Ask an EngineerLong Lasting, High Precision, High Force, Low Maintenance
Why consider roller screw linear actuators? There are many considerations for selecting the best screw technology for electric linear actuator performance in an application.
Tolomatic offers a range of high-force electric linear actuators featuring standard planetary roller screw technology. When you work with Tolomatic for roller screw linear actuators – you have access to a range of heavy-duty designs from rod style, to precision stages, to hygienic options and more. At the same time with Tolomatic you’re guaranteed help selecting the optimal screw technology for your specific application. We don’t take a “one technology” approach to customer needs – we help provide industry-best sizing, selection, quality and application advise backed by reliable aftermarket service.
Videos
Explore Key Features of Planetary Roller Screws
Explore Unique Advantages of Roller Screws
Watch Planetary Roller Screws in Action
Successes
Challenge: Resistance spot welding (RSW) chassis
Product Family: Electric Rod Style Actuator
Product Used: CSWX
Challenge: Eliminate hydraulics to position rollers on a timber planer
Product Family: Electric
Product Used: RSA64 HT
Product Family: Electric
Product Used: RSA & RSX Actuators
Challenge: Wheel bearing press.
Product Family: Electric
Product Used: RSX Extreme Force Electric Linear Actuator
Application Description
Articulate the concrete slurry dispensing head forming exterior/interior walls used in residential construction.
Challenge: A manufacturer of high-quality castings needed an electric actuator to replace existing high maintenance hydraulic actuators.
Product Family: RSX Extreme Force Rod-Style Electric Actuator
Product Used: RSX15
Challenge
A distributor was approached by a customer requesting a powerful and versatile actuator that could be configured in multiple ways to fit their existing equipment.
Product Used: RSX Extreme Force Rod-Style Electric Actuator
Product Type:Modified Standard
FAQs
Explain anatomy of a planetary (standard) roller screw
Planetary roller screws (also called standard roller screws) have precision-ground threads that match multiple precision-ground rollers in the nut. These rolling elements transmit force very efficiently. Roller screw components provide more points of contact allowing for higher force capability and longer life.
Using a linear actuator with roller screw technology allows engineers to reach new levels of control, performance, and efficiency in applications that were previously dominated by hydraulic cylinders.
Tolomatic manufacturers standard roller screws for its actuators. These screws are case (surface) hardened before precision grinding, resulting in very deep case hardness and high Dynamic Load Rating (DLR*).
What is Dynamic Load Rating (DLR)?
DLR is an industry standard term that represents an applicable constant load (in direction and magnitude) where a ball bearing device (or power screw) will achieve 1,000,000 revolutions of rated life or L10 life estimation at 90% reliability. DLR is usually provided by the manufacturer.
How do you select the correct screw for heavy duty, high force linear actuator applications?
There are several screw technology options to consider when specifying high force electric linear actuators – standard planetary roller screws, inverted roller screws and ball screws. Each technology has its advantages and disadvantages when compared to one another.
To select the best option, it is critical to let the application specifications be the guide. Some companies only sell ball screw linear actuators — electric, heavy duty or otherwise — and some companies only sell roller screw linear actuators. Take caution when evaluating “there is only one technology” type vendors. Every application is different and both technologies have their unique strengths.
Tolomatic manufactures both roller screw and ball screw high force electric linear actuators. Tolomatic’s online electric actuator sizing software guides engineers through application specifications including force, speed, dwells, life estimates and other factors in order to make the correct choice.
What’s the difference between ball and roller screws (inverted and planetary)?
Standard Planetary roller screws offer the highest dynamic load rating for the longest life of the three technologies. Additionally:
- Both roller screw technologies are good choices for repeated stress applications (pressing, inserting, riveting) in the same area of actuator stroke.
- Roller screws have a significant increase in contact area which allows for longer life and higher forces exerted in the same package size compared to ball screws. However, this increased contact area also creates more heat with the same amount of work.
- Ball screws, because they have less contact points, are a little more efficient in heat management than roller screws which allows them to operate cooler in high duty cycle and high speed applications.
- Heat management is a major factor in how well lubricants hold up over time and whether the actuator or screw can last as long as expected.
For a more visual understanding of these comparisons, you can review the table below.
What’s the difference between how standard and inverted roller screw linear actuators work?
An inverted roller screw operates much the same as a standard roller screw except the functions of the nut and screw are reversed so the rollers move inside the nut.
Most inverted roller screws used in linear actuators are produced using a process other than grinding to inexpensively create threads inside the nut. The hardening process is performed after the nut is machined and results in a much shallower case hardness depth and softer threads than those of standard roller screws. This leads to a significantly lower DLR* (lower life) and more challenges with maintaining lubrication.
Take a Closer Look at Tolomatic Roller Screw Linear Actuators
Precision ground planetary roller screws provide higher force capability, efficient operation, and longer machine life.
Hydraulic-class electric linear actuators that are roller screw driven, and provide extremely high forces, precision, and long life. Ideal for hydraulic replacement. Forces up to 100,000 lbf (445 kN).
316 stainless steel construction and IP69K rating provide an electric rod style actuator ideal for food, beverage, and pharmaceutical machines. Forces up to 7,943 lbf (35.3 kN).
Electric rod actuator integrated with a servo motor in a single, compact design that integrates with 3rd party drives and accessories. Forces up to 8,044 lbf (35.8 kN).
Combines a hygienic electric rod actuator and motor into one package. It is IP69K, built with 316 SST, and works with 3rd party drives and accessories. Forces up to 2,500 lbf (11.1 kN).
Design that combines an electric rod actuator with guide rods, mounting blocks, and bearings. Ideal for applications requiring guidance and support of the load. Forces up to 4,160 lbf (18.5 kN).
Rugged stage with twin profile rails and a machined base, providing a highly rigid and accurate actuator. Mult-axis configurations are standard and ideal for adding a 7th degree of freedom for robots. Loads up to 4,320 lbs (1,960 kg).
Integrated servo motor/actuator used in robotic resistance spot welding which offers a compact, power dense actuator solution with best-in-class performance. Forces up to 4,050lbf (18kN).