Avoiding Bad Vibes...Vibration Monitoring on Hammermills
06/01/2009
Avoiding Bad Vibes: Vibration Monitoring on Hammermills
Hammermills are used in a variety of industries to pulverize, crush or grind friable materials, effectively reducing large particles into a granular finished product size. They can be used to crush a wide range of materials such as coal, limestone, cereal grains, animal products, wood, and sewage sludge to name a few. In normal operation, some vibration will be present on the hammermill; in a fault condition vibration levels will increase significantly requiring immediate attention from the operator.
Hammermills can fail for a variety of reasons. As the hammermill reduces material the abrasive action of the hammers and the material being reduced can wear the hammers out unevenly causing the mill to go out of balance and vibrate excessively. This excessive vibration can damage not only the hammermill itself, but if left unchecked can lead to hammers breaking off and causing catastrophic damage to machinery and product. Imbalance due to uneven hammer wear can be detected by a vibration monitor mounted on the enclosure of the hammermill.
Excessive vibration usually indicates the need for maintenance such as adjusting or turning the hammers in order to have them wear evenly. Significant damage can also be caused if a hammer or part of a hammer breaks off during particle reduction. This can have catastrophic results as the broken piece can damage other hammers, puncture the discharge screen and taint large quantities of the product being processed. This type of occurrence can also be detected quickly as an increase in vibration due to major imbalance within the hammermill. Once again, mounting a vibration monitor on the external enclosure of a hammermill will provide a means of quickly identifying a fault condition, and enabling immediate shut down of the hammermill to minimize both machine damage and product waste.
Electro-Sensors, Inc is a leading manufacturer of industrial speed and vibration monitoring equipment. Their vibration monitors can be used almost anywhere that there is need to detect over or under vibration in industrial machinery such as on hammermills, vibratory conveyors, or fans.
Typical Application
A typical application would involve a feed mill manufacturing varying types of animal feed that requires an economical, but reliable early detection system to indicate a fault condition in their hammermill. This would be done by monitoring for excessive vibration caused by imbalance from either worn or broken hammers. This application requires a vibration monitor that is simple to install and easy to calibrate requiring minimal process downtime. The vibration monitor must have an adjustable vibration alarm trip point, and an adjustable alarm delay for machine start up. The vibration monitor electronics must be in a compact and rugged enclosure to enable easy installation and reliable performance in a harsh environment. Early identification of a fault condition and being able to immediately shut down the hammermill to minimize both machine damage and product waste is integral to the smooth and safe operation of the feed manufacturing process.
Electro-Sensors provided an economical vibration monitor from the VS-Series of monitors; model VS-1 to be mounted directly to the housing of the hammermill. The VS-1 accepts and input voltage of 24vdc with the option of a 115vac power supply to cover most applications. It has an adjustable alarm trip point along with a trip point delay and a relay output that can be wired to an alarm circuit or motor shutdown circuit for the hammermill. The VS-1 is unique in that it has 3 LEDs on the front cover for at-a-glance visual indication of the circuit condition – this provides an easy means of visual machine status inspection. The VS-1 easily mounts directly to the outer surface of the hammermill enclosure via 4 bolts, and calibration is quick and easy – minimizing costly machine downtime. The VS-1 is delivered on site as a self-contained system for monitoring vibration and can be installed without the need for any additional brackets or mounting equipment.
Benefits
The VS-1 is an economical vibration monitoring system that comes in a rugged and compact enclosure enabling installation on virtually any piece of machinery to be monitored. The VS-1 has an adjustable alarm trip point range of 0.1 - 2.2 in/s rms enabling it to be used across a broad range of vibratory applications. The alarm delay serves the twin purposes of allowing the hammermill to get up to speed and into normal operating mode, and also when operational, the hammermill must exhibit a fault condition for a specified time before the relay will trip. This avoids false alarms on startup and during normal operation. Simple installation and calibration allow it to be installed quickly without long periods of costly process downtime. The VS-1 is also available in an XP housing.
