Comprehensive overview of powder coating systems

China's labor force is very cheap ", so most enamel production is done by manpower However, when the quality of production requirements must be stable and consistent, automation equipment must be used even if the labor force is cheaper "Cheap" labor can also make costs high due to the potential for large amounts of waste and rework Most repetitive and dirty work should be done by machines as much as possible, because workers will be bored with this kind of mechanical work and reduce productivity The fundamental way out is to realize the overall transformation, change the mode of production, improve the level of labor productivity, stabilize product quality and reduce costs Now the powder spraying process is introduced for your reference only A cooperation: powder spraying system is a kind of cooperation among the buyer, powder manufacturer and equipment supplier These three parties are equally responsible for the successful operation of a powder spraying system ◇ the equipment supplier must be a long-term cooperator who can design and provide the buyer with the spraying equipment that can spray the workpiece efficiently and successfully under the actual production conditions, and recover the overspray powder He must be equipped with a well-trained service team, with sufficient spare parts, be able to install and maintain the equipment, and provide the buyer with operation and daily maintenance training ◇ the powder manufacturer can prepare and provide powder that meets the requirements of surface protection, and its particle size requirements and chemical characteristics are suitable for fluidization, transportation, charging and effective recycling ◇ the buyer has the most critical responsibility for the successful operation of the equipment According to the production requirements, the buyer should use the application and maintenance knowledge obtained in the training to carry out standardized operation In order to better select these three partners, and to make a choice in the shortest time, it is better to use the recommended powder when carrying out the working trial spraying in the equipment manufacturer's laboratory, so as to ensure the compatibility of the powder with the equipment and the effect of the powder spraying application and coating B powder spraying environment: powder spraying must be carried out in a clean environment Many large companies with large output have independent "powder spraying room", which has the following advantages: ◇ an independent area with "temperature adjustment" can be provided, and the ideal powder spraying environment can be achieved by installing air conditioner It is ideal to be used in high humidity climate area ◇ no ventilation equipment is required, and the maximum powder loading rate is exerted to better keep the powder in the powder room, which is particularly suitable for the factory workshop with large loading and unloading doors near the powder spraying area ◇ reduce the rate of waste products and ensure a clean and pollution-free production environment The dusting chamber is usually made up of three foam plates Positive air pressure is applied to the powder chamber and the humidity is kept constant to ensure uniform powder The powder room must be installed in a less than 18 m / sub area C facility ◇ a set of powder spraying system shall be equipped with stable power supply to protect application equipment and delicate circuit board components in filter element cleaning timer ◇ dry and clean air with appropriate pressure may be the most important factor, but it is also the least noticed factor by the buyer and supplier The largest power consumption component is the fan motor in the recovery system For the automatic system, the power is between 7.5-15kw The power consumption of other electric equipment is very small, including the power supply of the spray gun, the moving motor of the gun (0.5-1.0kw), and the powder equipment (about 0.5KW) The air from the air compressor contains water and oil Therefore, it is necessary to install air dryer and oil filter between air compressor and powder room, which can automatically remove moisture and oil, dry the input air and keep the air pressure at 90-100psi The dew point is kept at about 2 ℃ The pure air of the instrument (dew point temperature is 15 ℃) can not meet the requirements of the powder spraying system Powder coating has strong water absorption, which will reduce its fluidization, transportation and charging capacity Due to water vapor in the air with incomplete drying, it may cause damage to the filter element in the recovery system when it is blowback cleaned If the air dryer is far away from the powder room, or the air pipe passes through the air-conditioned area, it is better to install the combined filter in front of the powder room D the reliability and durability of pre-treatment powder coating are inseparable from the conditions of powder, metal substrate and workpiece The pre-treatment includes several processes, mainly using the clip nozzle: ◇ clean the metal surface, remove the greasy and dirt formed in the forming process ◇ remove the surface rust and soak the turbid metal with acid solution to improve the combination fastness of powder and workpiece ◇ before powder spraying, spray a layer of antirust layer on the surface of the workpiece to prevent the workpiece from rusting due to the accidental damage of the spraying surface Most of the monochromatic metals are treated with iron zinc "phosphating" for anticorrosion, while the non-ferrous metals are usually treated with chromate The whole pretreatment process usually consists of three to five processes E hanging chain is often used in large factories that manufacture similar parts of hanging chain and hanging appliance, and the workpiece is transported from the front treatment to the powder room curing furnace If the workpiece is not particularly large or heavy, the "monorail" hanging chain is often used This type of catenary suspends the workpiece with a single structural beam, and transports the workpiece at a constant speed from the continuous conveying chain The catenary speed is determined by the speed of the slowest process If the space of the factory is limited, or the workpiece is heavy, large and long, P & & F catenary can be used The initial investment of P & & F type catenary is high, but its vertical and horizontal travel can be adjusted, which can match with the slower process, and can stop a workpiece at a certain station to operate it, and then return to normal transportation High temperature resistant lubricating oil and / or ventilation pipe shall be used for the catenary passing through the curing furnace ◇ the metal hanger used to hang the workpiece for powder spraying may be the most important factor in the initial investment cost and daily operation cost when establishing a new system ◇ the denser the workpiece is hung on the catenary, the lower the linear speed is Generally speaking, the lower the catenary speed is, the lower the initial input cost and daily operation cost of the whole system is Enamel spraying line has two sets of conveying chains and hangers, one for pretreatment / powder spraying and the other for oven drying The workpiece is manually moved from the front processing / spraying conveyor chain to the hanging chain of the oven which can bear the high temperature in the enamel oven Another reason for using two sets of conveyor chains is that when the conveyor chain passes through the powder room, it will be coated with a layer of enamel powder When it passes through the oven, the enamel powder on the hanging appliance will melt and stick to the hanging appliance Before the next use, the solidified enamel powder on the hanging appliance must be removed In the actual production process, many enterprises put the hanger in the final consideration, resulting in the expensive and inefficient powder spraying system Based on the weight, size and shape of the workpiece, it is generally considered that more hangers can be used to increase the hanging density and reduce the cost of each workpiece High density hanging has the following advantages: 1 Reduce the cost of a single workpiece The cost is mainly related to the pretreatment system For drying and curing ovens, the cost of passing one workpiece and one thousand workpieces in a given period of time is the same 2 Improve the powder loading rate in the powder room Most of the powder is attached to the workpiece, while only a few enter the recovery system 3 Improve the uniformity of the film thickness of the workpiece to reduce the fat edge and dead angle The design, construction and cleaning of hangers are very important for the operation of powder spraying process Efficient powder spraying depends on the electrostatic attraction between the charged powder particles and the workpieces to be coated, which are connected to the conveying chain through the hanger and grounded Poor design and manufacturing, pasted with powder will seriously hinder the work pieces on the powder, resulting in a large number of manual spray, high scrap rate, but also need to clean the powder room frequently F powder spraying system powder spraying system includes powder room, which is a closed space for powder spraying operation on workpieces Because the powder room structure and the design of the powder room air flow are very important for the powder spraying operation, the powder room must be customized according to the needs of customers The size of the largest piece to be painted and the method of spraying must be considered The powder room is usually composed of stainless steel base plate, powder room top and powder room wall The powder room top and powder room wall are usually made of stainless steel plate or translucent plastic such as polytetrafluoroethylene 1 Spray plastic steel plate is the cheapest When it is used with translucent plastic plate to build powder room, it is very economical and can be used reliably for a long time 2 The powder wall made of stainless steel is very popular in China, because it is very durable and can maintain a good appearance for a long time Matte stainless steel plate (such as 3042b) is not obvious for scratches, so it is very common Polished stainless steel plate is beautiful in appearance However, due to too strong reflection of light, it will cause difficulties in manual re spraying and lead to "excessive cleaning" during color change 3 Solid polypropylene is very popular in North America It can penetrate natural light and is not as easy to stick powder as steel powder wall It is better to use polypropylene to make powder roof The powder top is the most difficult to clean area in the powder house This material is not easy to stick to powder Only a few fluorescent lamps are hung above the outside of the powder room, and the powder layer can be well lit Some customers require to use stainless steel powder roof and install the fluorescent lamp in the powder room Many users' practice has proved that the lamp shaft will form a scattered large shadow in the powder room At the same time, the fluorescent lamp will absorb the powder, so it needs to be cleaned frequently The size of powder room is designed according to the size of the coated workpiece For large workpieces, if the linear speed is high, they need to be equipped with large powder room and large recycling system In general, if the coated workpieces are very high (higher than 180mm), customers should consider rotating them 90 degrees to make them relatively shorter and enter the powder room for spraying This is very helpful to reduce the cost of powder room, curing furnace and pre-treatment system, as well as the operation cost If customers want to use automatic spraying, they must consider purchasing gun movers At the same time, the powder room should be equipped with an "automatic gun slot" so that the gun can move up and down Many workpieces cannot be painted 100% automatically Usually, a manual operator is needed to paint the Faraday area This can be done by setting a manual station on the powder room In China, it is usually used to spray the workpiece automatically first, and then spray the missing part manually The practice in North America has proved that if the manual position is placed between the automatic spraying, the spraying effect is better In this way, the operator can better observe the parts to be repainted, and spray appropriate amount of powder, instead of spraying excessive powder like putting the manual station at the end Recovery system the recovery system is a mechanical device used to collect the powder particles in the air flow of the powder room, separate them from the air flow and recycle the powder The recovery system uses fans to extract the air flow from the powder room at an average rate of about 100-120fpm The powder air flow not adhering to the workpiece is