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Why You Should Select a VFD Control for Your Hennig Conveyor

December 01, 2021

Conveyors & Filtration

The “classic,” low-cost solution for a machine tool chip conveyor is usually a model that features a top-mounted gearmotor, a torque limiter (slip clutch), and a drive chain that connects the two. On budget conveyors, the gearmotor is wired directly to an on/off control. There are several limitations to this setup. 

  • The mechanism that protects the conveyor in the event of a jam is a torque limiter. The torque limiter clutch breaks free and spins until the conveyor is stopped. This protects the conveyor belt and gearmotor, but if the conveyor is not shut down in a reasonable time, the torque limiter will be damaged and must be replaced. 
  • The torque limiter is a 'dumb' device, and setting breakaway torque accurately is difficult. 
  • There is very limited conveyor control (on and off only).
  • There is limited conveyor functionality.

An improvement to the “classic” chip conveyor is to add a push-button control box, making the conveyor safety feature the torque limiter. One improvement the push-button control box offers is the ability to have the conveyor run in both forward and reverse, assisting operators in clearing jams. If the jam is not cleared, however, the operator will still need to shut down the conveyor. An emergency stop (E-Stop) button is also added for additional safety. 

Variable Frequency Drives (VFD’s)

Due to the ever-increasing demand for improved chip conveyor functionality and efficiency, Hennig has offered VFD's (Variable Frequency Drives) as a standard for most new conveyor products for several years.

Hennig standard conveyors feature a direct drive motor with a VFD control, providing many advantages over the “classic” solution:

  1. Elimination of Mechanical Torque Limiter Protection
    The VFD senses the gearmotor current draw to protect the conveyor.
  2. Adjustable Speed Control
    Belt speed can be optimized between the need to transport heavy chip loads and slowing the belt to reduce coolant carryout. The use of rapid on/off cycles can be eliminated, reducing potential conveyor damage.
  3. Automatic Jam Detection and Removal
    As stated above, the VFD is programmed to detect excessive gearmotor current draw. This allows the VFD to shut down a jammed conveyor to prevent damage. A recent Hennig innovation is an automated jam clearing VFD program. When a jam occurs, the conveyor will stop and run-in reverse. It will do this operation 3 times before the conveyor stops. We have found this to be successful in clearing jams without operator intervention.
  4. Efficiency
    A direct drive motor converts supplied power into more useful work while the VFD control allows for minimum power consumption for a given usage model. Conversely, a top-mounted motor with a drive chain wastes power due to frictional losses. 
  5. Power Protection
    A VFD conditions the supplied factory power—meaning the gearmotor runs at the optimal voltage and frequency, preventing motor damage from ‘dirty’ power.
  6. Spare Parts Reduction
    Several wear and service part needs are eliminated with a VFD/direct-drive motor conveyor.
  7. Durability
    Gearmotor start-up by the VFD reduces inrush current, protecting the motor and allowing for extended motor life.
  8. Simplicity
    The Hennig standard offering with local control requires only a single power cable for the conveyor. The power cable supports the VFD control functions and the gearmotor power needs.
  9. M-Code Options
    Local control (using the VFD to control the conveyor) can be supplemented with remote control from the machine tool via “M-Codes”.
  10. Cost
    As functionality increases, a push-button control box becomes much more expensive than a VFD.

Variable Frequency Drive (VFD) with a yellow emergency stop button stops the conveyor only.

  

Variable Frequency Drive (VFD) with a red emergency stop button stops the conveyor and the machine.

  

Is your shop still using outdated conveyors? Hennig offers a variety of chip conveyors to accommodate a variety of applications, so update your chip management system and maximize chip removal efficiency—contact one of our experts today.

Already know what you need? Request a quote with our Chip Conveyors and Filtration Division today!

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