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Technical Information >> (2A) Electrophoretic Process & Various Performance Test
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Electrophoretic Process
Electrophoretic coating is also referred as electrocoating method which uses an electrical current to deposit lacquer on metal substrates such as Aluminium, Copper, Gold, Silver, Brass, Zinc Rich Metals, Zamac, Galvanized /Galvaneal. Stainless steel, CRS/HRS etc.
The electrocoat system applies a DC charge to a metal part immersed in a bath of oppositely charged lacquer particles. The paint particles are drawn to the metal part and lacquer is deposited on the part, forming an even, continuous film over the entire surface, until the coating reaches the desired thickness.
Electrophoretic lacquering is a 'Continuous process after plating' as it could be continuation of electroplating line followed with lacquering tank, which is also described as 'wet on wet' plating process. The Electrophoretic lacquering is an advanced form of lacquering with a simple process using waterbase solutions and with low risk of fire and safer environment. It has excellent throwing power to coat difficult shapes evenly. Metal products coated using this method are artificial jewellery, gift items, door handles, hardware products etc.
Performance Test and Associated products/ information
Solid Content Factor Test
For this test, the working bath material is analysed using a refractometer. 7% to 9% bath solids is classed as good.
Salt Spray Corrosion/Salt Test
This is a test to see the resistance of the plated items to salt. It is carried out in a corrosion cabinet.
SHINEX TC on chromated brass gives in excess of 240 hours and
SHINEX HB chromated brass gives in excess of 480 hours.
Perspiration test is another name for the same test
Film Thickness Test
This is done on plated items to see the thickness at various places. An electronic pen device is used, which shows the micron thickness.
Pencil Hardness Test
This is done by scratching the plated item to asses what force it takes, before it scratches. This is measured as 4H to 5H pencil hardness. This test is done by a special pressure scratch using the appropriate pencil. Scratch Resistance Test or Abrasion test are another names for the same test.
Acetone Resistance Test
This test is done by taking acetone on a piece of cotton or fabric and physically give double rubs to the plated item to see if the film wears off. SHINEX LB passes 200 double rubs and SHINEX HB passes > 500 double rubs.
Conductivity Test
The conductivity of the solution needs to be maintained at recommended level to achieve good deposition. Conductivity varies for various lacquers. For Shinex TC and HB lacquer it is 450-650 µS/cm and Shinex Anodic lacquer it is 500-850 µS/cm. It changes on the usage/production carried and bath contamination. The test is done using a conductivity meter. The good conductivity is between recommended range, If it is higher than recommendation range, which could be due to carrying over contamination an additional filtration is necessary.
Ampere
Ampere is not relevant as electrophoretic process insulates and ampere drops.
Measuring pH
The pH is measured with a pH meter and standard electrodes. The pH is difficult to measure as there tends to be lot of drift caused by the emulsion particles fouling the electrodes. Even so, pH measurements are useful.
The pH of a new solution is about 5.0 when it has settled down (after 48 hours). Prior to this time, the pH will be high due to the acid being locked up in the disperse phase. High pH accompanied by high conductivity will indicate the drag in of cleaning materials (or other alkalis). Low pH accompanied by very high conductivity may indicate the drag in of acids and/or metal ions. If the low pH is due to normal acid build up, no permanent harm is done. High pH causes precipitation.
In both the above cases the contaminants should be removed by ultra filtration. On a closed loop system, increasing the rate of dumping of permeate will correct the situation on a day to day basis.
MEQ Test
There is replenisher available which is added to bath on the basis of tank solution test on the refractometer. 10mls to be added to 50 litre bath will increase MEQ by 2. (0.2 mls / litres bath). (SHINEX TC would be 35 to 40 and for SHINEX HB would be 40 to 50). MEQ reading is Acid content of the bath. Information on how to measure MEQ is available on request.
In general if you have particular technical question on operating bath you would need to know following.
Bath volume : How many litres
Which lacquer:
Refractometer reading:
MEQ reading:
Conductivity reading : How many microsiemens
U / F Permeat refractometer reading:
What solvent has been added and how much
What is happening, what is technical problem
UV Resistance
SHINEX TC and SHINEX HB, both have excellent UV resistance.
Stripping coating
Add 100ml Shinex striping solution to 1 litre of Demineralise water. To strip coating fill the solution in a container which has a heating bar. At 70 degrees submerse components in the solution.
Waste Treatment
Notify authorities to remove the material. or neutralize with Shinex waste Neutralizer. It will precipitate the lacquer, it will form like a sticky mess at the bottom. Discard the clear liquid on top (mainly water) and dispose resin jelly in tub.
For more information write to us on
info@shinextechnologies.co.uk
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