Preliminary Requirements

Safety Requirements

WARNING

IT IS THE RESPONSIBILITY OF THE OPERATOR TO OBTAIN AND OBSERVE THE MANUFACTURER'S MATERIAL SAFETY DATA SHEETS FOR CONSUMABLE MATERIALS. THESE CONTAIN INFORMATION SUCH 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.

CAUTION

IF THE PROCEDURE IS APPLIED TO STEEL PARTS WITH A TENSILE STRENGTH OF MORE THAN 65 TON F/SQ IN. (1000 MN/SQ M), OR A HARDNESS VALUE OF MORE THAN 310 HV (302 HB), A STRESS-RELIEF HEAT TREATMENT, FOLLOWED BY A DE-EMBRITTLEMENT HEAT TREATMENT, MUST BE APPLIED BEFORE THE PLATING PROCEDURE. THIS WILL PREVENT CRACKS, CAUSED BY HYDROGEN EMBRITTLEMENT.

Procedure

1. SUBTASK 70-33-16-500-001 Safety Precautions

   1. Cyanide poisoning will occur if:

      1. You eat or drink cyanide.

      2. You breathe hydrocyanic gas.

      3. Cyanide soaks through your skin.

   2. Warning signs of cyanide poisoning are:

      1. Dizziness, nausea, general weakness and headache.

      2. Palpitations.

      3. Feeling of suffocation, with tightness in the throat.

      4. Pallor, deep breathing and unconsciousness.

2. SUBTASK 70-33-16-300-001 Clean the Parts

   1. Remove the oil, grease and carbon particles, as specified in SPM TASK 70-11-03-300-503 or SPM TASK 70-11-14-300-503.

3. SUBTASK 70-33-16-300-002 Remove the Remaining Plating

   1. For the purposes of this TASK, stainless steels are the austenitic alloys (for example, 301, 302, 304, 310, 321 and 347). The corrosion resistant steels are martensitic and ferritic iron-based alloys (for example, 410, Greek ascoloy, 430, 44C). Steels are low alloy steels (for example, 9310, 9315, 4130, 4340 and 17-22A).

   2. Stainless steel and nickel base parts.

      1. Stainless steel and nickel base parts can be put into the nitric acid stripping solution specified in SUBTASK 70-33-16-100-001. The solution must be kept at a temperature of 59 deg F to 77 deg F (15 deg C to 25 deg C).

      2. After the parts are put fully into the correct solution they must be fully flushed in clean, cold, water. They must then be put fully into clean, hot, water at a minimum temperature of 176 deg F (80 deg C ), removed and dried with clean, dry, compressed air.

      3. If it is necessary to remove any remaining silver plate or corrosion, abrasive blast the part by SPM TASK 70-12-01-120-501, SPM TASK 70-12-02-120-501, SPM TASK 70-12-08-300-503, SPM TASK 70-12-11-300-503 or SPM TASK 70-12-12-300-503. If SPM TASK 70-12-02-120-501 or SPM TASK 70-12-11-300-503 is used, dry the part before blasting.

      4. If the procedures that follow will not be applied immediately, apply temporary protection to the steel parts; as specified in SPM TASK 70-38-05-380-501.

   3. Low alloy steel parts.

      1. Chemically strip the remaining plating by one of the following methods:

         1. Method A

            1. Put the parts fully in one of the following solutions (no current) as specified in SPM TASK 70-33-27-330-501, until all plate is removed, Solution Code 54 or Solution Code 56 or Solution Code 60. The solution temperature must be 120 deg F (49 deg C) maximum.

         2. Method B

            1. Put the parts fully in Solution 204 at room temperature as specified in SPM TASK 70-33-27-330-501, until all plate is removed (anodic current only, 10 to 15 ASF). Continuous movement of the solution in the tank is required.

         3. Method C

            1. Put the parts fully in Solution Code 203 as specified in SPM TASK 70-33-27-330-501, until all plate is removed. The solution temperature must be 100 deg F - 110 deg F (38 deg C - 43 deg C). The current must be 5-6 Volts, anodic only, 100 ASF maximum.

      2. After the parts are put fully into the correct solution they must be fully flushed in clean, cold, water. They must then be put fully into clean, hot, water at a minimum temperature of 176 deg F (80 deg C), removed and dried with clean, dry, compressed air.

      3. If it is necessary to remove any remaining silver plate or corrosion, abrasive blast the part by SPM TASK 70-12-01-120-501, SPM TASK 70-12-02-120-501, SPM TASK 70-12-07-120-501, SPM TASK 70-12-08-300-503, SPM TASK 70-12-11-300-503 or SPM TASK 70-12-12-300-503. If SPM TASK 70-12-02-120-501 or SPM TASK 70-12-11-300-503 is used, dry the part before blasting.

      4. If the procedures that follow will not be applied immediately, apply temporary protection to the steel parts; as specified in SPM TASK 70-38-05-380-501.

4. SUBTASK 70-33-16-300-003 Machining

   1. If machining is necessary to remove a worn area, full instructions will be given in the Engine Manual together with the plating data necessary to increase the part to its initial dimensions.

5. SUBTASK 70-33-16-300-004 Stress-relief of Steel Parts

   
   CAUTION
   IF THE PROCEDURE IS APPLIED TO STEEL PARTS WITH A TENSILE STRENGTH OF MORE THAN 65 TON F/SQ IN. (1000 MN/SQ M) OR A HARDNESS VALUE OF MORE THAN 310 HV (302 HB), A STRESS-RELIEF HEAT TREATMENT IS NECESSARY BEFORE THE PLATING PROCEDURE TO PREVENT CRACKS CAUSED BY HYDROGEN EMBRITTLEMENT.

   1. Parts with a high tensile strength or hardness value refer to CAUTION in this subtask must be heat treated at 374 deg F to 410 deg F (190 deg C to 210 deg C) for one hour, unless specified differently in the Engine Manual.

      1. Steel parts must be stress-relief heat treated if the tensile strength is in the range of 930 MN/m2 to 1080 MN/m2 or if the hardness value is in the range of 286 HB to 321 HB.

      2. The necessary heat treatment for steel parts with tempering temperatures of less than 392 deg F (200 deg C ) is specified in the Engine Manual.

6. SUBTASK 70-33-16-300-005 Prepare the Parts for Plating

   NOTE

   A special jig can be used if necessary, for the shape and quantity of the parts to be plated. If a special jig is necessary, the special jig will be specified in the Engine Manual.

   1. Connect the parts together with CoMat 02-015 COPPER WIRE or CoMat 02-016 COPPER WIRE. Make sure that all the wires used are sufficient for the necessary current capacity and that the wires have good electrical contact with the parts.

   2. Degrease the parts, as specified in SPM TASK 70-11-03-300-503.

7. SUBTASK 70-33-16-300-006 Stop-off the Areas Not to be Plated

   NOTE

   Alternative stop-off procedures (for example, lacquer) can be used.

   1. Use a brush to apply CoMat 01-085 ETHYLENE GLYCOL (ETHANEDIOL) lightly to the area to be plated so that the stopping-off wax does not bond to that area. Do not let the ethylene glycol run areas that are not to be plated because acid leakage onto those areas can occur if the wax does not become bonded.

   2. Put the assembly three times into CoMat 02-017 WAX or an approved alternative, at a temperature of 194 deg F (90 deg C). Let the assembly become sufficiently cool for the wax to set before it is put in again. This will give a wax coating, that is approximately 0.0625 in. (1.59 mm) thick.

      1. During the first time in the wax, let the assembly get to the wax temperature before it is removed from the wax. This will give a correctly bonded initial thin coating before the second and third coatings are applied.

   3. While the wax is warm, cut around the edges of the area to be plated. Remove the wax to show the bare metal. The edges of the remaining wax coating must be bonded to the part so that the solutions used during the subsequent operations cannot become caught.

   4. Degrease the bare metal refer to SPM TASK 70-11-26-300-503. Rub the bare metal with a soft cloth and CoMat 02-008 PUMICE POWDER, then flush with a clean, cold, water flow and/or spray to remove all the pumice powder.

8. SUBTASK 70-33-16-300-007 Clean and Etch the Parts

   1. Clean all parts with electrolytic caustic cleaner refer to SPM TASK 70-33-86-300-503 for approximately three minutes. Alternatively, alkali clean the parts as specified in SPM TASK 70-33-02-100-501, SUBTASK 70-33-02-300-003 paragraph C.

      1. If water breaks occur, clean the area with CoMat 02-008 PUMICE POWDER and a clean, soft, wet cloth. Alternatively, a small, rigid brush can be used. Fully flush in a clean, cold, water flow to remove all the pumice powder.

   2. Fully flush in a clean, cold water flow.

   3. Do steps A and B again.

   4. Etch the parts, as specified for the base material to be plated, as follows:

      1. For steel parts, put the parts fully into the sulfuric acid etching solution refer to SPM TASK 70-11-38-300-503 at a temperature of 54 deg F to 75 deg F (12 deg C to 24 deg C), then etch anodically for 45 seconds at a PD of 6 volts to 8 volts DC. Alternatively, use an aqueous solution of 66.8 oz/gal to 77.0 oz/gal (520 g/l to 600 g/l) of CoMat 01-050 SULFURIC ACID H2SO4 refer to SPM TASK 70-33-14-300-503 or etch the parts, as specified in SPM TASK 70-33-05-300-503.

      2. For stainless steel parts, etch the parts anodically for 45 seconds in one of the solutions specified in step (1) as for steel parts. Etch the parts cathodically at 6 volts to 8 volts for 5 seconds to 10 seconds refer to SPM TASK 70-11-38-300-503. Alternatively, stainless steel parts can be etched by the same procedure as that specified for nickel base alloys below.

      3. For nickel base alloy parts, etch the parts in the ferric chloride solution refer to SPM TASK 70-11-39-300-503 at 59 deg F to 77 deg F (15 deg C to 25 deg C) for 90 seconds to 120 seconds.

   5. Fully flush the parts in a clean, cold water flow, then immediately transfer all steel, stainless steel and nickel base parts to the nickel chloride strike solution refer to SUBTASK 70-33-16-100-004 at room temperature 59 deg F to 77 deg F (15 deg C to 25 deg C). Put the parts fully into this solution for one to two minutes at six volts, then remove them. Alternatively nickel chloride strike the parts as specified in SPM TASK 70-33-06-300-503, SUBTASK 70-33-06-300-001. Flush the parts again in a clean, cold water flow.

9. SUBTASK 70-33-16-300-010 Silver Strike/Plate the Parts

   1. Turn on the electrical current. Put the parts fully into the silver strike solution refer to SUBTASK 70-33-16-100-008 at room temperature 59 deg F to 77 deg F (15 deg C to 25 deg C), then strike at six volts for one minute to two minute. The current density is usually 20 A/sq ft to 25 A/sq ft (2.15 A/sq dm to 2.70 A/sq dm).

   2. Transfer the parts from the silver strike solution refer to SUBTASK 70-33-16-100-008to the silver plating solution refer to SUBTASK 70-33-16-100-009, kept at a temperature of 68 deg F to 86 deg F (20 deg C to 30 deg C), without a cold water flush. The electrical current must be turned on before the parts are transferred.

   3. Silver plate at 0.5 volt to 1.0 volt for sufficient time to give the necessary thickness of silver, which will usually give a current density of 5 A/sq ft to 10 A/sq ft (0.54 A/sq dm to 1.08 A/sq dm). The solution temperature must be kept at 68 deg F to 86 deg F (20 deg C to 30 deg C). For solutions that you use continuously, add 0.1 g/l of CoMat 01-288 AMMONIUM THIOSULPHATE each day before plating. Dissolve the ammonium thiosulfate in a small quantity of water before it is added to the plating solution.

   4. After removal fully flush the parts in a clean, cold water flow to remove all the silver plating solution.

   5. Put the parts fully into hot water, at a temperature of approximately 212 deg F (100 deg C), to remove the stopping-off wax.

   6. After removal from the hot water dry the parts with clean, dry compressed air.

   7. Put the parts fully into a dewatering oil refer to SPM TASK 70-38-05-380-501.

10. SUBTASK 70-33-16-300-011 De-embrittlement of the Steel Parts

    
    CAUTION
    IF THE PROCEDURE IS APPLIED TO STEEL PARTS WITH A TENSILE STRENGTH OF MORE THAN 65 TON F/SQ IN. (1000 MN/SQ M) OR A HARDNESS VALUE OF MORE THAN 310 HV (302 HB), A DE-EMBRITTLEMENT HEAT TREATMENT IS NECESSARY AFTER THE PLATING PROCEDURE TO PREVENT CRACKS CAUSED BY HYDROGEN EMBRITTLEMENT.
    
    CAUTION
    IF DE-EMBRITTLEMENT TREATMENT IS REQUIRED IT MUST BE CARRIED OUT AS SOON AS POSSIBLE AND MUST NOT BE LATER THAN 16 HOURS AFTER PLATING TO AVOID CRACKING FROM HYDROGEN EMBRITTLEMENT.

    1. Clean the parts. Refer to SPM TASK 70-11-03-300-503.

    2. Increase the temperature of the parts in an air circulating oven as follows unless specified differently in the Engine Manual.

       1. For coatings up to 0.010 in. (0.254 mm) thick: 554 deg F to 590 deg F (290 deg C to 310 deg C) for 2 hours.

       2. For coatings of 0.0001 in. to 0.0002 in. (0.0025 mm to 0.0051 mm) thick, on parts with threads or on other parts: 464 deg F to 500 deg F (240 deg C to 260 deg C) for 2.5 hours or 374 deg F to 410 deg F (190 deg C to 210 deg C) for 8 hours; which will be in relation to the tempering temperature of the base material.

       3. Steel bearing cages: 554 deg F to 590 deg F (290 deg C to 310 deg C) for 1 hour which is also used as a bond check.

    3. Apply temporary protection refer to SPM TASK 70-38-05-380-501 to steel parts, which are not fully silver plated or if the subsequent inspection procedure is not to be done immediately.

11. SUBTASK 70-33-16-300-012 Inspection Procedure

    1. Examine the parts to make sure that the silver plate is of the correct thickness and is free from bubbles, particles and cracks.

    2. Remove all unsatisfactory plating and apply again.

12. SUBTASK 70-33-16-300-013 Machine the Parts

    1. Machine the parts, if specified in the Engine Manual.