by winterheating » Tue Nov 17, 2009 11:06 pm
TORX (pronounced "TORKS", rhyming with "forks"), developed by Camcar LLC of Acument Global Technologies (formerly Camcar Textron), is the trademark for a type of screw head characterized by a 6-point star-shaped pattern (in the same way that slotted heads, Phillips, hex socket, and Robertson have linear, cruciform, hexagonal, and square tips, respectively). People unfamiliar with the trademark generally use the term star, as in star screwdriver or star bits. The generic name is hexalobular internal driving feature and is standardised by the International Organization for Standardization as ISO 10664. TORX is frequently styled Torx despite the official all-caps trademark styling.
By design, TORX head screws resist cam-out better than Phillips head or slot head (flathead) screws. Where Phillips heads were designed to cause the driver to cam out, to prevent over-tightening, TORX heads were designed to prevent it. The reason for this was the development of better torque-limiting automatic screwdrivers for use in factories. Rather than rely on the tool slipping out of the screw head when a torque level is reached, thereby risking damage to the driver tip, screw head and workpiece, the driver design achieves a desired torque consistently. Camcar LLC claims this can increase tool bit life by ten times or more. Today there are also other solutions, such as the AW type of screw head developed by the Würth group in Germany.
TORX drive system was developed in the Camcar Technical center, located in Rockford, Illinois, USA.
TORX screws are commonly found on automobiles, bicycle brake systems, hard disk drives, computer systems (Compaq uses almost exclusively T15 screws) and consumer electronics. Initially, they were used in applications requiring tamper-resistance since the drive systems and screwdrivers were not widely available; as drivers became more common, tamper-resistant variants, as described below, were developed.[1] Today, TORX screws are also becoming increasingly popular in construction industries.
Camcar LLC developed an improved profile, designated TORX PLUS.
See Standard Torx Tools Index
Point to Point Dimensions
Size Inch
P to P Metric
P to P Maximum Torque
Range
T1 .031 .81mm .02 to .03 N m
T2 .036 .93mm .07 to .09 N m
T3 .046 1.10mm .14 to .18 N m
T4 .050 1.28mm .22 to .28 N m
T5 .055" 1.42 mm .43 to .51 N m
T6 .066" 1.70 mm .75 to .9 N m
T7 .078" 1.99 mm 1.4 to 1.7 N m
T8 .090" 2.31 mm 2.2 to 2.6 N m
T9 .098" 2.50 mm 2.8 to 3.4 N m
T10 .107" 2.74 mm 3.7 to 4.5 N m
T15 .128" 3.27 mm 6.4 to 7.7 N m
T20 .151" 3.86 mm 10.5 to 12.7 N m
T25 .173" 4.43 mm 15.9 to 19 N m
T27 .195" 4.99 mm 22.5 to 26.9 N m
T30 .216" 5.52 mm 31.1 to 37.4 N m
T40 .260" 6.65 mm 54.1 to 65.1 N m
T45 .306" 7.82 mm 86 to 103.2 N m
T50 .346" 8.83 mm 132 to 158 N m
T55 .440" 11.22 mm 218 to 256 N m
T60 .519 13.25 mm 379 to 445 N m
T70 .610 15.51 mm 630 t0 700 N m
T80 .690 17.54 mm 943 to 1048 N m
T90 .784 19.92 mm 1334 to 1483 N m
T100 .871 22.13 mm 1843 to 2048 N m
1 N m = 8.851 lbf • in
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