Problems and development of metalworking fluid in mold manufacturing
Problems of metalworking fluid in mold manufacturing
Metalworking fluid plays an important role in the process of cutting and grinding die steel. It has been proved by practice that the proper metalworking fluid can reduce the cutting temperature by 60~150 ℃, reduce the surface roughness by 1~2 grades, reduce the cutting resistance by 15~30%, increase the service life of the tool and the grinding wheel by several times, and wash away the iron filings and ash from the cutting area, thus improving the production efficiency and product quality, so it is widely used in mold processing.
A. The cooling effect can reduce the temperature of the cutting area in a timely and rapid manner during the cutting process of the workpiece, that is, reduce the temperature rise usually caused by friction. Cooling also affects the cutting efficiency, cutting quality and tool life.
B. Lubrication can reduce friction between cutting tool and workpiece. The lubricant can soak between the tool and the workpiece and its chips, reduce friction and adhesion, reduce cutting resistance, ensure cutting quality, and extend tool life.
C. The washing action causes the chips or abrasive particles to be washed away from the processing area of the tool and the workpiece, so as to prevent them from sticking to each other and sticking to the workpiece, tool and machine tool
D. The anti-rust function shall have certain anti-rust performance to prevent the workpiece and machine tool from rusting. If the anti-rust performance is improved, it can also partially replace the inter-process anti-rust.
The above four properties of cooling, lubrication, washing and rust prevention are not completely isolated. They have both unified aspects and opposite aspects. For example, cutting oil has good lubricating and antirust performance, but poor cooling and cleaning performance; The cooling and washing properties of the aqueous solution are good, but the lubricating and antirust properties are poor. Therefore, the advantages and disadvantages should be comprehensively weighed when selecting cutting fluid. The performance of cutting fluid shall meet the following requirements: large thermal capacity, good thermal conductivity and good cooling effect. It has high oiliness or adsorption on metal surface. It can make the formed adsorption film have high strength, firmly adsorb on the metal surface, and play a good role in lubrication. Good rust resistance, no corrosion to metal, and no damage to the accuracy and surface roughness of the machine tool and workpiece due to corrosion. Low surface tension, easy to spread evenly, conducive to cooling and washing, and has good lubricity. It is easy to use, low in price, easy to configure, and preferably suitable for a variety of metal materials and processing methods (such as turning, grinding, planing, etc.). It has certain transparency, and does not smoke when improving the cutting speed. It is harmless to human body, non-toxic and odorless. It will not harm the skin and nasal mucosa, and will not irritate the eyes. Good stability and long service life. During long-term use and storage, there shall be no stratification, precipitation and mildew. Due to the large amount of cutting waste liquid, waste liquid treatment shall be considered to avoid environmental pollution.
1. Water quality
The water-based cutting fluid needs to be diluted by adding water in a certain proportion. Generally, it is not suitable to use water with a hardness of more than 400, because the calcium and magnesium ions contained in the high hardness water will make the anionic surfactant ineffective, lotion will decompose, and water insoluble metal soap will appear. Even if the emulsion is made of non-ionic surfactant, a large number of metal ions can also make the micelles aggregate, thus affecting the stability of the lotion. Too soft water should not be used. Emulsion prepared with too soft water is easy to produce a lot of foam during use. The appropriate hardness of the water used to prepare the emulsion should be 50~200. It can be mixed with deionized water and untreated industrial water. Generally, it is forbidden to use treated sewage, water containing chemicals and secondary water to prepare the emulsion. Softened water for boiler should also be used with caution. Users in hard water areas can use the sodium carbonate method to soften the water and then use it. It is necessary to prevent the pH value of the water after softening from being too high. Excessive use of water softener will destroy the stability of the emulsion.
2. Foam
The problem of excessive foam will occur in the use of water-based cutting fluid and clean cutting oil. If the pump speed is too high, the liquid will be turbulent, or the oil pipe resistance will form a jet that will increase the liquid foam. The mixing of cutting fluids with different properties (such as the mixing of clean cutting oil and emulsion) will also increase the foam. Before changing the cutting fluid of the machine tool, clean the oil tank and circulation route. In addition, when preparing the emulsion, avoid intense stirring and air stirring. Over softened water and alkaline water will increase the foam of emulsion. Fluid circulation pump seal is not tight will also increase the liquid foam. The harm of foam makes the cooling lubricant invalid and the oil tank volume wasted. The coolant with severe foam will cause damage to machine tools, tools and workpieces.
The methods to avoid foam are as follows: in the centralized cooling system, the pipelines are in series in stages, and the pipeline pressure near the cooling tank should be lower. Ensure that the level of cutting fluid is not too low, check the level in time and add cutting fluid in time. Control the cutting fluid flow rate not too fast. When designing the sink, pay attention not to have too many right angles to the sink. When using cutting fluid, the cutting fluid nozzle angle should not be too straight.
3. Sealing of machine tool
Check the shaft seal of the machine tool frequently (especially when the emulsion is used as the coolant) to prevent the cutting fluid from flowing into the gear box, headstock or other sealed transmission mechanism of the machine tool. If the emulsion enters the mineral oil lubrication system, the machine tool will be worn. Centralized cooling and lubrication system is often used in large mold processing workshops. The coolant of this kind of circulating system is continuously recycled, and the service life of the oil pool is very important. Pay attention to ensure the smooth flow of the liquid circulation route, and timely remove the metal chips, metal powder, mold mucus, decomposition of the cutting fluid itself, and grinding wheel chips from the circulation route to avoid blocking. The concentrated solution of the cutting fluid and the oil leaked from the machine tool are divided into two parts every 20 to 30 minutes under aerobic conditions. Anaerobic bacteria live in the environment without oxygen, split into two every hour, metabolize and release SO2, smell rotten eggs, and the cutting fluid turns black. When the number of bacteria in the cutting fluid is greater than 106, the cutting fluid will stink. In recent years, Shenzhen Gangsong Technology Development Co., Ltd. has developed a precision ultra-fine filtration method, which can remove 1 μ The solid, liquid and fungus pollutants of m can save the trouble of putting fungicides on a regular basis and reduce the harm of fungicides to people and the environment.
The methods to control the growth of bacteria include using high-quality and stable cutting fluid. Preparation of concentrated solution with pure water is not only easy to prepare, but also can improve the lubricity of cutting fluid, reduce the amount taken away by cutting chips, and prevent bacterial erosion. During use, the ratio of concentrated solution in the cutting fluid should be controlled to not be too low, otherwise it is easy to make bacteria grow.
Since the oil used by the machine tool contains bacteria, it is necessary to minimize the mixing of the oil leaked by the machine tool with the cutting fluid. When the pH value of cutting fluid is 8.3~9.2, bacteria are difficult to survive, so new cutting fluid should be added in time to improve the pH value. Keep the cutting fluid clean, and do not contact the cutting fluid with dirt such as dirty oil, food, tobacco, etc. Use fungicides frequently. Keep the workshop and machine tool clean. If there is no filtering device in the equipment, the floating oil shall be skimmed regularly to remove the dirt.
4. Labor hygiene and environment
The main reason affecting human health and environment is the base oil and various additives contained in cutting fluid. The high density mineral oil (relative density greater than 0.9) contained in the cutting fluid is a mineral oil with high aromatic content and is easy to be emulsified, but the polycyclic aromatic hydrocarbons (PCAH) in it is a carcinogenic component. Sodium nitrite and triethanolamine have been widely used in emulsions and are effective antirust agents. Since nitrosodiethanolamine was proved to be a carcinogen, its use was banned in some countries in the 1970s. In addition, in order to avoid oil rash and folliculitis skin allergy caused by mold operators contacting oil, fungi and metal chips in cutting fluid, operators should wear protective oil, work clothes and gloves, and pay attention to avoid direct contact between skin and cutting fluid.
Future trend and application cases of metalworking fluid
The policy measures of the Chinese government to "maintain growth and expand domestic demand" are being put into practice, and the revitalization plans for key industries have also been issued. Metal processing and CNC machine tools have been included in the Pearl River Delta planning outline. The Dongguan municipal government has allocated 2 billion yuan for the expansion of small and medium-sized enterprises in Dongguan. We can see that the purchasing power of mold enterprises in Dongguan and South China is improving, and the products needed for transformation will be more extensive and more new products will be required. With the financial crisis slowly going away, China's mold and its processing market will be revitalized again! After experiencing the test of the economic crisis, Luo Baihui, an expert member of the Shenzhen Die and Mould Technology Association, pointed out that the demand of metalworking fluid users in the die and mould industry will change in the direction of energy efficiency, health and environmental protection, and economic cost.
1. Efficient and energy-saving lubrication technology
The mold manufacturing industry has been making unremitting efforts to innovate and strive to improve productivity while maintaining processing quality. Manufacturers and suppliers are constantly looking for ways to achieve this goal. Lubrication is closely related to the operation of mechanical equipment. Some people vividly compare lubricating oil to the blood of mechanical equipment. It can be said that without lubrication, there is no mechanical equipment. Efficient and reasonable lubrication technology is the basic measure to ensure and improve the energy-saving, efficient and long-term normal operation of mechanical equipment, the lifeblood of mechanical operation, and the applied science to serve the national economic development and people's welfare. Therefore, the development and application of advanced lubrication technology and high-performance lubricants is the premise to ensure the energy saving, efficient and normal operation of people's life and work and machinery in all walks of life. Without efficient and reasonable lubrication technology, there will be no advanced machinery operation, and there will be no advanced production and economic prosperity. Therefore, all industrial countries attach great importance to the research, development, promotion and application of advanced and reasonable lubrication technology. According to Japan's articles on friction economy, in 1970, Japan's annual economic benefit increased by 2 trillion yen due to the improvement of lubrication technology. Nagoya Steel Plant only improved the lubrication technology, achieving an annual economic benefit increase of 2 billion yen, and at the same time, the number of mechanical equipment accidents decreased by 90%.
At present, the effective utilization rate of mechanical energy in the world is only about 30% on average, and 50% - 60% of the total energy consumption is consumed by mechanical equipment friction. According to the calculation of Professor Vogel of Germany, 1/3 to 1/2 of the world's energy production is lost on friction loss, while Professor Joost of the UK pointed out that 30% to 40% of the world's energy consumption is consumed on friction loss. Of course, some friction and wear are inevitable, but with the progress of friction and lubrication science and technology and the improvement of lubrication management level, some of them can be saved. Japan has greatly reduced the wear of machinery and saved power by 10% to 20% by regulating the design and operation of energy-saving lubricating grease and adopting energy-saving lubricating grease and other measures. By adopting energy-saving lubricating grease alone, the internal combustion engine can save fuel by 5% to 10%, and energy-saving mechanical oil and hydraulic oil can save power by 7%.
2. Healthy and environmentally friendly metalworking fluid
Metalworking fluid mainly plays the role of lubrication and cooling in mold manufacturing, as well as the role of rust prevention and cleaning. Up to now, chlorinated solvents are still the most economical and effective way to clean stubborn oils. However, based on environmental protection and human safety, most chlorinated solvents have been restricted or prohibited. AONA Petroleum (China) Co., Ltd. has been concentrating all its efforts on the precision manufacturing industry, and has quietly provided metalworking oil and auxiliary cleaning agents for many mold industry manufacturers for a long time. DH200 is a new solvent with alkyl bromide as raw material, which is close to chlorinated solvent in terms of size and performance, while DH200 is not flammable/contains no ethylene/does not contain chlorine molecules/does not damage the atmosphere, its physical properties and high cleaning power are similar to trichloroethane and trichloroethylene, and it has low ozone destruction coefficient (ODP), low heating coefficient (Global Warming Potential=GWP), and no flash point, It is one of the best substitutes for chlorinated agents at present. The United States Environmental Protection Organization has passed legislation several years ago to replace HCFCs with DH200, which is currently the best environmental cleaning agent.
What can you do to actively protect the environment and optimize your production process? In fact, you can work with chemical suppliers to further optimize your chemical addition. You can manage a stable system according to the specific metalworking process and the recommended liquid level, which will achieve the best cost efficiency. In addition, you can also manage your system by considering the best level and flow according to the production trend.
3. Economical metal cutting fluid
With the economic crisis sweeping the world, people began to try to reduce the use of metalworking fluids. At present, the main methods in use include reducing the amount of chemicals added, using a smaller filtration system, and the application of micro-lubrication (MQL). Only reducing the amount of chemicals added may increase your overall production cost. Due to the lack of lubrication or wetting, the machining performance of the tool will gradually decline (the service life of the tool will be reduced), and the cleaning system often needs to be cleaned, resulting in high chemical and waste liquid treatment costs. If only a small filtration system is considered, it must be able to provide sufficient flow of coolant for the tool to achieve maximum cooling and lubrication, and enable it to effectively remove metal chips, which also increases the relevant processing costs. Micro-lubrication (MQL) is used to rapidly spray a small amount of coolant on the cutting contact point for cutting. Any coolant is not recycled, and many processes are very simple and do not need to use high liquid level to wash the tool.