Plastic powder by flame spray gun is heated to a molten state after the flame jet to the workpiece surface to form a spray coating technology.
Plastic flame spraying the surface of the main materials used to improve the physical, chemical and mechanical properties, and the role of both the surface decoration. glue stick Currently, the technology has been gradually applied to product manufacturing, equipment maintenance and preparation of anti-corrosion coating and so on. With the need for modernization of industries and plastic plastic flame spray technology will be more and more wide application of the flame.
Principles of a plastic flame spraying.
Plastics are used for flame spray thermoplastic and thermoset plastics. glue gun Thermoplastic when heated, the increase of temperature was gradually softened and molten state, will harden after cooling. At the same time, this process is reversible.
This feature of thermoplastic spraying is needed. Therefore, it is mainly used for flame spraying of the plastic is thermoplastic, which is the most widely used polyamide 1010, or 1010, as well as polyethylene, such as polyethylene PE.
Common feature of thermoplastics with low melting point, for example, the melting point of nylon 1010 is 200 - 210 degrees, the melting point of 123-130 degrees polyethylene; powder ignition temperature or decomposition temperature difference from the melting temperature smaller. Therefore, the flame spraying of plastic to be effective in controlling the flame temperature and heating degree on the plastic powder. To ensure that both the heating of the plastic particles in the molten state, but also lower than the ignition or decomposition temperature, or plastic powder will burn or deterioration. This is the key technology of plastic flame spray. Solution to this problem is in the original gas torch gas welding torch on the basis of oxygen - acetylene flame to add a layer of outside air (referred to as aerosol or air curtains), the flame directly heats the air, and then let the air in the heated plastic powder, which spray can achieve the required heating temperature to complete the spraying operation.
Second, plastic spraying process.
To be sprayed surface spray degreasing and cleaning the surface to be sandblasted --- --- --- flame preheating the surface to be sprayed plastic coating spray to reduce or eliminate stress treatment ---- --- cool wash (to be sprayed surface degreasing and cleaning should be considered part of the specific circumstances, generally divided into weight, and sperm washing. sperm washing, the commonly used acetone cleaning).
Spray application of the surface of the sand to be sucked shot blasting gun, air pressure 0.4 - 0.7MPa, sand the sharp white fused alumina, particle size 20 mesh. Blasting the surface to be sprayed should be carefully carried out, until the surface of uniform to be sprayed silver. Preheat the purpose is to improve the coating adhesion.
Three characteristics of plastic spraying technology and application.
(A) plastic spray technology features:
Spray plastic spray and other techniques and compared to other spraying process, and the following characteristics;
1, simple equipment, do not need large equipment and special purpose machine, oven and so on.
2, the process is simple, easy to master simple plastic flame spraying process, process continuity requirements is low, less parameters, the operator would only require a short training, can grasp, after several tests, can develop a reasonable process specifications.
3, abundant sources of material mainly of plastic material is flame spray powder materials, and other necessary support materials are not many, and some occasions, you can use instead of plastic materials precious metals such as copper, chromium and nickel.
4, high efficiency production efficiency of plastic spraying ten times higher than the plating to a few times, but generally do not need the vehicle before spraying, grinding and other machining, thereby reducing the processing time.
5, the heat of the workpiece when the workpiece small plastic spray the heating temperature is generally 130 - 250 `C or so, in this temperature range, the workpiece does not change the general characteristics of the heat treatment. In addition, compared with the welding, plastic spraying has little effect on the workpiece, can effectively prevent the thermal deformation of the workpiece. While the small workpiece in the welding, they were often prone to deformation.
6, wide range of applications using plastic coating can be in steel, cast iron, copper or aluminum and other metal surface to form a 0.1-0.5 mm thick coating can be used with dynamic and static sealing and leak-proof with or from, antiseptic occasions.
7, spray plastic spray coating layer with excellent performance impact strength, shear strength, toughness, resistance to repeated deformation of the fatigue strength are better than epoxy bonding. Corrosion resistance of plastic spray coating well, generally are not comparable to the metal. It also has good sound absorption, insulation and electrical insulation properties, can be used in a variety of special requirements of the occasion. Plastic spray coatings have excellent mechanical processing properties, can be various forms of mechanical processing.
Plastic spray coating finish when turning up to spend 8, grinding finish of flowers 12. Therefore, the size and geometry of the workpiece easy to guarantee. In addition, if the plastic coating layer by adding a variety of modified material that the spray coating significantly improved the physical and mechanical properties of a particular aspect, such as increased strength, increased wear resistance, increased thermal conductivity and so on.
8, the cost of low-cost plastic coating around the metal coating 1/6--1/8; vibration welding 1/3-1/5; chrome one to several dozen one-tenth.
9, the operating conditions are good plastic coating generally does not produce carbon monoxide, ozone and acid and other harmful gases, it does not produce arcing, and other harmful ultraviolet rays. Therefore, do not pollute the environment and harm the operator.
There are also some plastic spray shortcomings. The main disadvantage is the hardness of coating layer, less intense, less heat and thermal conductivity. For general nylon, plastic coating layer is only a maximum operating temperature of 100-150 degrees.
(B) plastic flame spray applications.
1, restore worn-out parts of various sizes bearing shaft installed the site, box bearing shell holes, the governor thrust disk, and other wear and tear, wear parts can be sprayed nylon or plastic cover, in order to restore the worn parts size.
2, for the bearing material by grinding and sliding bearings in various parts of the surface coating with nylon layer can effectively improve the bearing performance. Moreover, as nylon has good flexibility, can reduce the stress concentration, so that load distribution, so as to achieve reduced vibration and reduced noise. In practice, for moving with the pieces, and often wear to restore the size and layer coating by grinding together, the two spray coatings also play a role. If repair crankshaft bearings, camshaft bushings, water pump bearings and other machine tool guide.
3, repair corrosion, cavitation (cavitation) cylinder engine parts, water sets and other long-term contact with water, especially in coastal areas, seawater salt composition high, corrosion and cavitation phenomenon is very serious. Is the water pump impeller and pump the general case, the work will occur in the cavitation phenomenon. In these parts of the surface coating of plastic cover, can extend the life of parts. In addition, hull, organic farming (roll) part of the boat into the water spray plastic coating can also receive a good preservative effect.
4, as the sealing material sealing the pump casing, pump shaft seal parts of the distribution of pump valve disk and a variety of conical, cylindrical and planar valve sealing surface, can be sprayed nylon or plastic. After spraying of nylon or plastic, do not grind, just turning to the technical requirements can be achieved.
5, broken stick fill in the cast iron parts for the flow of the pores or loose texture caused by oil spills, leakage of the metal box, the body can be sprayed in the defect site, used to plug the holes and the eye socket, as used in the trachea, the water pipe, tubing plugging.
6 large-shaped insulating coating rectifier, welding machine, start the motor wires are relatively thick, the insulation is damaged, you can also use the spray coating method to repair. For some parts of local needs insulation, plastic coating to be more suitable. In addition plastic coating in the high-frequency, high-pressure situations, it can be applied.
7, shock, vibration absorbing material feed mechanism a lot of noise at work, poor working conditions, the operator gets tired easily. This could be in contact with the workpiece feed mechanism parts of spray coating, which can significantly reduce noise and improve working conditions.
8, decoration, rust-proof layer of various machine tools, ships, vehicles, handle, door handles and other control parts, usually decorated with the electroplating solution to rust problems.
9, insulation materials, some of the pneumatic tools, compressed air flow in contact with the operator will feel very cold pipes, especially in winter, the operator may even be frostbite. If the contact areas in the hands of nylon or plastic spray coating can greatly reduce the hazards of freezing on the operator.
10, paper size of the shaft and sleeve, size guide wheel. Can be applied plastic coating process.
11, oil, acid, reduction, cylinder size salt and chemical containers, plastic spraying process can be.
12, coastal preservation equipment, mining equipment corrosion, corrosion and other structural parts, plastic spraying process can be.
Four spraying plastic materials and modified materials.
(1) plastic material used in spraying.
A variety of thermoplastic materials such as polyethylene, nylon, and thermosetting materials such as epoxy resins can be used for spraying.
(2) modified material.
Spray in plastics, the plastic coating layer can improve the physical, mechanical, chemical and optical properties and change the color of the material, called the modified material. Often referred to as the modified functional filler material. A wide range of modified materials, a modified material can often play several roles, the use of which may have the purpose of highlighting a particular role. Such as graphite, tungsten disulfide, aluminum, copper, glass powder, quartz powder, paint, mica and other modified materials.