High Force Linear Latching Solenoid solution Guide

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WL1253 Linear Latching Solenoid Precision Control Guide

The linear latchin solenoid is an electromechanical device capable of keeping the position of its plunger (extending/retracting) without the use of electrical power constantly。 It applied is referred to as Linear Latching Solenoid. The latching type employs a permanent magnet to create a locking effect, compared to regular solenoids, which require a current to maintain a position. A momentary pulse of electricity will switch the state of the plunger (between two stable states e.g. latched in / latched out). The latching solenoid will then hold the plunger in its new state until the next pulse occurs. Linear Latching Solenoids do not consume any power while in a latched state making them useful in battery operated devices.

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Linear Latching Solenoid Product Overview

Linear Latch Solenoids are relatively small bi-stable devices that maintain their state without the need for electricity. Consists of a coil, a permanent magnet, a plunger and a housing. Application of a short current (12V pulse for 50 ms) will cause the plunger to move to one side and reversing the polarity to the other side. The magnet will hold the plunger in its position using grams to kilograms of holding force depending on the solenoid model. The typical stroke length of a Linear Latching Solenoid is between 3mm and 15mm. These solenoids are very useful in battery-powered devices such as smart locks and shutoff valves for household gas supplies. The lack of continuous current makes them less likely to overheat and usable in hazardous or closed spaces.

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Linear Latching Solenoid Technical Datasheet

rand	Weilong Technology	Model Number	WL1253
Rated Voltage (V)	DC 36V	Rated Power (W)	30.9 W
Work Model	Push-Pull Type	Holding Force (N)	3000 GF
Stroke (mm)	6 MM Customized	Reset Time(s)	0.2
Service Life	100 Thousand Times	Certification	CE, RoHS, ISO9001,
Material	Superior Magnet Iron	Lead Wire Length (mm)	200 MM
Install Style	Screw	Tolerance of Dimension	+/- 0.1 MM
Water-proof	None	Insulation Class	B
Hi-Pot Test	AC 600V 50/60Hz 2s	Pushing Force	600 Gf
Working Temperature	-10°C-100°C	Duty Cycle	1-100%
Thread Depth (mm)	/	Payment Term	TT, or LC At Sight
Sample Order	Yes	Warranty	1 Year
MOQ	1000 pcs	Supply Ability	5000 pcs per Week
Delivery Time	30 Days	Port of Loading	shenzhen

The working Principle of Linear Latching Solenoid

Linear Latching Solenoid is comprised of an electromagnet and permanent magnet. If the permanent magnet is static, it holds the ferromagnetic plunger in either an extended or retracted position with no electricity applied to it. An application of a DC pulse of the appropriate polarity will result in the creation of an additional magnetic field around the plunger. If the current applied creates a magnetic field that opposes the field created by the magnet, then its holding force is nullified and the plunger is moved by an opposing mechanical force such as the spring. Otherwise, a reverse current will strengthen the magnetic field and pull the plunger into another position, which will be held after reaching its new stop point by the magnet. The electric current can now be switched off and will remain locked in its final position until the next current is applied.

Main Characteristics of a Linear Latch Solenoid

The characteristics of a linear latching solenoid are: bi-stable operation, zero power consumption while latched and reduced heating. Thanks to the internal permanent magnets, the holding force is relatively higher per its size. These solenoids are fast reacting and are bi-stable in terms of operation (they can function both ways). Linear Latch Solenoids usually operate at low direct currents (3V to 24V) since they are designed for high duty cycle operations due to the short pulse duration. Other characteristics include compact design, magnetic shielding availability and the ability to be operated with battery power.

How to avoid Common Mistakes During Linear Latching Solenoid at the Design beginning

1) Constant Power Mode. Only ever pulse the solenoid for 20-100 ms. The coil will overheat and be burned out due to excessive power dissipation.

2) Incorrect Polarization of the coil. H-bridges are mandatory for linear latching solenoids as regular transistors allow powering only in one direction. The reverse polarity of the input current causes the plunger to travel back to its original position.

3) Forget about Back EMF. Once the pulse is completed, the collapse of the magnetic field creates an overshoot and voltage spike across the coil. Add flyback diodes or Zener diodes in a pair.

4) Over-Load Condition. The maximum holding force provided by the magnet has its limitations. Do not attempt to apply loads that exceed the specified maximum value and add mechanical stop for excess force.

5) Weak Battery Capacity. The inrush current can go up to 1-2 Amperes even at 12V. Check that the battery provides sufficient capacity and does not drain under the peak current load.

6) Installation in Ferromagnetic Environment. Steel parts nearby can interfere with the magnetic flux lines and decrease the holding force by half or more. Avoid installing latching solenoids near any ferrous material (brass, aluminum preferred)

7) Ignoring Demagnetization Effects. The repeated pulses, reverse polarizations or overheating can eventually demagnetize the internal magnets. Keep pulse and coil width within specifications and ambient temperature low.

Linear Latching Solenoid Industrial Application

The energy efficient nature of latching solenoids allows them to be used in various devices and industries. Linear Latching Solenoids are used in smart metering devices (water/gas meters) as automatic shutoff valves (one pulse stops the flow, second resumes it) where they can run on batteries for years. Used in home automation systems controlling electronic door locks and window operators that maintain their state even without power supply. Linear Latch Solenoids are used in portable medical devices such as infusion and ventilators to control their fluid/air flow without running down their batteries. In automotive industry, these solenoids are used in EV charging port locks, trunk release mechanisms and shift selectors interlocks. Linear Latching Solenoids find wide use in manufacturing industry as emergency latches for equipment or machines. These include devices such as electronic safe locks, smart card based access control systems and vending machines dispensers. “Low power consumption makes them useful in agriculture for irrigation or solar power applications. Linear Latching Solenoids are utilized in toys and hobbyist equipment. Linear Latching Solenoids find extensive use as electric door pops and coin counters. They do not overheat like regular duty solenoids thus can be used in sealed compartments (underwater valves). Being able to retain its position makes them useful for fail-safe systems requiring that last command be retained after power loss. It is this property that makes Linear Latching Solenoids suited for IoT and sensor technologies.

Why The Linear Latching Solenoids Are Getting So Popularity?

Growing demand for energy saving actuating mechanisms due to IoT boom and global energy concerns explains the growing popularity of linear latching solenoids. Billions of battery-powered smart devices for agriculture, oil/gas industry, home automation systems require actuators that will allow them to change state and remember it. The usual solenoids will drain batteries in hours. A latching one will last for years working on just two AA batteries. Plus, there is no heat generated during the hold state which means these solenoids can be installed in plastic and explosion proof containers with confidence. Solar-powered remote monitoring is another emerging market demanding energy efficient actuators. Modern latching driver circuits are more affordable and compact, so the complexity level is reduced. Currently, sealed low cost latching solenoids are available commercially and are used in consumer electronics like smart latches for cabinets and robotic toys. Fail-safe mechanical memory of latching solenoids is another selling point useful in home automation and car manufacturing industries. In short, they meet the three basic criteria of contemporary electronics: efficiency, compactness, intelligence.

Linear Latching Solenoid Advantage and Disadvantage

The Advantage of Linear Latching Solenoid

Zero standby power – once latched, the solenoid uses no power and so is perfect for battery operated systems and energy harvesters.

No heat dissipation – cool operation makes it usable in completely sealed and explosion proof applications.

Safe mechanical memory – once unlatched, the position of the plunger is remembered even if power is lost, no backup battery is needed to maintain valve position.

Compact design – small footprint with powerful magnets providing strong holding without a winding.

High lifetime due to low duty cycle – short pulses minimize the stress on coil and arcing between contacts.

The disadvantage of Linear Latching Solenoid

Requires bidirectional drive system. Simple transistors won’t do the job. Additional complexity with the H-bridge driver or relay module.

Less pulling power compared to standard solenoids. Latching devices are weaker since the permanent magnet opposes the movement during the pulse.

Inappropriate for fast pulsing operation. Normal solenoids do a better job if switched every second. Fast switching demagnetizes the magnets and overheats them in case of frequent reversals.

Sensitive to external magnetic fields. A strong magnet or excessive current nearby will demagnetize the permanent magnet.

Holding force is fixed. It cannot be adjusted by lowering the current (since there is none) and is defined by the magnetic strength of permanent magnet.

Linear Latching Solenoid Trouble Shooting

Solenoid doesn’t latch (moves but doesn’t stay there)

Cause: Too short pulse width. Demagnetized by high temperatures and/or shock.

Solution: Increase pulse width to 50-100 ms. Replace the solenoid if magnet is damaged by heat (>120C).

Solenoid doesn’t move at all during the pulse

Cause: Short-circuited solenoid coil, mechanical binding due to dirt in the plunger or broken driver circuitry.

Solution: Check coil resistance with the multimeter – if it’s infinite, then the wire is broken. Clean the internal surfaces of plunger bore with isopropyl alcohol. Test H-bridge driver voltage using an oscilloscope.

Intermittent latching (especially one-way)

Cause: Asymmetric polarity, insufficient pulse current or jamming.

Solution: Ensure positive polarity attracts plunger into the solenoid while negative pushes it out and vice versa. Install low ESR capacitor near the coil to stabilize output voltage or decrease pulse rising time.

Solenoid latches but unlocks under slight load.

Cause: External load surpasses the magnetic field of the permanent magnet, or iron/magnetic hardware used for mounting solenoid.

Solution: Get yourself a stronger solenoid. Replace ferromagnetic mounting screws with brass/aluminum.

Solenoid gets hot even when pulsing

Cause: MCU glitch keeps transistor conducting all the time, or pulse width is mistakenly defined in seconds instead of milliseconds.

Solution: Check programming code to see if output pulse is disabled immediately after activation. Consider adding a hardware watch dog to shut off power after 200 milliseconds.

FAQs of Linear Latching Solenoid

1. How are latching solenoids different from ordinary ones?

While the regular type must have continuous current flow to keep plunger in place, the latching version requires just a pulse to lock plunger in the activated position using its magnetic power. Regular solenoids automatically revert to neutral position after power is removed by their natural elasticity, assisted by the return spring. Latching versions do that automatically with the help of built-in magnets which exert holding power without consuming any electricity.

2. Does polarity matter for latching solenoids?

Yes, indeed, polarity matters greatly. Latching solenoids are bipolar, meaning that current flow can create additional magnetic field inside coil which pulls the plunger together with the field produced by magnets and keeps it in latched position. To unlock, reverse polarity pulse should be applied to cancel the permanent magnet’s field, after which the plunger reverts to its neutral position due to mechanical elasticity

3. Why should I use an external resistor in my latching solenoid application?

Some latching solenoids require the use of an external resistor to manage demagnetization current necessary for unlocking the device. After applying reverse pulse, both coil and resistor become part of circuit and conduct current. It allows you to balance the coil and magnet forces reliably. Refer to technical specifications of particular device for details.

4. Can I supply continuous voltage to my latching solenoid?

Of course, you shouldn’t feed continuous power to a latching solenoid. They are meant for pulses of up to 100 milliseconds. Insulation and coil wire are optimized for intermittent work. Continuous current will quickly overheat and destroy the coil. The purpose of these solenoids is to hold position without wasting power。

5. What are major advantages of latching solenoids?

There are four key features that distinguish latching solenoids from other types: they need no current to hold position, they do not produce any heat in the idle mode and provide fail-safe mechanical memory. These characteristics make latching solenoids perfect for battery operated devices and sealed housings.

6. What is the lifetime of linear latching solenoids?

Life expectancy ranges anywhere from 200,000 to more than 5 million cycles depending on solenoid brand. But in reality, life expectancy depends on various factors including side loads, pulse frequency, environmental conditions (such as temperature or humidity) and electrical parameters. You’d better run tests under your specific operational conditions.

7. What are mounting precautions for a latching solenoid?

Mounting hardware should always be chosen appropriately for particular application. Longer mounting screws may easily damage internal coil wiring. Also, note that magnetic mounting screws and nearby metal plates can divert the flux lines and greatly lower solenoid holding power –

8. Are there different types of latching solenoids?

Indeed there are two major designs. In a unidirectional holding design, magnets hold plunger only in the pulled-in position while the opposite position requires a return spring. Bistable latching solenoids have permanent magnets and two coils/pole pieces to hold plunger in either position without any spring at all.

How to Select a Linear Latching Solenoid?

To properly select a Linear Latching Solenoid consider the following characteristics:

1 Force and Stroke.

First, determine the maximum holding force (the amount of force required to displace the plunger against an external load) and stroke (distance plunger travels). The holding force of a solenoid with the magnet is normally listed. Make sure it exceeds the maximum worst case load with 30% additional margin. As for the stroke, typical Linear Latch Solenoids offer anywhere between 2 mm and 10 mm. Longer stroke lowers the holding force.

2 Electrical Parameters

Determine the voltage (typical values are 6V, 12V and 24V DC) and pulse duration you can afford (30-100 ms). You will have to supply sufficient number of watt seconds to overpower the holding force of the magnet. The more often you pulse the solenoid, the higher its power consumption and faster it will burn out. You need to calculate the coil resistance and the peak current you need to overcome. The coil resistance can be calculated based on the power consumed. Check the power consumption of your driver circuitry (H Bridge or relay contacts).

3. Physical Characteristics.

Measure the space available for installation. Larger size means more force available. Determine how you plan to mount the solenoid. The gravity may aid or obstruct the holding process. Some solenoids include internal return spring, thus mono stable. Bi stable solenoids will require no opposition to their movement from external springs.

4. Environmental Parameters.

In case the solenoid is exposed to moisture or outdoor conditions, choose waterproof or IP-rated models. Permanent magnets suffer reduced efficiency when temperature rises (Neodymium loses their strength around 80 degrees C). If the environment is subject to vibration, then check whether the plunger might become detached from the latched position due to impact.

5. Drive Circuit.

A Linear Latch Solenoid requires bi-directional current drive (reverse polarity to unlatch). Use either H-bridge or dual contact relays to achieve the desired effect. Make sure to add flyback diodes to reduce voltage spike. – Never run Direct Current through latching coils since it will destroy the coils as it wasn’t designed to dissipate power at DC.

6 Mechanical Life (100,000 cycles).

Make sure to check the product documentation on mechanical lifetime. Rapid pulsing might damage the permanent magnet and shorten its effective lifetime. In that case, regular (non-latching) solenoids should be used.