TASK 70-16-06-350-022
1 . General.
A.Laser marking is a marking process which employs the use of a low or medium power ND:YAG or CO laser to produce controlled depth dot matrix or engrave patterns in coatings or base metal. Typical systems use either a fixed-beam and mask or a moving-beam and computer-controlled galvanometers.
B.This specification will control the laser process by depth of penetration and by type of laser method used (continuous wave or pulsed energy laser modes).
C.It is important to follow the appropriate manual for detailed instructions on location and size of the mark and the method used. Some applications on rotating hardware may require post mark surface conditioning (shotpeening).
2 . Equipment.
Subtask 70-16-06-350-221
A.Laser marking equipment typically requires the use of the following:
(1)A low to medium power laser (5 to 50 watts power typical) with appropriate control accessories such as flat field lenses, automatic shutter controls, computer-controlled galvanometers for a moving-beam system, or appropriate masks for a fixed-beam system, and appropriate fixturing to insure proper part positioning.
(2)A working enclosure that adequately shields the surrounding area from laser energy emissions. View ports will have adequate filter lenses, and all openings should be interlocked with the laser power supply to prevent laser operation while the safety enclosure is open. It is recommended that machine operators wear filtered goggles or glasses supplied by the laser equipment manufacturer.
(3)Test pieces and measuring devices that will ensure that the marking system is operating properly and that the part fixturing system provides correct alignment.
3 . Marking Parameters.
Subtask 70-16-06-350-222
A.The type of marking method and the depth of penetration shall be as follows:
 
Marking Method
Depth
 
Inch
MM
 
minimum
maximum
minimum
maximum
 
Dot Matrix Mode
 
Shallow
0.0001
0.0003
0.003
0.008
 
Intermediate
0.0004
0.001
0.010
0.03
 
Deep
0.001
0.003
0.03
0.08
 
Engrave Mode
 
Shallow
0.0001
0.0006
0.003
0.015
 
Intermediate
0.0007
0.004
0.018
0.10
 
Deep
0.004
0.010
0.10
0.25
B.The marking methods shall be identified per the following:
 
METHOD
TYPE
 
1A
Dot matrix, shallow penetration
 
1B
Dot matrix, intermediate penetration
 
1C
Dot matrix, deep penetration
 
2A
Engrave, shallow penetration
 
2B
Engrave, intermediate penetration
 
2C
Engrave, deep penetration
C.The character size will be controlled by the requirements as specified in the appropriate manual. If no character size limits are given, a size shall be chosen which will insure legibility and allow the marking to remain within the defined marking boundaries.
4 . Procedure.
Subtask 70-16-06-350-223
A.Marking parameter determination:
(1)Pre-establish and store the part marking procedures into the machine memory or on floppy disk or cassette. Mark the trial pieces used for program build and parameter verification. Record the depth of penetration by methods such as cross section or ellipsometric comparison. Ensure that the material used for parameter evaluation is in the same material family as the pieces to be marked.
(2)If a program does not currently exist for a piece part, make sample markings on scrap material and determine the depth.
B.Verify fixturing and part/beam location.
(1)Before pieces are marked, verify that part location and beam location are aligned so that part marking will be in the location required. Typical alignment techniques are to use a HeNe laser beam to monitor the marking beam path (by running the actual program with the marking laser unpowered), or to use the marking beam at low power setting on a piece of white paper that is covered with black toner (i.e., from a copying machine). Adjust fixturing or beam location to insure proper mark location.
C.Prepare part(s) to be marked as follows:
(1)Ensure area to be marked is clean and free from any surface debris.
(2)Warm up the laser system and ensure that the part/beam orientation is correct.
(3)Set the laser power setting and verify as correct for the depth of penetration desired.
(4)Correctly load the characters to be marked on the part into the machine working memory or configure the mask with the appropriate stencil and correctly load it.
WARNING:
DIRECT OR REFLECTED LASER RADIATION CAN CAUSE EYE DAMAGE. IT IS STRONGLY RECOMMENDED THAT PERSONNEL WORKING WITH THE LASER MARKING MACHINE WEAR APPROPRIATE SAFETY GLASSES OR GOGGLES AS RECOMMENDED BY THE LASER EQUIPMENT MANUFACTURER.
D.Mark parts.
(1)Load the first part onto the fixture and close the safety enclosure.
(2)Verify that information to be marked on the part is correct. If information is incorrect, adjust characters as needed.
(3)Cycle machine.
(4)Remove part from machine and inspect for proper mark location. Verify that alpha and numeric characters are correct.
(5)Reload the machine with another part to be marked. If a different marking is required (serial number change), adjust the marking information. Cycle the machine for the remaining parts.
5 . Quality Assurance.
Subtask 70-16-06-350-224
A.Inspect marked parts for proper marked information and location.
B.Parts with improper marking can be re-marked in an alternate area with prior approval of GE Product Support Engineering. A series of lower case "x's" will be marked over the incorrect mark.
C.Parts with marks in an improper location must be reviewed through GE Product Support Engineering to determine usability.