- Sinking, drifting, sticking, rebounding, and heavier operation are not "normal running-in" and should be treated as follows.Troubleshooting processprocessing.
- First principle:Disable first, uninstall first, confirm safety first, and then check them one by one according to compressed-air supply, vacuum, machinery, fixtures and safety functions.
- Abnormal sinking is often associated withcompressed-air supply/balance/sealing/loadRelated; drift is mostly related toDamping/loose installation/air pressurerelated; binding is more often associated withBearing/track/foreign matter/clamp interferencerelated.
- Continuous sinking under load, failure of clamps to clamp or release, emergency stop failure, air line burst, etc.Immediately tag out and remove from service。
If you continue to use it with the fault, it may cause the workpiece to slip, the tooling to collide, personal injury or equipment damage. This article combines the on-site maintenance experience of the Pneumatic Industrial Manipulator to explain how to initially judge and deal with such abnormalities, and provides a comparison table of "fault phenomena-possible causes-inspection methods-handling suggestions".
01What is abnormal sinking, drifting and stuck?
- abnormal sinking: When the workpiece is no-load or loaded, it moves downward on its own without performing the lowering operation, or it continues to fall slowly after stopping. This often manifests as the workpiece gradually sliding down after being adsorbed or clamped, and the manipulator being unable to hover.
- drift: The equipment moves on its own in the direction of rotation, translation or lifting after no one pushes it or touches it slightly. The on-site performance often appears as "unable to stop" or "going astray on its own".
- stuck: The equipment does not move smoothly at a certain position, and the pushing resistance increases significantly, or even gets stuck, falters, makes abnormal noise, or cannot be reset.
- rebound and impact: Sudden rebound, jitter, impact or rapid movement occurs when the equipment stops.
- Operation becomes heavier: The originally light power-assisted operation has become laborious, and lifting, rotation, and translation are not as smooth as before.
Once these phenomena occur, they cannot be simply classified as "normal running-in" or "occasional problems" and should be handled according to the troubleshooting process.
02The first principle when an abnormality is discovered: control the risk first
When you find that the Pneumatic Industrial Manipulator is sinking, drifting, stuck or rebounding, the first principle is not to continue trying, but to control the risk first. The operator should immediately stop the current handling action and put the workpiece back on the support surface, tooling or pallet under safe conditions to avoid the workpiece hanging in the air; if the equipment can still be controlled, it should move slowly to a safe position and do not pull or force it to reset quickly; after confirming that the workpiece has been put down safely, notify the maintenance personnel or equipment administrator to check.
For Pneumatic Industrial Manipulator failures, the compressed-air supply status should be maintained or stabilized to avoid equipment imbalance caused by sudden air loss. However, if there are obvious air leaks, out-of-control movements, inability to release the clamp, or personnel safety risks on site, measures such as emergency stop, isolation of the compressed-air supply, and warning areas should be taken in accordance with the company's safety regulations. Under no circumstances is it recommended that operators repeatedly test faults with load.
03Abnormal subsidence: possible causes and troubleshooting directions
The subsidence of the Pneumatic Industrial Manipulator is usually related to compressed-air supply, balance system, seals and load changes. First check whether the compressed-air supply pressure meets the equipment requirements, whether the setting value of the filter pressure reducing valve has been adjusted, and whether the pressure gauge fluctuates. When the compressed air pressure in the workshop is insufficient, the balance force of the equipment decreases and it is easier to sink under load.
Secondly, check whether the pneumatic tubing and joints are leaking: the pneumatic tubing is aged, bent, worn, loose quick-in connectors, and the valve group is poorly sealed, which may cause the pressure to be unable to be maintained. For cylinder-type balanced structures, cylinder seal wear, internal leakage and valve group failure should also be considered. Load exceeding the setting is also a common reason - if the workpiece, fixture, suction cup frame is temporarily replaced, or accessories are added, the actual load may exceed the original setting range, making it difficult for the equipment to hover.
04Drift: possible causes and troubleshooting directions
Pneumatic Industrial Manipulator drift usually occurs when the equipment continues to move slowly after stopping, or cannot stop stably in a certain direction. When troubleshooting, you should first distinguish whether it is drifting in the lifting direction, or drifting in the horizontal rotation or track translation direction. Drift in the lifting direction is mostly related to improper balance adjustment, load changes, and unstable air pressure; horizontal drift may be related to insufficient joint damping, brake mechanism wear, uneven track installation, uneven ground, and loose columns or bases.
Loose installation is a factor that cannot be ignored: loose column base bolts, deformation of rail suspension points, and increased cantilever connection gaps will all change the stress state of the equipment and cause deflection or automatic slip. Equipment managers should check the locations of anchor bolts, connecting flanges, cantilever joints, track end limits, etc. to confirm that the installation foundation is reliable.
05Stuck and heavy operation: possible causes and troubleshooting directions
Common causes of stuck handling equipment include worn spherical bearings, lack of oil or wear on pin bushings, track contamination, damaged rollers, foreign object interference, mechanical deformation, improper lubrication and fixture structural interference. If the jamming occurs at a certain fixed position, you should focus on checking whether there are foreign objects, deformations, collision marks or limit interference at that position; if the entire stroke becomes heavy, you should check the compressed-air supply pressure, balance system, joint lubrication, bearing resistance and track cleaning.
Fixture structural interference is also common. After long-term use of custom tooling, the gripper jaws, connecting rods, pins, springs, and limit blocks may become worn or loose, resulting in unsynchronized movements, incomplete return, or interference with the workpiece. Such problems cannot be solved by increasing operating force, otherwise the fixture may be deformed or the workpiece may be damaged.
06Causes of rebound, impact and unstable movement
When the equipment rebounds or impacts, it usually indicates that there is an abnormality in the action speed, air pressure, throttling or load center of gravity: air pressure fluctuations can cause lifting or clamping movements to be fast and slow; improper throttle valve settings can cause the cylinder to expand and contract too fast; operators push and pull too fast, which may also cause the manipulator to swing inertly.
Load center of gravity shift is another important factor. For workpieces of the same weight, if the clamping point changes, the workpiece is eccentric, and the suction cups are unevenly arranged, impact and rebound are likely to occur when the equipment moves or stops. If the rebound is accompanied by obvious abnormal noise or jitter, or it still cannot stop stably after an emergency stop, the equipment should be stopped immediately and maintenance personnel should check the brakes, valve groups, cylinders, joints and limit mechanisms.
07Special issues in vacuum gripping scenarios
vacuum gripping failure often manifests itself as prolonged vacuum gripping time, insufficient vacuum gauge reading, workpiece slipping during transportation, unclean release, or partial leakage of the suction cup. Common causes include air leakage from the suction cup, hardening and cracking of the suction cup, rough or oily surface of the workpiece, insufficient air supply from the vacuum generator, clogged filters, air leakage from the vacuum pipeline, etc.
If the edge of the suction cup becomes hard, curled, or cracked, or there is dust or debris on the suction surface, clean and check the status of the suction cup first; if it still cannot be restored after cleaning, replace the suction cup. For workpieces with rough, breathable or deformed surfaces, it should be confirmed whether the original fixture solution is still suitable. The lack of vacuum gripping cannot be made up by simply increasing the operating speed. Air leakage from the fixture may also come from the suction cup seat, vacuum tube, quick-plug connector, distribution block, valve group seal, etc. It can be located by listening to the sound of air leakage, observing the vacuum gauge, and performing segmental sealing tests.
08Troubleshooting—Cause—Check—Treatment Checklist
| Symptom | Possible Causes | On-site inspection methods | Recommended Action |
|---|---|---|---|
| Slowly sinks after being loaded | Insufficient air pressure, air hose leakage, cylinder seal wear, and load exceeding setting | Check the pressure gauge, listen for air leakage, and check the weight of the workpiece | Stabilize the compressed-air supply, repair air leakage points, and reconfirm load and balance |
| It sinks even without load | Balance parameter changes, valve group abnormalities, cylinder internal leakage | No-load hover test to observe pressure maintenance | Take it out of service and have the valve block and cylinder seals checked by maintenance personnel |
| Horizontal drift | Insufficient joint damping, uneven track, loose installation | Check joints, rails, anchor bolts and levels | Adjust damping, tighten mounting points, review track and foundation |
| Stuck at a certain position | Foreign object interference, abnormal positioning, and structural deformation | Observe the stuck position, check collision marks and limits | Remove foreign matter, repair the limit, and correct the structure if necessary |
| Full stroke operation becomes heavier | Insufficient lubrication, bearing wear, track contamination, abnormal air pressure | Check lubrication, rollers, bearings, air supply pressure | Clean and lubricate, replace worn parts, and restore compressed-air supply parameters |
| Rebound or impact when stopping | Air pressure fluctuations, improper throttle setting, operating too fast, center of gravity shift | Observe the action speed, check the throttle valve and load attitude | Adjust throttling, standardize operations, and optimize clamping positions |
| vacuum gripping is unstable | The suction cup is leaking, the workpiece is rough, the filter is clogged, and the vacuum is insufficient. | Look at the vacuum gauge and check the suction cup and filter | Replace the suction cup, clean the filter, and check the vacuum pipeline |
| Clamp release is not smooth | Air path blockage, spring fatigue, mechanism interference, valve group abnormality | No-load test fixture opening, closing and resetting | Clean the pneumatic line, replace the spring, check the valve group and interference |
| Abnormal behavior still occurs after emergency stop | Abnormal braking or safety circuit, influence of air circuit residual pressure | Verification of emergency stop function under low-risk conditions | Disable it immediately and have the safety system inspected by professionals. |
09In what situations must it be deactivated immediately?
When the following conditions occur, the equipment should be stopped immediately and operations with load should not be continued: the equipment continues to sink under load and the operator cannot control it stably; the clamp cannot be reliably clamped or released; the vacuum gripping is insufficient and the workpiece has a tendency to slip; the joints are obviously loose, shaking, or make abnormal noises; the emergency stop button is ineffective or the brake fails; the air hose bursts, serious air leaks, or the pressure gauge fluctuates violently; the limiter fails and the anti-fall device fails; the clamp structure is deformed, the weld seam cracks, or the connecting bolts are loose.
10What can operators do and what should be left to maintenance personnel or manufacturers?
What operators can do: Stop using and put down the workpiece after discovering an abnormality; observe the location, direction and working conditions of the fault; check whether the compressed-air supply pressure gauge is obviously abnormal; check whether there is dust, oil or damage on the surface of the suction cup; confirm whether the workpiece is overweight, unbalanced or placed abnormally; explain the time of the fault, load conditions and operation process to the maintenance personnel.
Work that should be handled by maintenance personnel or equipment manufacturers: Adjust balance parameters, disassemble and inspect valve groups and cylinders, deal with cylinder seal wear, replace key pneumatic circuit components, adjust throttle valves and braking mechanisms, disassemble and assemble spherical bearings, correct rails and structural parts, inspect safety circuits, and re-evaluate the load-bearing capacity of fixtures. For custom tooling and customized pneumatic lines, it is not recommended that on-site personnel change the pipeline, modify the valve group or cancel the safety interlock based on experience.