How to choose a magnetically coupled rodless cylinder
The first question is where the load goes. Basic and direct mount cylinders (CY3B, CY3R) are not guided, so the load must ride on an external guide. Guided series (CY1S-Z, CY1L, CY1H, CY1F) carry the load and resist moment on the carriage itself. Within the guided series, move from slide bearing to ball bushing to linear guide as load, moment, and precision requirements go up.
| Series |
Guide |
Bore sizes (mm) |
Choose it when |
| CY3B / NCY3B |
None (basic type) |
6, 10, 15, 20, 25, 32, 40, 50, 63 |
You already have a guide and need the widest bore range |
| CY3R / CY3R-N |
None (direct mount) |
6, 10, 15, 20, 25, 32, 40, 50, 63 |
You want to bolt the body straight to the machine, with or without a switch rail |
| CY1S-Z / NCY2S |
Slide bearing |
6, 10, 15, 20, 25, 32, 40 (CY1S-Z) |
You need an integrated guide for light to moderate loads |
| CY1L |
Ball bushing |
6, 10, 15, 20, 25, 32, 40 |
You want smoother, more consistent travel than a slide bearing |
| CY1H |
Linear guide, single or dual axis |
10, 15, 20, 25, 32 |
Load, moment, or positioning precision exceeds what CY1S or CY1L can handle |
| CY1F |
Low profile guide |
10, 15, 25 |
You need a guided slider in limited height |
| REA family |
Basic (REA), slide bearing (REAS), direct mount (REAR), high precision guide (REAH) |
25 to 63 (REA); 10 to 40 (REAS, REAR); 10 to 32 (REAH) |
Workpieces are fragile, such as wafers, disks, or LCD substrates, and you cannot accept shock at stroke ends |
| CYP / CYV |
Guided, clean room (CYP) and high vacuum (CYV) |
15, 32 (CYV) |
Particle generation or vacuum compatibility drives the selection |
Maximum operating pressure for CY3B and CY3R is 0.7 MPa, with an ambient temperature range of -10 to 60 °C. Confirm allowable load, moment, and holding force for the exact bore and stroke in the SMC series catalog.
Options that cause ordering mistakes
Magnetic holding force (H or L). CY1S-Z and CY1L are offered with a high or low magnetic holding force, selected by a letter in the part number. Holding force sets how much load and impact the carriage can take before it decouples, so match it to your load before matching price.
Switch rail on direct mount cylinders. CY3R includes a switch rail for auto switches. CY3R-N is the version without a switch rail. If you plan to sense position on the cylinder, order CY3R.
Stroke adjusters and shock absorbers. CY1S-Z, CY1L, CY1H, and CY1F are configured with an adjuster or stopper option at the stroke ends, including shock absorbers. Adding an adjuster after the fact usually means a different part number, so decide at order time.
CY1S vs. CY1S-Z. SMC is replacing the original CY1S with the CY1S-Z series. When replacing an installed CY1S, check the CY1S-Z equivalent with us before ordering.
mm stroke vs. inch stroke. CY series part numbers give stroke in millimeters. The NCY3B and NCY2S inch stroke versions give stroke in inches and hundredths of an inch, so read the stroke code carefully before ordering a replacement.
Clean room prefix. SMC clean room versions carry a 12- prefix (for example, 12-CY3B and 12-REA). A standard part number without the prefix is not a clean room cylinder.
Magnetically coupled rodless cylinder FAQ
How does a magnetically coupled rodless cylinder work?
Permanent magnets in the piston attract matching magnets in the external carriage through the wall of a sealed cylinder tube. When air pressure moves the piston, the carriage follows it. Because the tube has no slot, there is no external air leakage.
What happens if the carriage decouples?
If load, impact, or speed exceeds the magnetic holding force, the carriage can separate from the piston. It can usually be re-coupled by moving it back over the piston position. Repeated decoupling means the application needs a larger bore, the high holding force version, or a mechanically jointed cylinder.
Do I need an external guide?
Yes for CY3B, CY3R, and the basic REA, which are designed to be used with an external guide that supports the load. No for CY1S-Z, CY1L, CY1H, and CY1F, which have an integrated guide on the carriage. Check allowable load and moment for the bore and mounting orientation in the SMC catalog.
What is the difference between CY1S, CY1L, and CY1H?
All three are guided magnetically coupled rodless cylinders. CY1S uses a slide bearing, CY1L uses ball bushings for smoother travel, and CY1H uses internal linear guides on one or two axes for higher load, moment, and precision than CY1S or CY1L.
What does the N in NCY3B and NCY2S mean?
SMC lists NCY3B and NCY2S as the inch stroke versions of its basic type and slide bearing magnetically coupled cylinders. Stroke is specified in inches rather than millimeters. Choose them when matching inch stroke equipment or replacing an existing NCY cylinder.
When should I use a mechanically jointed cylinder instead?
Choose a mechanically jointed rodless cylinder (SMC MY series) when loads are heavy, impacts are high, or the carriage must never decouple. Choose magnetically coupled when you need a sealed tube with no external leakage and loads stay within the magnetic holding force. See all rodless cylinders to compare both types.
Need help sizing a magnetically coupled cylinder?
Automation Distribution is an authorized SMC distributor. Send us your load mass, stroke, speed, and mounting orientation, and our team will help you choose the series, bore, holding force, and options.
Contact Automation Distribution
