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Definition of A Powder Coating Line
A powder coating line is a production line that goes through the following series of operations, including pre-treatment, powder coating, heating, and curing processes.
The Powder Coating Line Equipment
The components of the painting line mainly include pre-treatment equipment, powder spraying system, painting equipment, oven, heat source system, electric control system, hanging conveyor chain, etc.
1. Pre-treatment equipment: spraying multi-station pre-treatment unit is a common equipment for surface treatment, the principle is to use mechanical flushing to accelerate the chemical reaction to complete the process of oil removal, phosphating, washing, and so on.
2. Powder spraying system: the key part of the powder spraying system is recommended to use imported products, powder spraying room, electro-mechanical lift, and other components are all localized.
3. Spraying equipment: the production of paint spraying, the use of oil spraying room, water curtain spraying room, widely used in bicycles, automotive steel plate springs, large loaders surface coating.
4. Drying oven: The drying oven is one of the important pieces of equipment in the painting production line, its temperature uniformity is an important indicator to ensure the quality of the coating.
5. Heat source system: Hot air circulation is a more common heating method, which uses the convection conduction principle to heat the oven and achieve the drying and curing of the workpiece.
6. Electrical control system: Centralized control can use a programmable controller to control the host, according to the control program prepared for each process for automatic control, data acquisition, and monitoring alarm.
7. Suspension conveyor chain: A suspension conveyor is a conveyor system for industrial assembly lines and painting lines.
Powder Coating Line Process Operation
- Put in the product: put the painted object into the plug-in and start working.
- Electrostatic dust removal: to remove the oil and dust brought by injection molding.
- Pre-heating: to give the painted object a little temperature for better coloring.
- Primer spraying: the color of the plastic itself is covered, for the production of the required color first primer spraying.
- Drying: through the temperature of the IR area in the tunnel, the semi-dry state, for the next spraying for preparation.
- Surface spraying: spray the color required for coloring.
- Smooth and dry: smooth and dry through the tunnel.
- UV spraying curing: and UV coating with the use of UV365nm light in the coating requirements of the amount of color (800 ~ 1200mj) for instant curing.
- Shipment and check packaging.
Powder Coating Line Process Management
The painting line process is divided into pre-treatment, powder coating, heating, and curing. To manage this process, the following points need to be noted.
1. Production Management of The Pre-treatment Section of The Powder Coating Line
Pre-treatment has a manual simple process and automatic pre-treatment process, the latter is divided into automatic spraying and automatic dipping spraying two processes. The surface treatment must be carried out to remove oil and rust before the workpiece is powder-coated. In this section, there are more liquids used, mainly rust remover, grease remover, surface conditioning agent, phosphating agent, etc.
In the pre-treatment section of the painting line or workshop, the first thing to note is the development of the necessary strong acid and alkali purchase, transportation, storage, and use system, to provide workers with the necessary protective clothing, safe and reliable loading, handling, configuration apparatus, as well as the development of emergency measures in the event of an accident, rescue methods. Secondly, in the pre-treatment section of the painting line, as there is a certain amount of waste gas, waste liquid, and other three waste materials, so in terms of environmental protection measures, it is necessary to configure extraction and exhaust, liquid discharge, and three waste treatment devices.
The quality of the pre-treated workpiece varies due to the pretreatment liquid and the process of the coating line. The workpiece is better treated, the surface oil, rust to exhaust, to prevent a short period again rust, generally should be in the pre-treatment after a few processes, phosphate or passivation treatment: before spraying powder, should also be phosphate workpiece for drying, to its surface moisture. Small batches of a single production, generally using natural drying, sun drying, air drying. For large quantities of flowing work, generally take low-temperature drying, using ovens or drying channels.
2. Powder Coating Organization of Production
For small batches of workpieces, manual powder spraying devices are generally adopted, while for large batches of workpieces, manual or automatic powder spraying devices are generally used. Whether it is manual powder spraying or automatic powder spraying, it is very important to keep the quality level. It is important to ensure that the sprayed workpiece is evenly powdered and of uniform thickness to prevent defects such as thin spraying, missed spraying, and rubbing off.
In this process of the coating line, attention should also be paid to the hook part of the workpiece, before entering the curing process, the powder attached to it should be blown off as far as possible to prevent the curing of the excess powder on the hook, some of the difficulties in removing the remaining powder before curing, the hook should be stripped in time to ensure that the hook has cured the powder film, to ensure that the hook conducts well, to facilitate the next batch of workpieces easy to powder.
3. Production Management of The Curing Process on The Powder Coating Line
This process should pay attention to the following matters: if the workpiece is sprayed, if it is a small batch of single-piece production, pay attention to prevent touching down the powder before entering the curing oven, if there is the phenomenon of powder rubbing, the powder should be sprayed in time. When baking strict process and temperature, time control, pay attention to prevent color difference, over-baking or too short a time caused by insufficient curing.
For large quantities of automatically transported workpieces, in the same way before entering the baking channel to carefully check whether the leakage of spray, spray thin or local rubbing powder phenomenon, such as the discovery of unqualified pieces, should be good to prevent the entry into the baking channel, as far as possible to take off the re-spray. If individual workpieces are not qualified due to thin spraying, they can be re-sprayed and cured again after curing out of the baking tunnel.
Classification And Characteristics of Powder Coating Lines
- Air Coating Line
Air painting line is the most simple painting equipment, it does not require high environmental needs when painting and does not require special disposal, but this kind of painting line does not have a high utilization rate for paint goods, and the painting effect is relatively poor. It is not suitable for fine equipment painting, such as car exterior paint. The air coating line is relatively large in terms of pollution to the environment compared to the two other types of coating lines, and the air coating line does not dispose of the air during the spraying process, so the appearance of the goods after spraying is simple to occur in the air.
Therefore, the air coating line is a kind of coating equipment that is not conducive to environmental protection and has a low working efficiency.
- High-Pressure Airless Coating Line
Compared to the air coating line, the high-pressure airless coating line has a higher spraying effect. Because it has made special treatment of the spraying environment, it has improved the effect of spraying goods. The airless coating line can improve the adhesion of the paint and extend the life of the layer. The coating line is a relatively environmentally friendly coating line compared to the air coating line, and it is also a coating machine with a relatively good coating effect. However, as the high-pressure airless coating line needs to be sprayed under airless conditions, the demand for the environment is relatively high, which also results in the application scale of the coating line being bounded.
- Electrostatic Spraying Equipment
Electrostatic spraying is a high-efficiency, high-quality spraying machine that can be used in combination with air and mixed air spraying and incorporates the strengths of each. The electrostatic coating line is through an electrostatic field, with negative ions of paint sprayed on the workpiece goods, through the effect of each other floating in the appearance of the workpiece, and then constitute a kind of protective layer. Compared to air coating lines, high airless coating lines are more environmentally friendly, more intelligent, and more economical in terms of paint products.