Photoelectric Sensor Topic: Fiber Unit Models Less Affected by Repetitive Bending

FAQ No. FAQ00313

Question

When using a Fiber Unit mounted to a movable part, are there models that are less affected by repetitive bending?

Answer

Seven models are recommended: E32-T11 Fiber Unit, E32-T21, E32-T22B, E32-D11, E32-D21, E32-D21B, and E32-D22B. (These have a bending radius of R4.)

Explanation:

The allowable bending radius of most Fiber Units is 25 mm minimum. Only the seven models listed above have an allowable bending radius of 4 mm. The fiber flexing characteristics have a strong relationship with the bare fiber diameter (see note 1). A bending radius that is 3 times or less the diameter exerts excessive force on the fiber and reduces the optical characteristics (see note 2 on light intensity).

Models

Bare fiber diameter

Flexing resistance data

(light intensity retention, see note 3)

E32-T11
E32-D11

16 x 0.265 dia.

Value after flexing 1,000 times at a bending radius of 4 mm (with no change)/Value after flexing 1,000,000 times (approx. 80%)

E32-T21
E32-T22B
E32-D21
E32-D21B
E32-D22B

4 x 0.25 dia.

Value after flexing 1,000 times at a bending radius of 4 mm (with no change)/Value after flexing 1,000,000 times (approx. 85%)

E32-TC200
E32-DC200

1 x 1 dia.

Value after flexing 1,000 times at a bending radius of 5 mm (approx. 95%)

Note:

1. Flexible Fiber Units (E32-[][]R) have an allowable bending radius of 1 mm, but do not handle repetitive bending well, so they should not be mounted on movable parts.

2. The light intensity of a Through-beam model is reduced to 50%, which reduces the sensing distance by about 30%.

3. Light intensity retention (%) formula

The Fiber Units listed above have a structure that strongly withstands the bending radius R by using fibers with ultra-small diameters.

Note: Flexible Fiber Units (E32-[][]R) have an allowable bending radius of 1 mm, but do not handle repetitive bending well, so they should not be mounted on movable parts.

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