What are the rust removal processes for steel and wood desks and chairs?

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School desks and chairs have various types and specifications. Steel-wood desks and chairs are commonly used. In order to extend the service life of steel-wood desks and chairs, the steel surface needs to be pickled and phosphated during the production process. This process can make the surface of the steel tabletop smooth and play the role of rust removal and rust prevention. The following steel-wood desk and chair manufacturers will introduce to you the steel-wood desk and chair rust removal process!

Pickling and rust removal process

The method of pickling to remove rust and scale is a more widely used method in the industrial field. Utilize acid to dissolve oxides and mechanically peel off hydrogen generated by corrosion to achieve the purpose of removing rust and scale. The more common ones used in pickling are hydrochloric acid, sulfuric acid, phosphoric acid, and mixed acids. Nitric acid is rarely used because it produces toxic nitrogen dioxide gas during pickling.

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1. Hydrochloric acid

Hydrochloric acid pickling is suitable for use at low temperatures, should not exceed 45°C, and use a concentration of 10% to 45%. It is also advisable to add an appropriate amount of acid mist inhibitor.

2. Sulfuric acid

The pickling speed of sulfuric acid at low temperature is very slow, so it should be used at medium temperature, the temperature is 50~-80°C, and the use concentration is 10%~25%.

3. Phosphoric acid

The advantage of phosphoric acid pickling is that it will not produce corrosive residues (more or less there will be some residues after pickling with hydrochloric acid and sulfuric acid), and it is relatively safe. The general use concentration is 10%~40%, and the treatment temperature can be from room temperature to 80°C.

4. Mixed acid

In the pickling process, the use of mixed acids is also a very effective method, such as hydrochloric acid-sulfuric acid mixed acid, phosphoric acid-citric acid mixed acid.

5. Corrosion inhibitor

A proper amount of corrosion inhibitor must be added to the pickling and rust removal and scale removal bath solution. There are many types of corrosion inhibitors, and it is relatively easy to select. Its function is to inhibit metal corrosion and prevent “hydrogen embrittlement”. But when pickling “hydrogen embrittlement” sensitive workpieces, the choice of corrosion inhibitors should be particularly careful, because some corrosion inhibitors inhibit the reaction of two hydrogen atoms into hydrogen molecules, namely: 2[H]→H2↑, so The increase in the concentration of hydrogen atoms on the surface of the metal enhances the tendency of “hydrogen embrittlement”. Therefore, it is necessary to consult the relevant corrosion data manual, or do a “hydrogen embrittlement” test to avoid the use of dangerous corrosion inhibitors.

Anti-rust and phosphating process

The early application of the phosphating process is rust prevention. The steel parts are phosphated to form a layer of phosphating film to prevent rust. The anti-rust period of the phosphate anti-rust treatment work piece can reach several months or even several years (for oil-coated work piece), it is widely used for anti-rust and anti-rust phosphating during the process, transportation, packaging, storage and use. There are three main types of iron-based phosphating, zinc-based phosphating, and manganese-based phosphating:

1. Iron-based phosphating

The main bath composition of iron-based phosphating is ferrous phosphate solution, which does not contain oxidation promoters and has high free acidity. The iron-based phosphating treatment temperature is higher than 95°C, the treatment time is more than 30 minutes, the phosphating film is more than 10g/m2, and it has the dual functions of rust removal and phosphating. This high-temperature iron-based phosphating rate is too slow, so it is rarely used now.

2. Zinc-based phosphating

Zinc-based phosphating is also a widely used anti-rust phosphating, usually nitrate is used as an accelerator, the treatment temperature is 80~90°C, the treatment time is 10~15min, the phosphating film is more than 7.5g/m2, the phosphating film The microstructure is generally a densely packed needle piece.

3. Manganese phosphating

Manganese-based phosphating has better performance for anti-rust and phosphating. The microstructure of the phosphating film is densely packed and is a widely used anti-rust and phosphating. It can be added with or without accelerator. If nitrate or nitroguanidine accelerator is added, the speed of phosphating film formation can be accelerated. Usually the treatment temperature is 80~100°C, the treatment time is 10~20min, and the film weight is above 7.5 g/m2.

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Adjust the activation process

The workpiece treated with strong alkali and strong acid will cause the phosphating film to be coarsened, and the surface adjustment activation can refine the crystal grains:

1. Iron-based phosphating generally does not require adjustment of activation treatment.

2. Zinc-based phosphating can be adjusted with oxalic acid and colloidal titanium.

3. Manganese phosphating can be activated with insoluble manganese phosphate suspension.

After phosphating, the chromate sealing of the workpiece can greatly improve the rust resistance. If it is oiled or dyed, the rust resistance can be increased by several or even dozens of times.
The above is the entire content of the rust removal process for steel and wood desks and chairs. In summary, the rust removal process for steel and wood desks and chairs includes pickling and rust removal, rust prevention and phosphating, adjustment and activation, etc. Henan Youte School Equipment Co., Ltd. The steel-wood desks and chairs produced are of excellent quality, advanced technology, and perfect after-sales service. If you have any needs, you can call or leave a message for consultation at any time.

Steel-wood desks and chairs electrostatic spraying process and principles and advantages

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Steel-wood desks and chairs are student desks and chairs with wood as the layout substrate and steel as the skeleton substrate. The more characteristic process is the electrostatic spraying process, which is easy to operate, environmentally friendly, and does not pollute the environment. For example, the painting process will cause the phenomenon of flow, so it has become a commonly used desk and chair for students in modern times. The following desk and chair manufacturers will introduce to you the electrostatic spraying process, process principles and advantages of steel and wood desks and chairs!

1. Electrostatic spraying process of steel and wood desks and chairs

1. Surface pretreatment: mainly degreasing and rust removal, the method is the same as the pretreatment of applying liquid paint.

2. Scrape putty (repair defective products): Scrape conductive putty according to the degree of defects of the workpiece, and smooth it with sandpaper after drying, and then proceed to the next process.

3. Protection (also known as masking): If some parts of the workpiece are not required to be coated, they can be covered with protective glue before preheating to avoid spraying paint.

4. Preheating (thick coating): Generally, preheating is not required. If the coating is required to be thicker, the workpiece can be preheated to 180~20°C, which can increase the thickness of the coating.

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5. Spraying: In a high-voltage electrostatic field, connect the powder spray gun to the negative electrode, and the workpiece is grounded (positive electrode) to form a loop. The powder is sprayed from the spray gun with the help of compressed air, which is negatively charged, and is sprayed on the workpiece according to the principle of opposite sex attraction.

6. Curing: After spraying, the workpiece is sent to a drying room at 180~200°C for heating to solidify the powder.

7. Cleaning: After the coating is cured, remove the protective material and smooth the burrs.

8. Inspection (respray for defective products): Check the coating of the workpiece. Any defect such as missing spray, bumps, needle bubbles, etc., needs to be reworked and resprayed.

Second, the principle of electrostatic spraying of steel and wood desks and chairs

The electrostatic spraying of powder coatings is called plastic spraying, and its principle is to use the phenomenon of corona discharge to make the powder coatings adsorb on the workpiece. The process is: the powder coating is sent to the spray gun by the powder supply system by compressed air gas, and the high voltage generated by the high-voltage electrostatic generator is added to the front of the spray gun. Due to corona discharge, dense electric charges are generated nearby. The powder is sprayed by the gun nozzle. When it exits, it forms charged paint particles, which are attracted to the workpiece with the opposite level of electrostatic force. As the sprayed powder increases, the electric charge accumulates. When it reaches a certain thickness, static electricity is generated. Repulsion does not continue to absorb, so that the entire workpiece obtains a certain thickness of powder coating, and then the powder is melted, leveled, and solidified by heat, that is, a hard coating film is formed on the surface of the workpiece.

Three, steel and wood desks and chairs electrostatic spraying advantages

1. Compared with the traditional spray painting process, electrostatic spraying has significant advantages. It does not need thinner materials, and the construction is non-polluting to the environment and harmless to the human body;

2. The coating has excellent appearance quality, strong adhesion and mechanical strength;

3. The curing time of spraying construction is short, the corrosion resistance and wear resistance of the coating are much higher, and no primer is required;

4. The construction is simple, and the technical requirements for workers are low. Some construction occasions have clearly stated that electrostatic spraying technology must be used;

5. The cost is lower than the painting process, and the flow phenomenon common in the painting process will not appear during the electrostatic powder spraying process.

The above is a detailed introduction to the electrostatic spraying process, process principles and advantages of steel-wood desks and chairs. The electrostatic spraying process of steel-wood desks and chairs is surface pretreatment, scraping putty, protection, preheating, spraying, curing, and cleaning. , Inspection and other steps, the principle is to use the phenomenon of corona discharge to make the powder coating adsorb on the workpiece. This process has the advantages of green pollution-free, simple construction, and short curing time.

How to install the auditorium soft chair? Installation steps method introduction

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Auditorium chairs are a very common seat in our lives. They are often used in meeting rooms, auditoriums, etc., and even seats in many public areas now use auditorium chairs. More and more people like the auditorium chair. There must be something unique and something worthy of appreciation. Although the types of auditorium chairs are different, the installation methods are still the same. In fact, the introduction to the installation steps of the auditorium chair is still very detailed. As long as we can install it correctly and do a basic test, it will also be beneficial to the long-term application of the auditorium chair. Today, I will introduce how to install the auditorium soft chair and how to install it.

The installation process of the auditorium soft chair is a work with a certain technical content; after the parts of the seat are sent to the installation site, first check whether the parts are complete. The large parts include the chair frame, cushion, backrest, etc., while some small parts are included. The components are the key to the installation. Whether the screws are the size required for the installation is also very important whether the site is a wooden floor or a concrete floor; therefore, on-site installation is also a tedious and technically difficult task.

Multimedia classroom soft chair

1. Install the seat

We need to use screws to install the relevant seats and do points, and then install the armrests on both sides, we must ensure the stability of the installation of the armrests. Because many of the chairs in movie theaters are row-by-row, but have separate armrests, fixing work must be done well.

2. Install the bracket and guard plate

The installation of the bracket and the guard plate in the installation steps of the auditorium chair are very critical, so special attention must be paid to the fixing work. You need to install the bracket on the armrest frame, then you need to use suitable plastic nails to fix it, and then insert the guard plates of the two armrest frames.

3. The backrest link

After completing the other parts of the link, you need to determine the link of the backrest position, and also need to have the anti-skid position fixed. Because the fixed position of each auditorium chair is different, the screws used are also different, so be sure to fix the position of the backrest.

Auditorium chair

4. Fixed on the ground

Because of the different types of auditorium chairs we choose, there will be some differences in the installation steps of the auditorium chairs. Therefore, we must pay special attention to the fixed position. Generally, the position of the tripod can be specified first, or after the assembly of the auditorium chair is completed, the fixing can be carried out, so that a good application effect can be guaranteed, and the fixing can be determined. The stability.

5. Adjust the size and adjustment of the auditorium chair

(1) Test the size of the auditorium chair and repair it, and check whether all of it is tight.

(2) Use 8*55mm screws to fix the foot cover to the ground, and then cover the blind cover.

The above is an explanation of the steps for the installation of the auditorium chair. What needs to be reminded is that in the installation process, in addition to measuring the installation site, drawing lines and punching holes, it also needs the ability to adapt to changes, such as the wooden floor used on the site. The thickness is too thin, should you consider changing to another type of screw, etc.