Tuesday, 8 August 2017

How To Prevent Actuator Side Load Failure



Let's talk about side loads (also called overhung loads) for a minute. A side load is any load that is exerted perpendicular to the direction of a linear actuator's travel.


side load failure

All actuators are limited in the amount of side load that they can handle. Side loading any type of actuator will reduce it's life and should be avoided. The side load rating for a device can be found on the corresponding data sheet. Putting too much side load on an actuator can have various negative effects including:
  • Reduced actuator speed
  • Reduced actuator lifespan
  • Increased project costs resulting from frequent parts replacement

Actuator's Intended Use

Linear actuators are intended to be loaded in-line with the device. When moving in or out it should be pushing or pulling the load directly with minimal side load. We provide a figure for maximum side load because we know that nothing is perfect and there will always be some amount of side load on the device. Just understand that side loading is hard on a rod actuator and even a small amount can reduce the life of the unit.

Related article: Tips For Extending The Life Of Your Linear Actuator

How Side Loading Affects Actuators

There are a few different ways. First, side loading increases internal friction. This causes the motor to work harder and can reduce the motor's life. Second, excessive loads perpendicular to the device can prematurely wear out the drive nut and/or lead screw. Third, loads above the rated figure could result in structural failure of the device.

In order to ensure that you're not overloading your device, always check the datasheet. Actuonix provides a figure for the maximum allowable side load at full extension in newtons. This makes it easy for you to figure out if you're exceeding that load or not.

Alternatives To Side Loading

If your project requires a significant side load, you have a few options.

1. Redesign your mechanism to reduce side load.

Changing the amount of side load required from your actuator may just mean a minor adjustment to the design of your project. If you can not make such an adjustment, consider one of the next two options.

2. Use a linear slide rail. 

linear slide rail

Linear slide rails are simple to use and reasonably inexpensive. To use a slide rail you need to mount the rail to something that is permanently fixed in position. You then mount the moving mechanism that is causing the side load to the sliding block on the rail. Last, you connect the actuator to drive the slide block, and your load, along the rail. The slide rail can handle much more side load then the actuator and doing this you will prevent overhung load failure of your actuator.

3. Use a track actuator

mini track actuator

A track actuator is similar in operation to a standard rod actuator in that is uses a lead screw and drive nut. The key difference is rather than extending a shaft in and out, the body of the actuator itself is longer and a mounting block slides in and out with the load attached. A track actuator is convenient because it offers the functionality of an actuator and a slide rail, but keeps your design simple as it's one device instead of two. This also helps keep your costs down.

Repeated Actuator Failure

If you're experiencing repeated equipment failure or shorter than expected actuator life, check the side load and make sure it's in spec. You may be experiencing overhung load failure. Being over the manufacturers recommended side load figure can reduce the life of your device considerably.

If you have any questions about how to support a side load, or the capabilities of the device you're using, give Actuonix a call. We can help you with the product information you need before you load your actuator.

If you have any questions about our products or how to integrate them into your project, give us a shout, we're always happy to help.

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