Bucket conveyors are frequently used in many process settings for bulk material conveyance. As an equipment choice, bucket conveyors can offer many years of reliable service, provided they are application engineered and properly installed, operated, and maintained. This article presents five key tips that will allow users to obtain the maximum performance from their bucket conveyor and reduce the incidence of downtime and lost throughput.

Tip #1: Avoid Dropping Material into the Conveyor Infeed from an Excessive Height

A key aspect of bucket conveyor operation is to ensure the successful transfer of material from an upstream feeding process into the conveyor. To achieve this, particular attention should be paid to the height from which material is dropped into the conveyor. A low drop height means a gentler product transfer, maintaining product integrity, while reducing the amount of dusting and providing better overall infeed control. Higher discharge elevations can also cause certain products (i.e., those with rounded or spherical particles) to bounce and may cause containment issues at the conveyor infeed.
    
Product dusting can result in the deposition of material onto surrounding equipment and structures, necessitating cleanup. Dusting may also cause the build-up of material within fully enclosed bucket conveyors, which can result in accelerated equipment wear and tear. Finally, product dusting may create an explosive atmosphere, as well as constitute a health hazard.
    
To avoid the performance losses associated with feeding from an elevated drop height, a good rule of thumb to follow is to always feed material into the bucket conveyor from the lowest drop height possible. Ideally, material should be gently deposited into the conveyor, rather than being dropped in from an excessive height.
    
If upstream feeding processes are difficult to modify for achieving a lower drop height, a common solution is to raise the lower portion of the bucket conveyor. This can be easily accomplished by installing a bucket conveyor equipped with custom-sized legs to raise the infeed elevation. In addition, adjustable floor supports enables minor height variations and provides leveling for uneven floors.

Tip #2: Ensure an Even Distribution of Material in the Buckets

When material is unevenly distributed within the conveyor’s buckets, product spillage and asymmetrical wear of the bucket surfaces can result.  Often a design issue, this problem frequently arises when product is being fed in at right angles to the conveyor (for example by a vibratory feeder or belt conveyor). As product is fed into the conveyor, it tends to accumulate on the feed side of the buckets, causing wear and overfilling on that side.
    
The remedy to this problem lies in good equipment design. A well-designed conveyor will be equipped with a bias-cut infeed chute which ensures even distribution of product within the buckets, even when fed at right angles.

Tip #3: Ensure Optimal Bucket Fill

A common operating mistake is to run a bucket conveyor at a speed that either under-fills or over-fills the buckets. While operating speed is often a function of the type and bulk density of material being conveyed, for every material there is an ideal operating speed that results in an optimal bucket fill. Under-filling buckets by running the conveyor too fast can shorten conveyor life as the conveyor runs longer than necessary to move the amount of product required. While over-filling the buckets by running too slowly results in product spillage and loss. The trick is to find, and set, the operating speed that results in an optimal bucket fill for the type of material being conveyed.
    
Product spillage resulting from bucket over-filling imposes two penalties. First, there is the material and throughput loss, and the need for cleanup. Secondly, spillage of material into the infeed or discharge areas of the conveyor may result in equipment wear and tear as the bucket drive assembly moves through the accumulated material. If the accumulated material is sticky or abrasive in nature, accelerated wear and compromised performance of critical drive components may result.     

Equipment suppliers will often quote conveyor capacities as function of operating speed and volume required, using a specified percentage to which the capacity of the individual buckets on the machine are filled. For example, some bucket conveyor capacities are quoted using a 67 percent bucket fill rate. Using these parameters, an engineering calculation can be made that shows the capacity rate of the equipment as the bucket speed and material weight changes. Care should be taken to select equipment which can be run at the speed needed to achieve the desired throughput for the material being conveyed, while achieving the bucket fill percentage recommended by the equipment manufacturer.

Tip #4: Inspect the Unit Regularly

Like any type of operating equipment, bucket conveyors may experience unplanned downtime if basic preventive maintenance routines are not followed. Consider implementing the following to improve equipment performance by reducing the occurrence of unplanned downtime:

•    Inspect the bucket conveyor regularly. Performing regular and standardized inspection of equipment is a simple practice that is often overlooked on shop floors. Implementing basic autonomous maintenance routines where equipment operators perform a standardized inspection of the unit at shift start-up or handoff is a good way to identify and “nip problems in the bud” before they result in equipment losses.  
•    Regular equipment inspections can detect the unwanted build-up of material that can lead to the failure of buckets and drive assembly components. The need to perform frequent inspections to detect material accumulation and other problems is particularly acute on enclosed units.  Often, these units are installed in applications where hazardous materials are being conveyed, which in turn leads to reluctance to open the equipment for inspection. Nonetheless, even in these applications, frequent inspection of the equipment to check for material build-up and other problems will pay dividends in reducing the incidence of equipment failure and loss.
•    Follow the recommended preventive maintenance routines provided by the equipment supplier. Following recommended routines to the letter can go a long way to preventing downtime and ensuring equipment reliability and longevity.
•    Always install factory replacement parts. Jury-rigging equipment or using replacement parts other than those provided by original equipment manufacturer is never a good idea. A bucket conveyor is an intricate piece of equipment whose performance depends on many different components successfully working together. Using makeshift or non-original parts may degrade equipment performance and compromise safety.
•    Use the equipment for the purpose intended. Sometimes, equipment that was designed and purchased to convey a certain type of material will be pressed into service when alternative materials have to be handled. Depending on the material characteristics, the conveyor may or may not perform effectively in this new role. Other times, the production requirements increase meaning that the conveyor has to handle more product than originally designed, and therefore needs to operate faster. Accelerated wear and downtime may result if the conveyor is unable to successfully handle material other than that for which it was originally designed. If this happens to you, call the original equipment manufacturer for advice.

Tip #5: Maintain Open Communication with Your Equipment Supplier

Bucket conveyor performance can often be markedly improved through open communication with your equipment supplier. Reputable and experienced vendors are always willing to offer advice and suggestions for improving equipment performance. Equipment suppliers who have extensive experience in conveying materials are a rich resource from which to draw advice and guidance for overcoming performance challenges.
    
A key challenge in bulk material conveying is to understand how various materials will interact with the equipment when they are conveyed. Experienced equipment suppliers have extensive knowledge of material characteristics and behavior that they have built-up over years of performing material tests and solving customers’ conveying challenges. Choosing an experienced equipment supplier and maintaining open communication to resolve issues as they arise is a key element in attaining high levels of performance from your bucket conveyor.
    
James Bransfield is the engineering team leader for UniTrak Corporation Ltd, manufacturer of the TipTrak line of bucket conveyors. Bransfield is responsible for UniTrak’s product engineering function and has more than 20 years experience in designing bucket conveyors. For more information, contact Bransfield at [email protected] or visit www.unitrak.com.

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