The Electroplating of door hardware accessories

The electroplating is the ordinary surface treatment of the screws or the products like the fasteners. Usually, the corrosion resistance is the main evaluation criteria of the quality of electroplating, and its appearance is followed. The corrosion resistance is the products need to be tested in its corrosion in the imitated working environment which is set the test condition up .The quality of the electroplating screws can be controlled by the followings,
1. Appearance
The hardware screws are not allowed with no plating part, being charred, rough, dark, skin, crusting condition and obvious stripes. And are not allowed to have the pinhole pork, black plating slag, the loose of the film, cracks, peeling and serious inactivating traces.

2. Hydrogen brittleness
In the process of the processing, especially in the acid pickling and the alkali wash and the following electroplating process, the surfaces of the hardware screws will absorb the hydrogen atom, and the mental plating deposits will capture the hydrogen. And when the fasteners are tightened, the hydrogen will transfer to the concentrated part of the stress, and then will raise the pressure and exceed the basic strength of the metals so that the surface will be slightly cracked. The hydrogen is very active and it will be permeated to the new formed crack.
3. The plating distribution
Using the different participation methods, the plating part of the concentration on the surface of the fasteners is different. When the screws are electroplated, the mental deposits is not deposited evenly on the peripheral edge, the thick plating is obtained by the corner. And in the thread of the fasteners, the thickest plating part is the top of the thread, and along the side of the thread, the deposit become thinner and thinner, and the thinnest is the bottom of the thread. On the contrary, the thicker plating part is deposited at the corner and bottom of the thread in the hot-dip galvanizing. And the metal deposition is similar with the hot-dip galvanizing, but it’s more smooth and its thickness on the surface is more evenly.
4. The thickness of the plating part
The service life of the construction hardware in the corrosive atmosphere  is proportional to its plating thickness. And the general economic thickness of the electroplating part is  0.00015in～0.0005in(4～12um).And the average thickness of hot-dip galvanizing is 54um (its footpath ≤3/8,43um),and its smallest thickness is 43um(its footpath ≤3/8,37um).