Mitsubishi M800/M80 spindle synchronization: why the two feedback phase differences disagree
Using IB-1501273-L to distinguish SP sync ph1 FB, SP sync ph2 FB, stored phase difference and synchronization-error peaks before treating unlike angle readings as an encoder fault.
Contents
Suppose a maintenance handover contains two spindle synchronization screenshots: one highlights SP sync ph1 FB, the other SP sync ph2 FB. Both show angles, but a difference does not by itself establish spindle phase drift. These fields treat the stored phase difference differently. Match the item and operating conditions before comparing them.
Screen and synchronization modes covered
This article follows the Mitsubishi M800/M80/E80 Series Maintenance Manual, IB-1501273-L, revision L, §4.7.2, printed pages 105 and 107. The path is Diagn → Drv mon → Spindle unit. The SP synchronization fields below apply to spindle synchronization I, tool spindle synchronization IA/IB and tool spindle synchronization II as listed in that manual. Do not transfer their definitions directly to guide bushing spindle synchronization, synchronous tapping, M800V/M80V or machine-builder screens.
“Reference spindle” and “synchronized spindle” describe roles in the particular synchronization relationship. SP1/SP2 or main/back spindle labels alone do not establish those roles. This article reviews existing records; it does not instruct readers to start synchronization, change phase or make a test cut.
Separate four easily confused items
| Monitor item, in deg | Manual definition | How to use the record |
|---|---|---|
| SP syn phas er | The phase difference stored in memory by calculating the phase shift value. | Identify the stored phase difference; do not simply call it the current tracking error. |
| SP sync ph1 FB | The current feedback phase difference including that stored phase difference. | Compare it with the same named field. |
| SP sync ph2 FB | The current feedback phase difference excluding that stored phase difference. | Do not treat ph1 and ph2 as two sensor readings that must be identical. |
| SP syn er comp | The error compensation amount in the listed synchronization modes. | Record it separately from stored phase difference and synchronization error. |
The page defines inclusion and exclusion, but provides no signed arithmetic formula, angle-wrapping rule or acceptance threshold for direct workshop use. This article therefore does not prescribe a fixed signed result for ph1−ph2 or declare a full-turn difference acceptable. Numerical reconstruction requires the corresponding control-function and machine documentation.
Current synchronization error and peaks are separate evidence
SP sync error is the current synchronization error between the reference and synchronized spindles. SP sync err +P is the maximum angle by which the synchronized spindle advances beyond the reference spindle; SP sync err -P is the maximum angle by which it lags behind. SP syn err P-P is the synchronization-error width. Preserve the full field names rather than labeling all of them “phase.”
A current value and a maximum describe different things. A small current error cannot exclude an earlier peak, and a large peak does not establish that the error is still present at the screenshot time. The cited page 107 does not specify the retention or clearing conditions of these SP peaks. Do not borrow the “most recent 2 seconds” window from servo current monitoring or the reset rules for synchronous tapping.
The same page lists GB sync items for the reference spindle and guide bushing spindle. They are not substitutes for the SP sync fields. Similar names do not mean that the same components participate in synchronization.
Reviewing before-and-after maintenance screenshots
- Record the control and spindle-drive models, software versions, synchronization mode and reference/synchronized roles. Keep the screenshot time and full page.
- Give SP syn phas er, SP sync ph1 FB, SP sync ph2 FB and SP syn er comp separate columns. Compare the same field before and after maintenance; “ph1 before, ph2 after” cannot establish a phase change.
- List SP sync error and the three peak/width items separately. Identify whether each existing production record shows startup, steady operation, deceleration or stop. Screenshots taken at different times are not a simultaneously sampled waveform.
- Check existing records for phase calculations, setting changes or control-mode changes between the captures. Mark missing information as unknown. Do not repeat phase calculation just to complete a worksheet.
- If the same field under comparable conditions still changes inexplicably, pass the complete records and alarms to the responsible specialist. This can narrow an investigation, but cannot independently separate mechanical transmission, detector feedback and control-setting faults.
An example of an invalid comparison
Suppose only ph1 was saved before maintenance and only ph2 afterward, with no SP syn phas er record. Even a substantial difference does not establish that maintenance shifted the phase. The defensible conclusion is “different fields were compared, and the stored phase-difference context is missing.” This is an illustrative record review, not a machine test, and it also cannot prove that the machine is fault-free.
Safety boundaries and source
Do not clear phase data, change gains, relax synchronization checks or bypass interlocks to make the two values match. Incorrect phase can create mechanical hazards during workpiece transfer, clamping or coordinated motion. For abnormal motion or alarms, stop safely under the machine builder’s procedure and have qualified personnel plan further checks. One monitor screenshot does not authorize a return to machining.
Source: Mitsubishi M800/M80/E80 Series Maintenance Manual, IB-1501273-L, revision L, §4.7.2, printed page 105 (screen access) and page 107 (SP and GB synchronization fields). Field definitions come from the manufacturer. The record-review method and hypothetical situation are editorial explanations; no machine test was performed.