AirTAC RMT Series Magnetically Coupled Dual-Rod Rodless Cylinder: The Ultimate Engineering Guide

In the grand narrative of industrial automation, actuators are the foundation. Traditional rod cylinders have supported production lines for a century, but their inherent structural flaw—the rod sticking out—is a constant nightmare for mechanical engineers. This rod doubles the installation length and introduces contamination risks through its dynamic seal.

Enter the Rodless Cylinder. And the crown jewel of this family is the Magnetically Coupled Rodless Cylinder. By achieving a fully sealed, leak-free design, it redefines linear motion. The AirTAC RMT Series is not just an actuator; it is a complex mechatronic unit integrating high-precision guidance with non-contact power transmission.

This deep technical guide will strip away the marketing fluff. We will dissect the RMT series from microscopic magnetic physics to macroscopic engineering logic, providing you with a panoramic view for your next big project.

1. Core Design Philosophy: The Physics of Zero Leakage

To understand the RMT, you must look into its "Heart"—the magnetic coupling drive system. Unlike mechanical rodless cylinders that use a slit and seal band, the RMT transmits power through physical isolation. It uses invisible magnetic field lines to penetrate a solid metal wall, achieving "Action at a Distance."

1.1 The Rare Earth Flux Loop

Inside the RMT piston are high-performance Rare Earth Magnets (NdFeB). Outside the cylinder tube, the slider (carriage) holds matching magnets with opposite polarity.
When these magnets align, the N-pole and S-pole attract, creating a closed, high-density magnetic flux loop. This creates an "Invisible Connecting Rod." When air pushes the internal piston, the powerful magnetic attraction instantly overcomes static friction, dragging the external slider along. It looks like magic, but it's physics.

1.2 True "Air Tight" and "Dust Tight"

Mechanical rodless cylinders have a slit sealed by a flexible strip. Over time, this strip wears out, leading to leaks.
The RMT abandons this compromise. The cylinder barrel is a seamless pressure vessel.

• Zero External Leakage: Ideal for expensive gases or vacuum environments. No rod seal to wear out means longer maintenance intervals.
• Dust-proof Excellence: In a flour mill or ceramic plant, rod cylinders drag dust inside, destroying seals. The RMT is physically isolated. Even if the outside is caked in dust, the inside remains pristine.

2. The Dual-Guide Revolution: Solving the Side Load Pain

If magnets solved the sealing problem, the "Dual Guide" design solves the magnetic cylinder's weakness: Rigidity.

The Torsion Dilemma

Basic magnetic cylinders (like the single-tube RMS series) can rotate freely. If the load is off-center, torque will twist the slider, breaking the magnetic coupling.
The RMT Series fixes this by integrating Two High-Precision Solid Guide Rods parallel to the main barrel. This creates a stable "Three-Axis" flat structure.

The Mechanics of Stability

1. Side Load Resistance: The two guide rods take all the shear force and bending moments, protecting the thin-walled main barrel from deformation.
2. Anti-Rotation Rigidity: The wide stance of the dual rods converts torque into radial pressure on the bushings. This exponentially increases resistance to rolling moments compared to a single tube.

3. Deep Dive into Specs: The Logic of Selection

3.1 Bore & Force Quantification

The RMT Series offers five bores: 16, 20, 25, 32, and 40mm.
• 16mm: The "Precision Assassin" for electronics. 140N Holding Force.
• 20 & 25mm: The "Backbone" of assembly lines. 220N / 345N Holding Force. Perfect balance of size and power.
• 32 & 40mm: The "Heavy Tanks." 560N / 880N Holding Force. Can replace small electric actuators for heavy lifting.

3.2 Stroke Flexibility

Standard strokes go up to 500mm, but custom strokes can reach 1000mm or even 1500mm.
Note: For ultra-long strokes (>1m), the barrel will sag under its own weight. Consider intermediate supports.

3.3 Speed Dynamics

Range: 50 ~ 400 mm/s.
Why 400 mm/s Limit?
1. Eddy Currents: High speed generates heat in the metal tube, potentially demagnetizing the magnets.
2. Impact: High-speed stops create massive shear forces that can cause decoupling. Buffering is essential.

4. The Art of Cushioning

In linear motion, "Moving" is easy; "Stopping" is art. The RMT has a 3-tier defense against impact.

Tier 1: Rubber Bumpers (Standard)
Basic protection for low speeds.

Tier 2: Adjustable Pneumatic Cushioning (Standard)
Traps air at the end of the stroke to create an air spring. You can fine-tune the deceleration curve with a needle valve.

Tier 3: External Hydraulic Shock Absorber (Optional)
The ultimate defense. Converts kinetic energy into heat. Essential for high-inertia loads or speeds near 400 mm/s. It allows for a "Perfect Stop" without decoupling.

5. Installation Engineering

5.1 Clean Air Requirement

AirTAC mandates 40μm filtration. Why?
The gap between the internal piston and the tube wall is microscopic. Metal chips or rust particles will scratch the inner wall, destroying the seal. In cold environments (-20°C), you must use a dryer to prevent ice crystals from seizing the piston.

5.2 Magnetic Environment

Mounting Surface: If you mount the RMT directly onto a steel plate, magnetic flux will divert into the steel ("Magnetic Shunting"), weakening the holding force.
Solution: Use a non-magnetic spacer (Aluminum, 10-20mm thick) between the cylinder and the steel base.

6. Applications: Where RMT Shines

7. Maintenance: Decoupling Reset

Scenario: You hit a hard stop, and the magnets separated. The piston is at the end; the slider is in the middle.
Fix:
1. Cut air pressure.
2. Push the slider by hand towards the piston end.
3. Feel for the resistance drop, then a strong "CLICK."
4. Test run slowly.
(Caution: Watch your fingers!)