3-04. EXTERNAL CLEANING. All machine tool systems shall be drained prior to external cleaning operations. External cleaning usually will apply to cleaning various heavy or set-up types of preservative compounds from assembled machines, In no instance shall more than 60 hours elapse before the application of final preservative. Maximum results are obtained by removing inspection shields prior to washing. 3-05. Assembled machines may be cleaned by other methods such as wash- ing with pressure with hot-water—base detergents, steam or combination of steam or water with detergents or alkalies. Precautions shall be taken to prevent penetration of the cleaning materials into critical operating parts of machines, All motors, control panels, boxes and simi- lar units should be shrouded prior to cleaning, and care should be exer- cised to avoid direct application of the cleaning material to the shrouds. 3-06. Where only a small mmber of machines are being prepared for storage, hand cleaning of the external surfaces may be more practicable. Methods and materials shall conform to Specification JAN-P-116, 3-07. Following external cleaning, all removable accessories and at- tachments shall be detached. bled as specified in 3-02, 3-08. INTERNAL CLEANING. The basic machine shall then be disassen- Internal cleaning shall be conducted to re- move fram internal surfaces all contaminants, such as operating oils, coolants, corrosion and sludge accumulations, 3-09, CLEANING EQUIPMENT. Where large-scale cleaning operations are involved, use of equipment such as hot-solvent washers and vapor degreasers, is recommended. Cleaning equipment of this type will remove accumulations of lubricating, coolant, and similar residues, and most or all sludge accumilations, Where few machines are handled, the in- ternal cleaning operations may be limited to hand cleaning with solvent conforming to Specification P-S-661, and to the use of small degreasers conforming to Specification JAN-P-116. 3-10, Where vapor degreasing is used the cleaned surfaces shall be covered immediately with a preservative coating, as trichlorethylene leaves surfaces devoid of oil film and subject to corrosion. Assemblies or parts containing organic materials such as fiber bearing re- tainers, packings, insulation, or plastics shall not be placed in vapor degreasers. Solvent hand cleaning shall be done by scrubbing with sol- vent~soaked rags and/or nonmetallic bristle brushes, Where solvent hand-cleaning methods are used, thorough cleaning of critical parts, such as bearings, can be accomplished only by the use of at least three solvent baths, two for cleaning and one for rinsing, as required. After cleaning, all parts shall be thoroughly dried. 18-28