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THE DISTRIBUTOR’S LINK
BRUNO MARBACHER DRIVING SYSTEMS FOR FASTENERS – THE VERTICAL WALLED SYSTEMS from page 10
¤ There is no cam-out effect with this drive, however,
shallow socket drives, the corners may be rounded
during tightening and loosening.
¤ This drive can be reused serval times. Shallow
sockets require more careful handling to make sure they
can be reused.
Other critical features do not apply or are not
prominent.
Shallow Socket Drives
Low socket cap screw per DIN 6912 have shallow
sockets with a pilot hole. They are used in applications
where head height clearance is restricted. This drive has
a cylindrical pilot hole at the bottom of the drive to accept
a similarly sized socket key with a pin that functions a
guide. However, because the pilot hole extends past the
head of the fastener, DIN 6912 will never be threaded
completely up to the head. If you require a metric low
head socket that is fully threaded, one should choose
one per DIN 7984. The screws with shallow socket have
to be tightened with a lower torque. There is technical
literature available that lists recommended tightening
torques.
The shortcomings of shallow sockets apply to inch
socket drives as well.
Double Hex Drive Twelve-Point Socket
The Double Hex Drive has two overlapping rotated
hexes. It looks similar to a spline drive screw, but they
are incompatible; standard hex keys can be used with
this socket drive.
Doubles hexes are more likely to become stripped.
They are most likely to be used on set screws where the
socket can be deeper.
Compared with the 6-point socket, a 12-point socket
has twice as many points, given us more options to align
the tool (key).
Torx
The hexalobular socket screw drive, often referred to
by the original proprietary brand name Torx. It uses a
star-shaped recess with six rounded points. Torx is also
known as six lobe drive, six lobular drive, or T sockets.
It was designed to allow higher torques transfer from
the driver to the bit compared to other drive systems.
The drive was developed in 1967 by Camcar Textron.
Feature & Concerns:
¤ Torx is very popular in the
automotive and electronics
industries because of
resistance to cam-out, and
extended bit life, as well as
reduced operator fatigue by
minimizing the need to bear
down on the drive tool to prevent cam-out.
¤ In comparison to cross recesses and hexagon
sockets, hexlobular drives engage better. They do not
cause stress riser, nor do they wear out as much.
¤ Torx has a very high torque capability. It has,
however a poor off angle capability, the driver basically
has to be as inserted at a straight angle
¤ Torx is a very durable drive, offering repeated
assembly, ideal for maintenance and repairs.
¤ Same drive size for Inch or metric screws, making it
easier to convert to metrics without a tooling change.
¤ Its stick fit property is excellent, it holds the screw
to the driver bit very well.
¤ The head tensile
stress area must be
larger than the shank
stress area, 1.4 x
larger for regular
tensile testing, 2 x
larger if fasteners are
subjected to wedge
tensile test.
If the head stress area is smaller than the stress area
in the shank, the head may twist off during assembly.
This is essentially true to all socket drives.
Other critical features do not apply are not prominent.
Torx Plus
Developed in 1992, it is Intended to provide extended
tool life over a standard Torx system. Can incorporate
additional advanced features to improve use with
automated equipment or where stick fit is required. Torx
is defined by radii, the Torx Plus by ellipses.
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