HEXALOBULAR DRIVE SOCKET SCREWS Fastener drive styles are generally selected based on the type of application and the required clamping force. This clamp load is used to determine the size of fastener required to limit the applied stress of the joint and it is also used to calculate the required tightening torque. It is this tightening torque that has the greatest influence when selecting a drive style and there are a number of options available depending on the particular application. In the past, Pozi drives have been particularly popular for low torque applications where the driver will cam out to prevent over-tightening. Recently however, with the development of better torque-limiting automatic screwdrivers, manufacturers can now use more effective tools to optimise the tightening process and reduce losses and tool damage. Rather than relying on the tool slipping out of the screw head when a torque level is reached, the drivers are now designed to constantly achieve the desired optimum torque, thereby reducing damage to the driver tip, screw head and workpiece. This gave rise to the design of hexalobular style drive systems where increased tool engagement virtually eliminates camout ensuring a more controlled and effective torque transfer. This greatly reduces the end load requirements and can also reduce worker fatigue and muscular stress during manual assembly. Although these drive systems are not yet considered to be off the shelf items they are increasing in popularity and can now be found in a limited range on the shelves of certain stockists. The following diagram illustrates the features of hexalobular drives that enhance performance. Torx Drive ° Elliptical based geometry broadens the contact surface to maximise the engagement of driver and recess, eliminating damage from point to point contact. ° Small drive angle (15 deg) optimises torque transmission virtually eliminating radial stresses to increase tool life. This also enables the use of recesses with thinner walls. ° Six driving lobes offer faster tool engagement and maximises torque transfer with increased torsional strength. ° Hexalobular tools seat both metric and imperial sized fasteners. Torx Plus Until recently the only available hexalobular drives were Torx drives, manufactured under license from a company called Acument, the parent company of Textron Fastening Systems. This patent has now expired and Acument are now marketing their new hexalobular drive. This drive is claimed to have a genuine zero degree drive angle to further enhance the torque transmission and eliminate radial forces. In addition to this Acument also claim a 50% reduction in driver tool tolerance and boast a 25% average improvement in driver torsional strength. This increase in performance comes with an increase in cost that many manufacturers may find difficulty justifying, especially when there are now international standards available specifying standard hexalobular drive screws that do not require a special license to manufacture. Hexalobular Drive Screws There are now various international standards available to cover hexalobular drive screws that offer the same performance and use the same tooling, but do not require a special license to manufacture. This presents an attractive alternative that can be sourced from an increased number of suppliers, without having to pay a license fee required to manufacture to the Torx Drive specification. These ISO standards are listed below. 1.800.ANIXTER | anixter.com Products. Technology. Services. Delivered Globally.
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HEXALOBULAR DRIVE SOCKET SCREWS
Fastener drive styles are generally selected based on
the type of application and the required clamping
force. This clamp load is used to determine the size
of fastener required to limit the applied stress of the
joint and it is also used to calculate the required
tightening torque. It is this tightening torque that
has the greatest influence when selecting a drive
style and there are a number of options available
depending on the particular application.
In the past, Pozi drives have been particularly popular
for low torque applications where the driver will cam
out to prevent over-tightening. Recently however, with
the development of better torque-limiting automatic
screwdrivers, manufacturers can now use more
effective tools to optimise the tightening process and
reduce losses and tool damage. Rather than relying
on the tool slipping out of the screw head when a
torque level is reached, the drivers are now designed
to constantly achieve the desired optimum torque,
thereby reducing damage to the driver tip, screw head
and workpiece.
This gave rise to the design of hexalobular style drive
systems where increased tool engagement virtually
eliminates camout ensuring a more controlled and
effective torque transfer. This greatly reduces the
end load requirements and can also reduce worker
fatigue and muscular stress during manual assembly.
Although these drive systems are not yet considered
to be off the shelf items they are increasing in
popularity and can now be found in a limited range
on the shelves of certain stockists. The following
diagram illustrates the features of hexalobular drives
that enhance performance.
Torx Drive
° Elliptical based geometry broadens the contact surface to maximise the engagement of driver
and recess, eliminating damage from point to point contact.
This international standard specifies the shape and
basic dimensions of hexalobular internal driving
features for bolts and screws, including the gauging
limits and methods for GO and NO GO gauges. It also
defines the curvature of the contour of the hexalobular
internal driving feature along with information to draw
the driving feature listed in the Annex of the standard.
Counterbore: c ≤0.13mm up to socket
No.15, and ≤0.25mm over socket No.15.
Penetration depth r: see relevant
product standard.
Note: the contour of the bottom of the
socket beyond the gauge is at the option
of the manufacturer.
DIN EN ISO 10664 : Hexalobular Internal Driving Features for Bolts and Screws
ISO Hexalobular Drive Dimensions (mm)Nominal Dimensions Gauging Limits (GO)
Recess Reference A B A B6 1.75 1.27 1.695 - 1.709 1.210 - 1.224
8 2.4 1.75 2.335 - 2.349 1.672 - 1.686
10 2.8 2.05 2.761 - 2.776 1.979 - 1.993
15 3.35 2.4 3.295 - 3.309 2.353 - 2.367
20 3.95 2.85 3.879 - 3.893 2.764 - 2.778
25 4.5 3.25 4.451 - 4.465 3.170 - 3.185
30 5.6 4.05 5.543 - 5.557 3.958 - 3.972
40 6.75 4.85 6.673 - 6.687 4.766 - 4.780
45 7.93 5.64 7.841 - 7.856 5.555 - 5.570
50 8.95 6.45 8.857 - 8.872 6.366 - 6.380
55 11.35 8.05 11.245 - 11.259 7.930 - 7.945
60 13.45 9.6 13.302 - 13.317 9.490 - 9.504
ISO 14583: Hexalobular Socket Pan Head ScrewsThis standard covers hexalobular socket pan head screws of product grade A size M2 up to and including M10. For specifications not listed in this standard
see existing international standards like ISO 261, ISO 888, ISO 898-1, ISO 965-2, ISO 3506-1, ISO 4759-1.
ISO 14584: Hexalobular Socket Raised Countersunk Head ScrewsM2 up to and including M10. For specifications not listed in this standard see existing international standards like ISO 261, ISO 888, ISO 898-1, ISO 965-2,
ISO 14580: Hexalobular Socket Cheese Head ScrewsThis international standard specifies the characteristics of hexalobular socket cheese head screws in product grades A with thread sizes from M2 up to and including M10.
If in special cases, specifications other than those listed in this standard are required, they should be selected from existing international standards like ISO 261, ISO
888, ISO 898-1, ISO 965-2, ISO 3506-1, ISO 4759-1.
ISO 14584: Hexalobular Socket Raised Countersunk Head ScrewsM2 up to and including M10. For specifications not listed in this standard see existing international standards like
ISO 261, ISO 888, ISO 898-1, ISO 965-2, ISO 3506-1, ISO 4759-1.
Dimensions in millimetres
Dimensions in millimetres
ISO 14586: Hexalobular Socket Countersunk Head Tapping ScrewsThis international standard covers the characteristics of hexalobular socket countersunk head tapping screws
with thread sizes from ST2.9 to ST6.3 inclusive. If specifications other than those listed in this standard are
required they should be taken from existing international standards such as ISO 1478, ISO 2702, ISO 4759-1.
ISO 14587: Hexalobular Socket Raised Countersunk Head Tapping ScrewsThis international standard specifies the characteristics of hexalobular socket raised countersunk head tapping
screws with thread sizes from ST2.9 to ST6.3 inclusive. If specifications other than those listed in this standard are
required they should be taken from existing international standards such as ISO 1478, ISO 2702, ISO 4759-1.