FEATURE NEWS:
Pay-off applications using permanent magnetic brakes
In the past, conventional pay-offs have always relied on ropes, belts and springs for tensioning. Nowadays, however, perma-nent magnetic brakes are rapidly replacing these.
The main advantage of using a magnetic brake is that there are no wearing parts. While ropes, belts and springs are affected by the passage of time, as well as any change in temperature or humidity, the torque of permanent magnetic brakes stays the same day after day.
Another advantage of these brakes is their ease of adjustment and repeatability. Magnetic brakes are generally calibrated with numerical torque settings directly displayed on each brake, so that several units can be easily set to the same torque setting.
Pay-offs that use ropes, belts and springs require an experienced operator to fine-tune the torque of each brake in order to achieve equivalent results across several units. In general, therefore, the torque of these conventional pay-offs will usually change in a relatively short period of time. Also, permanent magnetic brakes use no electricity. There are no slip rings or wiring required for operation, and, because magnetic brakes are self-contained, they require no external power source. This gives the units much more portability, and
makes it far easier to incorporate magnetic brakes into a strander or other machine.
The possible disadvantage is cost. But while ropes, belts and springs cost less than magnetic brakes, the downtime resulting from incorrect torque settings, the amount of scrapped cable, and the wasted operator time quickly erases any short-term cost concerns.
When using a magnetic brake, you need to determine the required torque for your application. Generally, you can do this by using a simple spring scale and a string to determine the tension. Multiply the tension by the radius of the reel to get the torque.
All magnetic brakes are rated according to their torque range, and many magnetic brake manufacturers have websites that can help walk you through this calculation.
One example is www.magnetictech.com. Simply click Products, then Hysteresis Brakes & Clutches, and finally, Selection Criteria.
Most applications will use a simple timing belt to replace the existing rope, belt and spring. Some manufacturers even supply mounting brackets, drive plates and shaft-clamping devices to help ease the transition. If the magnetic brake is to support a heavy reel, however, you will
need a stronger bearing structure. Check with the manufacturer to see if they offer brakes with roller type bearings.
All brakes also generate heat as they work. Make sure, therefore, to check with the manufacturer to confirm that your pay-off is running at a safe rpm to dissipate this heat.
Examples of typical pay-offs based on magnetic brakes include: portable small pay-offs using magnetic brakes, timing belts and flange-type bearings to support the reel; compact vertical stands using magnetic brakes; retrofit applications using magnetic brakes, mounting brackets and gears.
Company: |
Magnetic Technologies Ltd |
Country: |
USA |
Fax: |
+1 508 987 2875 |
Email: |
|
Website: |
www.magnetictech.com |