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Spring black treatment

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Spring black treatment

Release date2015-05-13 Author Click

(1) spring blackening process

Alkaline chemical oxidation treatment is black, is the processing of the qualified spring into the concentrated alkali solution containing heat treatment, so that the surface of the spring to obtain a layer of compact oxide film, this oxide film has anti-corrosion effect.

Spring in the heated solution, due to alkali corrosion of the spring surface to produce iron ions (ferrous compounds) in the base by adding oxidant - sodium nitrite oxidation process can be changed to produce a dense oxide film on the surface of the spring (four Iron oxide). This oxide film is mainly composed of magnetic iron oxide, oxide film formation time of 30 to 60 minutes. If the time is prolonged, the thickness of the oxide film can not be increased. crafting process: 

(To copper) - pickling - cleaning - oxidation (or secondary oxidation) - cleaning - hot water cleaning - saponification - immersion film device oil change - storage.

The procedure requirements

Name of the formula and technical requirements Remarks

One to the oil 1. Chemical to the oil NaoH100 ~ 150 g / L + Na2CO320-27 g / l heated to the boiling point of the drum to add a small amount of waste acid and iron quietly

2. Wash the oil with petrol or diesel. 3. Remove oil and rust by sandblasting or blasting

4. Quenching and tempering of the spring drum can be used to oil and rust

Two to copper with chromic acid 250 ~ 300 g / l + ammonium sulfate 80 to 100 g / l without copper can save this process plus flooding 1 to 2 minutes, and then washed in water

Acid pickling with 30% industrial hydrochloric acid leaching 1 to 2 minutes to remove oil and rust pickling time can not be too long four cleaning cleaning in the weak base and in the tank to prevent acid into the oxidation tank

Sodium hydroxide 650-700 g / l + sodium nitrite 100-150 g / l Heating to 140-144 DEG C, holding for 30-60 minutes NaoH: NaNO2 = 5-8: 1

6. Wash and rinse in flowing water after oxidation

7 hot water cleaning hot water 90 ~ 100 , cleaning 1 ~ 2 minutes

Eight saponification 10 ~ 20% Industrial soap or triethyl oleic acid soap Heating 50 ~ 60 1 ~ 2 minutes Temperature can not be too high

9 on oil immersion MS-1 water film replacement rust oil

Ten storage

(2) blackening process rules

(I) to work every day after the start power to the bath heated to the boiling point, Grilled to the slot of iron oxide (precipitate);

(II) to remove the precipitate after adding about 0.5kg of yellow blood salt (potassium ferrocyanide);

 () adding a certain amount of sodium nitrite according to the technical requirements of blackening process (5 to 8: 1);

(IV) with a thermometer to measure the temperature of the black bath to ensure that bath temperature 140 ~ 144 , if the temperature is too high to add water, and control the heating power;

(V) before the black, the spring must be fully pickled and cleaned, the tension spring must be mounted vertically for easy cleaning;

() must be strictly enforced when the technical requirements of the liquid surface of the oil residue to be timely removed, the bath should be promptly added;

() After the spring, the spring must be sprayed by high pressure water, washed by boiling water, and saponification temperature controlled at 50 ~ 60 ;

() Leakage of excess spring oil after the installation box, storage. The iron frame of the spring must be sprayed with high pressure water and then reused.

() get off work, the oxidation tank to add a certain amount of sodium hydroxide (meet 5 to 8: 1), turn off the power. Cleaning, cleaning the workplace, to keep the site clean and tidy;

Precautions for blackening operation

(I) oxidation of the workpiece if found linked to yellow frost phenomenon, indicating the bath temperature is too high, too little water.

() oxidation of the workpiece is not black, gray, is the bath temperature is too low or lack of sodium nitrite.

() oxidation of the boiling point of 140 in the following will add sodium hydroxide.

() saponification tank should always add soap or triacetin soap soap to maintain a certain concentration.

(V) silicon oxide film to allow the film was brown or brownish-black;

() black self-test workpiece, the process should be carried out before the spring oil, 2% copper sulfate solution soak for 30 seconds after the precipitation of copper is not qualified.

3% copper sulfate drip test. The workpiece was spotted with copper sulfate or 2% copper sulfate etch test, the workpiece was completely immersed in the copper sulfate solution, and after 30 seconds, the oxide film was visually observed to be non-discolored. Droplet test and corrosion test are not in the workpiece before oil, finished product sampling should be cleaned with alcohol before the oil. After black oxidation of the workpiece in the normal custody of the next year does not rust.

2. Spring phosphating treatment

Phosphating is to prevent the spring in the transport and use of a process of corrosion by phosphating spring in the air, animal and plant mineral oil and toluene and other organic solvents have anti-corrosion ability. The spring is suitable for zinc phosphate treatment to avoid hydrogen embrittlement. Phosphate film thickness than the oxide film, usually 5 to 10 microns. Usually phosphating corrosion resistance than oxidation. In particular, phosphate treatment is suitable for the spring on the protection of the former process.

(1) spring phosphating process cold water hot water

(1) to the oil to the rust - to the copper - cleaning - phosphate - cleaning - passivation - cleaning ---- saponification - immersion film replacement oil - storage

Phosphating process

Technical specification

One to the oil

1. Peening or sandblasting to remove oil and rust and oxide for quenching and tempering springs

2. Gasoline washing, drying can be phosphated (can be washed two or three times) is mainly used for thin spring

3. Chemical to oil NaoH100 ~ 150 g / L 20 ~ 70% Na2CO2 heated to 100

4. Roller to oil and rust for tensile springs

2 to copper chromic acid 250 to 300 g / l, ammonium sulfate 80 to 100 g / l without water, copper can save this process

Three wash tap water rinse to remove acid

45-35 g / l, zinc nitrate 55-75 g / l Temperature 70 ~ 80 for 10 ~ 15 minutes, total acidity 48 ~ 60 free acid 2.5 ~ 6.7 sulfate Q 0.5

5. Wash the tap water rinse

Six passivation potassium dichromate (K2Cr2O2) 80 to 100 g / l 90 to 100 seven washing tap water rinse

Eight cleaning hot water 90 ~ 100 cleaning 1 to 2 minutes

Nine saponification 10 to 20 grams / liter industrial soap tablets or triacetin soap 50 to 70 C 1 to 2 minutes

10 oil on the oil film amount of oil

Eleven storage

(2) spring phosphorus process rules and precautions

 (I) before going to work every day to be strictly checked to be phosphating the surface of the spring, requiring clean, bright. Do not allow any oil, dirt, rust classes, such as copper layer.

() open the phosphating tank, passivation tank, hot water tank. Saponification tank heating power, the phosphating bath to ensure that the 70 ~ 80 , passivation tank 90 ~ 100 , hot water tank 90 ~ 100 , soap slot 50 ~ 70 .

() before the use of phosphating the frame by the full spray washed and then into the spring, when the frame must be installed or on the cleaning of polyester-cotton gloves, spring shall not have a large area or line contact.

() phosphating process strictly when the phosphating process requirements, insulation 10 to 15 minutes.

(V) phosphating spring after the need to fully rinse with tap water.

() spring in the passivation tank insulation of about 1 to 2 minutes, after passivation to tap water full spray.

() The spring and then into the hot water tank cleaning 1 to 2 minutes and then into the saponification tank 1 to 2 minutes, and then send the paint or oil at the end of the Department of Qi painted.

() after get off work, turn off the power, carefully cleaned to ensure that the factory clean and tidy.

() phosphating tank to add manganese phosphate and zinc nitrate by 1: 2, passivation tank in the waste potassium dichromate to focus on unified treatment, saponification tank should always add soap or triacetin soap soap.

(X) If you do not passivate, you can save the operating procedures VI.

() Phosphating before the spring sandblasting, shot blasting and cleaning of the interval of not more than 4 hours, clean up after the spring must be placed in a clean frame.

(3) phosphating quality inspection methods (I) immersion method

3% sodium chloride NaCl, temperature 15 ~ 25 , soaked for 2 hours without rust as qualified.

() one of the drip method

Copper sulfate CuSO20.5N 40 mg Sodium chloride Nacl 10% 20 mg Sulfuric acid. 0.1 N 0.8 mg. After a little bit of yellow can not afford the quality of the longer the better, do not change color within 3 minutes for qualified.

() of the drip method

Copper sulphate CuSO4, SH20 66 g / l, sodium chloride NaCL 32.5 g / l, hydrochloric acid HCL 1:10 1.2 g / l, and dripping for not less than 3 min.

() soaking method

Copper sulfate 5% solution, dip 1 minute after the surface of the workpiece does not appear yellow for qualified.

In the inspection of the quality of the workpiece phosphating at the same time, the phosphating bath must be regularly tested total acidity, free acid, acid root parameters to ensure that the quality of daily work phosphating.


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