As the core linear actuator of automation equipment, the servo electric cylinder is widely used in precision assembly, intelligent warehousing, automated production lines, aerospace simulation and other fields due to its advantages of high precision, high rigidity and easy control.
However, in the long-term high-load operation, it is easy to appear problems such as precision drift, abnormal noise and vibration, overload alarm, and stalling due to factors such as mechanical wear, electrical interference, installation deviation, and operating condition adaptability, which directly restricts production efficiency and equipment life.
Duyue Precision Technology (Suzhou) Co., Ltd. has been deeply engaged in the field of precision transmission. Based on years of R&D, production, and after-sales experience, the servo electric cylinder is deeply disassembled into five major categories of core faults, and the root causes are analyzed from five dimensions: mechanical, electrical, installation, environment, and selection, to help enterprises quickly locate the problem and accurately solve the fault, ensuring the stable operation of the production line.
1. Abnormal positioning accuracy: repeated positioning is not accurate, position drift
Fault phenomenon
Repeated positioning accuracy exceeds the deviation, workpiece assembly misalignment, size deviation;
The position drifts randomly during operation, resulting in "lost steps" and "inadequate positioning";
There is an "empty travel" when reversing, and there is a delay in response.
Core causes
Mechanical transmission wear (the main reason)
The long-term load operation of the ball screw unit, the wear of the ball, the deformation or rupture of the retainer, and the increase of the backlash of the screw nut unit lead to the generation of dead travel error during the reverse movement;
The guide rail slide block wears out, the installation base surface is uneven, the load is unbalanced, causing unilateral wear, uneven force during movement, and directly destroying positioning accuracy.
Parameter configuration error
The electronic gear ratio, pulse equivalent, and screw lead parameter settings are not matched, resulting in a fixed percentage deviation in the positioning distance;
The servo gain is set too high, and the system stiffness is too strong, causing vibration and overshoot during positioning, which affects stability.
Coaxiality deviation during installation
The motor, coupling, and lead screw have excessive axial deviation, which generates additional lateral force during operation, aggravates the wear of transmission components, and also causes position deviation.
2. Noise and vibration: large running noise, obvious vibration
Fault phenomenon
It makes a sharp squeal, a "click-click" impact sound, or an irregular friction sound during operation;
It vibrates and jerks when running at a low speed, and the vibration intensifies when running at a high speed, accompanied by body shaking.
Core causes
Lubrication system failure
Grease dries out, deteriorates, or is not added enough, and dry friction forms between the screw and nut, the guide rail and the slide block, producing sharp noises and accelerating wear;
The lubricating grease model does not match the working condition (such as using ordinary lubricating grease in a high-temperature environment), which causes the lubricating grease to be lost at high temperatures, resulting in lubrication failure.
The transmission components are worn out or damaged.
The ball bearing of the ball screw wears out and falls off, the retainer breaks, and the balls collide with each other during operation, producing a "click-click" sound;
The bearing is worn out, the clearance is too large, and the vibration increases when it rotates at high speed, causing resonance.
Load and speed do not match
When the running speed exceeds the upper limit of the lead screw DN value (DN value = lead screw diameter × rotational speed), the frictional resistance increases sharply, resulting in jerking and vibration;
The load is unbalanced, the center of gravity is offset, and the uneven force during operation causes vibration.
Poor installation and fixing
The rigidity of the equipment base is insufficient, the fixed bolts are loose, and resonance occurs during operation, amplifying the vibration and noise;
The deviation of the parallelism of the guide rail and the uneven running resistance of the slide block cause the vibration.
3. Overload / Overheating / Overcurrent alarm: frequent shutdown, motor overheating
Fault phenomenon
The overload alarm is triggered after running for 10-3O minutes, and the over-temperature shutdown occurs when the temperature is too high in summer;
There was an overcurrent fault during startup, and it couldn't run;
The motor casing temperature exceeds 80°C, and it is even hot to the touch.
Core causes
Overload (most common cause)
The actual load exceeds the electric cylinder's rated thrust for a long time, and the motor runs with high current continuously, triggering overload protection;
The brake is not installed in the vertical working condition, and the load drop causes the motor to be subjected to reverse force, causing the current to surge instantly.
Poor heat dissipation conditions
The ambient temperature is too high (> 40 ℃), the seal is too tight, the motor heat dissipation is blocked, and the heat accumulation causes overheating;
Frequent start and stop, switch between forward and reverse, repeated impact of motor, heat accumulation too fast.
Mechanical blockage increases load
Foreign objects (dust, chips) enter the cylinder body, the screw rod and nut, the guide rail and slide block are jammed, and the motor load suddenly increases;
Poor lubrication leads to dry friction, and the running resistance increases exponentially, triggering overcurrent.
4. Freezing / Stalling: Operation freezes, unable to move
Fault phenomenon
The motor hums but the shaft does not move when it suddenly freezes during operation;
It crawls, jerks, or even completely stops at low speeds;
The resistance to manual pushing and pulling is very great, and it cannot be moved.
Core causes
Foreign body intrusion and seal failure
Dust, metal chips, and corrosive media enter the cylinder body and adhere to the surface of the screw and guide rail, causing blockage;
The aging and damage of the sealing ring lead to the failure of the sealing, the intrusion of foreign objects and the leakage of lubricating grease, which aggravates the dry friction.
The lubrication is seriously poor.
It has not been maintained for a long time, the lubricating grease has been exhausted and dried, the transmission parts have direct metal friction, and finally bite and lock.
The selection does not match the working condition.
The thrust selection is too small, the motor torque is insufficient under heavy load conditions, and it cannot drive the load;
The speed selection is too high, exceeding the upper limit of the lead screw DN value, and the friction resistance is too large, resulting in stuttering.
V. Seal failure and corrosion: oil and dust leakage, rust on the shell
Fault phenomenon
Oil and grease leakage at the cylinder head piston rod, external dust enters the internal;
The surface of the casing and piston rod is rusted and corroded, with spots and peeling;
Seals deteriorate quickly in harsh operating conditions, significantly reducing their service life.
Core causes
Operating environment is harsh
Food, chemical, pharmaceutical and other industries are in a long-term humid, acid and alkali corrosion, multi-dust environment, sealing parts are easy to age, harden and break;
High temperature accelerates the aging of seals, while low temperature causes them to become brittle and lose their sealing performance.
The seal selection is incorrect.
Insufficient corrosion resistance and high-temperature resistance due to inappropriate material selection (e.g., using ordinary rubber seals in corrosive environments), leading to rapid failure.
Damage to the piston rod
Scratches and bumps on the piston rod surface damage the sealing surface, causing oil and dust to leak, and corrosive media can easily invade the interior.
VI. Diaoyu Precision: Fault Prevention and Optimization Suggestions
The core causes of servo electric cylinder failure can be summarized into four categories: improper selection, improper installation, lack of maintenance, and poor environmental adaptability. Based on many years of industry experience, Diyue Precision puts forward the following optimization suggestions to reduce the probability of failure from the source:
Scientific selection, matching working conditions
Accurately calculate parameters such as load, speed, travel, and ambient temperature, and select an electric cylinder that matches the thrust, speed, and precision level; Customized model of stainless steel material + fluororubber seal in high temperature and corrosive environment.
Standard installation, strict control of precision
When installing, strictly calibrate the motor, coupling, and spindle coaxiality (≤0.05 mm) to ensure the parallelism of the guide rail;The base should have sufficient rigidity, and the fixed bolts should be evenly tightened to avoid resonance.
Regular maintenance to extend life
Establish a point inspection system: inspect the lubrication state every 3 months and replenish the appropriate lubricant; Clean the encoder and check the wiring every 6 months; Replace the aging seals every year and clean the foreign objects in the cylinder.
epilogue
The stable operation of the servo electric cylinder is the key to the efficient production of the automated production line. Most faults are not sudden, but the result of the accumulation of long-term small deviations.
Duyue Precision Technology (Suzhou) Co., Ltd. has always adhered to The concept of "precise manufacturing and reliable operation" controls the quality of the entire process, from R&D and design to manufacturing and after-sales maintenance, while providing customers with free selection and one-stop services to help enterprises avoid failure risks and maximize equipment value.