutting conditions are more stringent, and sometimes there will be broken edges and taps. The cutting fluid is required to have low friction coefficient and high extreme pressure at the same time, so as to reduce the friction resistance of the tool and prolong the service life of the tool. Generally, the composite cutting fluid containing both oily agent and extreme pressure agent should be selected. In addition, the permeability of cutting fluid during tapping is very important. Whether the cutting fluid can penetrate into the blade in time has a great impact on the durability of the tap. The permeability of cutting fluid is related to viscosity. Oil with low viscosity has better permeability. If necessary, a small amount of diesel oil or kerosene can be added to improve the high permeability effect. In some cases, such as blind hole tapping, it is difficult for cutting fluid to enter the hole. At this time, the effect of using cutting fluid with high viscosity and strong adhesion is better

the following are the formulas of several cutting fluids for tapping:

10% sulfurized fat oil, 10% chlorinated paraffin, 8% fat oil, 72% l-an15 full loss system oil. Suitable for tapping steel and alloy steel

0%jq-2 extreme pressure lubricant, 10%jq-1 precision cutting lubricant, 70%l-an15 full loss system oil. Suitable for tapping steel and alloy steel

5%jq-2 EP lubricant +20% diesel engine oil +60%l-an15 full loss system oil. Suitable for aluminum and aluminum alloy tapping

30%jq-2 extreme pressure lubricant +10% chlorinated paraffin +10% fatty oil +50%l-an32 full loss system oil. Suitable for iridium stainless steel and blind hole tapping

20% EP emulsified oil + 80% water, suitable for thread machining of steel standard parts

4 reaming

reaming is the precision machining of holes, which requires high precision. Reaming belongs to low-speed and small feed cutting, which is mainly the extrusion cutting between the tool and the hole wall. The chip fragments are easy to stay in the tool slot or adhere to the edge of the tool, which affects the extrusion effect of the blade belt, destroys the machining accuracy and surface roughness, increases the cutting torque, and also produces chip buildup, increases tool wear. Reaming basically belongs to the boundary lubrication state, Generally, high concentration EP emulsion or EP cutting oil with good lubricating performance and certain goodness can be used to obtain good results. For deep hole reaming, deep hole drill with good lubrication performance is used for cutting, and various equipment information oil is also provided to meet the process requirements

5 broaching

broach is a processing tool with many cutter teeth juxtaposed according to the blade and tooth rise along the axis direction. The characteristic of broaching is that it can process workpieces with complex shapes with high precision. Because broach is a valuable tool, the tool durability has a great impact on the production cost. In addition, broaching is precision machining, which requires strict surface roughness of the workpiece. During broaching, the cutting resistance is large, chip removal is not easy, the cooling condition is poor, and the workpiece surface is easy to be scratched, so it is required that the lubricity and drainage performance of the cutting fluid are good. There are special broaching oils with sulfur-containing extreme pressure additives in China

for broaching of stainless steel and heat-resistant alloy, the following formula can be used:

20% jq-2 extreme pressure lubricant, 15% chlorinated paraffin, 1% sben-80, 64% l-an22 full loss system oil

6 drilling

drilling with a general fried dough twist drill belongs to rough machining. It is difficult to remove chips during drilling, and the cutting heat is not easy to export, which often leads to the annealing of the blade, affecting the service life and processing efficiency of the drill. Selecting cutting fluid with good performance can prolong the service life of the drill several times or even more, and the productivity can also be significantly improved. EP emulsion or EP synthetic cutting fluid is generally selected. EP synthetic cutting fluid has low surface tension and good permeability. It can cool the drill bit in time, which is very effective in prolonging tool life and improving machining efficiency. For difficult cutting materials such as rusty steel and heat-resistant alloy, extreme pressure cutting oil with low viscosity can be selected

7 deep hole drill

deep hole drill (gun drill) is a deep hole processing technology developed in recent years. Traditional deep hole machining (also the ratio of depth to aperture is greater than 5) requires multiple processes such as drilling, boring, rough reaming, grinding and so on to process holes with high precision and low surface roughness. The new process adopts a tool with special structure and a high-pressure cooling and lubrication system, which can simplify the above-mentioned multiple processes into a continuous tool path to complete a considerable depth of high-precision and low surface roughness hole machining. This process has high efficiency and remarkable economic benefits

deep hole drilling cutting fluid with excellent performance is one of the keys of deep hole drilling processing technology. Deep hole drilling cutting fluid must have the following properties

good cooling effect, eliminate the heat generated by deformation and friction, and inhibit the formation of debris

good high-temperature lubricity, reduce the friction and wear of the blade and support, and ensure that the tool maintains a good lubrication state under the high temperature of the cutting area

good permeability and chip removal make the cutting fluid penetrate into the blade in time and ensure the smooth discharge of chips. Therefore, the cutting fluid of deep hole drill is required to have high extreme pressure and low viscosity. At present, 801 deep hole drill cutting oil produced in China has good high-temperature lubricity, cooling and chip removal. It has been widely used in imported and domestic deep hole drill machines with good performance

8 gear processing

when hobbing and gear shaping, the cutter teeth cut intermittently and have impact force, so the cutter teeth are easy to wear, especially in large feed and high-speed cutting, the wear of the cutter teeth is more serious, so the cutting fluid is required to have good lubrication performance. In the past, 20 or 30 machine oil was generally used as cutting oil in gear hobbing and dbj01 (3) 8 (2) 002 "technical specification for construction of exterior wall external insulation polymer cement mortar adhesive". Because the machine oil does not contain additives, the machined gear surface roughness is poor and the tool durability is low. In recent years, many factories have added 15% JQ-1 precision cutting lubricant on the basis of the original machine oil, so that the roughness and precision of the machined gear surface can meet the requirements of precision automobiles, and the tool durability is also significantly improved. This is because after adding JQ-1 into the machine oil, the friction coefficient is reduced by about 30%, and the load bearing capacity is increased by more than 50%, which greatly reduces the friction resistance during cutting, and significantly improves the machining quality and tool durability. For hobbing and gear shaping of high hardness materials, the cutting oil with chlorine additives and organic molybdenum additives has obvious effect

for high-speed gear cutting, using oil-based cutting fluid will produce large oil smoke and pollute the environment. Moreover, due to insufficient cooling, it will often cause workpiece surface burns, affect processing quality, and aggravate tool wear. At this time, it is best to choose water-based cutting fluid with strong extreme pressure, such as water-based synthetic cutting fluid containing sulfur and phosphorus extreme pressure additives or high concentration extreme pressure emulsion, which can overcome oil pollution during high-speed cutting, The machining quality and tool wear are better than oil-based cutting fluid. However, for the original gear hobbing and gear shaping machine tools, measures must be taken to prevent water from entering the rotating part, so as to avoid machine tool failure

gear processing with cemented carbide tools, most of which used to be dry cutting, resulting in higher workpiece temperature and lower tool life. The recently developed EC hobbing hard gear cutting oil can be successfully used for hobbing, reducing the temperature of the workpiece, improving the machining accuracy of the gear, and prolonging the service life of the tool by 80% - 100%

shaving requires high surface quality. In order to prevent sticking, cutting oil containing active extreme pressure additives can be used. Because shaving produces fine chips, it is best to use low viscosity cutting oil in order to make the chips easy to wash off. If the chips are not separated smoothly, the machined surface quality will deteriorate

9 grinding

grinding can obtain high dimensional accuracy and low surface roughness. During grinding, the grinding speed is high, the heat is large, and the grinding temperature can be as high as 800 ~ 1000 ℃, or even higher, which is easy to cause workpiece surface burns, surface cracks and workpiece deformation due to the effect of thermal stress, grinding wheel wear passivation, abrasive particles fall off, and grinding debris and grinding wheel powder are easy to splash, falling on the surface of parts and affecting the machining accuracy and surface roughness, processing toughness and plastic materials, The grinding wheel will lose its grinding ability if the grinding debris is embedded in the gap on the working surface of the grinding wheel or fused with the processing metal on the surface of the grinding wheel. Therefore, in order to reduce the grinding temperature, wash off the grinding debris and grinding wheel dust, and improve the grinding ratio and workpiece surface quality, cooling performance and

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