Ogura has two types of permanent magnet slip clutches and brakes. These are the PHT and OP series. They are designed for torque limiting and continuous slip. Once the desired torque is reached, the unit will slip at the preset torque amount. When used as a brake, torque is produced magnetically so it eliminates high breakaway torques that can occur with mechanical devices. They do not produce wear particles, so there is no contamination. Torque is consistent over a given speed range. Units are provided with hollow bores or with stainless steel custom shafts. OPL units come factory set for a given torque but PHT units are mechanically adjustable through their torque range and can be set by the user.

PHT clutches and brakes range in torque from very low to 7 Nm / 62 lb-in. No power is required as torque is simply controlled by opposing magnets and a hysteresis ring. Since torque is controlled magnetically*, the internal surfaces never touch, and no frictional wear occurs (except of bearings). Torque is very accurate and stable. Units can be used on vertical or horizontal applications. Control of tension on wire, paper, film, and foil are very common with these types of units. In addition, they can be used as a torque limiter/overload coupling. So, once the exact tightening torque is required on the output, for example with a screw cap, the unit simply slips at the predetermined torque.

OPL clutches range in torque from very low up to 0.4 Nm / 3.5 lb-in static torque. No power is required as torque is transmitted through the use of permanent magnets and magnetic particles. Torque is fixed at the factory. Units are built with bushings, but for higher speeds or higher loads, ball bearing units are available. The most common application for OPL units is for paper feeds on printers and copy machines. Units will slip if the paper jam occurs protecting the gear train in the machine. Since units are sealed, they are unaffected by paper dust or printer ink. Also, since the units operate magnetically, they do not produce any wear particles that contaminate printing and/or medical equipment.

Magnetic particle units can be sized for continuous slip or overload protection. Torque is produced magnetically, eliminating high breakaway torques that can occur with mechanical devices. They do not produce wear particles, so there is no contamination to the clutch or brake and there are no wear particles that are produced to contaminate machine parts or materials. Torque is consistent over a given speed range. Units are available with hollow bores or with steel shafts that can be customized. Magnetic particle clutches and brakes of the OP series are rated up to 25 Nm / 221 lb-in torque. Larger OPB particle brakes can be supplied with built-in fans for additional heat dissipation for heavy slip applications. Torque control is very precise. Slip speeds can be precisely controlled by using a constant current power supply. If general tension control is required, a simple variable DC control can be used. Power controllers are also available from Ogura.

Benefits you will see using Ogura permanent magnet clutches and brakes:

• Torque in PHT units is created magnetically, so there is no frictional wear
• Units are sealed to prevent unit contamination and contamination of machinery
• Torque is consistent over a given speed range
• OPL has fixed torque but on the PHT units, it is variable

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