Preliminary Requirements

Safety Requirements

WARNING

IT IS THE RESPONSIBLITY OF THE OPERATOR TO OBTAIN AND OBSERVE THE MANUFACTURERS MATERIAL SAFETY DATA SHEETS FOR CONSUMABLE MATERIALS INFORMATION SUCHA AS, HAZARDOUS INGREDIENTS, PHYSICAL/CHEMICAL CHARACTERISTICS, FIRE, EXPLOSION, REACTIVITY, HEALTH HAZARD DATA, PRECAUTIONS FOR SAFE HANDLING, USE AND CONTROL MEASURES AND ALSO TO TAKE LOCAL REGULATIONS INTO CONSIDERATION.

WARNING

EVERY POSSIBLE CARE MUST BE TAKEN TO AVOID THE SOLUTION COMING INTO CONTACT WITH THE EYES OR BARE SKIN. PROTECTIVE CLOTHING INCLUDING RUBBER GLOVES AND GOGGLES MUST BE PROVIDED FOR THE OPERATORS WHEN PREPARING AND USING THE ACID SOLUTION. RUBBER GLOVES SHOULD BE CHECKED REGULARLY FOR PIN HOLES AND REPLACED IF NECESSARY.

WARNING

SAFETY NOTICES MUST BE PLACED IN A CONSPICUOUS PLACE.

WARNING

EYE-WASH BOTTLES AND HF BURN JELLY MUST BE PROVIDED AS CLOSE AS POSSIBLE TO THE PLACE OF WORK.

WARNING

IF SKIN BECOMES CONTAMINATED WITH THE SOLUTION IT MUST BE RINSED WITH COPIOUS AMOUNTS OF CLEAN RUNNING WATER.

WARNING

ALL BURNS, HOWEVER SLIGHT, SHOULD BE TREATED AT THE NEAREST SURGERY OR FIRST AID POST.

WARNING

THE SURGERY MUST BE TOLD WHICH SOLUTION (THE ACIDS INVOLVED) HAS CAUSED THE BURN PARTICULARLY IF HYDROFLUORIC ACID IS A CONSTITUENT.

WARNING

THE OPERATORS MUST ALWAYS WEAR THE PROTECTIVE CLOTHING SUPPLIED, WHICH INCLUDES RUBBER GLOVES AND EYE PROTECTION

WARNING

IF SODIUM HYDROXIDE SOLUTION GETS INTO THE EYES FULLY FLUSH THEM, WITH CLEAN WATER, THEN GET MEDICAL TREATMENT IMMEDIATELY.

WARNING

A SUPPLY OF BUFFERED PHOSPHATE SOLUTION MUST ALWAYS BE EASILY AVAILABLE, TO APPLY TO BURNS.

WARNING

CARE MUST BE TAKEN WHEN YOU ADD COMPOUNDS WHICH CONTAIN SOLID SODIUM HYDROXIDE TO WATER, BECAUSE HEAT IS GIVEN OUT WHEN THE COMPOUND DISSOLVES. MAKE MUCH MOVEMENT OF THE SOLUTION, WITH AIR OR MECHANICAL METHODS, AS YOU ADD THE COMPOUND TO THE SURFACE OF THE SOLUTION. DO NOT ADD LARGE QUANTITIES OF THE COMPOUND, TO ONE SMALL AREA OF THE TANK, BECAUSE THE SOLUTION WILL BOIL.

WARNING

THE INSTRUCTIONS GIVEN BY THE SAFETY OFFICER MUST ALWAYS BE OBEYED.

CAUTION

THE PROCEDURE MUST BE CAREFULLY CONTROLLED AND MUST ONLY BE USED, ON ENGINE PARTS, WHEN SPECIFIED IN THE ENGINE MANUAL FOR AN APPLICABLE PART. THE SUSPENDERS, NECESSARY FOR IMPORTANT PARTS, ARE SPECIFIED IN THE ENGINE MANUAL. IT IS IMPORTANT THAT THE SUSPENDERS ARE INSTALLED, ON THE CORRECT LOCATION OF A PART, TO PREVENT THE HEAVY CLAMP LOAD OF THIN PARTS (SUCH AS COMPRESSOR DISK DIAPHRAGMS OR OTHER THIN PARTS), WHICH CAN THEN MOVE AND APPLY A BENT FORCE, TO CAUSE EMBRITTLEMENT DURING THE ELECTROLYTIC ETCHING PROCEDURE.

Procedure

1. SUBTASK 70-33-87-300-001 Procedures to Etch Gears and Case Hardened Parts

   
   CAUTION
   ALL PARTS MUST BE DE-EMBRITTLED AFTER ETCHING, IN A HOT OIL BATH, FOR TWO HOURS AT 248 TO 284 DEG F (120 TO 140 DEG C).

   1. The parts to be etched hang in the form of an anode in a tank that contains the etching solution. The tank is usually used as the cathode; but a cathode with a special shape can also be used when necessary. An electric current then goes through the part which causes the metal to be removed from it.

      1. Install the parts on to the suspenders, as specified in the Engine Manual.

      2. Vapor degrease (refer to TASK 70-11-01-300-503) or hot aqueous degrease (refer to TASK 70-11-34-300-501) the parts.

      3. Caustic clean the parts (refer to the SPM TASK 70-11-24-300-503).

         NOTE

         In hot areas a temperature of 86 to 95 deg F (30 to 35 deg C) can be used. But, at this temperature, the etching time must be decreased by 50 percent.

      4. Keep the temperature of the etching solution at 50 to 68 deg F (10 to 20 deg C).

      5. Set the voltage control to give an open-circuit voltage of 10 volts.

      6. Hang the parts from the busbar, so that they are fully in the solution. Make sure that there is a good contact between the busbar and the suspender.

         NOTE

         When the etching starts, a voltage decrease will occur; which will be in proportion to the current flow through the part. No adjustment must be made for such a voltage decrease.

      7. Turn on the electrical supply, anodically.

      8. Etch the parts for the time specified in the Engine Manual (refer to step (4) NOTE:).

      9. Flush the parts in a clean, cold water flow. Remove the parts from the suspenders then hang them on a clean rope or other device. Make sure that the etched surfaces are not touched.

      10. Flush the parts again in a clean, cold water flow.

      11. Put the parts fully into the neutralizing solution (refer to SUBTASK 70-33-87-100-002) at approximately 68 deg F (20 deg C).

      12. Fully flush the parts in a clean, cold water flow with an air/water gun.

      13. Put the parts fully into an approved dewatering oil (refer to the SPM TASK 70-38-05-380-501) at a temperature of 221 to 230 deg F (105 to 110 deg C).

      14. Remove the parts and let them drain.

          NOTE

          The recommended oil is CoMat 10-024 LUBRICATING OIL.

      15. De-embrittle the parts in a hot oil bath for two hours at 248 to 284 deg F (120 to 140 deg C).

2. SUBTASK 70-33-87-300-002 Procedures to Etch Important Rotational Parts

   
   CAUTION
   TO PREVENT CRACKS CAUSED BY HYDROGEN EMBRITTLEMENT, WHEN ETCHING STEEL PARTS WITH A TENSILE STRENGTH ABOVE 65 TON/F SQ IN. (1000 MN/SQ M) OR A HARDNESS VALUE ABOVE 302 HB (310 HV), STRESS-RELIEVE HEAT-TREAT THE PARTS (AT 554 TO 590 DEG F (290 TO 310 DEG C) FOR TWO HOURS) BEFORE ETCHING THEN DE-EMBRITTLEMENT HEAT-TREAT THE PARTS (AT 374 TO 410 DEG F (190 TO 210 DEG C) FOR TWO HOURS) AFTER ETCHING, IN A THERMOSTATICALLY-CONTROLLED OVEN.
   WHEN NECESSARY, THE STRESS-RELIEF AND DE-EMBRITTLEMENT INSTRUCTIONS ARE GIVEN IN THE ENGINE MANUAL.
   OBEY THE CAUTION, GIVEN IN SAFETY PRECAUTIONS, PARAGRAPH 2.

   1. Vapor degrease (refer to TASK 70-11-01-300-503) or hot aqueous degrease (refer to TASK 70-11-34-300-501) the parts.

   2. When specified in the Engine Manual stress-relieve the parts in a hot air oven at 554 to 590 deg F (290 to 310 deg C), then let them become cool.

   3. Install the parts on to the suspenders, as specified in the Engine Manual.

   4. Vapor degrease (refer to TASK 70-11-01-300-503) or hot aqueous degrease (refer to TASK 70-11-34-300-501) the parts.

   5. Caustic clean the parts (refer to the SPM TASK 70-11-24-300-503).

      NOTE

      In hot areas a temperature of 86 to 95 deg F (30 to 35 deg C) can be used. But, at this temperature, the etching time must be decreased by 50 percent.

   6. Keep the temperature of the etching solution at 50 to 68 deg F (10 to 20 deg C).

   7. Set the voltage control to give an open-circuit voltage of 10 volts.

   8. Hang the parts from the busbar so that they are fully in the solution. Make sure that there is a good contact between the busbar and the suspender.

      NOTE

      1. The correct cycle, for an applicable part, is given in the Engine Manual. This cycle can be different (to that given in SUBTASK 70-33-87-300-001) if the current is changed from anodic to cathodic, for some parts, to help with the cleaning procedure.

      2. When the etching starts, a voltage decrease will occur which will be in proportion to the current flow through the part. No adjustment must be made for such a voltage decrease.

   9. Turn on the electrical supply, cathodically or anodically, as necessary.

   10. Etch the parts, with the cycle specified in the Engine Manual (refer to step F. NOTE:).

   11. Flush the parts in a clean, cold water flow. Remove the parts from the suspenders, then hang them on a clean rope or other device. Make sure that the etched surfaces are not touched.

   12. Flush the parts again in a clean, cold water flow.

   13. Put the parts fully into the neutralizing solution (refer to SUBTASK 70-33-87-100-002) at approximately 68 deg F (20 deg C).

   14. Fully flush the parts in a clean, cold water flow with an air/water gun.

       NOTE

       If it is difficult to keep the water temperature at 212 deg F (100 deg C), the parts can be put fully into water at a lower temperature; of at least 185 deg F (85 deg C).

   15. Put the parts fully into clean, hot water (that is at a temperature of 212 deg F (100 deg C) until the parts and the water are at the same temperature.

   16. Remove all the water with clean, dry compressed air while the parts are hot.

       NOTE

       It is permitted to de-embrittle the parts at a higher temperature of 572 deg F (300 deg C), but a change of surface color will occur.

   17. When specified in the Engine Manual de-embrittle the parts for two hours, in a hot air oven at 374 to 410 deg F (190 to 210 deg C).