Machine Screws 51 Head Style Reference Chart ...................................... 52 Drive Style Reference Chart ...................................... 53 Head & Drive Dimensions Flat 82° ................................................................... 54 Flat 100° ................................................................. 54 Flat Undercut ......................................................... 55 Torx ® Flat ............................................................... 55 Pan .......................................................................... 56 Combination Pan .................................................... 56 Combination Round ............................................... 57 Combination Truss ................................................. 57 Round ..................................................................... 58 Phillips Binding ..................................................... 58 Slotted Binding Undercut ...................................... 59 Truss ....................................................................... 59 Oval ........................................................................ 60 Head & Drive Dimensions (continued) Oval Undercut ........................................................ 61 Hex ......................................................................... 62 Hex Washer ............................................................ 62 Hex Washer w/Phillips Recess ............................... 63 Fillister ................................................................... 64 Torx ® Pan ............................................................... 64 Pozidriv ® Flat ......................................................... 65 Pozidriv ® Pan ......................................................... 65 Square Flat ............................................................. 66 Square Pan .............................................................. 66 Thread Gaging Notes .................................................. 67 Thread & Hole Dimensions; Mechanical and Performance Requirements Machine Screws ............................................... 68-69 SEMS ............................................................... 70-72 ®Torx is a registered trademark of the Camcar Corporation, division of Textron Industries. ®Pozidriv is a registered trademark of the Phillips Screw Company. Kanebridge’s fasteners with a 1A-drive are not manufactured by or connected with the producers of Pozidriv® fasteners.
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Machine Screws New Pgs-98Machine Screws 54 Head Dimensions 82° Flat 100° Flat T 80˚ 82˚ H J M A N R G F Protrusion gage Edge of head may be rounded or flat A Amin FLAT HEAD 100°
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Machine Screws
51
Head Style Reference Chart...................................... 52
®Torx is a registered trademark of the Camcar Corporation, division of Textron Industries.®Pozidriv is a registered trademark of the Phillips Screw Company. Kanebridge’s fasteners with a 1A-drive are not manufactured by or connected with theproducers of Pozidriv® fasteners.
Slotted pan heads have a flat or gently roundedtop surface, cylindrical sides and a flat bearingsurface. Phillips and Torx® pan heads have a
rounded top, cylindrical sides and a flat bearingsurface.
Has a general purpose bearing area. Can be substitutedin most applications for round, truss or binding heads.
BindingHas a rounded top surface and slightly tapered
sides. The bearing surface is flat with the slottedvariety having an annular undercut adjacent to the
shank.
Preferred design for making a firm electrical connection.
Flat 82°A countersunk head with a flat top surface and a
cone-shaped bearing surface with a head angle ofapproximately 82°.
Used in applications where protrusion of the fastenerabove the mating surface is unacceptable. Use a
protrusion gage when measuring head height.
FlatUndercut
Similar to an 82° flat head except that the head isundercut to 70% of its normal side height.
Standard for short lengths because it allows greaterlength of threads. Also avoids transition fillet and
assembly interference.
Flat 100°A countersunk head with a flat top surface and a
cone-shaped bearing surface with a head angle ofapproximately 100°.
Preferred over an 82° flat head when fastening in softmaterials--the 100° countersunk head distributes
pressure over a larger surface area.
FillisterHas a rounded top surface, cylindrical sides, anda flat bearing surface. The greater side height is
what distinguishes a fillister head from a panhead.
Preferred style for use in counterbored holes.
Indented Hex Has an indented top surface, six flat sides, and aflat bearing surface.
Preferred in high volume assembly where pneumaticequipment is used to drive the screw. Can transmit
significantly higher tightening torque levels than otherhead styles.
Indented HexWasher
Has an indented top surface, six flat sides and aflat washer which projects beyond the sides andprovides a flat bearing surface. The washer and
hex head are formed together as one piece.
Offers greater protection to the mating surface than astandard indented hex head. Increased bearing area
reduces likelihood of crushing mating surfaces.
TrussHas a low rounded top surface with a flat bearingsurface greater in area than a round-head screw
of the same nominal size.
Weaker than pan or round heads but preferred inapplications where minimal clearance exists above thehead. Truss profile provides a trim, finished assembly
appearance.
OvalA countersunk head with a rounded top surface
and a cone-shaped bearing surface ofapproximately 82°.
Preferred over a flat head in conical applications, or whena more decorative finished look is desired. Countersunksurface nests into mating countersunk application sites.
OvalUndercut
Similar to an 82° oval head except that the headis undercut to 70% of its normal side height.
Standard for short lengths because it allows greaterlength of threads.
Round Has a semi-elliptical top surface and a flat bearingsurface.
Sometimes preferred over pan head for its smoothsurface and appearance.
Machine Screws
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Drive Types
DRIVE TYPES FOR MACHINE SCREWS
Schematic Drive Type Uses
PhillipsMost recommended drive type. Provides
good control in driving. Always use a driverbit in good condition.
Slotted
Accepts standard blade screwdrivers.Requires less downward pressure to driveslotted parts than it does those with cross-recessed openings. Use proper fitting blade
to minimize slippage.
Combination: Phillips/SlottedAccepts phillips and standard blade
screwdrivers. Often used when fastener isexpected to be driven and backed-out several
times.
Hex / Slotted-Hex Accepts hex wrench. Slotted drive is addedto make it easier to remove the fastener.
Torx®Positive-engaging, fast-locating method oftransmitting torque and optimizing worker
efficiency.
Pozidriv®-Alternative(Type 1A)
Design offers even greater control in drivingthan Phillips drive. Used in automotive and
appliance manufacturing.
Square SocketIncreases productivity with excellent torque
transmission and resists cam-out. Distinctiveappearance which discourages tinkering.
®Torx is a registered trademark of the Camcar Corporation, division of Textron Industries.®Pozidriv is a registered trademark of the Phillips Screw Company. Kanebridge’s fasteners with a 1A-drive are not manufactured by or connected with theproducers of Pozidriv® fasteners.
Machine Screws
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Head Dimensions 82° Flat100° Flat
T
80˚82˚
H
JMA
N
R
G
F
Protrusiongage
Edge of head maybe rounded or flat
AAmin
FLAT HEAD 100° FOR MACHINE SCREWSASME B18.6.3-
1998
NominalSize
A H J T M R N F GPhillipsDriverSize
Head Dimensions Slot Dimensions Recess Dimensions Protrusion AboveGaging Diameter Gaging
NOTE: Without any single set of standards for the size of cross-recess (Phillips) drives used in hex headmachine screws, two sets of recess dimensions are listed below. Variations are due, in part, to differences inthe tooling sold in the United States compared to that used by foreign manufacturers. Kanebridge offers thisinformation as a service to fastener distributors and makes no recommendation re: which design is preferable.
A
H
UF
WM
N
GM
N
Machine Screws
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Head Dimensions Fillister &Torx® Pan
O
MAJ
H T G
N
R D
H
G
FILLISTER HEADS FOR MACHINE SCREWS ANSI B18.6.3
NominalSize
A H O J T M G N
PhillipsDriverSize
Head DiameterHeight of Head
Width of Slot Depth of SlotDimensions of Recess
Side Height Total Height Diameter Depth Width
Max Min Max Min Max Min Max Min Max Min Max Min Max Min
®Pozidriv is a registered trademark of the Phillips Screw Company. Kanebridge’s fasteners with a 1A-drive are not manufactured by or connected with theproducers of Pozidriv® fasteners.
Machine Screws
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Head Dimensions Flat Square SocketPan Square Socket
This type of recess has a square center opening, slightly tapered side walls and a conical bottom.
M
F T
A
M H
T
P
A
Machine Screws
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Thread Gaging
Notes on Thread Gaging
•Thread gaging is one method of testing the acceptability of machine screws, SEMS and nuts. It is possiblethat parts which are near a limit may be accepted by one type of gaging yet rejected by another. A productscrew thread is considered acceptable when it passes any of the permissible gages in ANSI B1.3, providedthat those gages are within the tolerances specified in this standard.
•Many commercial applications will accept a screw that, although may not pass a gage test, will accept amating nut. It is important to know the customer’s requirements concerning thread quality when testingmachine screw threads.
•Go gages check either the maximum-material limit or size to assure interchangeable assembly of maxi-mum-material mating parts.
•NO GO gages inspect the functional diameter limit of product internal thread. In applying the NO GO gage,the functional diameter is acceptable when gaging elements do not pass the product thread. The NO GOgage can also indicate out-of-roundness of the pitch cylinder.
•Thread gages are normally set to master gages with a range of calibration precisions such as Class X(looser tolerance) or Class W (tighter tolerance). They are also set by technicians with slight variations inhand pressure. For these reasons, gage setting variability should be considered during thread inspection.Also, the NO GO gage can be confounded by undersized, error laden threads which in fact are undersized onpitch diameter but with helix, flank or similar out of tolerance conditions large enough to not enter therequired number of turns.
•FOR THESE REASONS, THREAD INSPECTION SHOULD CONSIDER GAGE AND OPERATOR VARIABILITYWHEN PASSING QUALITY JUDGEMENTS ON MACHINE SCREW THREAD QUALITY.
Machine Screws
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Axis of screw thread
Basicmajor
diameter
Minordiameter
Basicpitch
diameter
L
L
aTensile strength values are based on 60,000 psi. and apply to carbon steel screws and SEMS only. Hex and Hex Washer head machine screws ofsufficient length may be wedge tensile tested. Other head styles may be axial tensile tested.
Thread Dimensions
EXTERNAL THREADS FOR MACHINE SCREWS AND SEMS ASME B 1.1
Up to 1/2 in., incl. Over 1/2 to 1 in., incl. Over 1 to 2 in., incl. Over 2 in.
0 thru 12 -0.02 -0.03 -0.06 -0.09
1/4 thru 3/4 -0.03 -0.03 -0.06 -0.09
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Mechanical & PerformanceRequirements
Steel &Stainless
Description A straight shank fastener with external threads designed to go through a hole or nut that is pre-tapped to form a matingthread for the screw.
Applications/Advantages
Machine screws form a fastening superior in strength to spaced thread screws.Zinc yellow screws are popular in electronics applications.
Stainless steel machine screws are used in applications which require general atmospheric corrosion resistance, in foodprocessing machinery and refrigeration equipment. Stainless is also superior to steel in withstanding some elevation in
application operating temperature while maintaining its strength.
Material Steel: AISI 1006 - 1022 or equivalent steel.Stainless: SAE 18-8 stainless steel, passivated.
Machine screws which have a nominal diameter smaller than #4 are not subject to tensile testing. No. 4 and No. 5 machinescrews which are shorter than 1/2" are not subject to tensile testing. Machine screws of diameters No. 6 to 1/2" inclusive,
which are shorter than either 1/2" or 3D (where D is the nominal screw size in inches) are not subject to tensile testing. Suchmachine screws of a size to be tested shall meet the tensile load requirements given on page 54.
Plating See Appendix-A for information on the plating of steel machine screws
*Hardness and tensile strength standards are offered as guides only for stainless machine screws. There is currently no national standard for these performance requirements forstainless machine screws.
HOW SEMS SPECIFICATIONS VARY FROM MACHINE SCREWS•The maximum diameter of the unthreaded shank shall be less than the maximum major diameter of thethread by an amount sufficient to prevent disassembly of the washer from the screw.
•The unthreaded length on fully threaded screws is measured to the contacting face of the washer instead ofto the bearing face of the screw.
•The minimum underhead fillet radius is equivalent to 5% of the basic screw diameter.
Description A machine screw and free-spinning lock-washer manufactured as one assembly. Steel SEMS are available with the following types ofwashers: internal tooth, external tooth, split-lock and square-cone®. Stainless SEMS are offered with external tooth lock washers.
Applications/Advantages
The washer/screw assembly makes this a locking screw with the washer providing the locking action. Machine pre-assembly providescost savings to the end user.
Internal Tooth SEMS: Recommended when it it desirable to hide the teeth for appearance or to prevent snagging.External Tooth SEMS: Preferred over the internal tooth style as the teeth provide greater torsional resistance being on the larger radius.
Split-Lock SEMS: Preferred over tooth lockwasher SEMS for use with hardened bearing surfaces.Square-Cone® SEMS: Provides a higher retained clamp load & improved compensation for thermal cycling and vibration. Can accept ahigh tension load and maintain spring action. The washer design makes for better control during installation, and improved tool bit life.
Ideal for clamping fragile materials and for spanning large clearance holes.
MaterialSteel Screws-- AISI 1022 or equivalent steel.
Steel: 60,000 psi. minimum. No. 2 diameter SEMS screws are not subject to tensile testing. No. 4 SEMS screws shorter than 1/2" arenot subject to tensile testing. SEMS screws of diameters No. 6 to 10 inclusive, which are shorter than 1/2" or 3D (where D is the
nominal screw size in inches) are not subject to tensile testing. Such SEMS screws of a size to be tested shall meet the tensile loadrequirements given on page 54.
Stainless: No. 4: 99,000 psi. minimum; No. 6 & No. 8: 96,000 psi. minimum. Note: No. 4, No. 6 and No. 8 SEMS screws which areshorter than 1/2" are not subject to tensile testing.
Plating See Appendix-A for information on the plating of steel SEMS.
®Square-Cone is a registered trademark of Shakeproof division of Illinois Tool Works.
Machine Screws
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SEMS Washer Specs forPan Head screws
Tooth-lock, Split& Conical
O.D. ThicknessO.D. Thickness
O.D. Thickness
A B
W
t T
*Dimensions of Square-Cone® washers are to Shakeproof specifications.®Square-Cone is a registered trademark of Shakeproof division of Illinois Tool Works.
TOOTH-LOCK WASHERS FOR PAN HEAD SEMS ASME B18.13-1996
Nominal Size or BasicScrew Diameter
Internal Tooth External Tooth
Washer ThicknessWasher Outside
DiameterWasher Thickness
Washer OutsideDiameter
Max Min Max Min Max Min Max Min
2 .0860 .016 .010 .185 .175 .016 .010 .180 .170
4 .1120 .018 .012 .268 .258 .018 .012 .230 .220
6 .1380 .022 .016 .288 .278 .022 .016 .285 .270
8 .1640 .023 .018 .338 .327 .023 .018 .320 .305
10 .1900 .024 .018 .383 .372 .024 .018 .381 .365
12 .2160 .027 .020 .408 .396 .027 .020 .410 .395
1/4 .2500 .028 .023 .478 .466 .028 .023 .510 .494
WASHERS FOR SPLIT-LOCK & SQUARE-CONE® PAN HEAD SEMS ASME B18.13,-1996Shakeproof*
*Dimensions of Square-Cone® washers are to Shakeproof specifications. Square-Cone® is a registered trademark of Shakeproof division of Illinois Tool Works.
Machine Screws
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Tooth LockSEMS Washer Specs forHex Washer Head screws
O.D. ThicknessO.D. Thickness
TOOTH LOCK WASHERS FOR HEX WASHER HEAD SEMS ASME B18.13-1996