What is a Linear Actuator & Why Would You Want One?

June 4, 2020 Matt Mowry

When I first started working in technical sales for igus® back in the year 2000, we had three series of linear slides: drylin R, drylin T, and drylin N. Drylin R and T were dimensionally similar to the round-shaft and profile guides that already existed within the industrial marketplace at the time—of course, our parts were made of dry-running plastic bearings and components—and drylin N was a more compact flat-rail.

Around 2003, we introduced what now many consider to be our flagship linear bearing product, the drylin W series, which expands upon the many benefits from the three series mentioned above by amalgamating them into one flagship series. It was after the introduction of the drylin® W that we began adding a new line of products—fully assembled linear actuators

What exactly is a linear actuator? 

Starting in the early 2000s, many linear bearing manufacturers began to notice an upward trend in regard to customers wanting what sounded like a ‘plug and play’ type linear bearing solution—a linear actuator. A linear actuator uses a rotary motor, such as a stepper, servo, brushless DC/DC, or similar motor, to convert the rotary motion produced by the motor into a linear motion that can travel on a set of linear bearings. Usually, this rotary motion is converted by using a lead screw, a timing belt, or a rack and pinion system; however, actuators can be comprised of many different components depending on what you are looking for. At the bare minimum, the drive method (aka timing belt or lead screw) would be incorporated into the linear bearing system as a one-piece, bolt-on solution. Most manufacturers also offer additional options, such as motor mounts and flanges, couplings, and motors. Other accessories, like motor and data cable assemblies, proximity sensors and cables, as well as motor drivers, might also be offered. To make things even more complicated, many manufacturers also offer fully assembled gantry robots, or linear robots, which usually combine two or three axes together to cover 3 degrees of motion.

igus ZLW belt-drive with motor coupled to the drive shaft

 igus SAW with motor coupled to the lead screw

Why use an assembled linear actuator when you could cobble one together yourself?

  1. Save design time.  Cobbling your own linear actuator together means going to one supplier, configuring one part that meets the requirements of your project, ordering that one part number, then rinse and repeat for all components involved. With a preassembled linear actuator, less time is spent checking the specs of the linear guides, the screws, and the axial bearings; less time is spent making drawings of custom machined housings, brackets, gears, etc. This allows you to spend more time designing the valuable aspects that your equipment offers to a customer, and less time designing at the component level for each linear motion application. 
  2. Limit your lead-time and purchasing costs.  Generally speaking, if you are ordering one part from one supplier at a time, your purchasing department will be spending a lot of time hounding multiple different suppliers and checking on parts. However, with an already assembled linear actuator, you reduce this time, in addition to cutting purchase orders.
  3. Improve your quality. Let the linear actuator manufacturers put their money where their mouths are. At this point, they are selling you a pre-made solution, so it should obviously be tested and assembled correctly. If any aspect of that actuator is not working properly, then they are responsible.
  4. Reduce you assembly time. Let the linear actuator manufactures assemble the parts that they have designed to fit together—the ones that they produce and test on a daily basis. This provides you with less to worry about in regard to ensuring that the shafting is aligned, that the proper clearance is set between the components to function properly, that the belt is set with the right tension, and that the motor is attached correctly. Allow the linear actuator manufacture to do their job so that you can focus all of your efforts onto the overall build while reducing the amount of time assembling subcomponents.

So, there you have it—a brief explanation of what linear actuators actually are and why they are becoming more commonplace within the realm of machine design. So many applications require linear motion functionality, and we are seeing more and more each day.

If you are interested in getting an idea of how linear actuators work in regard to an application, igus® offers several tools that can help check the functionality of our drylin linear actuators, including some nice motor options—also, had to drop a shameless igus® plug. Additionally, we offer another configurator that focuses on our popular HTS linear actuator series, which allows you to customize your components, add motors and manual accessories, as well as make custom modifications to the lead screw output. After you have configured your linear actuator according to your exact specifications, you can get a 3D step file, a 2D drawing, an exact price, and then order directly online!

If you are interested in speaking further with an expert about the linear motion requirements of your application, please do not hesitate to contact Matt Mowry, drylin Product Manager.

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