Advantages and Applications of Roller Hearth Systems

The following is an excerpt taken of an interview with Tim Donofrio, VP Sales, CAN-ENG taken from an article published in Heat Treat Today’s magazine, February 12, 2024, issue, entitled “5 Experts on the Advantages and Applications of Roller Hearth Systems”

Application Determines Customizable Furnace Features

This type of furnace is highly customizable, and, as Tim Donofrio, VP of Sales at Can-Eng Furnaces International explains, knowing the application will determine furnace features.

What Features Do You Offer on Your Roller Hearth Furnace for Annealing Various Materials?

The following is based on roller hearth furnaces operating at or above 1400°F.

Annealing furnace features depend upon the material being processed and the metallurgical process being carried out. They can be provided with a wide variety of features for preheating, annealing, slow cooling, oxidizing, or bluing and accelerated cooling.

Preheating features include direct or indirect heating applications, under air or controlled atmospheres. Preheating in some cases requires features for burn-off of residual blanking fluids prior to entry into the critical anneal chamber and as such, the off-gas must be appropriately addressed.

Annealing can be a direct or indirect heating application using natural gas, blended hydrogen/natural gas, and electrical energy sources. Process protective atmospheres include N2, Exothermic gas, Endothermic gas, N2 + H2 , and H2 . In some cases, process atmospheres must be carefully controlled and monitored to very low 02 PPM levels to ensure correct oxides are formed or, alternatively, a bright oxide-free finish is achieved, something very critical when annealing electrical steels for transformer core and motor annealing. Today we see a rise in the use of roller hearth furnaces for the manufacture of transformer core and motor cores, processing electrical steels and amorphous metals. This is largely a result of the electrification of the world.

Post-annealing cooling and bluing are paramount to the process success. In most cases, cooling and soaking stages are provided through the integration of direct and indirect cooling methods that include air, water, and externally chilled atmospheres that can be directly injected into the furnace system and recirculated.

How Is Your Roller Hearth System Unique?

Roller hearth furnaces are the work horse of the industry; they are used for a variety of other heat treating applications. For example, roller hearth furnaces can also be used for low temperature curing, tempering, and aluminum heat treating applications. These lower-temperature roller hearth furnaces do not operate above 1400°F and are built with different fabrication and refractory standards.

Of course, additional high temperature applications include neutral hardening, case hardening, carbonitriding, isothermal, and spheroidizing annealing and normalizing.
Can-Eng Furnaces International offers roller hearth annealing furnaces that meet the stringent demands of today's manufacturers where safety, product quality, and equipment reliability are at the top of our engineers' minds during design and development. Can-Eng has developed a strong user base that has benefited from design features that ensure tight temperature control and repeatable thermal profiles while also tightly controlling process atmospheres. This is achieved by integrating some of the best available heating and atmosphere technologies while being combined with state-of-the art automation and robotics to deliver the lowest cost of ownership processing systems to our clients.

What Are Best Practices for Training In-House Operators on Roller Hearth Annealing?

Our company promotes hands-on and classroom multi-level training of operators, maintenance staff, and engineers. This provides a complete and full understanding of the equipment and the opportunity to train within the company for future talent development.

What Are the Furnace's Operational Advantages?

Can-Eng integrates operator-friendly features that contribute to the reduction in energy and atmosphere consumption while minimizing the carbon footprint and emission levels. Combined with on-board system diagnostics, monitoring, and data collection, these allow for minimal operator involvement.

What Is the Most Common Heating Method?

Today, the most common methods are both natural gas and electric. However, Can Eng works to integrate features that provide our partners with the benefits of reusing waste heat sources such as flue gases within the system or facility to improve operating efficiencies.

What Are the Challenges in Operating This Type of Furnace?

These (atmosphere control, maintenance, uptime, and temperature control) are all typical challenges that are addressed in design. The key is to design flexibility, ease of use, and operator-friendly features to avoid problems in the future when the client wants to process different products in a different way.

For Additional information contact:

Tim Donofrio, VP Sales
tdonofrio@can-eng.com
www.can-eng.com