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Brakes for electric linear actuators

Eric Semmer | September 18th, 2017

Due to their precise and smooth operation as well as their high power density, it is obvious why electric linear actuators and servo motors have paved the way for superior control in many industries that require critical linear positioning.

 

KEB has acknowledged this trend and has had great success with the implementation of permanent magnet and spring applied brakes within our customer’s actuators and servo motors.

KEB Spring applied brake for an actuator

 

The linear actuator applications vary widely but can include military, food and packaging, and medical machinery. In such industries, there is significant demand for accuracy and repeatability. Missing a precise position or failing to hold a load in place without slippage could yield catastrophic results. Additionally, these machines are often times holding heavy and expensive equipment so incorporating a brake is often necessary for added security.

 

Brake Selection for Linear Actuators

KEB typically supplies 2 different brake products for electric actuator applications. They are Permanent magnet brakes and spring applied brakes. Both are power off brakes but each brake has its own advantages.

 

Permanent magnet brakes (see how PM Brakes work) offer better torque density. They have roughly 33% more torque in a given diameter, compared to spring-set brakes. So if a small brake diameter is required this style is preferred. As technology advances and machines become intricate, space often times is constrained, as a result, permanent magnet brakes have become a more attractive option to many customers. Permanent brakes also offer zero backlash performance and are well suited for high-precision applications.

servo motor brake
Permanent Magnet Brakes offer zero backlash performance

 

Although the P1 permanent magnet brakes are power-off, they are not spring applied nor are they considered fail-safe. For critical applications like lifting or hoisting, KEB spring-set brakes are preferred (see how spring set brakes work). KEB’s spring-set brakes provide reliable brake engagement in the case of loss of power or even excessive friction lining wear.

Spring-set brakes provide power-off braking for critical axes

 

Standard features for spring applied and permanent magnet brakes include:

  • Insulation class: Rated for ISO class F. Class H is possible if needed.
  • Protection: Rated at IP 20 protection however most customers typically locate brakes within the actuator housing yielding protection ratings up to IP 69.
  • Coil voltage: Most commonly 24VDC but all common voltages are available (12, 24, 48, 105, 205).
  • Certifications: CSA and UL listing are possible for both designs.
  • Hand Release*: Optional manual hand release (spring applied only). Note the hand release option does limit the IP rating as the brake release handle needs to travel outside the housing.
  • Dust boot: Optional dust boot for IP44 protection with exposed brake, this can be used with hand release (spring applied only)
  • Dimensions: Most metric/imperial bore sizes possible with keyways.


Custom Features

Beyond our standard product features, we can also offer custom features to accommodate the linear actuator design. The advantage KEB offers is that we will dive into your application as well as your specific actuator design and assembly to ensure we have an optimized solution. The primary location to mount a brake is often times within the actuator or servo housing on the back shaft of the motor.

 

This can be a hassle as there is often limited space and minimal flexibility on the brake profile that will fit within this section of the housing. By investing the time to understand our customer’s product we often times find small tweaks that we can do to our standard products to allow optimal fitment to accommodate the available real estate. Similarly, we can pinpoint custom features to implement that will ease or enhance assembly on the customer’s end.

actuator brake
Spring-set brakes provide power-off braking for critical applications

 

Some custom features we have accomplished in the past include:

  • Customer specified cable connectors.
  • Specified torque window
  • Custom mounting or flange to accommodate actuator housing.
  • Custom package to accommodate actuator housing.
  • Encoder mounting holes on brake magnet.
  • Extended hub collar to provide sandwich stack up assembly within actuator housing.
  • Cutouts along the side of the brake profile to allow wire passage.


Why Choose KEB?

Simply put, experience matters. KEB has been manufacturing brakes for 40+ years. During that time we have successfully partnered with many of the leading linear actuator companies to develop reliable high-performance actuator brake solutions.

minneapolis industrial manufacturing
Brakes are manufactured at KEB Americas ISO 9001:2015 facility right outside Minneapolis, MN

 

One reason KEB has earned our reputation in this corner of the industry is the flexible offering of solutions we have. Beyond our standard product line, we are willing to provide custom solutions to accommodate customer needs. This could be something as simple as special connectors or an adapter plate. Or it could be something with added complexity like a custom magnet with boosted magnetism.  We can even design drop in replacements for older or hard-to-source designs.

 

We have full design and manufacturing capabilities at our US location outside Minnesota and are willing to take on custom solutions to ensure we supply the right products for the specific application.

custom engineering brake
KEB utilizes advanced magnetic simulation software to optimize the product design and performance

 

Local engineering and production do not mean expensive – we work with our customers to offer economical solutions which meet the application requirements.

 

Obviously, a locally manufactured product helps us to be responsive. KEB America has successfully replaced a number of different European, Indian, and Chinese brake competitors. 10+ week leadtimes with sea freight shipments does not cut it in today’s demanding marketplace.

local brake manufacturing
KEB’s local manufacturing and QA allows responsive service

KEB – The Brake Partner for your Actuator

We’d love an opportunity to work on your next design project – Contact a KEB America engineer today!

 

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