Pre-process Pump Down
By Jim Grann, Technical Director
Q: In the aerospace industry, we often must subscribe to the customer’s tight tolerances and adhere to documented recipes. Deviating from those recipes to account for humidity would require extensive documentation and paperwork, possibly even re-qualification of the process. Are there any other tips or tricks in the humid summer months that you might recommend that can keep water vapor out of the furnace chamber between loading and unloading that wouldn’t require altering the proven and accepted recipe?
Aerospace companies (along with many other customers) are very particular about how their precision parts are processed, and for good reason. Hundreds of thousands of people rely on their systems to work invisibly and relentlessly in order to ensure the safety and reliability of their aircraft. Precision isn’t an option, and mandatory documentation helps the customer ensure precision.
Once the customer’s parts are in the furnace and the heat is on, that documentation is counting on the heat-treating process to track every minor deviation from the recipe. Small changes can make a big difference in the long-term durability of their parts. But up until the actual heating elements turn on, the preparation of the furnace environment remains in the operator’s hands.
One technique that has proven to be successful for Ipsen furnace operators in high-humidity environments has been to start each process with a vacuum cool event. The process of pumping duration is not normally considered part of the cycle. Reaching specific vacuum levels and maintaining them during the heat-treating process, however, is a part of the recipe.
Without turning on the heating elements, taking 30 minutes to achieve a lower vacuum within the furnace will accelerate water droplet evaporation, helping to considerably evacuate the vessel of retained water vapor within the hot zone. From that point, operators can start the heat-treating recipe with confidence that the process will begin from a consistently dry starting point every time.
Taking a bit of additional time at the beginning of a cycle, prior to energizing the heating elements, is a winning strategy. The time invested up front will reduce cycle holds caused by outgassing limits being activated, yield cleaner parts, and increase hot zone longevity.
If you’re struggling to keep atmospheric contaminants out of your furnace, or have another puzzle that we can help you solve, call us for technical support. Our support hotline is 844-Go-Ipsen, or fill our our online form.