GB/T 37707-2019Thermal spraying - Components with thermally sprayed coatings - Technical supply conditions (English PDF)

4.1.3 Preparing the instructions for thermal spraying (spray procedure

specification)

The manufacturer is responsible for preparing the spray procedure specification

in written form.

The spray procedure specification shall refer to the coating specification and

the manufacturing instructions, such as the list of parts, instructions of substrate

and spraying material, drawings and tests. If required, the spray procedure

specification can be qualified by a component-related spray procedure

qualification according to EN 15648.

4.2 Technical requirements

4.2.1 Spraying materials

Only spraying materials which are required in the coating specification and

indicated in the spray procedure specification shall be applied.

The spraying material shall comply with the technical supply conditions

indicated in GB/T 19356 (spraying powders) and GB/T 12608 (spraying wires,

rods and cords).

The conformity of the delivered with the required spraying material shall be

safeguarded, for example by comparing the composition indicated on the test

certificate with the required one. All spraying materials shall be stored in

suitable packages.

The processing instructions of the manufacturer/supplier of the spraying

material shall be considered.

4.2.2 Spray procedure specification

The spray procedure specification shall contain all parameters, including, for

the relative motion between the gun and the part or the identification number of

the motion programme, those which are necessary for the spraying process of

X: Usually, the test is applied as a shop test only. Tests can be required, if reference samples

are agreed between the contracting parties.

—: The test is senseless or not practicable.

a The determination shall be carried out according to GB/T 8642. In the test report, in addition

to results, it shall document the adhesive used and the bonding procedure.

b The preparation method for the test specimen shall be agreed upon between contracting

parties. This method can also be used to measure the coating thickness.

c If the test on the part is not acceptable, the hardness test shall be carried out according to

GB/T 4340.1.

d The number and design of the test specimen, test procedure and admissible crack structures

in the coating shall be agreed upon between the contracting parties.

e It shall carry out the test according to GB/T 4156. The test procedure and admissible crack

structures in the coating shall be agreed upon between the contracting parties.

Where a single part is to be coated, the percentage of the surface for random

testing shall be calculated according to the size of the coated area. The

influence of the process stability (process carried out manually, completely

mechanized, or controlled in closed-loop form) shall be considered when

random tests are specified.

5.3 Test on the part

Wherever possible, required tests shall be carried out on the part. The surface

characteristics shall be assessed by visual inspection carried out by a skilled

and qualified person according to GB/T 37421.

A 100 %-visual inspection shall be carried out on the coating, even if this is not

specified in the manufacturing instructions. In case of doubt about the quality

of the sprayed coating, the test's sensitivity shall be raised by using a

magnification of 6x to 10x.

5.4 Test on accompanying test specimens

Accompanying test specimens shall undergo the same operation steps of the

spraying procedure as the part itself. The test specimen's material shall

correspond to the material of the part in its mechanical and physical properties.

Tests shall be carried out according to GB/T 37421, if possible. Where test

procedures are not specified in the coating specification or in the test

instructions, the test method shall be agreed between the contracting parties.

5.5 Rejection of a defective coating

Where a sprayed coating or the accompanying test specimen did not pass the

required tests, the defective coating shall be removed. After cleaning and

preparation, the part and the test specimen can be coated again according to

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