March 2013 Archives

Following methods are in use for plating wear resistance testing.

(1) Falling-sand abrasion resistance test

As shown in [Fig.1], this is a plating wear resistance testing method using a device to let abrasives fall onto plated surfaces from regulated heights.

● Abrasive Artificial abrasive Silicon carbide abrasive C#80 as defined in JIS R6111 is used. Sufficiently pre-dried at 110℃ and kept in a desiccator. ●Falling The falling abrasive amount is to be 320±10g/min. ●Testing completion point When the base material is exposed. ●Determination based on mass variation Obtained by the following formula. WR=T/（w1-w2） 　　WR：Wear resistance （S/mg） 　　w1：Mass of test specimen prior to testing （mg） 　　w2：Mass of test specimen after testing （mg） 　　T：Testing time （S）

(2) Spray wear test

This is a plating wear resistance test method using abrasives sprayed onto the test specimen by compressed air.

●Abrasive Artificial abrasive Silicon carbide abrasive C#100 as defined in JIS R6111 is used. Sufficiently pre-dried at 110℃ and kept in a desiccator. ●Falling amount The falling J abrasive amount is to be 23±1g/min. ●Determination method 1.A method where exposure of the base material to be the end of testing. 2.A method to determine by measuring wear depth of the specimen surface. For the method 2. above, the max value of the wear depth after a certain amount of time of spray is measured with a surface roughness meter or a split beam microscope, and calculated with a formula below. WR=T/t 　　WR：Wear resistance （S/μm） 　　T：Testing time （S） 　　t：Max. wear depth （μm）

Corrosion resistance tests of platings are conducted with the following methods.

Salt water spray tests are often used to evaluate the corrosion resistance performances of metal materials and inorganic and organic plate coatings applied on metal materials. Neutral salt water spray test methods are explained here.

(1) Test equipment

The system is comprised of Salt water spray device, Specimen holder, temperature controllable spray chamber, Air saturator that saturates the test environment air with water. Required conditions for the test equipment are as follows.

	1.	The spray equipment is to be of Spray tower or Nozzle type.
	2.	The spray chamber is to be 0.2m3 or more.
	3.	The chamber ceiling or the cover is designed not to drip the test solution on the specimen.
	4.	The equipment is to be corrosion resistant.
	5.	The chamber environment is not to be affected by the external air, and the solution dripped from the specimen is not to be re-deposited on the specimen.
	6.	The test specimen can be held in prescribed angles.
	7.	Two or more spray liquid collectors with horizontal collection area of 80cm2 are to be provided.

(2) Test specimen

	1.	To be 70×150×1.0 or 60×80×1.0 flat plates, but they can also be of materials agreed upon by the parties involved.
	2.	The metal or plated metal specimens are to be properly cleaned.
	3.	Cut sections of the specimen are to be protected with tape, paint, paraffin, etc.
	4.	The specimen during the test is to be held at 20±5° in relation to the vertical line.
	5.	The positioning and spacing of the test specimens are not to prevent free falling of the spray, and the solution dripped from the specimen is not to fall on other specimen.

(3) Testing salt water solution

The solution is to be adjusted to salt concentration of 40g/L by dissolving class1 sodium chloride reagent in deionized water, with a specific gravity of 1.0250~1.026 at 25℃.

(4) Air supply

The compressed air used to spray the salt water solution is to be kept at 0.098±0.01Mpa.

(5) Spray chamber condition

	1.	Spray chamber and test solution reservoir is to be at 35±2℃.
	2.	The spray is to be of free fall, and not to be directly sprayed on the test specimen.

(6) Post testing handling of test specimen

	1.	Test specimen is to be removed carefully.
	2.	Immediately water wash at a room temperature and dry in order to remove the salt from surfaces.
	3.	Corrosion born products are removed by mechanical means such as brushing or chemical means.

(7) Judgment method (Listed elsewhere)

	1.	Area method: By Rating Number Evaluation.
	2.	Weight method: Weight variations before and after the test.

Platings corrosion resistance standards in application environments are approximately as follows. There are spraying times for salt water spray tests and CASS tests shown in the table. The rating numbers after these tests must be 9 (R.N.9) or greater.

The working process of electroplating, in an outline, is performed on the following order: Pre work→Pre process→Plating→Post process→Post work

(1) Rack plating

Plating is applied by hanging in the plating solution, with multiple electrical connections secured per each workpiece.

(2) Barrel plating

For small workpieces where rack plating method cannot be used (or not economical), many workpieces are plated by tumbling and energizing in a barrel that is very power saving. However, this method is not applicable for every plating case.

(3) Continuous plating (Hoop plating)

For plating long items such as wire material and hoops (strips), dedicated plating systems are used where the workpieces travel through the system for the complete plating process from pre-process to post process.

(4) Others

Basket plating, Brush plating, Partial plating, etc.

* marked process is followed by a water washing step.