Keeping equipment running safely and efficiently is necessary for sectors that depend on industrial assets for production. Operators of this machinery also must ensure that they neither void warranties nor ignore regulations that can make a facility non-compliant. Maintenance is key in such industries, which rely on the smooth operation of every piece of equipment to produce profits. Industrial facilities depend upon planned maintenance to limit unplanned downtime rather than reacting to maintenance issues as they occur, which costs far more and consumes more time to keep vital equipment running.

These days, manufacturers often couple maintenance plans with sensors tied to control systems, which note when equipment is operating at less than optimum levels. Computer systems also track maintenance schedules and part inventories, ensuring the proper components are available to limit downtime due to maintenance. rotor dryers are an integral part of many bulk material handling systems, and their upkeep is essential for several applications. With proper maintenance, these industry workhorses can continue operating for decades while performing their duties admirably.

Why Rotor Dryer Maintenance is Important

During material handling, rotor dryers are key machinery exposed to constant stress from heat and rotational forces. As with the upkeep of any other large piece of equipment, rotor dryer maintenance helps ensure longer service life, inhibits unplanned downtime, and generally lowers maintenance expenses. By monitoring and regularly inspecting a rotor dryer, maintenance problems can be kept to a minimum for every part of the machine. This also involves taking measurements during inspections while documenting any issues with the rotor drum and other aspects of a rotor dryer’s structural and mechanical system.   

Rotor Dryer maintenance should track the following: 

  1. Worn components
  2. Alignment of the rotor drum
  3. Drum’s positioning between thrust rollers (also referred to as float)
  4. Thinning, deformation or cracks on the drum
  5. Trunnions or tires on which the machine moves
  6. Seals (especially those that keep air from entering the drum)
  7. Proper inspection and maintenance of gears
  8. Follow preventive maintenance protocols
  9. Regular lubrication using the correct amount of recommended lubricant 
  10. Keeping vital spares on hand

When properly maintained, the rotor dryer’s rotating drums can reliably process materials for many decades. Yet often simple procedures are skipped or ignored, even though manufacturers have considerable capital tied up in a rotor dryer. Maintenance for these machines is normally very straightforward, but putting off rotor dryer upkeep will only make the job more difficult, as well as more expensive.

10 Maintenance Tips

Ignoring a potential problem with a rotor drum can lead to particularly calamitous situations for a rotor dryer. Maintenance issues for these drums should not be put off, as the cost, effort and time needed to fix them increase considerably if not corrected expediently. Manufacturers must consider the operating conditions under which rotor dryers must function, considering the specific applications for which they’re used. Maintenance must also take into account the other processes besides drying these machines perform, which may involve the cleaning, cooling, separation and shredding of bulk materials. These unique activities often place further stress on the drum and other rotor dryer components.

1. Replacing Worn Components

Just like with any industrial equipment, when rotor dryer parts wear too much, they lose their effectiveness. Waiting for them to completely break down will result in extended work stoppages, especially if vital parts aren’t on hand or readily available from a supplier. Additionally, a worn component can cause stress on other parts of the rotor dryer, leading to premature failure and even greater expense.

2. Keeping the Dryer Aligned

rotor equipment that isn’t kept properly aligned is a common issue; this is the case for every industrial facility that uses a rotor dryer. Maintenance should include checking the alignment of the rotor drum, as once it becomes misaligned it negatively affects all the rest of the drum’s components. Misalignment occurs once it goes outside of the original horizontal and vertical axes on which it normally rotates, which in turn causes excessive stress.

This subsequently leads to greater wear, often resulting in damage that requires replacement or repair of both the mechanical and structural components of the rotor dryer. Maintenance inspections should always ensure that a rotor dryer’s drum is positioned correctly on trunnion bases and doesn’t deviate from its central rotating axis. Though misalignment occurs for various reasons, realignment should be done sooner rather than later to prevent further issues. There are numerous methods for aligning a rotor dryer’s drum, but the most innovative and effective involves a laser tracking system, which allows for more precise alignment.

3. Fixing Improper Float

This refers to the drum’s positioning between the thrust rollers. The drum ought not to ride hard against either the downhill or uphill thrust rollers but rather “float” between them. Thrust rollers prevent the drum from drifting, providing a rotational point against which the tire rides. Though the thrust roller and tire can make contact with each other intermittently without causing a problem, should there be sustained contact between the two, it’s likely to cause damage that should be corrected without delay.

While protracted contact can damage essential parts, it also causes the drum to suffer from thrust overload, which puts added strain on roller shafts and bearings. Too much thrust may also be due to attempts to guide the drum into position, which can overly skew the bearings. The process of guiding the drum float back into the correct position is known as “training,” which is done during a laser alignment by incrementally skewing trunnion bearings to change the drum’s direction, affecting how much longitudinal thrust it undergoes. Someone with ample expertise best achieves proper float through training since extensive damage can occur if not performed correctly.

4. Issues with the Rotor Dryer Drum

While the drum tends to be pretty heavy-duty on a rotor dryer, maintenance issues will occur if it’s not looked after properly. Problems with the drum that occur due to lack of rotor dryer maintenance might include the development of thinner spots on the drum, deformation of the drum’s shape and cracks developing at weld points. A frequent reason for rotor dryer drum problems involves stopping its rotation when it still contains a hot load. This can happen due to a power outage or mechanical failure, resulting in damage due to heated material being in contact with a localized area of the drum’s interior for too long.

5. Dealing with Worn Trunnions & Tires

When tires or trunnion wheels become too worn, it puts more stress on other components of the rotor dryer. Maintenance should address this to avoid damage, which usually requires grinding down the surface of the riding rings on the tires or the rollers on the trunnions. However, replacement is the only choice if there’s already too much wear. There’s typically an underlying issue when tires or trunnions wear too quickly, which usually involves the alignment of the rotor dryer. Maintenance should also address any underlying issues, such as when the drum and tires become misaligned, an issue known as “axial runout,” which often presents as a tire that wobbles or vibrates too much.

6. Importance of Seal Repair & Replacement

Process efficiency in many material handling activities often necessitates the use of seals. The main role they play for the rotor dryer is how they prevent air from entering the drum. This allows operators to maintain a proper internal temperature so that material dries effectively. Seals also prevent material from escaping from the rotor dryer. Maintenance inspections should always look for signs of worn seals, which can lead to irregularity in temperatures and inadequate dust control. These can lead to inconsistencies in the end product and an increased need for cleanup.

7. Maintaining Gears

Proper lubrication of the gears should be a priority for those rotor dryers with a gear and pinion drive assembly. Additionally, rotor dryer maintenance inspections should check that pinion and girth gears interface appropriately. This will reduce wear to pricy drive components while also helping prevent damage to the gears, which typically require replacement rather than repair when they go wrong.

8. Preventive Maintenance Programs

As with most other types of industrial equipment, a preventive maintenance strategy offers the greatest cost-efficiency for the upkeep of a rotor dryer. Maintenance plans usually entail routine inspections, which normally include replacing too-worn parts. Assessments will occur at different intervals: annually, monthly, weekly, or daily. This helps keep unplanned downtime to a minimum, as smaller issues aren’t allowed to become serious problems.

With more modern machinery, sensors combine with software to track operational data, noting when conditions are off and require further evaluation. Whether collected via sensors or manually, standards help inspectors use operational data to determine the condition of a rotor dryer. Maintenance needs are then identified and prioritized. To ensure equipment lasts longer, both machine operators and maintenance workers should be trained on how best to care for the equipment, including documentation of both inspections and any maintenance that’s been done.

9. Proper Lubrication 

For industrial machinery like a rotor dryer, maintenance should include lubrication to prevent damage caused by wear to components from too much friction. However, manufacturer recommendations should always be followed concerning the amount and type of lubricant and the frequency of lubrication. It should be noted, too, that overly lubricating a rotor dryer can result in chemical degradation of components, contamination of other parts of the machine, damage to seals, fire hazards, higher energy costs, leaks, and other potential risks.

10. Retaining an Inventory of Essential Components

Keeping vital spare parts on hand is critical for equipment like a rotor dryer. Maintenance that involves replacing worn components with spares goes much more smoothly if the right parts are already on hand. Not only does this result in less downtime and fewer production hours lost, but it also reduces the need for expensive next-day shipping should a crucial operational component need replacement.

Selecting a Service Provider

While numerous companies make rotor dryers, Prater Industries offers a signature product that more efficiently achieves the same production goals as a rotor dryer. Made by IPEC, a subsidiary of Prater, our unique design combines the Rotormill – also known as a long gap mill – with our Rotordryer® system to provide high throughputs of finely milled material. Used for synchronized milling and drying of materials with high moisture content, the Rotordryer® can also be used for fiber fluffing and concurrent coating or mixing during milling. To learn more about our Rotordryer® and associated maintenance plans, we invite you to contact the material handling experts at Prater today.