Refurbished Heat Transfer Rolls—Good as New

Sonoco Clear Pack benefits from refurbished heat transfer rolls from Menges Roller.

Due to the long service life of most heat transfer rolls, the manufacturers and processors who use them are often prone to wait for problems before servicing their equipment. Unfortunately, that often puts them at a loss to understand why their rollers are losing efficiency, which may require companies to run the production line at a lower speed to achieve the correct processing temperature.

Considering the priority to keep production going, the first question is: ‘Can you have the roll repaired or refurbished, or is it necessary to have a new one fabricated?’ If you deal with an expert, and your damaged roll is not a “basket case,” there is a good chance that repairing or refurbishing can provide good-as-new performance while saving considerable time and costs.

“After years of service, the inside of your heat transfer rolls begin to look like the inside of the radiator on an old pick-up truck,” says Matt Menges, president of Menges Roller Company. “And no wonder. The rolls are going through stresses that are very similar to those of a radiator. The rollers conduct heat transfer either pulling heat out of your substrate or putting it in.”

He adds that if the process water in your roll, like the coolant in your radiator, isn’t tested frequently to ensure it is at the correct level to resist oxidation, improper pH, and contaminants, the inside of those rolls will corrode, degrading heat transfer efficiency.

As a manufacturer of new rolls and provider of a wide range of repair services, Menges says his firm frequently gets calls from customers who claim that their rolls have a blockage that inhibits the flow of the process fluids, which is critical to the roll’s heating or chilling performance.

When the process begins to suffer, operators will quickly ask their suppliers how quickly they can make a new roll. Unfortunately, in many instances, fabricating the new roll will take many weeks, and the delay may be worsened because the original roll drawings aren’t available or the original equipment manufacturer (OEM) won’t release them.

“In cases like that, the process operator or maintenance manager may want to consider having their roll refurbished,” Menges explains. “That may be a very practical alternative to having a new roll built, and can save considerable time and money.”

Either way, the roll manufacturer must have the capability of reverse engineering the worn roll during the disassembly process. To facilitate this process, the machinists will produce detailed drawings that can be used to accurately refurbish the existing roll or fabricate a replacement.

“As a major OEM supplier, we find it very beneficial, particularly with older roll designs, to have our engineers create computer-aided design (CAD) drawings to prove the design accuracy for repairing a roll,” Menges explains. “That also enables us to incorporate design improvements. The new drawings will expedite the fabrication of a replacement roll, if necessary, and provide the designs necessary for future reference.”

A case for refurbishing
In a recent case where refurbishing proved to be the best solution, Brian Varley, plant engineer at Sonoco Clear Pack, needed to repair or replace one of the large heat transfer rolls at the firm’s sheet extrusion operation. Clear Pack thermoforms plastic containers for several consumer product and food service companies, including packaging for single-serve condiments, fresh produce, and other food service needs.

“The shell surface on one of our tungsten carbide rolls was excessively porous,” Varley explains, “so it would not accept replacement tungsten carbide well enough, and would not polish properly.”

Varley had worked with Menges Roller for many years, so he consulted with them to analyze the problem and evaluate whether a new roll was needed or refurbishing the existing one was the best solution.

Even with laser welding, the supplier determined that the super-finish required for application could not be achieved. However, Menges recommended refurbishing the roll to save both production time and replacement costs.

“They removed the outer shell, installed a new one, and applied the tungsten carbide super finish to the roll,” Varley says. “However, once they removed the shell they found a number of other problems in the roll’s internals. There were some leaks that they were able to repair, and they also re-balanced the roll. After the refurbishing, which was done fairly quickly, we had a virtually brand-new roll for less than half the price of fabricating a complete replacement.”

Varley adds that he was confident about the refurbishing choice because he had experienced success with the process several times in the past.

“I’ve worked at large converter operations throughout my 25-year career,” Varley says, “and have experienced several situations where we had to make the choice of replacing or refurbishing large and complex process rollers.”

In an earlier instance at a cast film operation, there was a complete blockage of a heat transfer roll that ran in a line of 25 large, rubber-covered heat transfer rollers used in the production of cast film. Because the roll had been in service for over 20 years, Varley worked with Menges to determine if the roll should be repaired or replaced.

“A new roll core like this was in the $40,000 price range,” says Varley. “Plus, of course, there was the substantial added cost of downtime. Menges recommended repairing it, which was done for less than 40 percent of that cost. They replaced the outer shell, machined the internals to remove oxidation, and the internal shell was rewound to produce an even better cooling rate then when the roll was new.”

According to Matt Menges, most operations understand what they want heat transfer rollers to do to their webs, yet don’t realize the engineering expertise needed to achieve optimum performance, particularly when it comes to the choice of refurbishing or sourcing replacement rolls.

“Given the complexities, the customer relies on suppliers like us to handle all the complex calculations of flow rates, BTU output and input, deflection, pressure testing, and roll balance,” Menges explains. “And the roll finish is certainly a specialty, whether plasma, High Velocity Oxygen Fuel, chrome, rubber, or urethane.”

In the end, of course, the customer is mostly concerned about keeping production going, and that means getting fast service, whether replacing or refurbishing rollers.