BS/EN 4867-2019 pdf download.Aerospace series – Laser surface marking by discoloration.
5.2.3 Laser marking parameters
The laser source power shall be adapted to the material to be marked and the nature of the mask.
Pulse parameters:
pulse energy;
– pulse duration; beam profile.
5.3 Marking procedure
5.3.1 Prior to marking step
— Surfaces to receive marking shall be thoroughly cleaned to remove oil, water, grease, dirt, paint residues and other foreign material, hydraulic fluid, fuel, marking inks, and other surface contaminations.
— The surface cleaning shall be performed by any method able to completely eliminate all surface contaminations.
— When required, all surfaces designated for marking shall be cleaned by abrasive blasting with the abrasive media specified (under agreement between manufacturer and customer). All blast media shall be free of contamination that will affect the base material.
After cleaning a visual inspection of the surface to be marked shall be carried out. No visible imperfections should be observed. If imperfections are observed, they shall be reported so that remedial action can be done before the marking.
Mechanical or chemical properties are not affected by this marking process:
— in case of re-marking, the previous marking have to be removed or cancelled (see 5.4) the new marking has to be done in the specified area:
— the surface state of the part to be marked has an influence on the precision of the mark legibility. It is necessary to ensure that the initial surface state do not prevent the mark legibility (e.g. scratch, nick, dents…).
5.3.2 Marking during the manufacturing process
The parts shall not be subjected to any tensile, fiexure, torsion or other stress and to condensation phenomenon (relative humidity between 30 % – 80 %).
The surface to be marked is positioned in front of the laser beam to ensure that the marking is not distorted. In the case of a part having no flat surface (convex or concave surface), the marking shall be readable.
The marking operation can be done between two manufacturing operations of a part, the mark can be made illegible thanks to subsequent operations (example: heat treatment, chemical attack, machining. drilling. grinding, painting. coating). A surface treatment can be carried out, if the mark stay legible by naked eyes, optical and/or electronic device depending of the specification requirements.
5.3.3 After the marking procedure
The marking shall be free of burnings, blisters and discontinuities such as scratches, ruptures or other damages.
A visual inspection is done after the marking (see 5.3.5 visual inspection).
The inspection sampling of parts has to be agreed between manufacturer and purchaser regarding the criticality of parts.
5.3.4 In-production parts
The mark shall remain legible during all of the manufacturing stages, in case of erasing of the mark, the part shall be marked again in order to guarantee the identification of the parts.
5.3.5 Visual inspection
As a minimum, the following aspects shall be included in the visual inspection process:
5.3.8 Direct inspection
For direct inspection there shall be a direct line of sight to the surface being inspected.
Direct inspection may be performed with the aid of magnification up to maximum lOx.
For direct inspection, the access shall be sufficient to view the inspection surface within a maximum of 400 mm. The angle of inspection should not be less than 30° unless required by specific lighting and surface texture condition. Indirect inspection may be used to supplement direct inspection for example, to record the inspection result.
5.3.9 Indirect inspection
Indirect inspection Is when there is no direct line of sight to the surface being inspected.
Indirect inspection, using for example, mirrors, boroscopes, fibre optics or cameras, shall be applied when the access for inspection Is not possible or as specified by the engineering/design authority. Indirect Inspection may be used to supplement direct inspection for example, to record the inspection result.
Equipment used shall be suitable for inspecting all features to enable assessment of discontinuities defined within the relevant quality acceptance standards.
The lighting may be adjusted to improve the contrast between surface features and background. Lighting
conditions in direct inspection may not apply to indirect inspection.
5.3.10 Eyesight requirements
Marking laser operator shall fulfil the eye sight requirements of EN 4179.
5.4 Re-marking
One re-marking is allowed; any further re-marking shall be agreed between the interested parties. The re-marking shall not cause any surface alteration or damage.
In case of cancellation of an existing mark, It shall be cancelled or erased so that it may not be legible by an optical reader device, nor by an electronic device nor by naked eyes. The marking operation used for the cancellation shall be the one described in this standard.
An alpha numerical type of a linear mark shall be crossed with a dash (see Figures 2 and 3), in the case of a 2D mark, It shall be crossed as indicated in Figures 4 and 5 thanks to two diagonal lines that intersects at the centre of the mark In addition, two other dashes (one vertical, one horizontal) overlap the two lines of the frame margin of the data matrix’s symbol.BS/EN 4867-2019 pdf download.