Discussion on the implementation of the hottest gr

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Discussion on the implementation of green manufacturing in the whole life cycle of mechanical and electrical products


the modern machine manufacturing industry, which began in 1776, has provided many mechanical and electrical products with different performance for people's clothing, food, housing and transportation in the development of more than 200 years. These products have brought great convenience to people's lives and rapidly promoted the development of society. However, on the other hand, the waste produced by the machine manufacturing industry in the process of product manufacturing, as well as the waste produced by obsolete and scrapped products, have also caused great pollution to the earth's environment. These pollutants not only bring a variety of diseases to people's bodies, but also produce a large number of CFCs, leading to the formation of holes in the atmospheric ozone layer; A large amount of CO2 is produced to form the greenhouse effect, leading to global warming and sea level rise; The ecological environment of human beings is destroyed, and mega natural disasters occur frequently; The number of people with cancer has increased, the fertility of men has decreased, and people's health and even reproduction have been seriously threatened

as we all know, the whole life cycle of a machine goes through the stages of design, blank manufacturing, machining, heat treatment, assembly, packaging, use and maintenance, scrap recycling and so on. Each stage is closely connected with environmental protection, which may cause environmental pollution. In particular, some small and medium-sized enterprises only see the immediate interests, blindly buy some equipment that has long been eliminated and launch some seriously polluted projects, but they do not have the ability to deal with the "three wastes", which is particularly destructive to the environment

1 the rise and development of green manufacturing

in 1978, the Federal Republic of Germany first implemented the green product system, which was reviewed and evaluated by the national authority and labeled with a green mark. In view of the deteriorating global environment and the fact that manufacturing, as a pillar industry for people to create wealth, plays a leading role in environmental pollution, the American Society of manufacturing engineers (SME) systematically put forward the concept, connotation and main content of green manufacturing in green manufacturing in 1996. In 1998, SME published a report on the development trend of green manufacturing on the Internet, which further emphasized and introduced the importance of green manufacturing research and related issues [1]. The United States, Canada, Western Europe and other developed countries have conducted a lot of research on green manufacturing and related issues. The research of green manufacturing is being carried out rapidly in the world. In particular, the international organization for Standardization ISO issued the ISO14000 series of standards on environmental management system, which greatly promoted the research of green manufacturing. China promulgated the environmental protection law of the people's Republic of China on December 26th, 1989, and established the Huaxia environmental management system audit center of the State Environmental Protection Administration in January, 1996, which is specially responsible for the implementation, training and exchange of ISO14000 series standards in China. The promulgation of ISO14000 environmental management system standard has attracted the attention of many enterprises in China [2]

2 the meaning and implementation of green manufacturing

2.1 the meaning of green manufacturing

green manufacturing of mechanical and electrical products refers to the whole process of products from design, blank manufacturing, cutting, heat treatment, assembly, packaging, use and maintenance to scrap recycling, However, the coating components are very time-consuming, the consumption of sources, materials and energy is the least, and the pollution to the environment is the least, and the economic and social benefits of the enterprise are coordinated and optimized [3] 。

in the design stage, one is to consider the selection of materials, not only considering their wide sources and low prices, but also considering their utilization and pollution; The second is to consider the structural manufacturability of products, including ease of processing, ease of assembly and disassembly and recyclability

in the blank manufacturing stage, we should not only consider that the blank itself is easy to manufacture and economical, and the blank manufacturing method should have less pollution to the environment, but also consider that its cutting processing volume should be as small as possible and the material utilization rate should be high. In the cutting stage, it requires less cutting energy consumption, low tool wear, less waste, and less environmental pollution

in the heat treatment stage, we should not only consider that it is easy to obtain excellent mechanical and physical properties through heat treatment, but also consider the harm of toxic and harmful substances produced during heat treatment to workers' bodies and environmental pollution

at the stage of product packaging, we should not only consider the beautiful packaging and the uneasy damage of the packed items, but also consider the price and cost of packaging materials, the easy decomposition, recycling and reuse, and the environmental pollution caused by the waste of packaging materials

2.2 green material design of mechanical and electrical products

to implement green manufacturing, we must first realize green material design, and the realization of green material design requires not only the efforts of industrial and mining enterprises themselves, but also the joint cooperation of environmental protection departments, research units and government leaders. It is necessary to select materials reasonably, considering that they have wide sources, low price, low toxicity and low pollution, which is still difficult to achieve at present. Because the "mechanical design manual" only has the mechanical physical properties of commonly used materials, such as strength, elongation, impact value, hardness and other data, and does not have a wide description of its toxicity, side effects and sources, which makes it difficult for engineers and technicians to implement green manufacturing in product design. The compilation of this manual and database, including material toxicity, side effects and sources, can not be solved by the engineering and technical personnel of material manufacturers and material research institutes alone, but a large system engineering. First of all, we should investigate the mineral reserves of various materials, the difficulty of mining and refining production, in order to understand their sources; Moreover, the toxicity, radiation and pollution of various materials should be investigated. For example, lead, chromium, cadmium, phosphorus, arsenic, cyanide and other toxic substances are well known, but whether the alloys formed by mixing them with other substances and the compounds formed by chemical reactions are still toxic is not very clear. Moreover, new materials continue to come out, and there are more and more varieties. It is suggested that the government organize multidisciplinary technicians from geological resources, environmental protection departments, material manufacturers, material research institutes and medical units to jointly compile new material manuals and databases

2.3 green structure design of mechanical and electrical products

the ease of processing and easy assembly and disassembly in the structural manufacturability of products is relatively less difficult to implement, but it is also possible to do so only after we have a certain understanding of the characteristics of various processing methods and the status of our equipment. Structural manufacturability is relative, not absolute. Structural manufacturability is inseparable from processing methods, and the continuous emergence of new processing methods accelerates this uncertainty. For ordinary machining, the structural manufacturability may not be good, while for special machining, it may not be a problem. Recyclability is not only related to disassembly, but also related to the reprocessability of the material. It is not enough to rely solely on the personal experience of engineering and technical personnel. It is also necessary to compile manuals and databases for the structural manufacturability of various processing methods

2.4 green manufacturing of mechanical and electrical products blanks

in the blank manufacturing stage, due to the lack of materials and difficult circulation in the past planned economy era, almost all enterprises pursue the operation mode of "sparrow is small, five internal organs are complete, and everything does not ask for people", resulting in slow equipment replacement and serious lack of equipment capacity. After the reform and opening up, this situation has not changed much. This leads to low blank manufacturing accuracy and large machining allowance; It brings difficulties to subsequent machining, resulting in large waste of materials (millions of tons of chips produced by machining every year), low resource utilization, large tool wear and high energy consumption during cutting; The coolant used to reduce tool wear has increased environmental pollution. Due to the lack of large-scale equipment for blank manufacturing, some small and medium-sized enterprises only have 40% - 50% of the blank quality of parts after cutting. Although ferrous metal chips are not toxic, they cannot be said to be green manufacturing. Moreover, some blank manufacturing methods themselves, such as some small-scale casting and melting equipment (three section furnace, cupola, etc.), forging heating equipment (coal-fired, coke, heavy oil-fired heating furnace), are easy to produce SO2 to form acid rain, which also has great pollution to the environment. Therefore, in order to reduce the pollution in the blank manufacturing stage, we should reduce the self-made blanks of small and medium-sized factories, establish professional casting and forging factories, and adopt efficient and pollution-free heating equipment and casting and forging equipment to improve the manufacturing accuracy of blanks

2.5 green processing and heat treatment of mechanical and electrical products

the level of mechanical processing in China is still quite low, especially in some small and medium-sized factories, machine tools from the 1960s and 1970s are still used, and CNC machine tools are only available in some large enterprises. It leads to low cutting efficiency, low machining accuracy, low material utilization and high energy consumption. It is the only way for all factories to improve the level of numerical control and try to use efficient equipment and tools for processing. However, due to the lack of funds and technology in small and medium-sized factories, CNC will go through a long period of time. Therefore, it is suggested that the economic numerical control system should be used to transform the existing machine tools, and the workers should be trained in numerical control technology

in addition, attention should be paid to the selection and use of coolant during machining. For example, in some factories, in order to improve the durability of the tool during gear hobbing, gear shaping, milling and other processing, the tool is treated with ion coating or coating, which greatly improves the cutting speed, while the coolant still uses the EP cutting oil used in the original low and medium speed cutting. Due to the insufficient cooling capacity and high volatility of cutting oil, the workshop is full of volatile oil mist, causing air pollution in the workshop. It is suggested to use semi synthetic and synthetic water-soluble cutting fluid to replace cutting oil

in the stage of heat treatment and surface coating treatment, the heating of workpiece during heat treatment is less polluted by electric heating and natural gas and gas heating, and the heating of coal and fuel oil is more polluted; Quenching, surface quenching, quenching and tempering and other heat treatments in quenching, different materials use different coolants. The pollution caused by oil cooling is large, while the pollution caused by water cooling is small. However, water cooling may cause cracking of some workpieces with complex shapes made of highly hardenable alloys. Therefore, it is necessary to study new heat treatment coolants with weaker cooling capacity than water without causing pollution. The friction coefficient (0.29~0.38) of semi-metallic materials on the workpiece is lower than that of non-metallic materials. When electroplating decorative and anti-corrosion materials, it is mainly caused by the pollution caused by the discharge of electroplating residue. First, the corrosive acid residue during acid pickling in the preparatory process; The second is the residual heavy metals and toxic substances (such as potassium cyanide, sodium cyanide, etc.) in the plating solution. Electroplating solution treatment agent shall be used for standard treatment

2.6 green packaging of mechanical and electrical products

in the product packaging stage, it is mainly to select appropriate packaging technology and materials and implement green packaging. At present, the packaging materials used in China are basically corrugated cardboard, wood board and plastic. Paperboard is widely used because it is easy to recycle, can be degraded and has little pollution. However, the early production causes greater pollution to the environment, and its strength is low, which is easy to cause damage to the packed items. Due to its high strength, wood is also widely used in the packaging of large mechanical and electrical products. However, because wood is a non renewable material, excessive use will lead to ecological imbalance due to the massive cutting of trees, and some pests will live in it, resulting in a large number of pests spreading and destroying the forest. Foreign countries strictly prohibit the use of wood packaging for imported products. Plastic products are also widely used as packaging materials, but they are not degradable after being discarded, which is easy to cause environmental pollution. country

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