China piping solution supplier: www.epowermetals.com

Process flow of electro galvanizing

Job description

Plating (surface treatment) is a method of dipping the product in an ionic solution and connecting it to the cathode. At the other end. a suitable anode (zinc block) is placed. and a metal film is precipitated on the surface of the plated part through a direct current wave.

Scope

(1) Applicable to all bolts. screws. nuts. etc. that must be galvanized.
(2) The scope of work of the chemical inspection room of electroplating includes electroplating inspection. pickling inspection. waste water inspection. etc. Work items for electroplating ammonium chloride. zinc chloride determination: pickling phosphate concentration determination: wastewater yard COD determination.

Operation flow

Note: The fully automatic production line takes 3 minutes 40 seconds and 4 minutes 20 seconds to complete a cycle.

Equipment

Plating equipment. barrel. overhead crane. boiler. filter. rectifier. freezer. dryer. forklift. titration and

Analytical instruments (e.g. reflux condenser).

Measuring instruments

Buret. thermometer. PH test paper. specific gravity meter.

Materials

Zinc ingot. caustic soda. degreasing agent. water. hydrochloric acid. electrolytic degreasing agent. zinc chloride. ammonium chloride. hydrogen peroxide. luster. softener. cyanide. nitric acid. filtration aids. hydrochloric acid inhibitor.

Each build bath standards

(A) Pretreatment: 1. hot degreasing tank: (3000 liters) average weekly cleaning and bath construction. Do not make records.

  • (1) Hot degreasing agent 100KG.
  • (2) Caustic soda 75KG.

2. Rust removal tank: (2400L) Clean and build bath once a week on average. no record.

  • (1) The concentration is shown in SOP90-3/5- Hydrochloric acid concentration table for rust removal tank.
  • (2) Add 0.1-0.2% hydrochloric acid inhibitor when building the bath.

3. Electrolytic degreasing tank: (1300 liters) Clean and build the bath once a week on average. no record is made.

  • (1) Electrolytic degreasing agent 75KG.
  • (2) Flake soda 25KG.
  • (3) Voltage control 0-10 volts.
  • (4) Activation tank: (400 liters) clean and build bath once a day. no record.

(B) Plating tank: (14000 liters)

  • 1. Ammonium chloride 2280KG
  • 2. Zinc chloride 1000KG
  • 3. Luster agent 50KG
  • 4. Softener 400KG

(C). post-treatment.

  • 1. Activation build bath standard 1-5ml / L (nitric acid).
  • 2. Passivation as follows (volume 500 liters).
  • 3. Hot water tank (600 liters) to maintain overflow and constant temperature.

If the special requirements of some pipe households are involved and special control is needed. please see the “Special Characteristics Control Guideline”.

(A). the amount of material: 35%-85% of the drum volume is the limit. weight reference SOP90B table.
(B). Pre-treatment: (The following agents and precautions should be added during operation)
1. Hot degreasing tank.

  • (1) Every 12 hours of production plus 25Kg (heat treatment and tempering without oil immersion of the product every 24 hours of production plus 25Kg).
  • (2) Add 50Kg for every 12 hours of production (50Kg for every 24 hours of production for heat-treated and tempered products without oil immersion).
  • (3) Operation temperature control between 600C-850C (should be recorded in the checklist QC105E).
  • (4) Pay attention to whether the oil and water separation is good. and remove impurities and floating oil at any time.
  • (5) Caustic soda should be added to the overflow barrel before work. which is safer.

2. Rust removal tank.

  • (1) Pay attention to oil removal and add appropriate amount of water and hydrochloric acid before going to work every day.
  • (2) The concentration of hydrochloric acid is as follows.
  • (3) When shutting down. the products in the tank should be dropped out and put in the water tank.

3. Electrolytic degreasing tank.

  • (1) Electrolytic degreasing agent. 2 days to add once 25KG
  • (2) Flake soda: 25KG once every 2 days
  • (3) Temperature control between 150C-600C. (Should be recorded in the checklist)
  • (4) Voltage control between 0-10 volts. (No record)

(C). Plating tank.
1. Ammonium chloride is checked 2 times a month with a concentration of 170-250g/1. (Should be recorded in QC105Q form)
2. Zinc chloride is checked 2 times a month with a concentration of 35-80g/1. (should be recorded in QC105Q form)
3. Luster agent 200±20ml/KA.2H
4. Softener 300±20ml/KA.2H
5. Plating solution temperature between 160C-380C (should be recorded in the checklist)

  • 1. Plating solution specific gravity between 10-12. (Should be recorded in the checklist)
  • 2. The pH value of plating solution is between 5.6-6.2. (should be recorded in the checklist)
  • 3. Pay attention to the consumption of zinc ingots. and add them at any time. with the balance of zinc not less than 1/3 of the bath.
  • 4. Adjust the appropriate voltage between 2.5V-10V according to each product type (refer to SOP90B table in SOP9093) and record it in table QC105E. etc. The current meter is 100A-3500A. no record is made. Large screws and coarse tooth screws depending on the situation. need to adjust the operating speed to a minimum or stop-like. to prevent tooth injury.
  • 5. Add 2 liters of hydrogen peroxide before turning off the machine to prevent the ferrous content from being too high.
  • 6. Keep the plating solution clean. if there is too much oil slick. impurities. should immediately track the cause. if necessary. to clean the plating tank.
  • 7. Suspend the machine to adjust the rectifier flow to below 100A.

(D) Post-treatment.
1. The hot water tank should be kept overflowing with clear water. and the temperature should be controlled between 500C-850C. and the temperature should be controlled between 450C-550C when plating five colors. and it must be cleaned every 4 hours.
2. If there is any discrepancy in the operation conditions. it will not affect the quality of the product immediately. but must inform the supervisor immediately to make the necessary adjustments and pay special attention to the appearance of the product quality and film thickness in the independent inspection. and if necessary. it should be reworked.
3. The number of checks shall not be less than twice per shift.
(E) Hydrogen repellent treatment: hydrogen embrittlement repellent – all plated products with tensile strength greater than or equal to 1000Mpa (145KSi) or those with customer specified hydrogen repellent treatment will be given hydrogen repellent treatment within 2 hours after plating. The relevant parameters are recorded in the form “OS32-H”. etc.
(1) Tempered products

  • Hydrogen repelling temperature:1900C-2300C
  • Hydrogen drive time:3-10h

(2) Carburized parts and tin-welded parts

  • Hydrogen drive temperature:1400C-2300C
  • Hydrogen drive time: insulation 2-10h

Caution.

  • 1. Passivation treatment is not available when plating before hydrogen repulsion. and passivation post-treatment is carried out only after hydrogen repulsion is completed.
  • 2. The hydrogen embrittlement detection test is carried out within 16h after the hydrogen drive process is finished.
  • 3. The best time to carry out the hydrogen repellent treatment is within two hours after the zinc plating. not more than 4 hours.
  • 4. If there is any special requirement of hydrogen repelling from customers. it will be carried out according to customer’s requirement.

Post-operation treatment

Self-inspection.
(A). The discharger should take out samples from each barrel to see if there is any abnormality in the appearance.
(B). The operating conditions. if there is a discrepancy. although it will not immediately affect the quality of the product. but must immediately inform the unit in charge. the operation to be adjusted. and in the independent inspection. pay special attention to the quality of the product outside and film thickness. if necessary. to be redone.
(C). After independent inspection. if the product quality does not meet the requirements. should be the following treatment.
(D). Tied to the process flow card. must be checked after passing. before moving to the next process

Follow up works and handling methods.

(A). To determine the identity of the next process to move to the next process.
(B). To maintain the cleanliness of the handling. do not leave oil. to ensure that the products beautiful.

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