For the best powder coating results, the surface of the workpiece you will be spraying must be clean. The clean metal itself can be powder coated immediately, but it will not give you excellent durability and corrosion protection. Good pre-treatment allows the powder coating to better bond to the metal, withstand external weathering and prevent rusting of the workpiece. Pre-treatment can bring better results to the workpiece and you should always consider adding metal pre-treatment to the coating process.
The pretreatment method is divided into liquid processing and dry processing.
Hanna offers you reasonable and economical pretreatment methods to clean your workpiece.
According to the product size, different processing forms can be selected, the structure is reasonable and the ideal use effect can be achieved.
Depending on the quality and type of metal, different cleaning and pre-treatment methods should be considered. You should also be aware of the results you want to achieve and the requirements of your customers. The most common types of metal cleaning and pretreatment are water washing, degreasing, pickling, phosphating and sand blasting.
The form and characteristics of the pretreatment equipment:
1.Spraying type：Suitable for large pipes, long pieces and simple structure, generally adopts high structure to save ground space.
2.Submarine type：Suitable for all kinds of complex shapes of objects, the effect is good and save liquid.
3.Immersion Type：It is suitable for rusty serious workpiece degreasing and setting the trachea in the film groove. It can be adjusted between room temperature and 200 °C.
4.Shot blasting：For regular shape, etc., in the repair and shipbuilding industry, shot blasting (small steel shot) is often used in steel plate pretreatment (derusting before painting). Blasting with sand or shot peening is a good way to clean metal oxide scales, laser scales, rough welds or rusted steel.
5.Roller cleaning:The cleaning of casting parts is not only the use of shot blasting. For large parts usually need roller cleaning firstly, most of the sand on the surface is removed and then shot blasting or shot peening.
6.Sandblasting：Sandblasting is often used in the forming of ships or sections. It is not only rusting in the repair and shipbuilding industry, but also can be used to remove oil,which is very useful for painting. Sandblasting is commonly used for surface descaling of parts; for workpieces with high quality requirements for bonding surfaces, the surface must be treated with sand blasting.
A:Washing: Pressure washing, water washing or automatic cleaning is the most effective way to clean the metal before the next finishing stage. Steam cleaning or hot water helps to separate the oil and can be washed into the grooves or gaps of the workpiece.
B:Degreasing: Degreasing is the best way to clean the metal of oil, wax, or other substances to prevent the powder from sticking to the metal. For example, no degreasing pretreatment can cause difficulties in subsequent phosphating processes.
C:Pickling: Pickling metals with acidic product chemicals to promote adhesion of the powder coating to smooth or difficult to adhere to the metal. Aluminum is usually a very smooth substrate and therefore requires some surface treatment to remove oxidation and etch the surface.
D:Phosphating: Phosphating is used to improve the corrosion resistance of products. Iron phosphate is the most commonly used pretreatment method. This is a good way to improve powder adhesion and double or triple the powder's own corrosion resistance. It is the most common chemical pretreatment in the pure steel manufacturing process.
When designing the technology, it is necessary to select as much as possible the surface treatment process and method with high specificity, good treatment effect and low price according to the coating method, the material of the workpiece and the surface state. The surface treatment before painting is an important part of the coating. Thetreatment is good or bad, which not only affects the appearance of the workpiece, reduces the anti-corrosion performance, but also destroys the stability of the surface coating. Therefore, for the surface of the workpiece before painting,no oil, rust, no pretreatment drugs and phosphating sediments are required. If the degreasing and derusting is not clean, it not only hinders the formation of the phosphate film, but also affects the adhesion, decorative properties and corrosion resistance of the coating. The paint film is prone to defects such as shrinkage cavities and pinholes.
The washing in various stages of pre-treatment will have a major impact on the quality of the entire pre-treatment. If the cleaning is not clean, it will produce: 1. residual acid, phosphating liquid, flocculation of the resin in the paint liquid, stability deterioration; 2. Residual foreign matter (oil, dust), shrinkage, granules and other defects in the paint film; 3. Residual electrolytes and salts cause increased electrolysis reactions and pinholes,etc
Degreasing and derusting is the most important process in the surface treatment process, not only because the processing cost of the is the largest process in the entire surface treatment process, but the impact on the overall coating cost is very important. According to relevant user statistics, degreasing and derusting process cost accounts for about 1/2-1/3 the cost of the surface treatment, accounting for 1/6, 1/4 the total cost of the coating. At the same time, the processing quality of the degreasing and derusting process is guaranteed,the quality of the processing afterwards is relatively easy to obtain.
Our product advantages:
1. Adopt automatic conveying, which can increase production efficiency by 2-4 times than manual and semi-automatic production lines.
2. With automatic pretreatment, only one technician and two general workers are needed for the whole line, which can save a lot of manpower.
3. Spraying pretreatment can effectively reduce the length of the production line body, thus reducing the use of the site.
4. The submarine pretreatment can effectively reduce the length of the production line body, thereby reducing the use of the site, and can also clean the workpiece in all directions to ensure no dead angle.
5. The top of the shed body is designed with water seal to isolate the steam more thoroughly;
6. The shed body, cylinder block and spray pipe are all made of stainless steel and full welding to ensure the normal service life of more than 15 years;
7. The contours of each process section are provided with contoured baffles and matching transition sections to prevent cross-flow;
8. The top design has a wind trough, which can discharge the acid gas and vapor accumulated at the top in time.
What are your expectations for pretreatment?
1. Adsorption of powder coatings and metals?
2. Metal corrosion resistance?
3. High quality spray effect?
Contact us for more solutions.