Pneumatic cylinders convert compressed air into linear mechanical motion. Their core components are categorized by functions: motion transmission, sealing, guidance & buffering, and installation & detection.
1. Core Motion Transmission Components
| Component | Key Function | Critical Requirements | Common Materials |
|---|---|---|---|
| Cylinder Barrel | Main body that houses compressed air and the piston; provides a sealed chamber for pressure buildup | High structural strength, smooth inner wall (Ra ≤0.8μm), pressure resistance (0.4–1.0MPa) | Aluminum alloy (light-duty applications), carbon steel (heavy-duty scenarios) |
| Piston | Divides the cylinder barrel into two independent air chambers; converts air pressure into linear thrust | Excellent airtightness, low friction, wear resistance | Aluminum alloy with integrated rubber seals, carbon steel |
| Piston Rod | Connects the piston to external loads; transmits linear motion | High straightness (≤0.02mm/m), wear & corrosion resistance, fatigue resistance | 45# carbon steel (chrome-plated surface), 304 stainless steel |
| Front/Rear End Cap | Seals the two ends of the cylinder barrel; supports the piston rod and provides ports for air intake/exhaust | High rigidity, precise sealing groove machining, pressure resistance | Aluminum alloy (lightweight, cost-effective), cast iron (heavy-duty use) |
2. Sealing Components (Critical for Operational Efficiency)
- Piston Seal: Prevents air leakage between the piston and cylinder barrel to ensure pressure difference between the two chambers. Common types include O-rings, Y-rings, and V-rings. Materials: Nitrile Rubber (NBR, oil-resistant for standard applications), Fluororubber (FKM, heat-resistant up to 120°C for harsh environments).
- Rod Seal: Blocks internal air leakage and prevents external contaminants (dust, moisture) from entering the cylinder. Common types: U-cup seals, lip seals. Key requirement: Low friction coefficient to avoid piston rod wear while maintaining high sealing performance.
- Buffer Seal: Enhances the buffering effect by cooperating with buffer components; reduces air leakage during the buffer phase.
3. Guidance & Buffering Components
- Guide Bushing: Guides the piston rod’s linear movement; reduces lateral friction and prevents piston tilting. Materials: Bronze (oil-lubricated), PTFE (self-lubricating). Critical fit: Clearance with piston rod ≤0.1mm.
- Buffer Device: Reduces impact force when the piston reaches the end of the stroke, protecting the piston and end caps from damage. Two main types: Adjustable buffer valves (regulate exhaust speed to control buffer intensity), buffer sleeves (rubber or nylon for passive shock absorption).
- Exhaust Muffler: Installed on the end cap’s exhaust port; reduces exhaust noise to ≤85dB (meets industrial noise standards) and filters dust from the exhaust air.
4. Installation & Detection Components
- Mounting Bracket: Fixes the pneumatic cylinder to industrial equipment. Common types: Flange mount (for heavy loads), foot mount (for fixed installation), clevis mount (for oscillating motion), trunnion mount (for high-torque scenarios). Selection depends on installation space and force direction.
- Magnetic Switch: A non-contact sensor that detects the piston’s position (extended/retracted) by sensing the magnetic ring embedded in the piston. Sends electrical signals to the control system for automated operation. Compatible with NPN/PNP circuit types; working voltage: DC 12–24V.
- Air Fittings: Connect air hoses to the cylinder’s intake/exhaust ports. Common types: Quick-connect fittings (for fast assembly/disassembly), threaded fittings (G/BSP/PF standards for secure sealing). Requirement: No air leakage under rated working pressure.
Core Operational Logic
- Compressed air enters one of the cylinder’s chambers through the air fitting, creating pressure difference on both sides of the piston.
- The pressure drives the piston to move linearly, which further pushes the piston rod to transmit force to external loads (extension or retraction stroke).
- Sealing components maintain airtightness; the guide bushing ensures stable piston rod movement; the buffer device reduces impact at stroke ends.
- The magnetic switch feeds back the piston’s position signal to the control system; the exhaust muffler reduces noise during air discharge.
Key Selection Tips for Industrial & Export Applications
- Sealing Material: Choose NBR for standard oil-lubricated compressed air systems; FKM for high-temperature, corrosive, or chemical environments.
- Piston Rod Material: Chrome-plated carbon steel for general industrial use; 304/316 stainless steel for humid, marine, or food-processing scenarios.
- Mounting Type: Flange mounts for heavy-load static applications; clevis/trunnion mounts for dynamic oscillating motion.
- Magnetic Switch Compatibility: Confirm voltage and circuit type (NPN/PNP) to match the customer’s automation control system.