Preliminary Requirements

Safety Requirements

WARNING

FACE MASKS AND RUBBER GLOVES MUST ALWAYS BE WORN, BY THE OPERATORS, DURING THE BLASTING OR PEENING PROCEDURES OR WHEN THE EXHAUST FILTERS ARE CLEANED.

THE OPERATORS MUST NOT TOUCH THE POWDERED GLASS.

ALL EQUIPMENT MUST BE FULLY GROUNDED, TO REMOVE HEAVY ELECTRICAL CHARGES THAT CAN OCCUR DURING THE PROCEDURE.

DRY NON-METALIC BLASTING CAN BE USED ON TITANIUM PARTS IF THE FINE METAL POWDER, MADE DURING THE PROCEDURE, IS CLEANED THROUGH A CYCLONE WATER SYSTEM. ALSO, THE CABINETS MUST BE SUPPLIED WITH EXPLOSION-RESISTANT DOORS AND A CONTINUOUS LOW-SPEED AIR EXTRACTOR.

IT IS THE RESPONSIBILITY OF THE OPERATOR TO OBTAIN AND OBSERVE THE MANUFACTURERS MATERIAL SAFETY DATA SHEETS FOR CONSUMABLE MATERIALS 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.

Procedure

1. SUBTASK 70-38-04-100-001 Make-up Procedures

   1. Abrasive blasting.

      1. The abrasive content should be over 20 percent, by volume, with the fines less than 20 percent of the total solid content. The mixture should be renewed when these proportions are reduced, exceeded or when usage has removed the sharp corners from the abrasive.

      2. NOTE

         Lead contamination is more easily visible when the panel is slightly stained by immersion in boiling water.

         To establish freedom from lead contamination, blast a ferrous test panel; which can then be examined for adherent particles or lead smears.

   2. Shot and glass bead peening.

      1. The shot size, required for shot peening, is specified in the Engine Manual. A single nominal grade, within that range, can then be used. The nominal shot size should not be larger than half of the smallest fillet radius, within the area to be peened, or a quarter of the diameter, or width, of any aperture through which the shot must pass during the peening of shielded critical areas. The nozzles must be checked for size at regular intervals.

      2. The shot must be free of sharp edges. Cut-wire shot must be pre-used, or otherwise treated, to eliminate the sharp edges.

      3. Inspect the glass bead mixture regularly for broken particles, then renew if necessary.

      4. Before renewing the mixture, the interior of the cabinet must be thoroughly washed with clean water.

      5. Glass bead peening can be applied wet or dry; but the wet procedure is safer.

         1. As a wet procedure, the glass beads are sprayed as a water-based slurry to a nozzle, where they are futher accelerated by compressed air.

         2. The mixture is made up of 1 part of glass beads to 4 parts, by volume, of water.

      6. The dry procedure is applied in a low-pressure cabinet to confine the medium. The peening results as a combination of pressure on the bead container and an induction effect from the low-pressure cabinet.