Industrial Solenoid Noise: Causes & Fix Guide

Chapter 1: Introduction to industrial solenoid noise

There are plenty of problems connected with industrial solenoid noise, but don't worry because they can be solved easily. In automation systems, machinery, and control equipment, one may face issues such as a hum, buzz, or rattling sound. Despite seeming insignificant, unusual sounds are clear signs of some problems with magnetic performance, improper components alignment, or an unstable power supply. Left unsolved, noise leads to decreased solenoid life, additional costs, and unpredictable equipment failure. This guide explains how noise appears, provides solutions, and suggests methods to keep industrial solenoids working well.

Chapter 2: What causes noise in industrial solenoids? (Principle)

For industrial solenoids, two essential things play crucial roles:

- A fully closed magnetic circuit

- Proper contact between the moving core and the static core

The absence of either of them leads to unstable magnetic flux and repeated vibration of the core. Note: much of the noise comes from semi-closed magnetic circuitry.

 Chapter 3: Five Main Categories of Abnormal Noises Generation Causes

 3.1 Problems at Moving/Stationary Parts Contact Surface

Contact surfaces between the moving and stationary parts constitute vital sections for the magnetic flux passage. When the surfaces get dirty with debris, oil, and dust, the magnetic flux flow becomes impossible thus preventing full closing of the core and making an open gap between them. As a result, the cores begin knocking each other due to electromagnetic force, thus generating unusual humming noises. Also, tilting of the contact surfaces reduces the pulling force and makes it uneven thus causing the cores to be vibrating. Tightly fitted brakes also serve as one of the factors responsible for blocking the magnetic flux flow.

3.2 Abnormal Supply Voltage

Electromagnet pulling force directly depends on the supply voltage. Low voltage does not allow generating enough electromagnetic force to pull the core against the counteraction force represented by springs and brake friction. Thus, core stays half-way closed, vibrates all the time, and generates abnormal noises. This cause is frequently neglected in industrial environment.

 3.3 Assembly Faults, Misalignment Due to Vibration, or Mechanical Binding

Inappropriate assembling of the magnetic system, misalignments caused by vibration for a long period of time, or mechanical parts binding (needles, levers, etc.) prevent smooth and even core closing, thus causing discontinuity in magnetic flux flow and making core vibrating thus generating noises. Moreover, excess spring pressing increases the resistance and reduces the pulling force of the core.

 3.4 Wear of Components

Natural wear of core components:

Excessive wear of the core pole face surface prevents smooth closing of the core parts.

Breakage of shading rings (copper rings). Shading rings purpose is to suppress vibrations and generation of noises. However, when this part gets damaged, core starts to vibrate and generate high-pitched noise.

Interturn short circuits of coil cause abnormal current and magnetic flux generation and consequently abnormal pulling forces. It results both in generation of noise and overheating of coils.

3.5 Improper System Matching

Incorrect industrial solenoid selection is also the key point cause:

Insufficient pulling force of the industrial solenoid 

Incorrect stroke length

Mismatched voltage rating or the current

The above point will lead to unstable operation and persistent noise issues.

 Chapter 4: Step-by-step solution procedure of industrial solenoid noise issues

Perform steps in ease-to-hard order:

STEP 1: Check voltage supply

- Measure voltage

- Check wiring connection

STEP 2: Inspect core contact surfaces

- Find contamination

- Make sure the surfaces are clean

STEP 3: Check the mechanism movement

- Ensure smooth motion

- Remove any obstacles

STEP 4: Check internal parts of the electromagnet

- Inspect the shading ring

- See whether there are any damages to the coil

Chapter 5: Fast trouble-shooting table

   The following table summarizes targeted solutions for each cause:

 Chapter 6: How to avoid industrial solenoid noise?

6.1 Regular maintenance

Keep solenoids clean from dust and oil accumulation every three-six months.

 6.2 Correct installation

Make sure that all parts are precisely positioned and tightly attached.

 6.3 Appropriate product choice

Select the necessary voltage and power and use high-quality components.

Chapter 7:Tips on how to select a silent industrial solenoid

 Selecting a low-noise industrial solenoid requires far more than reviewing the basic specification. The primary contributor to noise in industrial solenoids comes from the physical impact between the metal plunger and the metal pole face of the solenoid.

 Please find below some concrete steps that will help you select the proper low-noise industrial solenoid with no change to the topic or facts provided.

 7.1. Go for Dual-Solenoid or Latching Mechanism

Industrial solenoids usually "slam" the plunger shut, which makes the signature sound "clacking."

Dual solenoids operate via dual-coils design. Such solenoids electromagnetically drive plunger both ways but with no spring return, thus reducing impact significantly.

Latching solenoids include permanent magnets to retain plunger position. In effect, the device consumes energy only to switch positions, making it silent (with the exception of humming in some instances).

7.2. Make Sure There Are Features to Reduce Impact

Asking manufacturer for some of the following examples will do the trick:

- Elastomeric dampers (rubber or polyurethane pads) attached to either pole face or plunger stop;

- Bumpers or O-rings integrated into the system to cushion last microns of movement;

- Tapered or stepped pole face that traps air during closing to create air cushion for the last phase of plunger contact.

7.3. Get "Variable Holding Force" or Soft-Land Drive Solenoid

The standard industrial solenoid produces full power right away, but electronics-controlled solenoids may feature PWM drives that allow for decreasing current post-seating and thus achieving softer landing.

Recommendation: If the design allows, order the product with integrated electronic control and programming options to enable slower engagement and reduced holding voltage. The design ensures absence of both "clack" and "humming."

 7.4. Stay Away From AC-Powered Solenoids

AC-powered devices tend to emit magnetic humming at line frequencies (either 50 or 60 Hz), which often is louder than impact itself.

DC-powered solenoids are totally silent, except in case of movements and seating. For the purpose of industrial application 24V DC solenoids are recommended.

7.5. Include Silence Among Your Specification Requirements

By default industrial solenoids do not have any rating with regard to their noise level. Thus, you are supposed to specify that in addition to all other requirements you need the measurement of sound pressure (dBA) at distance of 1 m. The best result here is under 45 dBA. Typical standard solenoid is around 65-85 dBA.

Note that the test condition must specify open-to-close cycle performed under the conditions of the required load and mounting (solenoids tend to be louder with rigid mounting on metal surface).

7.6. Consider Enclosed/Box Design Versus Open Frame

Open frame industrial solenoids produce the maximum noise level because they radiate impacts without any damping.

Box frame or tubular solenoids are somewhat quieter but they still make "clacking" sounds. Encapsulated or epoxy-potted solenoids dampen vibrations.

For quietest results consider fully encapsulated tubular solenoids with rubber end caps.

7.7. Check Operating Conditions and Temperature Rating

Some silencing features such as dampers and elastomers will deteriorate with rising temperature.

Continuous operation up to 100% duty cycle will require silicone rubber rather than regular rubber for dampers if your solenoid is to remain quiet.

Hot operating conditions mean higher humming because of changes in coil resistance; thus, the solenoid needs insulation class H (180°C).

 Summary Table

If you absolutely need near-silent (under 40 dBA), consider replacing the solenoid with a linear actuator (leadscrew + stepper motor) or a piezo actuator – but these are much slower and more expensive.

Chapter 8:  FAQs of Industrial solenoid noise

Q1: What is the main cause of humming sounds in electromagnets?

A: Humming means that the core is in a semi-closed mode of operation. Most often, the reason is a low voltage of the working circuit, which results in insufficient magnetic force to overcome resistance. To diagnose the situation, you need to measure the voltage using a multimeter. Dirty pole faces can also lead to a humming noise.

 Q2: How do I determine whether a noise has an electrical/electromagnetic nature or mechanical?

A: You need to conduct a simple power-off test: if there is silence right after turning off the power, then there is an electrical/electromagnetic problem (low voltage, damaged shading ring, faulty coil). If the sound lingers after turning off the power or gradually diminishes, then the mechanical causes are to blame.

 Q3: Why does a faulty shading ring produce a harsh noise, and can it be fixed?

A: Shading rings help suppress vibrations and make the device quieter. Without it, the core starts vibrating at a high frequency, resulting in harsh buzzing/screeching. It cannot be repaired; the only option is to replace it with an identical ring. Also, the core can be damaged by vibration and require replacement.

 Q4: What should be done when cleaning electromagnet pole faces?

A: Consider the following recommendations:

- Disconnect the power.

- Use only a soft cloth/brush; hard tools will scratch the surface.

- If there is rust/pitting, use a piece of fine sandpaper. But be very careful; removing too much material will cause unevenness.

- Make sure that the pole faces are thoroughly cleaned and dried before assembly.

 Q5: Does an over-tightened brake contribute to noise production? And if so, why is it often overlooked?

A: Yes. When the brake is too tight, there is greater resistance to core closure, and if there is not enough magnetic force to overcome it, the core vibrates and produces noise. Many maintenance workers focus their attention on the core and coils, and forget about the outside factors. Tightening the brake allows the core to close properly and eliminates noise.

 Q6: What are the consequences of electromagnet operation in a semi-closed position for a long time?

A: Extended operation in a semi-closed state entails:

- Core vibrations, contributing to the accelerated wear of the poles;

- Abnormal core current;

- Breakage of the shading ring;

- Overall reduced life span of the device.

Situations leading to semi-closure (too low voltage or binding) need to be addressed urgently.

 Q7: What are the maintenance operations that help reduce failure rates due to noise?

A: You should concentrate your efforts on the following:

- Regular Cleaning: Every three to six months, perform cleaning of the pole faces to get rid of oil, dust, dirt, etc.

- Regular Inspection: Pay attention to wiring tightness, proper spring compression, and brake setting.

- Absence of Abnormal States: Make sure the core is completely closed during operation.

 Chapter 9: Conclusion

As a rule, unusual sounds from industrial solenoids indicate the presence of blockages in the magnetic circuit and lack of solid contact between moving and stationary cores. Such problems can be quickly fixed by finding the reasons and using a proper solution. Besides, appropriate initial product selection and regularly cleaning and maintenance can help to prevent noise and increase the life of the electromagnet significantly.

We wish you good luck. If you have any other questions on the topic, please let us know.

Note: Turn off the equipment before conducting maintenance. It is convenient to begin with easier troubleshooting tasks like measuring voltage or cleaning pole faces and then move to harder tasks.