Alloy Engineering Blog

Weighing Advantages of Fabricated Batch Rotary Retorts

Several factors should be taken into consideration when deciding what retort is best for your application. For years, cast retorts were the only option, and even when fabricated retorts made their entrance into the market in the mid-1990s, cast retorts were still considered as a lower cost alternative for longer run applications in the metal-producing and heat treating industries. However, years of experience and data support the long term advantages of fabricated rotary retorts versus cast retorts.

Fabricated Batch Rotary Retort

Alloy Engineering (AECo) has been fabricating batch retorts for over 24 years. The design of fabricated batch rotary retorts for furnaces has been continually refined and enhanced over that period of time. Each design addresses specific application needs and has proven to maximize production and retort life. All indicators point to fabricated batch and continuous retorts as more efficient, longer lasting, and with greater flexibility than cast retorts.

Batch rotary retorts are used in carburizing and hardening furnaces used by manufacturers of ball and roller bearings, chains, fasteners, and automotive components. These replacements have proven to surpass the life cycle of cast retorts by up to 400% and, in many cases, cut production costs by up to 50%.

How? Well, a fabricated retort can be efficiently modified to meet increased production requirements. The size of the retort body can be increased, for example, to adapt for a larger batch load. A new casting mold would have to be formed to accomplish the same goal – at a greater expense and a longer lead time. Wrought retorts can be fabricated in as little as 12-14 weeks, which is a major advantage.

It’s also difficult to control the microstructure of cast retorts, while those fabricated from wrought materials have a homogeneous, small and tight grain microstructure that has proved to be highly resistant to the extreme furnace environments. The integrity of the wrought material results in fewer origination points for thermal stresses which can cause premature equipment failure. That ductility of the material resists thermal fatigue and thermal shock which translates into increased uptime and thus a lower cost/hour. Wrought retorts can also be routinely rebuilt in the failed areas, salvaging the remainder of the fabrication, which results in a lower overall cost of multiple retort purchases.

The fabricated batch rotary and continuous retorts also have a smoother, less porous, and more consistent surface finish than cast retorts. This helps to avoid focal points for the initiation of corrosion or areas for stress concentration in material fatigue situations. There is also less potential for marking of parts during production because of the smoother surface. Wrought retorts also weigh less and heat up faster than cast retorts, which is ideal for shorter cycle times.

Many of the features and benefits of fabricated batch retorts are the same as those provided by rotary retorts for continuous furnaces. Alloy Engineering’s advanced fabrication techniques minimize welding requirements. Optional equipment and accessories include support roller shafts, gas inlet tubes, discharge chutes, and charge chutes.

AECo has been fabricating high-temperature alloy furnace components since 1943. We have been developing and designing batch rotary retorts and continuous rotary retorts for high-temperature applications since 1995. We are experts at examining how systems and parts wear – and finding ways to improve them. Our focus is continuous improvement – and extended life cycles for the products we produce.

Our engineers will work with you to determine whether cast or wrought retorts are the best way to go for your particular needs. Depending on the application, sometimes cast will last longer. Our engineers have the expertise to determine the best option—even if the selection is not us.

 Rotary Retort Literature