What Does Annual Maintenance of a Pneumatic Industrial Manipulator Include?

Annual maintenance should focus on the load-bearing structure, pneumatic balancing system and custom tooling, identifying fatigue and wear, reduced leak tightness, changes in joint damping and tooling deterioration, and recording the corrective work. Follow the supplied manual and manufacturer's drawings for each model's tightening torques, pressures and strokes.

01Mechanical structure

Start with the load-bearing structure. Check foundation fixings, load-bearing connections, welds and slewing mechanisms for looseness, deformation, cracks and wear.

• Column and base: Check for loose anchor bolts, gaps or displacement between the base and foundation, and column deformation or corrosion. For overhead-mounted or rail-mounted installations, also inspect the overhead steelwork and suspension points.
• Connecting bolts: check major load-bearing bolts at joints, counterweights and arm connections. Retighten to the specified torque and apply witness marks.
• Welds: visually inspect load-bearing welds for cracks, flaking and rust staining; use dye-penetrant inspection where necessary. If cracks are found, stop using the equipment and contact the manufacturer. Do not resume loaded operation after unauthorized repair welding.
• Joint bearings and slewing mechanisms: move each joint to check for binding, unusual noise and excessive clearance. Verify smooth rotation, effective travel limits and stable positioning.

02Pneumatic system inspection

Inspect the pneumatic system through its supply, control and actuation stages, focusing on air preparation, circuit sealing, valve operation, cylinder movement and pressure indication.

• Air preparation (FRL): clean or replace filter elements, drain accumulated water and oil, and check stable output pressure. Check the lubricator oil level where a lubricator is fitted.
• Hoses and fittings: inspect for hardening, cracks, flattening, leaks and loose connections. Check each point with leak-detection fluid or an instrument while the circuit holds pressure.
• Valve assemblies: check directional, balancing and check valves for responsive operation and internal leakage.
• Cylinders: check piston rods for scratches and inspect cylinder operation for stick-slip, leakage and uneven motion.
• Silencers: check for oil contamination or blockage that can slow movement. Clean or replace as needed.
• Pressure gauges: verify accurate readings and intact dials so system condition can be assessed.

03Balancing system

Measure balancing performance without a load and with representative loads. Observe holding position, drift, rebound and lifting response, and consider operating force and feel when assessing system condition.

• No-load balancing: Move the arm up and down when there is no workpiece. It should be basically stationary at any height after letting go.
• Loaded balancing: repeat the test with representative workpieces to verify balancing under load.
• Drift: observe any slow rise or descent after releasing the handle. Minor drift often indicates circuit leakage or incorrect balancing pressure.
• Rebound: releasing the handle quickly should not cause noticeable rebound or vibration.
• Lift response: Response should track hand input directly, without lag or unintended motion, and operating force should remain uniform throughout the stroke.

04Tooling

Maintain tooling according to its actual configuration, inspecting contact surfaces, retention mechanisms and seals. Focus on wear, deterioration and abnormal motion that may affect workpiece stability or surface quality.

• Vacuum cups: inspect rubber hardening, cracks, deformation and contact-face wear. Replace according to condition.
• Jaws and contoured tooling: check contact-face wear, anti-slip features and full opening and closing.
• Internal-expansion mechanisms: check expanding elements, stroke, return and stable gripping force.
• Hook: Inspect the hook body for wear or throat-opening change and verify that the safety latch is effective.
• Buffer pads: inspect compaction, aging and detachment, which can increase impact loads.
• Seals: Check whether the vacuum and air circuit seals are aging and leaking, which is a common cause of performance degradation of vacuum tooling.

05Safety device inspection

Functionally test emergency stops, travel limits, brakes, drop prevention and air-loss protection, confirming each is effective. Visual inspection cannot replace operational verification.

• Emergency stops: verify prompt stopping and latching when pressed, and normal control function after reset.
• Limit: The limit in each direction should be triggered reliably to prevent overtravel.
• Brakes: verify prompt engagement, reliable holding and wear within allowable limits.
• Drop prevention: verify reliable locking under the specified simulated pressure-loss or loss-of-speed-control condition.
• Air-loss protection: simulate supply interruption and verify that the tooling retains the workpiece without unintended release and permits only controlled subsequent release.

06Fastening and lubrication

Apply tightening and lubrication requirements separately to each location: retighten load-bearing connections to the specified torque and use the specified lubricant on moving parts. Do not apply oil indiscriminately to non-lubricated locations such as brake friction surfaces and damping components.

• Fastening: retighten major load-bearing bolts at the foundation, column, arm connections, counterweights, joints and tooling mount to the specified torque and apply witness marks.
• Lubrication: replenish slewing bearings, joint pivots and sliding guides with the lubricant type and interval specified by the manufacturer. Avoid mixing lubricants.
• Locations not to oil indiscriminately: brake friction surfaces, damping-control components, the internals of certain pneumatic components and friction-based positioning structures. Incorrect lubrication can cause braking failure, abnormal damping or slipping.

07Load trials

After inspections and corrective work, unloaded, rated-load and representative-workpiece handling tests must be carried out in that order to verify equipment and tooling operation.

• Unloaded operation: test all joints throughout their travel. Check for unusual noise, binding and leaks, and verify normal balancing.
• Rated load operation: Load to rated load and verify the performance of balance, brake, clamp and safety devices under full load.
• Typical workpiece handling test: Use actual workpieces on site to simulate real handling movements to confirm that the feel, cycle time and safety meet production requirements.

08Annual maintenance checklist

The suggested intervals in the table apply to normal operating conditions. Shorten the relevant inspection intervals for heavy loads, high temperatures and dusty environments.

09Common maintenance findings

• Air-line aging: Hardening and cracking can cause leakage or hose rupture and are common causes of balance drift and increased operating force. Replace the complete hose section at the specified interval.
• Hardened cups: aging rubber reduces vacuum holding force and increases the risk of dropped parts. Replace cups promptly according to condition.
• Leaking fittings: a small leak at one fitting may be inconspicuous, but several leaks can significantly affect balancing. Check each point.
• Loose joints: bearing wear and increased clearance cause movement and unstable positioning. Adjust or replace affected components promptly.
• Heavier operating feel: check the pneumatic, balancing and lubrication systems for loss of leak tightness, internal valve leakage, inadequate lubrication and abnormal damping, and assess the causes together.

10Maintenance records and defect correction

Maintain a service file for each unit, recording the maintenance date, inspector, condition of each item, problems found, corrective measures, replaced parts, trial results and next maintenance plan. This makes equipment condition and repair history traceable.

Follow the sequence of identifying a defect, assessing its risk, correcting it or withdrawing the equipment from service, retesting and verification, and filing the records. Safety problems such as cracked welds, ineffective drop prevention or abnormal air-loss protection require the equipment to be taken out of service first. Return it to service only after satisfactory correction; do not operate with unresolved hazards. Use maintenance records to analyze recurring faults and adjust spare-parts stocks and maintenance intervals.

11Setting maintenance intervals for custom equipment

Once a year can serve as a maintenance baseline under normal operating conditions. For custom equipment, determine each inspection interval from the actual configuration, operating intensity and environment, using the following factors.

• Usage: short cycles and multiple shifts accelerate wear. Shorten inspection intervals accordingly.
• Dust conditions: Dusty environments such as casting, grinding, and welding will accelerate the deterioration of filter elements, seals, and moving pairs.
• Temperature: hot workpieces or hot workshops accelerate aging of rubber parts, seals and grease.
• Workpiece weight: prolonged operation near rated load increases fatigue demands on structural parts and cylinders.
• Tooling type: vacuum cups, jaws, internal-expansion mechanisms and heat-insulated tooling have different wear parts and maintenance priorities.