Kollmorgen SFD-M Absolute Multiturn Feedback Review: Specs, Price and Applications
Updated: 4 days ago
SFD-M is Kollmorgen’s battery-free absolute multiturn motor feedback technology for supported servo systems. It combines high singleturn resolution with retained turn information using energy harvesting. Treat it as a motor/drive feedback configuration rather than a universal external encoder that fits every motor.
Quick Verdict
Useful when retained motor position reduces startup work or battery maintenance. Check the supported motor, drive and firmware arrangement, then define how motor position maps to the machine coordinate system. Resolution and accuracy are different specifications.
Kollmorgen SFD-M Absolute Multiturn Feedback at a Glance
Specification | Details |
Singleturn resolution | 24 bits; 16,777,216 counts/revolution |
Multiturn range | 16 bits; 65,536 motor revolutions in source specification |
Angular subdivision | Approximately 0.0772 arc-sec per count |
Accuracy scope | Source: better than ±1 arc-min typical at 25 °C; ±3 arc-min worst case |
Retention | Energy harvesting; no backup battery or mechanical multiturn gear train |
Integration | Supported Kollmorgen housed motors and AKD / AKD2G configurations |
Price | Obtain exact motor/feedback configuration quote; no standalone universal price |
Design and Engineering Assessment
A tiny count increment is not the same as measurement accuracy. The 24-bit subdivision and arc-minute accuracy figures describe different properties. Use accuracy, repeatability and actual axis mechanics when defining useful process positioning.
Retained absolute motor turns can simplify startup, while load slip, changed couplings or machine maintenance can still invalidate a stored machine reference. The controller must handle the actual coordinate relationship and finite position range.
Battery-free retention removes one service item. It does not establish compatibility with every drive or immunity to installation faults. Confirm the actual feedback protocol, firmware and motor option.
Machine Coordinate Strategy
Define how encoder counts map through gearing and screw lead to the process point. Establish turn-range handling and what happens if mechanics are disconnected or replaced.
Decide which startup checks remain necessary for the machine. Absolute motor feedback can reduce homing needs without making every load-side reference check unnecessary.
Commission and Restore
Verify direction, scaling, motor identity and supported drive setup. Test a controlled power-off movement scenario only within the actual system instructions and machine acceptance plan.
Retain reference offsets, parameter backups and hardware/firmware identity. After service, verify the process-point position rather than trusting that the same displayed motor count proves unchanged mechanics.
Applications and Selection
Supported servo axes needing retained motor-turn information and an explicitly engineered machine-reference strategy.
For Kollmorgen SFD-M Absolute Multiturn Feedback, define the actual machine duty before selecting an ordering configuration. Include the required operating point, available installation space, environment and control interfaces. The specification table describes the product or family; the surrounding machine determines which of those features matters for the intended job.
Price and Value
Price: Request a quote for the exact configuration. Compare the product, compatible control equipment, required mechanical parts, cabling and commissioning as one installed system. A component price alone does not represent the cost of a working automation axis.
Evaluate an alternative against the same duty and acceptance criteria. Match the continuous operating requirement first, then compare transient capability, feedback, mechanical fit and support. This avoids choosing between superficially similar products whose ratings describe different operating conditions.
Pros and Cons
Advantages
Absolute singleturn and multiturn feedback
Battery-free retention architecture
High-resolution integration within supported servo systems
Limitations
Accuracy is much coarser than count subdivision
Not a universal interchangeable encoder
Machine references can still change after mechanical work
Who Should Consider Kollmorgen SFD-M Absolute Multiturn Feedback?
Consider Kollmorgen SFD-M Absolute Multiturn Feedback for supported servo axes needing retained motor-turn information and an explicitly engineered machine-reference strategy. Establish the required operating point and installation interfaces before choosing the configuration, and use a representative loaded cycle as the acceptance basis.
Kollmorgen SFD-M Absolute Multiturn Feedback FAQ
Is 0.0772 arc-sec the absolute accuracy?
No. It is nominal count subdivision; the accuracy specification is separate.
How many singleturn counts are specified?
16,777,216 counts per revolution.
Does battery-free mean no system maintenance?
It removes the encoder backup-battery requirement, not all system service tasks.
Can any motor use SFD-M?
Use a supported motor/drive/firmware configuration.
Does absolute feedback eliminate every homing check?
No. The actual machine reference and mechanics can still require verification.
What does the multiturn range describe?
The specified range of retained motor revolutions, which must be mapped to the machine coordinate system.
Does a motor encoder measure load backlash directly?
No. Downstream transmission error is separate.
What should be checked after mechanical service?
Direction, scaling, offsets and the actual process-point position.
Prices are indicative and may change. Confirm the final configuration, commercial terms and delivery schedule before ordering.
