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SMC auto switches — D-A / D-B / D-M9 series
Selection logic: for high cycle rates (over 100 cycles per minute) or longer life, choose the D-M9 solid-state series. For limited mounting space, or where a side lead or right-angle terminal is needed, choose the D-B series. For other standard applications, start with the D-A series. Before selecting, check the switch mounting groove on your cylinder.
Series overview
| Series | Typical models | Contact type | Features and when to choose |
|---|---|---|---|
| D-A series | D-A53, D-A93, D-A93L (3 m lead), D-A93V | Reed (contact) | General purpose; specified for most SMC standard cylinders; easy to install |
| D-B series | D-B53, D-B54, D-B73, D-B73L | Reed (contact) | Right-angle terminal or bottom lead design; choose when mounting space is tight |
| D-C series | D-C73 | Reed (contact) | For small-bore cylinders (CJ2 series) with narrower grooves |
| D-M9 series | D-M9B, D-M9BAL, D-M9BV, D-M9N | Solid state (contactless) | Popular for high-frequency use; no arc wear, noticeably longer life; includes water-resistant AL type |
| D-F8 / D-Y59B | D-F8NDC24V, D-Y59B | Depends on model | Driven directly from DC 24 V systems |
| D-Z series | D-Z73 | Reed (contact) | For specific SMC cylinder groove types |
| Mounting band | BA4-040 | — | Auto switch mounting band for Ø40 mm cylinders |
Selection tip: check the type and size of the switch groove on the cylinder body before matching a model. The D-M9 suffixes (B / BAL / BV / N) correspond to different lead wire directions and water resistance; for high-frequency or humid environments, consider the M9BAL first.
What is a reed switch?
A reed switch has two magnetic reeds sealed in a glass tube. When a magnet comes close, the reeds are magnetized and close, completing the circuit; when the magnet moves away, the reeds spring apart and the circuit opens.
Mounted on a cylinder, the switch senses the magnet ring on the piston: when the piston reaches the switch position, it sends a signal to confirm the cylinder stroke. This is why it is also called a cylinder reed switch or cylinder magnetic switch.
Reed vs. solid-state switches
| Type | How it switches | SMC models on this page | Use |
|---|---|---|---|
| Reed (contact) | Reeds pulled together by the magnet close a mechanical contact | D-A, D-B, D-C, D-Z series | Standard cylinders with normal cycle rates |
| Solid state (contactless) | Electronic element senses the magnetic field; no mechanical contact | D-M9 series | Equipment with high cycle rates and long-life requirements |
When selecting, also confirm: groove type and size on the cylinder, lead wire direction, lead wire length, 2-wire or 3-wire output, and operating voltage.
Applications
SMC auto switches are widely used for cylinder positioning in semiconductor equipment, automated control on electronics assembly lines, stroke feedback on robot arms and limit sensing for equipment protection. The solid-state D-M9 series is especially suited to high-speed reciprocating equipment such as SMT board loaders and dispensers, reducing sensor replacement and unplanned downtime.
Commonly used SMC auto switch models are available, and we support urgent quotes and volume orders. For help matching a switch to your cylinder, email us.
Related: FESTO reed switches · NORGREN reed switches · CHELIC CS-6T reed switch · AirTAC DMS electronic magnetic switch · SICK RZT7-03ZRS-KP0 reed switch · OMRON Z-15HW24-B basic switch
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