Mesh belt furnaces are the workhorse of the heat treating industry. With constant pressure to enhance performance and develop quality products, mesh belt furnaces are keeping up with the demand. In this article written by Tim Donofrio, vice president of Sales at CAN-ENG Furnaces International Limited, discover the ways mesh belt furnaces are addressing demands for innovation and quality.
This Technical Tuesday article appeared in Heat Treat Today’s February 2022 Air & Atmosphere Furnace Systems print edition.
Vice President of Sales
Can-Eng Furnaces International
Source: Can-Eng Furnaces International Ltd.
Introduction
Manufacturers of high volume, high strength metal components constantly face increasing pressures to improve and develop enhanced performance and quality products while simultaneously addressing cost pressures placed upon them. The quality products include cold-formed automotive fasteners and clips, construction nails and screws, cutting and timing chain products, drive system gears, and bearing components, to mention a few. These reference components all require different types of heat treatment processes that impart a unique thermal profile which results in making the component stronger, tougher, more flexible, resistant to wear and corrosion, and improves the overall life of the component.
Mesh Belt Furnaces — Background
Mesh belt furnaces are synonymous with high volume heat treatment of formed, forged, and machined metal components that require soft handling methods to prevent part damage during processing. Furthermore, these systems are well equipped with features that reduce the opportunity for part mixing and contamination within the system. Modern mesh belt furnaces have been put into production around the world to achieve capacities from 100 lb/hr to 7000 lb/hr. Manufacturers today often favor higher capacity heat treatment systems as they offer more efficient returns on investment over lower capacity systems. The heat treatment processes ideally suited for mesh belt furnace systems include neutral hardening, marquenching, austempering, light case carburizing, carbonitriding, carbon restoration, normalizing, and tempering. In most cases, these processes include a multi-step process which involves heating the product to austenitizing temperatures under a reducing or carbon rich atmosphere, followed by an automatic transfer for drop from the furnace belt conveyor into a liquid quench conveyor system where the material transformation takes place. Quench systems vary in size and capacities and are custom designed around the product being heat treated. Design features may include agitation, fluid flow, and conveyor design which can greatly influence the quench speed and material transformation that results in the final physical properties achieved through quenching. Mesh belt heat treatment systems can implement various quench medias that include oil, polymer, water, and molten salts.
Mesh Belt Furnaces — Benefits
Mesh belt furnace benefits have grown significantly from their earlier developments that targeted reduced part damage and part mixing potential. Today, users are exploiting the benefits associated with increased part size range processing flexibility and capability. In the early days, part processing size range was limited to parts that weighed less than 1lb and were less than 4” in length. Today, with design enhancements, users can now process a product range that includes part sections ranging from 3/16” to 1-3/8”, part lengths up to 12” long, and part weights exceeding 2.5lbs each. This increased processing flexibility is made possible through the integration of modernized automated loading and transfer systems that minimize part drop heights and inertia, ensure precise loading, convey, and distribute products that protect against part damage while also ensuring dimensional stability is maintained to acceptable levels.
Additional advancements in the application and use of molten salt quenching have been recently exploited in response to the demand for low distortion and low residual stress level part processing. These demands are largely a result of customers’ needs to engineer products that outlive and outperform previous designs. This is largely a result of recent advancements made to support the shift in transportation technology; most noticeably, vehicle electrification and increased demands of vehicle propulsion systems. This has resulted in improved austemper and martemper technologies, paving the way for new molten salt handling designs that increase the overall safety and use of the systems. Specifically, new techniques for molten salt quench agitation, distribution, and quench drop chute fluid control have greatly improved the controllability of these systems and have also greatly improved the maintainability which has traditionally been difficult for users of previous designs.
Conclusion
It is well understood that the mesh belt furnace design provides significant benefits over other continuous and batch type processing systems for processing high volume and high-quality components that require exact metallurgical properties. The benefits of this system are immense, and system customization allows for further benefits to be integrated. The benefits discussed earlier represent recent advancements made to the mesh belt atmosphere furnace system that users are enjoying today. It should be recognized that several other design benefits also include:
- Electrical heating systems, natural gas, and atmosphere reduction systems as a means of reducing users’ carbon footprint
- Improved temperature uniformity of systems to support the expectations of the Automotive Industry Action Group (AIAG) CQI-9 guidelines
- Hybrid quenching systems that allow for greater processing flexibility and sophisticated Industry 4.0 diagnostics, reporting and data archiving of equipment conditions, and process and product processing attributes
In closing, there are many options available to manufacturers requiring heat treating processes; therefore, the benefits of the mesh belt atmosphere heat treatment system should be strongly considered when seeking out the lowest cost of ownership for manufacturing processes.
About the Author:
Tim Donofrio, vice president of Sales at CAN-ENG Furnaces International Limited, has more than 30 years of thermal processing equipment experience. Throughout his career, he has held various positions within the custom engineered forging, commercial heat treating services, and custom engineered heat treating equipment industries.
Contact Tim at tdonofrio@CAN-ENG.com or (905) 380-6526.
