November 2011 Archives

This is a method of removing contamination from metal surfaces by the use of detergents made of chemicals and surfactants. The detergents pulls the contaminants from the metal surfaces and keep the contaminants stably suspended within the detergent in order to prevent from being redeposited on the metal.

1)Detergent types

Can be classified generally as follows.

(1)Alkaline salt water solution (caustic soda, sodium carbonate, sodium phosphate, silicate soda, etc. sometimes acidic detergents such as hydrochloric acid and acid/water solution are used) composition example is shown on [Table 1].

[Table 1] Example of alkaline degreasing bath for steel (g/L)

(2)Surfactant solution
(3)Alkaline degreasing solution (solution of alkaline salt and surfactant)
(4)Emulsified degreasing solution (solvent and surfactant)

2) Cleaning method

Functions of the detergents are: replace, solubilize, disperse, emulsify, saponify the contamination. There are following methods but since they all use solutions, they are strongly affected by the solution temperature. The higher the solution temperature, the higher the detergent power.

(1) Immersion, immerse and oscillate (Also called Immersion Cleaning. Work-piece is immersed in degreasing bath)
(2)Spray cleaning (Used when work-pieces are transferred on conveyors)
(3) Tumbling barrel cleaning (Small parts and detergent are placed in a barrel and tumbled)
(4)Steam cleaning (Used for cleaning large objects such as automobile)
(5)Brush cleaning (From hand brushing to automated rotary brush)
(6)Electrolytic cleaning (DC current is used with Immersion Cleaning)
(7)Ultrasonic cleaning (Ultrasonic wave is used with Immersion Cleaning)

3)Characteristic of this method

This method is applicable to all soiling and is suitable for rough cleaning, often used for pre-treatment of electro-plating, anodizing, PVD, CVD processes, as well as pre- and post processes for pickling and mechanical scale removal. The detergents are all low in costs and water rinsing can be used since they are water soluble, safe foe the operators without any risk of flammability or toxicity.

This standard is provided to define the effectiveness of the industrial hard anodize coating on rolled and cast aluminum material for the purpose of wear resistance improvements. The industrial hard anodizing is typically processed with low temperature or various organic acid based baths, and has higher coating hardness is more wear resistant compared to the conventional anodize coatings. The surface pore sealing process is not normally applied unless corrosion protection is required. In such case, the wear resistance tends to decrease.

(1) Types

Hard anodizing types are classified based on the base material as shown on [Table 1].

[Table 1] Hard anodizing types

(2) Coating thickness

The thickness is to be the average thickness as a general rule. The thickness and its uniformity are to be determined by agreements of the related parties.

(3) Coating hardness

The coating microhardness is to be as shown on [Table 2]

(4) Wear resistance

The wear resistance must be tested by either a reciprocating wear test, spray wear test, or flat plate wear test, and must comply to [Table 3], [Table 4], and [Table 5] each.

【表2】皮膜の微小硬さ

Note 1) 1 Wear resistance reference specimen is as follows.
Material: A1050P-H14 or H24, Dimension: 100×100×2mm Flat plate, Sulfate coating: Free sulfuric acid 180±2g/L, AL concentration 1~5g/L, Deionized water adjusted, Electrolysis condition: 0±0.5°C, Current density 3.5±0.35A/dm2, Electrolyte air agitated or recirculated, Coating thickness 50±5μm, Pores unsealed.

(5) Pencil scratch resistance test of paint coating

This test is performed as follows.

1. The pencil lead is pointed at the painted surface at a 45 deg. angle, pushed at a constant speed for 10mm distance (consumed time of 2~4 seconds) with enough force not to break the lead. Repeat 5 times at different locations.
2. The pencil scratch resistance is defined with the lead hardness symbol used when 4 out 5 tests show no coating breakage.

(6) Boiling water resistance test of the combined coating

1. A beaker (1 liter) per one test specimen is prepared, and the test specimen is put in de-ionized water.
2. The beaker is kept at 95°C for 5 hours. The specimen is removed and examined to have no abnormality.

(7) Abrasion resistance of Combined coating

Abrasion resistance of compound coating is shown in [Table 3].

[Table 3] Abrasion resistance of compound coating (s)

(8) Accelerated weathering test of paint coating

This is an accelerated weathering test using a "Sunshine Carbon Arc Lamp" where the specimen is exposed to the light for 250 hours and its gloss retention rate is examined to determine the discoloration.
The gloss retention rate is derived with the following formula.

G＝G2×100/G1
G: Gloss retention rate %
G1: Specular gloss at 60° before the test
G2: Specular gloss at 60° after the test

(9) Naming of combined coatings

The combined coatings are named with symbols based on the Type, Anodizing film thickness, Paint coating thickness, and Quality classification.
The quality classification symbols are as follows. Boiling water resistance: Z, Sand drop abrasion resistance test: WF, Spray abrasion resistance test: WJ.

*Example 1: B-9・7-WJ

Type B, Anodize thickness 9μm, Paint thickness 7μm, Spray abrasion test of the coating ([Table 3])

*Example 2: P-6・15-WF

Type B, Anodize thickness 6μm, Paint thickness 15μm, Sand drop abrasion test of the coating ([Table 3])

The standards define combined coating of anodic oxided and organic films applied on expanded aluminum materials for anti-corrosive and esthetic purposes. The Combined coating are coloring paint filmings applied after the anodizing process to give improved corrosion resistance, wheatherabilty, abrasion resistance wear property.

(1) Types

Combined filming types are classified as [Table 1] based on anodize film thickness, paint thickness, paint type.

• *1 Both anodize filming and paint filming are to be of the minimum thicknesses.
• *2 The clear filmings are meant to retain the original feel of the base materials with controlled amount of sheen.
• *3 The colored filmings are formulated with resin based paints with pigments intended to add colors.

(2) Filming performances

Combined filmings performances are shown in [Table 2]

[Table 2] Combined filming performances

• *1 Color differential ΔE*ab 3 or less

(3) Filming thickness test

Performed as follows with a eddy current thickness gage.

1. Pre-measured anodize film thickness is subtracted from the total coat thickness and the paint film thickness is determined.
2. The sum of the anodize film and the paint film is measured, then the paint film is removed with a solvent not evasive to the anodize film. The differential of the two determines the paint thickness.

(4) Paint film adhesion test

Using a cutter blade, 11 lines at 1mm interval reaching the depth of the anodize film. An adhesive tape is placed on the lines, then peeled upwards. It will be deemed 100/100 if the paint film does not peel off.