Performance Motion Devices CME N Series, Руководство пользователя

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62 ION/CME N-Series Digital Drive Developer Kit User Manual
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When using this method the thickness of the shim washer should be determined by the type and thickness of thermal
transfer material used to create a vibration resistant mount, while maintaining optimal thermal transfer. Note that in
this approach, the N-Series ION's fuse tab mechanism, which normally acts to limit the maximum force that can be
applied via the tabs, is effectively bypassed. Therefore it is up to the user to ensure that the force applied to the ION
unit’s heat sink interface, the limits for which are provided in the table below, are not exceeded. For more information
on PMD’s patented fuse tab design see
Section 3.7.2.3, “N-Series Drive Fuse Tab Design.”
To achieve the shim function using washers, the recommended dimensions are .280" (7.0 mm) outer diameter and
.105" (2.5 mm) inner diameter. Representative suppliers for washers such as this include Bokers, Superior Washer, and
Phoenix Specialty.
Two other mounting options use a nut and a screw. Most commonly M2 screws are used which go through the tab’s
M2.5 thread without engaging the thread, with the nut used to capture the M2 screw. The two possible orientations of
the nut and screw represent these two different mounting options. Note that if the preferred mounting orientation is
to have the screw heads facing the user PCB, it may be desirable to have holes in the PCB to give access to the ION
screw hardware. However if the ION is mechanically mounted first, and then soldered onto the user PCB, these access
holes may not be necessary.
3.7.2.2 Installation & Torque Limits
Before mating the N-Series Drive to the heat sink, in a typical installation a thermal transfer material will first be
installed to enhance thermal contact. Refer to
Section 3.7.2.4, “Thermal Transfer Materials,”
for more information on
selection of these materials.
Once this material is in place the tabs can be tightened under careful torque limit control. The table below shows the
recommended maximum torque for both M2 and M2.5 screws along with equivalent force values if an alternate
attachment method such as a clamp is used, or if shim washers are used as described above. These torque values were
determined using 18-8 stainless steel screws.
3.7.2.3 N-Series Drive Fuse Tab Design
N-Series IONs utilize a patented fuse-tab design to reduce the chance that overtightening of the tab attachment
hardware will cause damage to the N-Series ION unit.
When using shim washers or other approaches that raise the mounting interface under the N-Series ION tabs,
the ION unit's force-limiting fuse tab design is effectively disabled. It is therefore up to the user to ensure that the
mounting force limit on the ION unit's heat sink interface plate is not exceeded.
Type Minimum Recommended Maximum
M2 screw torque 0.082 N-m (0.722 in-lb) 0.094 N-m (0.836 in-lb) 0.113 N-m (1.00 in-lb)
M2.5 screw torque 0.113 N-m (1.00 in-lb) 0.130 N-m (1.15 in-lb) 0.147 N-m (1.30 in-lb)
Force 25 kgs (55 lbs) 29 kgs (68 lbs) 33 kgs (71 lbs)
Exceeding the N-Series ION’s mechanical attachment specifications indicated above may cause a failure of the
drive unit at the time of installation, or at a later time in the field.