When a machine design calls for a brake or clutch to deliver fast and accurate torque control, magnetic particle technology offers high torque output, precise adjustment and simplicity. This combination of features makes magnetic particle brakes (MPB) and clutches desirable for tension control in converting, winding and cable operations, while their simplicity makes them suitable for most any application including test benches, packaging and pharmaceutical equipment.
If you’re looking to control torque, MPBs offer a host of advantages versus other electromagnet brakes or friction brakes. Here’s an overview of their benefits, along with tips to help you implement the best-performing unit for your application.
How Magnetic Particle Brakes Operate
MPBs are constructed with a primary and secondary rotor. The space between the rotors is filled with a magnetic powder — typically iron, nickel or chromium. An electromagnetic coil excites the powder to create a magnetic field that can be adjusted when the applied current changes, resulting in a continuously adjustable magnetic current. When the secondary rotor is fixed to the equipment frame, the device acts as a brake. Otherwise, it acts as a clutch.
Magnetic particle technology offers many advantages, such as:
- Simple torque adjustment. The torque output is nearly linear in proportion to the applied current and is repeatable, making magnetic particle technology attractive for tension control in converting, winding and cable applications that often require continuous adjustment of rollers and tension components.
- Fast response. The magnetic particles react quickly to the DC power.
- No wear. Unlike friction brakes, there are no wearing parts. Abrasion does not occur, and MPBs don’t produce dust.
- Low power. 1.5 amps can generate 1,000 Newton-meters (Nm) of torque.
- Compact. Because MPBs have a low power requirement and deliver a high torque output, units offer a high torque-to-size ratio.
- Easy installation. MPBs are as simple to install as friction brakes. You can just slide the brake onto the shaft.
- Reliable and long-lasting. When properly sized, MPBs don’t break and can provide as many as 12 years of reliable operation before a small reduction of torque output occurs. In addition, these devices come with lifetime lubrication with no need for air and oil.
Consult With Your Brake Supplier to Ensure Optimal Performance
In addition to these advantages, machine designers can choose from a wide range of types and sizes of MPBs to suit specific application needs. For example, our Merobel family includes magnetic particle through-bore brakes and clutches in 10 sizes with torque outputs from 2 to 1,000 Nm, as well as magnetic particle output shaft brakes and brushless clutches from 0.2 to 5 Nm. Torque limiters are also available in 10 sizes with torque values from 0.15 to 85 Nm.
Redex can help you choose the best MPB for your application. We also offer a digital controller and sensors as part of a precise closed-loop system for feedback and control, and we can outfit your assembly with an appropriate fan or heat sink to ensure ideal thermal performance. To find out which MPB or clutch is best for your application, be sure to contact an Redex technical expert.
For more information about Merobel magnetic particle brakes, visit our product page.