Occupational hazards in the machinery industry

Mechanical manufacturing is an old and young discipline and the foundation of various industries. The level of machinery manufacturing is an important indicator of the level of industrialization and the degree of development of the country. The machinery manufacturing industry involves a wide range of industrial workers and the team is huge. According to incomplete statistics, there are about 150-200 million laborers in the machinery manufacturing industry in China. The basic production process is casting, forging, heat treatment, machining and assembly. So, what are the occupational hazards in the machinery manufacturing industry? The machinery manufacturing industry covers a wide range of industries, including the manufacture of various types of machinery such as transportation tools, machine tools, agricultural machinery, textile machinery, power machinery and precision instruments. There are generally foundry, forging, heat treatment, machining and assembly workshops. The hazards are about the same.

First, casting:

Can be divided into two major categories of manual and mechanical modeling. Manual styling refers to the process of major operations such as compacting sand, lifting molds, trimming, and closing boxes by hand. Labor intensity is high. Workers are directly exposed to dust, chemical poisons, and physical factors. Occupational hazards are large. Case 1 occurs in this production environment. The mechanical modelling has high productivity, stable quality, low labor intensity of the workers, less opportunity for workers to come into contact with dust, chemical poisons and physical factors, and occupational hazards are relatively small.

1. Dust Hazard: There are a lot of sand and dust in the molding and sand casting of the castings. The nature of the dust and the size of the hazards are mainly determined by the type of sand. If the quartz sand is used for modeling, the free silica content is high and its harm is harmful. maximum. In 2005, according to our detection of the dust concentration in the workplace of a molding workshop of a machine factory, the result was 27.5-62.3 mg/m3, with an average of 39.5 mg/m3.
2. Toxic substances and physical factors Hazard: The sand and sand cores are dried, smelted and poured to produce high temperature and heat radiation; if coal or gas is used as fuel, carbon monoxide, sulfur dioxide and nitrogen oxides will also be produced; if high frequency induction is used When the furnace or microwave oven is heated, there are high-frequency electromagnetic fields and microwave radiation.

Second, forging:

Forging is the application of external force to the billet to cause some or all of the billet's plastic deformation, thereby obtaining a forging processing method.
1. Physical hazards: Noise is the most hazardous occupational hazard in the forging process. Forging hammers (air hammers and pressure hammers) can generate strong noise and vibration. They are usually pulsed noises with a strength of more than 100dB (A). In 2005, according to our noise test for a forging workshop of a machine factory, the result was 83-100.2 dB(A) with an average of 92.08 dB(A). Punch and shearing machines can also produce high-intensity noise, but their strength is generally lower than that of a forging hammer.

The furnace temperature is up to 1200°C, and the forging temperature is also between 500-800°C. High temperature and strong radiant heat can be generated in the workplace during the production process.
2. Dust and poison hazards: Forging, forging, and forging processes can produce metal dust, coal dust, etc., especially in the fuel industry furnaces. The combustion forge can produce harmful gases such as carbon monoxide, sulfur dioxide, and nitrogen oxides.

Third, heat treatment:

The heat treatment process is mainly to change the properties (hardness, toughness, elasticity, conductivity, etc.) of the metal parts without altering the shape, and achieve the required performance in the process, thereby improving the product quality. Heat treatment includes normal processes such as normalizing, quenching, annealing, tempering, and carburizing. Heat treatment can generally be divided into ordinary heat treatment, surface heat treatment (including surface quenching and chemical heat treatment) and special heat treatment.

1. Toxic gas: A variety of auxiliary materials such as acid, alkali, metal salt, nitrate and cyanide, etc. are required for heat treatment processes such as normalizing, annealing, carburizing, and quenching of mechanical parts. These excipients are substances that have strong corrosiveness and toxicity. When cesium chloride is used as the heating medium and the process temperature reaches 1300°C, a large amount of cesium chloride evaporates, resulting in helium chloride dust contaminating the workshop air. During the chlorination process, a large amount of ammonia is discharged into the air of the workshop; during carburizing, cyanogen Chemical processes such as cyanide salts (potassium ferrocyanide, etc.) are used; nitrogen oxides are generated from the molten salt of the nitrate bath in the salt bath and the workpiece. In addition, organic solvents such as methanol, ethanol, propane, acetone, and gasoline are frequently used in the heat treatment process.
2, physical hazards: normalizing mechanical parts, annealing. Carburizing, quenching and other heat treatment processes are carried out at high temperatures. Various heating furnaces, salt baths and heated work in the workshop are all heat sources. These heat sources can cause high temperature and strong heat radiation in the working environment. Various motors, fans, industrial pumps, and mechanical operating equipment can generate noise and vibration. However, the noise intensity of most heat treatment plants is not large, and noise exceeding the standard is less common.

Fourth, mechanical processing:

The use of various machine tools for metal parts of the car, planing, drilling, grinding, milling and other cold processing; in the mechanical manufacturing process, usually through the casting, forging, welding, stamping and other methods of manufacturing metal parts of the blank, and then through the cutting process Made of qualified parts, and finally assembled into a machine.

1. General mechanical processing: Occupational hazards in the production process are relatively small, mainly the emulsion used in metal cutting and the effect of cutting on workers. The commonly used emulsion is an emulsion composed of mineral oil, naphthenic acid or oleic acid and alkali (caustic soda). Due to high-speed transport of the machine tool, the emulsion splashes, and it can easily contaminate the skin, causing skin diseases such as folliculitis or acne.

During the machining process, a large amount of metal and mineral dusts also occur during rough grinding and fine grinding. Artificial grindstones are mainly made of corundum (aluminum oxide crystals), in which the silica content is very small, and the natural grindstone contains a large amount of free silica, which may lead to aluminum pneumoconiosis and silicosis. The mechanical noise generated by most machine tools is between 65-80dB(A), and the phenomenon of excessive noise is rare.
2. Special mechanical processing: Occupational hazards related to special machinery processing are related to processing tools; for example, metal dust produced by electric discharge machining, high temperature and ultraviolet radiation of laser processing, etc.; electron beam X-ray and metal dust, etc.; metal dust exists in ion beam processing. , UV radiation and high-frequency electromagnetic radiation, if there is a tungsten electrode, there are ionizing radiation hazards; electrolytic processing, liquid injection processing and ultrasonic processing are relatively less harmful. In addition, the equipment operation generates noise and vibration.

Fifth, mechanical assembly:

Simple mechanical assembly process has few occupational hazards, and the hazards are basically the same as general mechanical processing. However, the occupational hazards in the complex assembly production process are mainly related to the special assembly process. If you need to use all types of electric welding, there are occupational hazards of electric welding; if you need to use adhesives, there is the problem of occupational hazards of adhesives. If you need to use the painting process, there is the occupational hazard problem of the painting process.

Sixth, protective measures:

Occupational hazards in the machinery manufacturing industry are mainly concentrated in the dust hazards in the foundry production process (Case 1), organic solvent hazards such as benzene and homologues in the coating production process (eg Case 2), and welding (smoke) dust in electric welding operations. Occupational hazards (case 3), for this reason, the problem of occupational hazard protection in the machinery manufacturing industry lies in:

1. Reasonable layout: In the layout of the workshop, consideration should be given to reducing cross-contamination of occupational hazards. For example, the smelting furnace in the casting process should be placed outdoors or away from public places where people are concentrated; riveting and welding, (painting) painting processes should be arranged separately.
2. Dustproof: Casting should use sand with low free silica content as much as possible, and reduce the manual modeling and sand cleaning operations. Sand cleaning is the highest concentration of dust in foundry production. It should be protected in a key way. For example, a high-powered ventilation and dust removal system should be installed and wet spraying operations should be carried out to reduce the concentration of dust in the air in the workplace. And do a good job of personal protection, wear dust masks that meet the relevant national standards.
3. Anti-virus and emergency rescue: Closed measures or installation of local ventilation detoxification devices shall be used for equipment that may generate chemical toxicants during heat treatment and metal melting. For workplaces that produce high concentrations of carbon monoxide, hydrogen cyanide, formaldehyde and benzene, and other highly toxic gases, such as certain special quenching, painting, and using adhesive positions, an emergency rescue plan for acute occupational poisoning accidents should be developed and warning signs set up. .
4. Noise control: Noise is one of the major occupational hazards in the machinery manufacturing industry. Noise control mainly includes the treatment of high-intensity noise equipment such as casting, forging, pneumatic hammers, air compressors, machining, grinding, punching, cutting, cutting, and cutting. High-intensity noise sources can be centrally arranged and sound-proof screens installed. Aerodynamic noise sources should be silenced at the intake or exhaust ports. The soundproof and sound-absorbing treatment shall be adopted for the centralized control room and post operation room. Noise prevention earplugs or earmuffs should be worn in workplaces where the noise intensity exceeds 85dB(A).
5. Vibration Control: Vibration is a relatively common occupational disease risk factor in the machinery manufacturing industry. For vibration equipment such as riveting, forging presses, sand tamping machines, sand falling, sand cleaning, etc., vibration reduction measures or rotation operations shall be adopted.
6, RF protection: should choose the appropriate shielding and shielding materials, to produce high-frequency, microwave and other radio frequency radiation shielding equipment or distance isolation protection and time protection.
7, heatstroke cooling: should be doing casting, forging, heat treatment and other high-temperature workers in summer heat and cooling work. It is advisable to adopt comprehensive measures in engineering, health care, and labor organization management, such as the rational arrangement of heat sources, supply of cool salty beverages, rotation operations, and air-conditioning of centralized control rooms and operation rooms.

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