How good is the pre treatment of spraying! 50

This is hard to say, 1. First of all, if you have not obtained an environmental protection certificate (sewage treatment), it is best not to use chemical rust removal.

2. You have to look at what kind of products are processed, for example, the structure of your product is more complex and inconvenient for polishing, then you had better use shot blasting or chemical treatment;

3. The cost should be compared with the income of local workers and the water and electricity required for processing and changing products. (You have a little more manpower input for polishing the painting, and you have a little more money for the potion if you remove rust chemically).

4. According to the current situation you described, you basically can't do phosphating treatment, even if you treat the quality of your products.

It is recommended to polish after grinding, and the groove can be degreased with some degreasing agent (laundry detergent is sufficient) for degreasing. Wash in two troughs with clean water. This way you should be able to hide the effect of spraying; Drawing:

If it's good, you should be able to pass level 1, impact: it depends on your powder condition; Salt spray experiment: powder can basically be satisfied.

Our factory does a listed company's equipment sheet metal spraying, last year because environmental protection is not allowed to drain, so we tested the three of several enterprises.

1. Quadruple. First, six-in-one phosphating, I can you:

1.These phosphating are all iron-based phosphating, not zinc-based phosphating.

2.Adhesion over 100 grids, impact test, a small part can meet the standards of our factory.

3.Long-term use stability is a key point, found that some enterprises, just start the test can be, but the actual production will be unstable, hanging white ash powder and other problems occasionally appear, is inexplicable, they manufacturers can't get it, need to re-slot. On the whole, some companies can use this product, but they need to find a regular company with stable quality and reliable reputation.

We have suffered a lot of losses, and some companies seem to be very cheap, but the actual weight, concentration, and quality are different every time.

The products of several factories have been used in turn, and now, the final choice of Party B's environmental protection 3 exempt oil phosphating liquid, has been used for more than half a year. Their product is a concentrate, and the concentration and actual weight are the same for each delivery, and the powder is sprayed on the line after soaking in a pool. The adhesion has been OK, their products are a little different from others, the taste is slightly fragrant, and the staff also prefer to use it.

It's just that it's not easy to cut, you can evaluate it yourself, and you can share it if you find something good.

1.After sanding, it can be painted directly, why do you need to remove rust from the drum after sanding? Is it rust again after sanding? If so, there is a problem with your production plan.

2.There are three slots of pickling line, and this process should not be used as soon as possible, otherwise the product quality is difficult to guarantee, and the pollution is serious.

3.From the cost point of view, if there is sewage treatment after pickling, the cost of the pickling process is high; If there is no sewage treatment, the cost of sanding is slightly higher.

Now our factory uses Party B environmental protection 3 free oil phosphating liquid, six-in-one, 1:62 slotting, 1 and a half years, no water has been drained, and the adhesion is OK.

There are three kinds of spraying pretreatment processes, and we take thermal spraying surface pretreatment technology as an example to make a brief introduction.

Thermal spraying surface pretreatment technology process 1: surface pretreatment

The purpose of surface pre-processing is to make the surface of the workpiece suitable for coating deposition and increase the bonding area; In addition, it is beneficial to overcome the shrinkage stress of the coating. Some parts of the workpiece are pre-machined accordingly to disperse the local stress of the coating and increase the shear resistance of the coating. A common method is to cut fillets and pre-make coating grooves.

Rough turning of threads on the surface of the workpiece is also one of the commonly used methods, especially when spraying large workpieces, it is often used to turn the threads to increase the area of the spike. There are two problems that should be paid attention to when turning threads, the first is that the thread section should be suitable for spraying, and the rectangular section or semicircular section is not conducive to the combination of coatings. In addition, the thread should not be too deep, otherwise it will be sprayed too thick and the cost will increase.

It is also possible to "kneurple" the coated surface or to combine turned threads and knurling.

Thermal spraying surface pretreatment technology process 2: surface purification

Methods such as solvent cleaning, lye cleaning and thermal degreasing are usually used to remove oil stains from the surface and maintain cleanliness. Commonly used cleaning solvents are: gasoline, acetone.

Carbon tetrachloride and tricocycladoxene chlorohexene. For large repair workpieces, lye cleaning is often used. Sodium hydroxide is generally used for lye.

or sodium carbonate, which is a less expensive method.

Thermal spraying surface pretreatment technology process 3: sandblasting roughening treatment

Sandblasting creates a uniform and uneven rough surface on the cleaned surface to facilitate the mechanical bonding of the coating. The clean sand particles driven by clean compressed air can be sprayed on the sensitive surface of the workpiece, which can produce compressive stress on the surface of the substrate, remove the surface oxide film, and produce lattice distortion on part of the surface metal, which is conducive to the physical bonding of the coating. The base metal is sandblasted to obtain a clean, rough and highly active surface.

This is an important pre-treatment method. The commonly used abrasives for sandblasting are: white fused alumina (pure alumina, brown corundum.

Alumina + iron oxide, silica sand.

Wait. White corundum sand has high hardness, low crushing rate and good sandblasting effect.

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Answer, the problem of spraying is that the viscosity of the paint is too low due to the excessive amount of thinner, and the countermeasure is that when the coating is applied vertically, the coating film flows downward, and the convex part is the phenomenon, and the coating effect is not good. Common coating defects and countermeasures 1. Vertical flow:

When coating on the vertical surface, the coating film flows downward, and the phenomenon of convex parts is not good. Causes: It may be too thick or too high a concentration of shabu-shabu at one time, too much spray gun gas, too much paint, and the nozzle is too close to the painting.

Countermeasures: dilute the excessive viscosity, adjust the spray gun gas, pressure, appropriate pressure and output, and the distance is appropriate (15cm-20cm). 2. Brush marks:

After brushing, the coating film is uneven in strips. Cause: During construction, the viscosity is too high, and the wet film is recoated.

Countermeasures: Adjust the paint to the appropriate viscosity, and when reapplying, the bottom film should be basically dry, and the brush should not be too forceful. 3. Pinhole:

After the coating film is dried, the coating surface is in the form of small holes, and the small holes are formed by the substrate on the surface. Causes: The coating film is sprayed too thickly, the drying temperature is too high, the coated object has moisture, dust paint, etc.

Countermeasures: The thickness of the spray should not be too thick at one time, the appropriate drying temperature should be controlled, and the coated object should be kept free of dust. 4. Dry spraying phenomenon:

When spraying, the atomized paint is partially dried before it reaches the object to be painted, and when it is re-attached, it forms a rough coating surface. Causes: The distance between the spray gun mouth and the coated object is too far during spraying, and the air pressure of the spray gun is too high.

Countermeasures: Adjust the distance between the nozzle and the object to be coated by about 15cm-20cm, and adjust the pressure to. 5. Albinism:

The surface of the coating film is pale and has no expected luster. Causes: Humidity is too high (above 80), the thinner grows too quickly, and the coating is too cold.

Countermeasures: The humidity of the coating should be more than 80, or 5-10 anti-white water can be added, and the diluent that dries too quickly should be used, and the coated object should not be too cold. 6. Peeling and falling off:

The coating film falls off the surface of the coated object in pieces. Causes: The substrate has wax, oil, water, etc., the lower coating is not dry and then coated, the substrate is too smooth, the wall has been powdered and rotated or inferior soil is used, and the attachment of tung is not enough.

Countermeasures: Completely remove the substrate to ensure that there is no wax, oil, water and other debris, and the old walls that have been pulverized must be eradicated; Use oil-based soil or water-based soil to flatten, completely dry and then coat the film. 7. Orange peel phenomenon:

The coating film is not smooth, like an orange peel-like concave and convex coating film. Causes: the diluent evaporates too quickly, the spray pressure is uncertain or the pressure is too large, the blowing distance is too far, the spraying is too thick at one time, and the bottom layer is not dry before coating.

Countermeasures: Use an appropriate diluent, control the pressure of the spray gun, the distance should be moderate, do not apply thick at one time, and the bottom layer is completely dry before applying. 8. Fading:

After a few days of coating, the color partially fades, and the color is not uniform. Causes: The new ones are not completely dry, and the alkalinity is too heavy, causing the color to fade.

Countermeasures: The new wall should be painted after one month, and the base should be treated with epoxy primer. 。

Safety technical measures for spraying operations: Spraying operators must be trained in safety technology, and are not allowed to work without training. All painting equipment and tools must be thoroughly inspected before painting work to confirm that there are no problems.

3.The ventilation and purification of the painting workplace shall meet the requirements of GB 6415. During the operation, the safety technology department of the enterprise should set up a special person to regularly measure the oxygen content and combustible gas concentration in the air in the confined space, the oxygen content should be more than 18%, and the combustible gas concentration should be less than 10% of the lower limit.

The cabin painting operation is equipped with at least two people to operate together, and if the work site is too narrow to accommodate only one person, the other person should be responsible for supervision. Painting at height should comply with the "Safety Regulations for Work at Height in Ship Construction". When multiple spray guns are operated at the same time, the spacing must be widened (about 5m) and sprayed in a certain direction and in the same direction.

If the equipment fails or there is an abnormal situation, the cabin personnel will be notified to withdraw from the cabin first, and the maintenance personnel will be overhauled. The high-pressure jet and leakage of airless painting will lead to serious injury accidents, and it should be done during the operation: the nozzle of the spray gun is not allowed to be pointed at others and oneself at any time; Do not touch the nozzle with your fingers, or peek into the muzzle; When cleaning the spray gun, it is necessary to cut off the pump drive source, release the pressure, and make the safety device sell to the spray gun before cleaning; When the spray gun is out of service, the safety latch must be pinned

After the operation is completed, the gun must be removed from the cabin in time and ventilation must continue until the paint film is completely cured. After the painting operation is completed, the workplace should be cleaned up in time, and the remaining paint and solvent should be sent back to the warehouse in time. Operators must wear protective masks, rubber gloves, goggles and other related protective equipment.

Precautions for painting:

The application of the paint must be carried out within the indoor temperature required by the product. Different products have different temperature requirements, which can be found in the product packaging or manual.

Each process is made sure to be dry before proceeding with the second process.

Use paints of the same substrate and do not mix different types of paints to avoid adverse reactions.

During construction, safety protection measures should be taken, such as wearing masks.

Maintain ventilation in the room to prevent poisoning.

When using corrosive materials such as tena water, wear rubber gloves.

Do not smoke or use open flames on the construction site to prevent fire or**.

Avoid forced construction in conditions of high humidity or cold.

If there are gaps in the ceiling or wooden partition that need to be covered, they can be treated with putty and then pasted with high-quality anti-crack tape; Cracks in the wall can be scraped open and filled with plaster, and then applied with high-quality anti-crack tape. The top coat is then painted.

Insist on buying paint from large shopping malls or experts to prevent counterfeiting, although ** will be slightly higher, but at least the quality will be guaranteed.

Before spraying, it is necessary to check whether the air pressure of the spraying is normal, and ensure that the filtration system is clean; Check the air compressor and the oil booth water dust separator to keep the paint hose clean.

Spray guns, painting hoses and paint mixing tanks should be stored in a clean place; In addition to dusting with a blow gun and a sticky dust cloth, all other pre-spraying processes should be completed outside the paint room; Only spraying and baking processes can be carried out in the paint room, and the door of the paint room can only be opened when the vehicle enters and exits, and the air circulation system during spraying must be activated when the door is opened to generate positive pressure to ensure that the dust outside the room cannot enter the room; You must wear designated spray clothing and safety protective equipment to enter the paint room for operation; When carrying out the baking operation, the flammable materials in the paint room must be taken out of the room; Non-essential personnel are not allowed to enter the paint room.

Didn't understand the landlord's explanation?

Common problems and solutions of spraying operations:

1.Phenomenon: Granulation.

Causes: The job site is unclean, and dust is mixed into the paint; If the paint is left for too long after mixing, the paint and the curing agent have produced copolymer particles; The oil output of the spray gun is too small, and the air pressure is too high, so that the paint atomization is poor or the spray gun is too close to the surface.

Solution: Clean the paint booth and cover the paint bucket; The paint is well blended and should not be left for too long; Adjust the gun to make it in the best working condition, and make sure that the muzzle is 20-50cm away from the object surface.

2.Phenomenon: Vertical flow.

Causes: Excessive thinner makes the paint viscosity too low and loses its viscosity; The oil output is too large, too close to the object surface or the spray operation is too slow; Too much fuel per injection, too thick or too short between resprays; The surface of the object is uneven, especially the shape of the streamlined body is easy to spend.

Solution: Proportioning according to requirements; Control the amount of oil output, ensure that the paint is separated and improve the running speed of the spray gun; Each spray should not be too thick, and it is best to master the interval painting time in two times; Control the amount of oil output and reduce the thickness of the paint film; Mix according to the instructions for use.

3.Phenomenon: Orange peel.

Reason: too much curing agent, so that the paint film dries too quickly and reacts violently; The spraying air pressure is too large, and the paint film is blown so that it cannot be leveled; The temperature at the job site is too high, so the paint film should be violent.

Solution: Proportionate according to the instructions for use; Adjust the air pressure, not too much; Pay attention to the on-site temperature, and add slow-drying thinner to inhibit the drying speed.

4.Phenomenon: Whitening.

Reason: The temperature and humidity of the operation site are high, and the paint film reacts violently, which may combine with the moisture in the air to produce whitening; Excessive curing agent, too much and too thick at one spray.

Solution: Pay attention to the humidity on site, and add anti-whitewater to prevent whitening; Proportional modulation, one spray should not be too thick.

5.Phenomenon : Blistering.

Raw solid: the compressed air is mixed with water on the paint film, the temperature at the job site is high, and the paint dries too quickly; The moisture content of the object surface is high, and the air humidity is high; Too thick for one spray.

Solution: Oil-water separation, note drainage; Add slow-drying thinner; The surface is clean, and the paint is added with anti-white water; It should not be too thick at one time.

6.Phenomenon : Shrinkage.

Cause: The primer or intermediate coat has not dried thoroughly before applying the topcoat.

Solution; Spray at the recommended thickness of coat per sweep gun.

7.Phenomenon : Wrinkling.

Causes: The drying time is too short or the paint film is too thick; Improper selection of curing agent in primer or putty; Incomplete primer putty; When spraying the topcoat, a gun is too thick, and the internal deep agent is not volatilized in time, and it is dry on the outside and not dry on the inside.

Solution: Give enough drying time between each coating; After drying, only the second spray or wet spray wet.