For different cutting types, the cutting characteristics of metal are different, and the more difficult cutting requires higher cutting fluid. Besides,the change of tool geometry and workpiece material will also change the difficulty of processing. How to choose cutting fluid for some common machining methods is briefly described below.
1cutting fluid for turning and boring
During 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, it is better to choose extreme pressure emulsion. 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.
2 cutting fluid for 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 fluids with good cooling and certain lubricating properties, such as extreme pressure emulsion, are 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 cutting fluid for thread machining
When cutting thread, the tool and cutting material form wedge-shaped contact, the three sides of the blade are surrounded by cutting material, the cutting torque is large, chip removal is difficult, the heat can not be taken away by the chip liquid in time, the tool is easy to wear, 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.
Reaming is the precision machining of holes, which requires high precision. Reaming belongs to low-speed and small feed cutting. It 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 nodules and 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, using deep hole drill cutting oil with good lubrication performance can meet the process requirements.
5cutting fluid for broaching
Broach is a kind of processing tool with many cutter teeth juxtaposed along the axis according to the blade and tooth rise. 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.
6coolant for drill hole
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 of the drill and processing efficiency. 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.
7on deep hole drill
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 cutting edge 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.
8 on gear processing
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 the 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.
Shaving requires high surface quality. In order to prevent sticking, cutting oil containing active extreme pressure additives can be used. In addition, 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 processed surface quality will be deteriorated.
9 cutting fluid for honing
The workpiece honed has high precision and low surface roughness. The particle size of iron powder and oilstone powder produced in the processing process is very small, which is easy to be suspended in the grinding fluid, causing oilstone hole blockage, affecting the processing efficiency and damaging the processing quality of the workpiece surface. Therefore, the cooling lubricant is required to have better permeability, cleaning and sedimentation performance. Water based coolant has poor sedimentation performance for fine powder, so it is generally not suitable for use. Oil based grinding fluid with high viscosity is also unfavorable to the sedimentation of powder, so mineral oil with low viscosity (about 2 ~ 3mm2/s (40)) is generally added with a certain amount of inactive sulfur fatty oil as honing oil.