5305-01-049-1251, SCREW,CLOSE TOLERANCE

National Stock Number:
5305-01-049-1251

Federal Supply Class:
5305

National Item Identification Number:
010491251

Description:
SCREW,CLOSE TOLERANCE

Detail:
A SCREW, MACHINE or SCREW, CAP, SOCKET HEAD whose unthreaded portion is of specified grip length, plated or unplated, and is machined to a tolerance of one thousandth (0.001 IN.) (0.025 mm) or less of a specific diameter for items (1.000 IN.) (25 mm) or less in diameter. Items over (1.000 IN.) (25 mm) in diameter shall have a tolerance of fifteen ten thousandths (0.0015 IN.) (0.038 mm) or less. The nominal major diameter of the threads shall be at least one thousandth (0.001 IN.) (0.025 mm) below the minimum shank diameter, but not below the minimum major diameter for applicable class of fit, as shown in the Screw Thread Standards, FED STD H28 and/or other nationally recognized standards. The head is designed to be held or driven with an inserted driver. It is not designed for rotation by the thumb and fingers. A locking feature may be incorporated in the design of the head or threads.

Manufacturer Information:

51B221-21	0JRC1	NORTHROP GRUMMAN TECHNICAL SERVICES, INC.
51B221-21	76823	NORTHROP GRUMMAN SYSTEMS CORPORATION

Techincal Specification:

FASTENER LENGTH	1.573 INCHES MINIMUM AND 1.620 INCHES MAXIMUM
GRIP DIAMETER	0.1885 INCHES MINIMUM AND 0.1895 INCHES MAXIMUM
GRIP LENGTH	1.297 INCHES MINIMUM AND 1.327 INCHES MAXIMUM
HARDNESS RATING	39.0 ROCKWELL C MINIMUM AND 43.0 ROCKWELL C MAXIMUM OVERALL
HEAD DIAMETER	0.361 INCHES MINIMUM AND 0.381 INCHES MAXIMUM
HEAD HEIGHT	0.103 INCHES MINIMUM AND 0.118 INCHES MAXIMUM
HEAD STYLE	PAN
INTERNAL DRIVE STYLE	OFFSET CRUCIFORM (TORQUE SET)
MATERIAL	STEEL COMP E4340 OR STEEL COMP 4340 OR STEEL COMP 4140 OR STEEL COMP 8740 OVERALL
MINIMUM TENSILE STRENGTH	180000 POUNDS PER SQUARE INCH
NOMINAL THREAD DIAMETER	0.190 INCHES
SPECIFICATION/STANDARD DATA	86823-51B221 PROFESSIONAL/INDUSTRIAL ASSOCIATION STANDARD
SURFACE FINISH	32.0 MICROINCHES GRIP
SURFACE TREATMENT DOCUMENT AND CLASSIFICATION	QQ-P-416 TY 2 CL 2 FED SPEC SINGLE TREATMENT RESPONSE OVERALL
SURFACE TREATMENT	CADMIUM AND CHROMATE OVERALL
THREAD DIRECTION	RIGHT-HAND
THREAD CLASS	3A
THREAD LENGTH	0.246 INCHES MINIMUM AND 0.323 INCHES MAXIMUM
THREAD SERIES DESIGNATOR	UNJF
THREAD QUANTITY PER INCH	32

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