Powder coating inspection standard

PURPOSE
This standard is to provide guidelines for the inspection of powder coating film.

SCOPE
This standard applies to all elevator and escalator parts, which need powder coating.

REFERENCES
Coating Film Thickness Measure Standard GB 1764-93
Coating Film Adhesion Measure Standard GB 1720-85
Coating Film Impact Resistance Measure Standard GB/T 1732-93

DEFINITIONS
1、Appearances
Place the parts vertically and check with light at eye level.

1.1、Even
The coating film must be even and smoothness all over the part. It is acceptable that has 0.5 mm² grain, spots, blisters and craters in less than 3 places per square meter.

1.2、Scratch
Shallow scratches can be acceptable if coating is not removed.

1.3、Lack of powder
It is unacceptable for lack of powder where can be easily seen.

1.4、Spot welding mark
It is acceptable if the spot welding mark has indicated on drawing.

1.5、Powder pile
It is unacceptable for powder pile where can be easily seen.

1.6、Color
It is unacceptable for any powder color change, which must be checked according to color matching card.

Thickness
Adopt Magnetic Thickness Meter which accuracy 2µ to check more than 3 places, The requirement is as follows:
The film thickness of textured powder coating is 60~120 micron;
The film thickness of gross powder coating is 50~100 micron;

Hardness
Adopt a 2H pencil to write a line, then check the powder coating dented or not. If no, it’s OK; If dented, It’s NG.

Adhesion
Method1 (crosscircle): Adopt Adhesion Instrument to cut a serial cross-circles, then check the coating film whether integrity or not. The adhesion must be not over 2 grade (total 7 grades).
Method 2 (crsshatch): Adopt knife to cut a serials of crosshatches (1~2mm), and paste an adhesive plaster (wideth 18~24 mm * length 50 mm, adhesion force > 2.94N/10mm) on the coating film. After 1~2 min., drag it off fastly at vertical direction, then check whether the film is 100% integrity or not.

Iimpact Resistance
Adopt 25 kg·cm impact resistance instrument to impact 3 places, then check the coating film whether cracked or not. If no, it’s OK. If cracked, It’s NG.

The hardness, adhesion and impact resistance test must be tacken on at least 2 sample panels, which have gone through the same manufacturing process and made per week interval under normal situation.

PROCEDURE
Whenever the paint line is running on a given day, perform self-inspection for every colour colour run during that day and record it.

QA select a major item from the beginning and end of the run and measure coating film thickness of 3 different points. QA patrol to check and record the quality problem.

QA should perform the hardness, adhesion and impact resistance test and record once every week and when QA thinks it necessary. if these tests fail, QA will issue the MRB report to solve.

EXHIBIT

Powder Coating Film Inspection Record G-MQ-07-18-FM1-0
Powder Coating Film Quality Test Record G-MQ-07-18-FM2-0