Super IQ®: The Next Step in Integral Quench Furnaces

Integral-quench furnaces (or IQ furnaces) are universal in heat treating facilities since they provide seamless hardening. They are proven as high production units with known maintenance costs, understood safety issues and with advent of oxygen sensors two decades ago, provide good repeatability.

However, while IQ furnaces are the workhorse of heat treating for high volume processes like carburizing and through-hardening, their performance has known limitations and represent the highest maintenance item in a heat treat shop. If one tries to increase production by speeding carburizing diffusion, the higher temperatures result in exponential damage to the alloys inside the furnace, further increasing maintenance costs.  Common practice is to always keep these furnaces running so as to not upset the delicate balance inside the atmosphere, which adds to operating costs over weekends or slow periods.

Atmosphere carburizing furnaces are plagued by high IGO (Intergranular Oxidation) and wide variety of case depth. Often a wider range of hardness case depths up to 0.5mm [0.020”] are used to cover process issues). Special shapes can be difficult to evenly carburize. 

Finally. many aspects of the atmosphere carburizing process have troublesome environmental problems relating to waste gases, safety issues related to flames and toxic gases, ergonomics issues related to high plant heat, flame curtains, and smell, and general discomfort related to potential hazards, like idling below 1400F with high hydrogen atmosphere. 

A Better Option

The proven SECO/VACUUM Super IQ furnace provides some significant upgrades on the limitations of current integral quench furnaces.  The unit uses a low-pressure processing chamber together with a positive pressure inert atmosphere oil quench tank (See Image 1). The Super IQ can replace existing units and work with existing loaders and is modular so it can fit where it is needed.  It can handle gross loads up to 3500 lbs. in the 36 x 36 x 48-inch workload capacity.  The low-pressure furnace uses nitrogen and acetylene, so endothermic generators are not required.

More Processing Capability and Flexibility

The Super IQ receives loads in the vestibule over the quench tank for a nitrogen purge before being transferred into the heating chamber. Once sealed in the heating chamber, heating begins in nitrogen to heat the load uniformly. Low pressure levels are achieved at elevated temperatures and acetylene carburizing can begin. The stages of “Boost and Diffuse” are pre-deterimined with some of the most sophisticated software and simulators in the industry, representing decades of learning and experience. After the heating period the load is transferred to the vestibule, lowered into the quench for highly agitated cooling in standard quench oils, then raised, and offloaded.

The unit can operate at temperatures over up to 2000° F for greater processing flexibility including tool steels and performing other processes like stainless annealing, etc., all without increasing maintenance needs

The low-pressure operation of the units provides another key advantage since there is no conditioning required. The units can stop and start at any time without any quality or time penalty and a changeover to different types of loads can be accommodated at any time.  This capability provides a huge flexibility boost for scheduling. 

Improved Quality

The Super IQ provides better quality parts with less variation in case depth (See Image2) without issues with microstructure like intergranular oxidation (See Image 3) and decarb.  This is due to the inherently better control of the gases in a low-pressure furnace and elimination of oxygen. Super IQ parts are much cleaner after heat treating. The furnace meets Class 2 AMS 2750F requirements.

Less Environmental Concern

With the Super IQ there are no open flames, no atmosphere burn-off, no CO in the plant and no high heat sources with the water-cooled walls. Endothermic generators are not needed.

Less Operating Costs

With increased productivity afforded with faster processing, especially deeper carburized cases, the Super IQ can produce more in less time, translating to a potential of $200,000 per year improvement in profit or avoidance in external processing costs (for captives).  Together with the affordable initial price and no endothermic generator needed, Super IQ is an easy decision for any commercial or and captive heat-treating facility.

Image 1: The Modular Super IQ Fits into Your Current Operations 

 
Image 2: Improved Consistency of Case Depth with the Super IQ. 

 
Image 3: Reduced IGO Using the Super IQ.

Comparing the intergranulation oxidation on the surface of a traditional integral quench furnace (Figure a at left) with the unaltered surface of the Super IQ (Figure b at right)

Image 4: Cleaner Parts after Processing

This image shows a comparison of traditional integral quench parts appearance at left and the Super IQ at right. In the inset it shows the parts pre- and post-heat treatment.