Correct selection of cutting fluids for the aerospace industry

For aerospace products, the process of achieving high quality, high efficiency and low cost of the product requires attention to every detail. The selection of cutting fluid is related to the surface quality and machining accuracy of the workpiece, and is closely related to the material to be processed, the machining process and the tool material. .

As structural members increasingly use thin-walled structural features and difficult-to-machine materials , they pose challenges to aerospace manufacturing precision. The requirements for cooling, lubrication, cleaning and rust-preventing performance of cutting fluids vary depending on the workpiece material, tool material, processing properties, processing content and process requirements. To ensure the ultimate quality of the product, you need to pay attention to every detail of the product processing process. At present, the commonly used knives in aerospace product processing are: carbon tool steel, alloy tool steel, high speed steel, hard alloy, ceramic and diamond. The materials to be processed for different tool materials are also different, and the cutting fluids used for various processing environments are also different.

In the manufacturing process of aluminum alloy products, most aerospace companies use emulsions. The cutting fluid used in general factories is a working emulsion diluted with a cutting fluid concentrate and water. The emulsion mainly functions as cooling, lubrication and swarf in the processing of aluminum alloy products. The choice of concentration, pressure and flow rate of the emulsion has a great influence on the processing quality of the parts. Open cutting method for turning and milling, smooth chip removal, low requirements on cutting fluid concentration, generally use cutting fluid with concentration of 3%~5%; cutting in drilling, tapping and other closed occasions, poor processing environment, chip removal Poor, the tool and the workpiece are mutually squeezed. In addition to the cooling and lubrication of the cutting fluid, the cutting fluid must be smashed. This DNT-method requires high lubrication performance of the cutting fluid. Generally, the drilling concentration is 5%. 8% of cutting fluid; when tapping, the workpiece is severely squeezed by the tool. It is more suitable to use cutting fluid with extreme pressure additive and concentration of 8%~10%. In the face milling process, the cutting speed is fast, the cutting amount of the tool is large, the chip is much, and the chips are washed away in time to avoid scratching the processed surface. This is the biggest problem facing the milling process, and should be flushed with a large flow cutting fluid. When performing hole machining, the chip removal is difficult, and the friction between the tool, the workpiece and the chip generates a large amount of heat, which cannot be transmitted in time, causing the tool to burn and seriously destroying the surface roughness of the workpiece. In order to solve this problem, in addition to rational selection of the geometric angle of the tool, to ensure the separation of chips, chip breaking, chip removal, the choice of cutting fluid is the key, then the cooling, lubrication, cleaning performance of the cutting fluid, such as extreme pressure Emulsion. Basso's BlasicutBC20 general-purpose metal cutting fluid is suitable for cutting machining of cast iron, steel-aluminum alloy and alloy steel with high cleaning requirements and high versatility. Castrol Alusol B is a high-quality solvent cutting fluid specially developed for the machining of aluminum and aluminum alloys. It is suitable for the processing of aluminum and aluminum alloy products widely used in the automotive industry and general engineering.

In the aerospace industry, titanium and titanium alloys are often used to make a variety of critical structural components, and the processing of such structural components places very high demands on processes, machine tools, tools, and cutting fluids. To meet these requirements, Basso Lubrication has developed a Vasco 5000, a water-based cutting fluid known as “revolutionary”. Compared to conventional products, this cutting fluid provides better and faster machining results, as well as longer tool life for improved reliability and productivity. One of the key factors that directly affects the quality of the process is the correct choice of cutting fluid. Of course, the use of coolant must be supported by corresponding innovative technologies. Sandvik Coromant invented the suction drill in the deep hole drilling process of titanium alloy, using two identical pipes to provide coolant and chip evacuation to form Wenqiu. The effect. After combining HPC (High Pressure Cooling) with Capto (Sandvik Interface Quick Change System), the company developed a complete titanium alloy milling series HP tool high pressure cooling system solution. The HP tool uses a fixed nozzle technology that ejects a high-speed parallel layer jet that accurately aligns the position where the blade needs to be cooled. The resulting jet accuracy and characteristics make this technology unique. Flowserve 's RENODRILL 2190 is suitable for high hardness materials and difficult machining processes such as deep hole drilling, gun drilling, broaching and tapping.

The wire cutting of domestic hard brittle materials, especially solar Si wafers, has developed rapidly in the past five years. As the wafers have developed toward large diameters and thin sheets, the processing process has also put forward many requirements for cutting fluids. Firstly, the cutting fluid itself must have the characteristics of no pollution, low viscosity, high sand content, low impurity content and no adverse effect on the downstream of the Si wafer. Secondly, the application of the cutting fluid has the wireless trace of the silicon wafer after cutting, easy to clean and cut out. The characteristics of high film rate and high qualified rate of finished products; once again, the specialization of cutting fluids. At present, the cutting fluids for domestic Si wafer cutting are single, no matter what equipment, thick steel wire, large particle size sand, Which cutting process basically uses the same cutting fluid, so the product is not targeted, causing many problems in the cutting process, so research and development of cutting fluids adapted to different cutting processes is an urgent problem to be solved. For wire cutting such as Ge and GaAa, oil-based cutting fluids are mostly used in China, and research on cutting fluids suitable for hard and brittle materials is the focus of future research.

With the increasing use of cutting technology, the amount of cutting fluid has also increased significantly, causing serious environmental pollution and increasing the manufacturing cost of the product. To reduce these negative effects of cutting fluids, the best approach is to use green processing technology. Minimum Quantity Lubrication (MQL) technology is being researched and adopted as a cost-effective and environmentally friendly processing method. MQL cutting technology is realized by mixing and compressing compressed air and a small amount of environmentally friendly cutting fluid into the cutting zone to provide precise amount of suspended particles to the cutting zone, that is, the diameter of the suspended particles is within the precise tolerance range to maintain the best. Wetting and lubrication properties, lubrication and cooling of tools and workpieces, reducing friction between the tool and the workpiece, inhibiting temperature rise and improving cutting performance. MQL cutting technology is a modern manufacturing mode that considers environmental impact and resource efficiency. The cutting fluid used should have the functions of cooling, lubrication, cleaning and rust prevention of traditional cutting fluid. It should also be non-toxic and harmless. The performance of the operator, non-polluting environment and not easy to spoil and deteriorate, is embodied in biodegradability, oxidation stability, storage stability, and cutting lubricity.

With the rapid development of modern processing technology, traditional clustering and specialized production have not adapted to the needs of modern processing. The flexible production and agile manufacturing of many enterprises and factories have become the modern manufacturing technology widely adopted at present, with mature technology and equipment. Selection and cutting fluid management pose new challenges. In the multi-tasking environment, the machine is required to install the card once, and complete the combined operations of face milling, cavity milling, feature displacement, drilling, reaming, boring and tapping, which requires the cutting fluid not only to have good cooling lubricity. There must also be extreme pressure resistance. Sometimes some aluminum alloy parts are inlaid with steel products, and the cutting fluid is required to have a certain anti-rust function. The German cutting machine series should be selected for the machining fluids for engine casing aluminum alloy products. With the development of green manufacturing, MQL technology has the characteristics of green machining process required for the development of green manufacturing in the 21st century in the technology of small and no cutting fluid cooling processing.