Reference Mark Selector And Limit Magnet Installation - Renishaw QUANTiC RTLC40 Installation Manual

Reference mark selector and limit magnet installation

For accuracy and ease of positioning of reference mark selector and limit magnets, the applicator tool should
be used. The magnet should be attached to the applicator tool as shown below and aligned with the outer
edge of the FASTRACK. Limit magnets can be positioned at any user defined location along the FASTRACK,
but the reference mark selector magnet should be positioned adjacent to the selected IN-TRAC reference
mark as shown below.
As the QUANTiC readhead passes the reference mark selector magnet or limit switch magnet, a force of up
to 0.2 N is generated between the magnet and the concentrators on the readhead. The design of the bracket
should be sufficiently stiff so that it is able to tolerate such force without distorting. Following the clamping
instructions on the scale installation will prevent this magnetic force from disturbing the scale.
Limit trigger point
The limit output is nominally asserted when the readhead limit
switch sensor passes the limit magnet leading edge, but can
trigger up to 3 mm before that edge ('RTLC40 / FASTRACK
installation drawing', page 4).
NOTES:
Reference and limit magnets may creep when influenced by magnetic materials in
u
close proximity. In such cases, they should be held in place using an additional fillet
of epoxy glue or similar along the outer edge of the magnet assembly.
The reference mark selector and limit actuator locations are correct for readhead
u
orientation shown
The reference mark selector magnet is only required for 'Customer selectable
u
reference mark' readheads. For more information refer to QUANTiC series encoder
system data sheet (Renishaw part no. L-9517-9778).
All limit and reference selector magnets should be aligned with the outer edges of
u
the FASTRACK .
External magnetic fields greater than 6 mT, in the vicinity of the readhead, may cause
u
false activation of the limit and reference sensors.
QUANTiC RTLC40 / FASTRACK installation guide
P limit magnet
Magnet applicator tool
Remove self-adhesive
backing paper
Selected IN-TRAC
reference mark
Reference mark
selector magnet
Q limit magnet
10