SMC MB1B40-100Z Square Tube Air Cylinder 40 mm

A lighter square-tube alternative to the tie-rod cylinder

MB1B40-100Z is a standard-type, double-acting, single-rod square tube air cylinder from the SMC MB1 series. The square aluminum tube with end covers has no tie rods outside the body, giving a cleaner profile, and the catalogue front page carries a “10% lighter” callout. Bore sizes are 32, 40, 50, 63, 80, 100 and 125 mm.

In the code MB1 is the series, B is basic mounting (L axial foot, F rod flange, G head flange, C single clevis, D double clevis), 40 is the bore in mm, 100 the stroke in mm and Z the current design suffix. Without a cushion letter the cylinder has air cushions; the N option selects rubber bumper instead, and J or K add a rod boot.

Technical specifications

Choosing mounting and accessories

The catalogue lists accessories in three groups: a single knuckle joint, a double knuckle joint with pin and a pivot bracket, which are ordered through accessory letters and shipped with the cylinder. Mounting brackets for the foot, flange and clevis styles are shipped together with the product but not assembled (see the note on the how-to-order page), so confirm what is mounted when the order is placed.

For clevis-mounted cylinders the knuckle joint takes up misalignment between the rod and the load; the basic and flange styles should be aligned carefully, because side force shortens seal life.

Compared with its neighbours in the SMC range

MB1 shares its bore range with the CP96 ISO cylinder (32 to 125 mm) and has nearly the same theoretical force table, but the CP96 is the one SMC describes as an ISO 15552 profile cylinder with standardised mounting dimensions, while the MB1 is presented as a square tube cylinder in its own catalogue. Check the dimension drawings if replacing an existing cylinder.

At the upper end of the 50 to 1000 mm/s speed range confirm the stroke-end energy and cushion setting, because a fast heavy load can exceed what the cushion absorbs.

Key features of the MB1B40-100Z

• Square aluminium tube without external tie rods: smooth outer faces collect less dirt and are easier to wipe down than a tie-rod design.
• Double acting: air drives the piston in both directions, giving controlled force on extend and retract.
• Air cushions as standard: adjustable cushioning at the stroke ends reduces impact and noise when moving loads at speed.
• Non-lube operation: the cylinder runs on clean, dry air without added lubricant, which avoids oil mist in the workplace.
• Auto switch capability: position sensors can be mounted on the body to signal stroke end positions to the control system.

Sizing the cylinder for the job

The theoretical output of 629 N extending and 528 N retracting at 0.5 MPa is a starting point. In practice, a load factor is applied to allow for friction, acceleration and pressure drop in the piping. For a dynamic load moving horizontally on guides, a load factor of around 50% of theoretical force is a common rule of thumb; for static clamping, a higher figure may be used. If the required force is close to the calculated value, the next bore size up, 50 mm, gives a safer margin.

Speed and cushioning

The cylinder can operate between 50 and 1000 mm/s. Higher speeds increase the kinetic energy that the cushion must absorb at the end of the stroke. Check the allowable kinetic energy in the SMC catalogue against the moving mass and speed, and add external shock absorbers if the value is exceeded. Speed controllers on the cylinder ports, set to meter-out, give smooth, stable motion.

Installation and maintenance practice

Align the rod with the direction of the load: side loads on the piston rod accelerate wear of the bushing and seals. Use a floating joint or knuckle where perfect alignment is difficult. Supply air through a filter regulator, and drain water from the system regularly. When maintenance is required, seal kits can be ordered for the bore size; record the full part number so the right kit is supplied.

Considerations for the Gulf region

Compressed air systems in Oman’s coastal industrial zones can carry significant moisture due to high humidity, especially when compressors draw in hot, damp air. A refrigerated or desiccant dryer and good drainage protect cylinder seals and auto switches. Where cylinders work outdoors or in dusty conditions, such as cement, mining or packaging plants, the J or K rod boot options help keep abrasive particles off the piston rod. The ambient temperature limit of 70 °C without switches, or 60 °C with switches, should be considered for equipment exposed to sun.

Data for your RFQ

• Full part number MB1B40-100Z, or the variant with mounting, cushion or boot options.
• Number of cylinders and spares, including seal kits.
• Auto switch type and quantity, if needed.
• Mounting brackets, knuckle joints and speed controllers.
• Delivery location and required date.

Documents and quotation

The linked SMC MB1 catalogue contains the how-to-order page, specifications, force and weight tables and dimensions. Please confirm mounting, cushion, boot and accessory options before ordering. See Pneumatic Cylinders for further cylinders. Seven Star LLC is an independent supplier and quotes the exact code on request.