|Home > Enameling > Equipment > Pretreatment equipment > Pickling|
|Pickling (metal treatment with an acid solution) is typically used for
the pretreatment of
rusted steel and for activating the steel surface prior to applying a nickel flash for a
so-called direct-on white enamel process.
Pickling may be done by means of immersing products into a series of tanks or by spraying inside a conveyorized corrosion-resistant tunnel. This second option is rarely selected due to significant investment & maintenance cost.
At immersion pickling systems products are typically placed into stainless steel baskets and then transported from one tank to the next by a manually operated hoist or by a handling robot.
Below pictures of both material handling solutions.
Automatic immersion pretreatment system
Manual immersion pretreatment system
with manual hoist
Typical pretreatment stages for a direct-on white enameling process
|Description||Temperature (Celsius)||Duration (minutes)|
|1||Alkaline cleaning||80 - 90|
|2||Alkaline cleaning||80 - 90|
|3||Alkaline cleaning||80 - 90|
|4||Hot water rinsing||70 - 80||2 - 5|
|5||Cold water running rinsing||room temperature||2 - 5|
|6||Sulphuric acid||70 - 75||8 - 15|
|7||Cold water running rinsing||room temperature||2 - 5|
|8||Nickel replacement||70 - 75||5 - 6|
|9||Cold water running rinsing||room temperature||2 - 5|
|10||Cold water running rinsing||room temperature||2 - 5|
|11||Neutralizing||70 - 80||3 - 5|
NB : Depending upon the type of contamination, low temperature alkaline cleaners may be used.
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