Monday, October 16, 2017

Electroplating Plant

electroplating plant
Electroplating plant is should be arrange in serial work, because each process need different chemicals and from batch to another batch need rinsing in order not contaminated chemicals on the serial batch. Electroplating plant should be designed in semi batch process, can’t run in continuous process, because before and after electroplating process the object need certain treatment. Automatic process is not on the electroplating work but automatic mean every batch is doing by robot, so people just control of every step robot work and the quality of all process, including the quality of chemical solution bath concentration.

Each bath chemical solution is purpose for certain product, for example in producing chromium plating, there are bright chrome plating, black chrome plating , semi dull chrome plating, white chrome plating and any other chrome plated color. Only the preparation of base metal may can have the same process, for rinsing and polishing of each color of chrome plating can be in different method even can use the same equipment. Waste of rinsing and cleaning can be mixed for various chrome plating color, and need further waste treatment process, to make environment friendly.

General order of electroplating process such as follow:
Each of different process which use different chemicals must use different bath but for process which use same solution like just water may can use same bath, it is depend on the plant layout. Each plant can be different layout.

If there are any other electroplating purpose like Nickel plating which use different chemical solution, this need different bath, other wise they must clean the bath every do other kind of plating, and for this can be inefficient work. The plant which apply of many kind of plating can be arrange in serial process and parallel process order.

Sunday, October 15, 2017

Operating Conditions

Operating Condition of Electroplating Process

Bright Plate can be reliably obtained by properly coordinating temperature and current density within definite limits, taking into account the chromic acid concentration of the bath. The operating condition for bright plate should be on the temperature range of 25– - 55 C degree with current density range between 5 -– 25 A/dm2 for solution containing 250 g/l CrO3. For example to produce a bright plate deposit from a solution containing 250 g/l chromic acid and 2.5 g/l sulfate at a temperature of 40 oC, use cathode with current density between 3.1 and 15.5 A/dm2 but at 45 oC use current density about 50 % higher.

Plating at higher temperature and current densities has been proposed for hard chromium plating and porous chromium plating. This idea has been applied successfully to plate a small articles, but the power required for plating larger objects may be prohibited or unavoidable.

Chromium plating speed was vary depend on the chromium concentration on the bath. Billfinger suggests the use of higher temperature and current densities, combined with lower ratios of chromic acid to sulfate, to obtain higher plating speeds for hard chromium plating.

Throwing Power

Both the throwing power and the covering power of chromium plating bath are poor compare with copper or nickel plating bath. The conductivity is high but reduced by such impurities as iron and copper. The cathode polarization during chromium deposition is relatively constant and substantially the same as that obtained during electrolysis of the same concentration of pure chromic acid without chromium deposition. The major variable connected with throwing power in bright chromium plating are the current efficiency and the bright plating range. If a given set of condition gives the widest possible bright plate range and the plating is done at an average cathode current density near the upper limit of current density for this bright plate range, the optimum throwing power will be attained.

High Throw Bath

High-ratio baths containing relatively high concentration of organic acids have been developed which exhibit remarkable throwing power or covering power over bright nickel, almost as good as that of bright nickel bath themselves. These solution operate at lower current efficiencies to produce thin bright plates of good decorative value. It is a characteristic that the coverage increases with the time and the plate continuous to spread into the low-current-density area with longer plating. Thus plating times as long as 5 to 10 minutes are recommended instead of the 2 to 3 minutes often used for decorative plating.

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Hardness Test of Coating Plate

Steel coated with chrome plating or with nickel plating will have different hardness and looking. After coating with chrome or nickel then the surface become more interesting and stand to corrode. This is the basic purpose of steel coating. The stand to corrode and how long it can be stay on the surface depend on the dept of coating and the strength of coating material on the plate surface. One of how to test the strength of this using hardness testing. This tool work is use a fixed forced and given identifier, that show the harder of surface material.

The value of hardness test is identified by measuring the depth of the area of the surface by using several methods. One method to identify of hardness is use Rockwell hardness test method, this method is the most commonly used to test hardness of steel surface.

The standard of hardness is illustrated by the most hardest material is diamond which have hardness value of 10, other material will have below this.

Soft: scale value = 1 – 3
Medium hard: scale value = 4 – 6
Hard: scale value = 7 - 10

Saturday, October 14, 2017

Thickness Measurement of Plating

How to measure thickness of Plating 

Coating thickness can be measured by some tools that using one of these method: x-ray fluorescence, coulometric, beta bacscatter, magnetic induction, amplitude eddy current and phase sensitive eddy current. To make sure of what kind of thickness you will chose better ask to the supplier.

To measure the coating thickness on the plate, you can use x-ray fluorescence tools. This tools can measure the thickness of coating thickness of chrome, nickel and copper plated. The kind of coated of each coating material is no problem, like decorative chrome plating, black chrome, bright chrome, bright nickel plating. Because this tool to measure the thickness using x-ray fluorescence that work only on the base metal.

Wednesday, October 11, 2017

Electroless Nickel Plating

Electroless Nickel Plating, what is that? Electroless plating is an auto catalytic chemical technique used to deposit a layer of nickel phosphorous or nickel boron alloy on a solid work piece, such as metal or plastic. On this process is no need additional electric current because the electric charge is merging from the substance itself. The principle of work of this process is the present of reducing agent, for example hypophospite react with metal ions to deposit metal.

Electroless nickel plating often use in various type of parts to protect against wear and corrosion. Uniform deposit of nickel useful for hydraulic cylinders, worm feeds, gears, bellows, shafts, chain belts and other close filling components.

Nickel plating on subject can be doing in two kind of process, using electroplating method and can do by electroless nickel plating. For electroless nickel plating or coating then be classified in accordance with the thermal treatment applied:

  • Class 1 = no subsequent heat treatment: A bake for hydrogen belittlement relief is not considered a heat treatment.
  • Class 2 = using heat treated to obtain required hardness: this can be applied to all metals not affected by heating up to 260° C or above.
  • Class 3 = by non heat-treatable, and use beryllium alloys to improve adhesion nickel plating deposit.
  • Class 4 = heat-treatable, use aluminum alloy and heat applied to improve adhesion nickel deposit.

Quality of Plating Thickness

Beside divide into the class on the process do, electroless nickel plating also divide into the grade of coating thickness. There are three thickness class:
  • Grade A = 0.127 mm
  • Grade B = 0.254 mm
  • Grade C = 0.381 mm

Hard Electroless Nickel Plating

If use alloy with low phosphorous, plating utilizes a unique bath providing coating hardness up to 60 Rockwell. This result can be similar with hard crome Hard, with the advantage of a uniform thickness inside complex configurations, as well as outside. Low contain of phosporous have excellent result and resistance to corrosive and high pH chemicals.

The quality of electroless nickel plating may not stronger as using Nickel electroplating, but electroless nickel plating will improves the quality of components. Tight manufacturing tolerance can be achieved as the electroles nickel is deposited evenly on the surface of the parts. It can be also used to improve the surface of a component so that it is back within the specific tolerance, and provide a surface that allows post finishes to be carried out effectively produce bright surface coating.

Some example product of Electroless Nickel Plating as on the picture below:

Electroless nickel plating
Electroless plating product

Reaction on Electroless Nickel Bath

Electroless nickel bath contain of nickel ions, reducing agent, complexant, neutralizer, buffer, stabilizer and brighteners.

The reation on bath as follows:

1) NiSO4 + H2O → Ni2+ + SO42 - + H2O
2) NaH2PO2 + H2O → Na+ + H2PO2- + H2O
3) Ni2+ + H2PO2- + H2O → Ni + H2PO3- + 2H+
4) H2PO2- + H2O → H2PO3- + H2 (by catalist)

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