Magnetic Scale Read Head: Features and Usage Notes

The magnetic scale, also called a magnetic ruler, is a detector that records positions by magnetic wave counts using electromagnetic methods. It requires relatively low environmental conditions and offers strong resistance to surrounding magnetic interference, providing good stability in oily or dusty environments.

The working principle of the magnetic scale is magneto-electric conversion. To ensure a stable output signal amplitude from the read head, and considering the high magnetic reluctance of air, there should be no large or variable gap between the magnetic scale and the read head; contact operation is preferable. For this reason, tape-type magnetic scales press the head into the tape during operation so that even if the tape surface is uneven, the head maintains good contact. Linear magnetic scales typically have about a 0.01mm gap between the scale and the head; since perfect assembly and adjustment are not possible, linear magnetic scales effectively operate in a near-contact state.

Magnetic scale is also a displacement sensor. It is less expensive than optical grating scales and offers advantages such as simple manufacture, easy installation, convenient adjustment, wide measurement range (0.001mm to several meters), and strong anti-interference capability. Current achievable resolutions range from 1-10μm with system accuracy around ±0.001mm/m, and magnetic scales are generally affordable.

The magnetic scale measures displacement through the magnetic interaction between the scale and the read head. It is cost-effective and easy to install and use. If necessary, the original magnetic signal on the scale can be erased and re-recorded. Installing the scale on a machine and then recording the magnetic signals can eliminate installation errors and the machine's geometric errors.

Two key characteristics of magnetic scales are: first, the magnetic scale and read head operate in a near-contact mode. Because the working principle is magneto-electric conversion and air has high magnetic reluctance, a large or variable gap between scale and head is unacceptable for stable output. Tape-type scales press the head into the tape to ensure good contact even if the tape surface is uneven. Linear scales maintain an approximately 0.01mm gap, but practical assembly places them in quasi-contact operation.

Atonm magnetic scale read head products are compact and refined for easy installation in tight spaces. They use an all-metal housing and imported flexible wear‑resistant shielded cable, with anti-interference hardware and software design for enhanced reliability. High-resolution options include 1μm, 5μm and 10μm, or custom resolutions per customer requirements. Parallel installation minimizes mechanical conversion error and the devices withstand oil, liquids, dust and vibration in harsh environments.

When using magnetic scales, pay attention to the following points:

1. Keep the supply voltage stable (if display fluctuations do not exceed the supply voltage variation range, the electronic scale is considered normal).

2. The power supply must have sufficient capacity. If the power capacity is too small, the display may fluctuate during specific machine movements. For example, when mold closing or injection, display jitter may occur. This is common when the electromagnetic valve drive and the scale share the same power supply. In severe cases a multimeter will show voltage fluctuations. If static and high-frequency interference are ruled out and alignment is acceptable, a weak power supply may be the cause.

3. Static and RF interference can easily cause the electronic scale display to jump.

4. Alignment and centering must be good. If numeric jitter occurs, adjust angle and parallelism.

5. For long-used scales that accumulate contaminants or oil-water mixtures, brush contact resistance may be affected, causing display jitter; this may indicate early wear of the magnetic scale.

6. If data does not display or shows periodic jitter at a specific point, check whether connection cable insulation is damaged and causing intermittent grounding shorts with machine metal parts.