In the Fanuc α / αi, β / βi servo systems that we have dealt with, SV0436 is almost invariably due to a few real reasons, and they are all very "grounded”.
Often, the problem is not in the electrical cabinet at all, but in the machine itself. Mechanical loads, for example. Screws and guides are used for a long time, the lubrication does not keep up, and the resistance becomes a little bit bigger. You can't feel it in a single movement, but the motor keeps pushing harder, and Fanuc's software doesn't get confused, it honestly accounts for all this "extra force” in the thermal model.
There is also a very common situation where the acceleration and deceleration are set more and more aggressively in order to catch up with production. The machine looks fine on the surface, and the shafts are running fast, but every time you start and brake, the current spikes are secretly accumulating.
Over time, SV0436 comes out to remind you: "I'm a little overwhelmed.”
And then there's another point that's often overlooked - heat dissipation. We've taken apart quite a few Fanuc servo amplifiers, and the inside isn't bad, it's dirty. Fan speeds are down, heatsinks are dusty, temperatures in the electrical cabinet are stifling and you can't get out, in which case, even if the loads aren't exaggerated, the SV0436 will come on faster than you think.
There are some more insidious, such as motor cable, joint aging. Contact resistance becomes larger, the current naturally goes up, the software "see” is: "you this shaft, how so hard?”
How do we usually determine this in the field, instead of just replacing the parts right away?
To be honest, SV0436 is one of the worst alarms for "head-scratching”.
We usually look at a very realistic problem first: Is the shaft more "tired” than before? After the power failure, manually push a push, there is no obvious astringency; during operation, the alarm is not always in the heavy load, a long time after processing; is not a change of process, changed parameters, but did not reevaluate the whole.
If these places can find the cause, often do not need to move the amplifier at all.
However, if the mechanical, parameter, heat dissipation are clean, SV0436 still recurring under normal load, it is necessary to start seriously look at the servo amplifier itself. Aging power modules, inefficient internal heat dissipation, all of these can cause the "software thermal model” to reach its upper limit prematurely.
In Songwei, whether it is repair or used Fanuc servo amplifier, we will simulate the load conditions on the
Fanuc test bench to run for a period of time, not just to see whether it can power up, but to see it in the continuous operation, the thermal model is not stable. This is especially important for the SV0436.
This alarm, should I fix it or replace it?
Our experience is: if the problem is mechanical, parametric, or thermal, then repair the system, not the parts; if it is confirmed that the performance of the amplifier is degraded, then it makes sense to repair or replace it.
The real need to replace the entire unit with a new one is actually not a lot of cases, but before judging, be sure to measure clearly.
