One of the great benefits of a community of heat treaters is the opportunity to challenge old habits and look at new ways of doing things. Heat Treat Today’s 101 Heat Treat Tips is another opportunity to learn the tips, tricks, and hacks shared by some of the industry’s foremost experts.
For Heat Treat Today’s latest round of 101 Heat Treat Tips, click here for the digital edition of the 2020 Heat Treat Today fall issue (also featuring the popular 40 Under 40).
Today’s selection includes tips from Nutec Bickley on how to meet temperature uniformity requirements, and PhoenixTM on how to use “dash cam” tech in your furnace and address the technical challenges in thru-process temperature monitoring.
Heat Treat Tip #6
A Products Eye View in the CAB Furnace Using Optical Profiling
Ever wished you could see what truly happens to your product as it travels through your conveyorized CAB furnace? Well now you can! Thru-process Optical profiling is similar to temperature profiling but instead of measuring the temperature of the product the system records a high-resolution video of the products journey through the furnace. It’s like running your car “Dash Cam” but through the furnace at over 1000°F. The resulting video “Optical Furnace Profile” shows process engineers so much more about how their process is operating without any need to stop, cool and dismantle the furnace. This allows safe routine furnace inspection without any of the problems of costly lost production and days of furnace down time. From the video evidence, the root cause of process problems, possibly already highlighted by running the temperature profile system, can be identified accurately and efficiently. Furnace structural damage or faulty furniture such as recirculating fans, control thermocouples or heater elements can be detected. Buildup of unwanted flux within the furnace can be monitored allowing accurate service and clean down schedules to be planned preventing future unplanned costly line stoppages. Damage or distortion of the conveyor belt compromising the safe smooth transfer of product through the furnace can be isolated with accuracy helping reduce corrective action turnaround times.
(PhoenixTM)
Heat Treat Tip #7
3 Tips to Meet Temperature Uniformity Surveys
- Adjust the burners with some excess air to improve convection.
- Make sure that the low fire adjustment is as small as possible. Since low fire will provide very little energy, it will make the furnace pulse more frequently and this will improve heat transfer by convection and radiation.
- Increase internal pressure. This will “push” heat to dead zones allowing you to increase your coldest thermocouples (typically near the floor and in the corners of the furnace).
(Nutec Bickley)
Heat Treat Tip #12
Temperature Monitoring When the Pressure is On!
high-performance gas quench deflector.
Increasing in popularity in the carburizing market is the use of batch or semi-continuous batch low pressure carburizing furnaces. Following the diffusion, the product is transferred to a high-pressure gas quench chamber where the product is rapidly gas cooled using typically N2 or Helium at up to 20 bar pressure.
In such processes, the technical challenge for thru-process temperature monitoring is twofold. The thermal barrier must be capable of protecting against not only heat during the carburizing but very rapid pressure and temperature changes inflicted by the gas quench. From a data collection perspective to efficiently perform temperature uniformity surveys at different temperature levels in the furnace it is important that temperature readings can be reviewed live from the process but without need for trailing thermocouples.
During the gas quench, the barrier needs to be protected from Nitrogen N2(g) or Helium He(g) gas pressures up to 20 bar. Such pressures on the flat top of the barrier would create excessive stress to the metal work and internal insulation / logger. To protect the barrier therefore a separate gas quench deflector is used. The tapered top plate deflects the gas away from the barrier. The unique Phoenix design means the plate is supported on either four or six support legs. As it is not in contact with the barrier no force is applied directly to the barrier and the force is shared between the support legs. The quench shield in addition to protecting against pressure, also acts as an additional reflective IR shield reducing the rate if IR absorption by the barrier in the vacuum heating chamber.
(PhoenixTM)
