1, Pre- treatment process of Battery steel shell electro plating:
Degreasing (chemical method) → Degreasing ( chemical method) → Hot water rinse → Cold water rinse → Unloading → Loading → Hot water rinse → Cold water rinse → Pure water rinse → Derusting → Flowing pure water rinse → Pure water rinse → Deep nickel electro plating
2, Chemical degreasing of Battery steel shell electro plating:
Degreasing solution formular:
Sodium hydroxide: g/L————–20
T: ℃ —————65 ~ 70
t: min —————≥45
Process operating highlights should include following aspects:
( 1 ) Barrels loading qty and loading volume at best of 2 /3 of barrel volume. If too little, the production efficiency will too small; If too much, the rotation of steel shield inside the barrel will be uneven, then will not good for getting rid of oil and other solid contaminants.
( 2 ) Tank liquid surface level control:
The reason why using pure water with bath is there is many Cr in tap water, when steel shell stays in the air, dehydration is easy to produce rust. The liquid level should higher than barrel. Otherwise, since the steel sheel is a large blind hole L, which is large volume, light weight, therefore inside the blind hole will remain portion gas. Then make some steel shell suspended on liquid surface or internal solution results degreasing effect. With the evaporation of solution, shall add pure water timely.
( 3 ) Oil contamination removal of wave surface:
As production progresses going on, there are many oil contamination will be accumulated on the degreasing liquid, so must remove them promptly. Because the internal solution exists very much small suspended oil droplets, must be removed constantly. Otherwise, if solution suspension too many, the after rinse will bear too much, while will increase the opportunity of taking oil into the solution, and shorten maintenance period, then affecting products quality and production efficiency improving.
( 4 ) Magnetic iron droplets removal:
The steel shells in punching process will produce many magnetic iron, to effectively remove, the barrel speed should as quickly as possible, control within 10 ~ 20r/min, to strengthen the stirring force of barrel; and appropriate increase solution temperature, because high temperature has a certain of weakening effect to magnetic, furthermore in degreasing agent has many surface active agent. And these surface active agents have good affinity effect to metal surface, meanwhile also absorb magnetic scrap iron. Under the condition of high temperature and rotation of barrel, these magnetic scrap iron will be easily peeled from steel shells. In the production process, please do not salvage steel piece or steel shell fall into the tank with a magnet, resulting steel shell internal magnetic reinforce then can not clean and causing rust after plating.
( 5 ) Electroplating solution routine maintenance:
As the production move on, the solution dissolve oil contamination, scrap iron, and some solid waste from steel shells cleaning, as well as the degreasing agent decompose under high temperature, the solution cleaning effect will be deteriorated. Therefore, other than adding pure wanter for liquid level, as well as adding degreaser and caustic soda, should also remove these
suspended solids. But conventional filtration is too much workload, low efficiency, still the effect is not good. Because these solids both big and many, therefore, can add two spare reserve baths, for natural precipitation 2 ~ 3h, then oil contamination floating to solution surface, solid impurity settle to the tank bottom. Cleaning the cleaning tank. Then make the clean solution to original tank, to supply solution liquid level, and continue to production usage, generally it is better treat once every 48 working hours.
3, Hot water rinse to degreasing:
PH: ————— 10 ~ 12
T, ℃: ————– 45 ~ 50
t, min: ————– 3 ~ 5
All cleaning water shall replace every shift to keep wash water clean. The purpose of water rinse is to avoid introducing impurities ions such as Ca2+, Mg2+. To control pH2 ~ 3. One more activate steel shell surface, use dilute H2SO4 rather than dilute HCI, in order to avoid a level increasing in plating bath.
5, Loading and unloading:
Degreasing barrel and nickel plating barrel can not be mixed each other, because outside degreasing barrel there sticked many degreaser and caustic soda and small amount of dirt, not easy to washing clean. So the barrel shall exclusive using and make sure surface clean for steel shell and barrel surface before electroplating.
Derusting technical processes:
Hydrochloric acid ( chemically ): g/L——————7 ~ 9
Hexamine: g/L ——————3
t, min: —————————- 4 ~ 6
Pure water bath, adding hexamethylenetetramine to prevent partial excessive corrosion for steel shell in derusting process. In general, update every two continuously working weeks .
Pre-treatment is an important step in electro plating process, since it will directly affect the quality of plating. Especially when in deep nickel electroplating for steel shells. When products with high quality requirements, then require more stable, reliable pre-treatment, to ensure high quality plating products.