With several factors at play, demand for roofing granules has gone through the proverbial roof, and manufacturers are doing everything they can to keep up.
This surge in demand, combined with the abrasive nature of roofing granules, has put added strain on roofing granule production equipment, leaving plant managers with a challenge, as endless production runs leave little room for unexpected downtime and repairs.
As such, preventative rotary drum maintenance has never been more critical at roofing granule manufacturing facilities. What follows are guidelines from the FEECO Customer Service Team on keeping rotary drums operating reliably with minimal downtime during busy times.
Rotary Drum Maintenance for Roofing Granule Manufacturers
Rotary drums are the foundation of the roofing granule production line, accomplishing everything from preheating and coloring, to curing and cooling. As a result, many of the basic preventative maintenance procedures required of rotary drums in any production setting are applicable here.
What is unique to roofing granule facilities is that they tend to experience accelerated wear due to abrasion, particularly if equipment was not designed to the level of duty required by the industry. This abrasion, combined with demanding production schedules, can wreak havoc on a facility, especially considering that many of them are advanced in age. Left unchecked, this type of scenario quickly leads to premature equipment failure.
“With the increase in demand for roofing granules, we’re seeing a lot of our customers looking to upgrade their facilities and replace aging infrastructure, but with such busy schedules, they want to do it in as little time as possible,” says Craig Peppin, FEECO Customer Service Manager.
“That’s why preventative maintenance is so essential. You take a little time now to prevent extended downtime down the road. If you run these machines to the point of failure, you’re going to be down for a while waiting on a replacement.”
Fortunately, a good preventative maintenance program goes a long way, with the following procedures being vital components.
FEECO Rotary Dryer
Regular Inspections
Routine inspections are the least costly and most effective preventative maintenance tool plant managers have at their disposal. Regular inspections track changes in the equipment over time and ensure problems are caught early, before they become major issues.
Operators should be provided with an inspection schedule outlining daily, weekly, monthly, and quarterly inspection points. This should include check points such as:
- Gear/Chain lubrication
- Bearing condition
- Graphite block lubrication
- V-belts
- Reducers
- Couplings
- Thrust roller assemblies
- Contact between thrust rollers and tires
- Contact between tires and trunnions
FEECO typically recommends plant managers also bring in the OEM or a qualifed service provider to conduct a thorough annual inspection. In roofing granule plants, however, the potential for accelerated wear often means this type of inspection should be conducted more frequently.
Monthly Dynamic Inspections
Plant managers can take advantage of FEECO’s Monthly Dynamic Inspections as a way to streamline equipment monitoring and maintenance procedures while minimizing downtime.
Each month, or quarter, depending on the chosen schedule, one drum is shut down for a “static” inspection, in which a Customer Service Engineer thoroughly evaluates the condition of the drum both inside and out. Any issues that can be addressed during shutdown are, as are any predetermined necessary repairs. All findings and any changes made are recorded and provided in a report detailing the drum’s condition and any components that require attention.
A FEECO Customer Service Engineer inspects the interior of a rotary kiln
During the same visit, all other drums on site remain in operation and receive a “dynamic” inspection, which assesses overall unit condition, major contact points, thrust loads, and other basic operating parameters.
This systematic approach to multi-drum facilities makes implementing a preventative maintenance schedule seamless.
Minimize Fugitive Material
Fugitive material is a problem in any type of plant, creating housekeeping issues, presenting safety hazards, and resulting in lost material. In roofing granule plants, the abrasive nature of granules presents additional risk, particularly when it comes to tires and trunnions.
Material allowed to build up in trunnion pits can cause substantial wear on trunnions and tires, getting into the pinch point and abrading tires and trunnions. Any other mechanical components where granules are allowed to gain entry will also wear quickly.
Replace Liners as Needed
While rotary drums destined for the roofing granule industry are fabricated using abrasion-resistant materials, liners provide added protection against abrasion in non-heated rotary drums, as well as high-wear areas such as chutes and transfer points.
Rotary drum liners are the first line of defense against abrasion, providing a wear point to protect the drum shell. As such, liners should be regularly inspected for wear and replaced as needed to maintain continued protection.
A rotary drum liner protects the drum shell from the abrasive materials being processed within
Ensure Proper Lubrication
As with any rotary drum, adequate lubrication (both type and quantity) at all necessary points is essential to keeping rotary drums in good working condition. Most importantly, this includes using graphite block lubrication (never oil) for tires and trunnions, occasionally “roughing up” the surface of the graphite block for maximum transfer. Adequate gear and pinion lubrication is also essential.
Monitor Backlash (Gear & Pinion Drive Only)
On drums utilizing a gear and pinion drive assembly, backlash (the distance between the non–driving sides of adjacent gear teeth of two meshing gears) should be checked from time to time.
Backlash is an indication of gear and pinion alignment. If the gear and pinion are allowed to fall too far out of alignment, abnormal wear on the gear teeth can occur, and if not caught early, could lead to fatigue failure.
Misaligned gears can also cause increased vibrations, which can wreak havoc on the drive components, trunnions, tires, bearings, and more.
Backlash is just one of several rotary drum measurements essential to keep an eye on as part of a preventative maintenance program.
Protect Tires & Trunnions
In addition to keeping tires and trunnions properly lubricated, grinding to address wear may also be required now and then.
Tire and trunnion wear can result from a number of factors, including misalignment, poor housekeeping, fugitive material, and more.
Grinding is a resurfacing technique that reconditions worn tire and trunnion wheel surfaces to like-new condition. Any signs of wear on either tires or trunnions should be addressed as quickly as possible to prevent further damage.
It’s also important to note that the need for frequent grinding is an indication that there is an underlying issue, typically one of misalignment.
Ensure Proper Rotary Drum Alignment
Rotary drum alignment is one of the most important contributors to the overall longevity of a drum. A misaligned drum puts undue stress on each and every component in the system, resulting in excessive wear and often premature failure. As such, early identification of misalignment is critical. Misalignment is typically indicated by abnormal auditory cues such as vibration or chattering, as well as wear on tires and trunnions.
A rotary drum alignment should also be performed after any major repairs or the grinding of tires and trunnions, as this can change base conditions.
Keep Burners & Combustion Chambers Tuned
Though not necessarily a maintenance concern, ensuring burners and combustion chambers are operating properly can have a significant influence on efficiency in rotary dryers and kilns.
Tuning combustion chamber controls helps to ensure efficient operation and minimize fuel use.
Keep Seals Maintained
Similarly, rotary drum seals, particularly on dryers, kilns, and coolers, should also be maintained as a way to maximize efficiency and keep fuel consumption in check.
Rotary Dryer Leaf Seal
Conclusion
As roofing granule manufacturers continue to ramp up production to meet unprecedented demand, preventative rotary drum maintenance remains a key factor in minimizing downtime and keeping production moving.
The FEECO Customer Service Team has the equipment and expertise to inspect, troubleshoot, and repair rotary drums in any capacity, whether they were manufactured by FEECO or not. For more information on our extensive parts and service program, contact us today!