TASK 70-42-01-350-003
1 . General.
CAUTION:
DO NOT USE ABRASIVES THAT INCLUDE A VITRIFIED BOND MATRIX ON TITANIUM ROTATING PARTS OR DAMAGE TO THE PART CAN OCCUR.
CAUTION:
FOR ALL ABRASIVES USED, CONFIRM WITH SUPPLIER IF THE PRODUCTS HAVE “VITRIFIED BOND MATRIX”. THE ABRASIVES WITH “VITRIFIED BOND MATRIX” ARE EXCLUDED FROM TITANIUM ALLOYS.
This procedure provides instructions for polishing bolt hole surfaces to eliminate tool marks, scratches, and other minor surface defects.
2 . Equipment.
Subtask 70-42-01-350-031
A.An air- or electric-powered rotary tool having a minimum speed of 4000 rpm is necessary. One having a speed of5000-8000 rpm is recommended.
3 . Materials.
Subtask 70-42-01-350-032
NOTE:
Equivalent substitutes may be used instead of the following items.
 
Consumable Product
No.
 
A. Polishing Compound.

 
(1) 240 grit aluminum oxide in soft grease
C10-096  
 
NOTE:
Any equivalent polishing compound must be removable by aqueous cleaning.
 
B. Wire Brushes.

 
(1) 0.003 inch (0.08 mm) wire
C10-097  
 
NOTE:
Brush diameter range of sizes should be about 0.031 inch (0.79 mm) larger than bolt hole to be polished.
4 . Procedure.
Subtask 70-42-01-350-033
A.Polish internal surface as follows:
(1)Mount a steel wire brush of the proper diameter in the chuck of the rotary tool.
(2)With the tool rotating at 4000 rpm minimum, pass the wire brush completely through the hole, and charge the brush with polishing compound in that position. Withdraw the rotating brush slowly and evenly.
(3)Repeat step 4.A.(2) until defects are eliminated or oversize limit is reached. Do not exceed limit.
NOTE:
The brush itself is not used to polish, but to carry the polishing compound. Nevertheless, the brush should be changed often enough to retain full size. It is suggested to change the brush after polishing one complete bolt circle.
(4)Examine the hole after polishing as follows:
(a)Check surface finish of wall to be sure that it meets detail part specifications.
(b)Swab etch the affected area per TASK 70-24-00-110-033, Etching Procedures for Fluorescent-Penetrant Inspection.
(c)Inspect surface per TASK 70-32-03-230-002, Spot-Fluorescent-Penetrant Inspection. No indications are permissible.