Magnetic linear encoder
Bogen ALS21 magnetic linear encoder
Absolute linear magnetic read head for LMSA scales, 1 µm resolution, up to 10 m/s, IP67.
Key specifications
| Ingress protection | IP67 |
|---|---|
| Linear speed (max) | 10 m/s |
| Interface | SSI, BiSS-C, NPN o.c. AB |
| Resolution | 1 |
| Temp | -25 to +85 C |
Series ranges as published; individual models vary. The full datasheet, drawings and CAD models are available on request.
Typical applications
What a magnetic linear encoder is
A magnetic linear encoder reads position from a magnetised scale, usually a flexible tape or a stainless-steel-covered strip with alternating poles, using a readhead with Hall-effect or magnetoresistive sensors. The readhead outputs incremental quadrature or analogue signals, or absolute position from a coded track. The scale can be cut to length and bonded to the machine, making long axes economical. Magnetic linear encoders tolerate dust, oil and coolant better than open optical systems.
When engineers choose a magnetic linear encoder
Choose a magnetic linear encoder for robust position feedback on long axes in harsh environments, such as woodworking, metal processing, packaging and linear motors on general automation. It is affordable and easy to install. The trade-offs are resolution and accuracy, which are typically lower than optical scales, and sensitivity to strong magnetic fields or ferrous debris. For precision metrology, optical or enclosed scales suit better.
How to specify the Bogen ALS21
Send these with your enquiry and an engineer can confirm the right ALS21 variant:
- Resolution and accuracy (µm)
- Measuring length (mm or m)
- Absolute or incremental output
- Interface: TTL, sin/cos, SSI, BiSS
- Ride height and alignment tolerances (mm)
- Maximum speed (m/s)
- Environment and IP code
Common mistakes to avoid
- Exceeding ride height tolerances during installation
- Exposing tape to strong magnetic fields or magnetic tools
- Ignoring thermal expansion of the tape and substrate
- Expecting optical-grade accuracy
Bogen ALS21: frequently asked questions
What is the Bogen ALS21?
Absolute linear magnetic read head for LMSA scales, 1 µm resolution, up to 10 m/s, IP67. Published series figures include linear speed 10 m/s. It is available through our supply network, and our engineers can confirm the right variant for your application.
Who makes the Bogen ALS21?
The Bogen ALS21 is made by Bogen (Bogen Magnetics) available through our supply network. Send us your requirement for pricing, lead time, datasheets and CAD.
What is the linear speed of the Bogen ALS21?
The published series maximum linear speed is 10 m/s. Individual models and sizes in the ALS21 range vary, so check the exact variant against your duty cycle, mounting and environment, or ask our engineers to confirm the right size for you.
How accurate is a magnetic linear encoder?
Accuracy depends on the scale and readhead, but magnetic linear encoders are typically accurate to several micrometres or tens of micrometres per metre, with resolution down to around a micrometre. This suits general automation and woodworking. For sub-micrometre accuracy, optical scales are usually needed.
Can magnetic tape scales be cut to length?
Many magnetic tape scales are supplied on a reel and can be cut to the required length, then bonded to the machine with adhesive backing and a cover strip. This makes long axes simple and economical. Follow the manufacturer's handling guidance to avoid damaging the magnetisation.
Further reading: How to select a linear encoder · Magnetic vs capacitive vs optical encoders · Encoders and feedback
Often compared with
Engineers specifying this series often compare it with:
Other magnetic linear encoder series
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