So you need to replace the molybdenum (moly) elements in your vacuum furnace, but as expected, you don’t want to break any of your components. We don’t blame you! To help make you the shop floor’s go-to-guy, we have some expert tips on how to avoid several removal process mishaps.
1. Run an anneal cycle on the hot zone.
The most beneficial step to perform during the moly element replacement process is to run an anneal cycle on the hot zone. Doing so minimizes the potential for broken components during disassembly and tremendously eases the work process.
The recommended cycle is as follows:
- Slowly heat up to above the recrystallization temperature of standard moly (1,800 °F [82 °C]), or lanthanum-doped moly (2,250 °F [1,232 °C])
- Soak at temperature for one hour
- Vacuum cool to ambient
2. Spray your furnace’s moly hardware, but not with oil!
Moly hardware connects most power feedthroughs and moly elements. Once you disconnect the moly element from the power feedthroughs, you can loosen the hardware by spraying the moly-threaded rods and nuts with alcohol or acetone. Alcohol and acetone evaporate cleanly and leave the parts and hot zone contaminant free. Avoid using WD-40 and other oil-based cleaners as these contaminate the parts and the hot zone.
3. Use the “one-hand” method to loosen hardware.
If possible (and based on the position and location of the moly hardware), the mechanic should place the wrenches on opposing nuts to be loosened in the “scissors” orientation. Next, use the squeeze of one hand to break the nuts loose.
Using one hand equalizes the pressure applied to the hardware and can reduce tool slippage, element breakage and personal injury. If jumpers are part of your configuration, you need to disconnect the moly hardware from them as well.
4. Listen for the tick!
If you ever hear a ticking sound while installing moly hardware, this indicates the hardware has cracked and, though it may appear to be intact, will fail when heated again. When replacing moly elements, you should not reuse the connecting moly hardware – namely nuts and bolts – due to their brittle nature from being brought to temperatures above recrystallization. It is better to replace any hardware that might have experienced microstructure cracking during disassembly and re-assembly.
Once you have completed the above steps and disconnected everything, remove the element retainer wires, hold-down rods and other devices.
The removal and replacement of heating elements is tricky, but following the outlined procedures can alleviate some of your frustrations. To help you be prepared for anything that might happen, Ipsen also offers element strip kits that come equipped with the parts and hardware most likely to be broken or damaged during the moly element replacement process.
Need to replace graphite elements? This short video walks you through the do’s and don’ts for removing and installing graphite elements.
For more information on replacing your heating elements or Ipsen’s element strip kits, contact our experts by calling Ipsen’s Aftermarket Support Helpline at 1-844-Go-Ipsen (Toll Free: 1- 844-464-7736; International: +1 815-332-2530) or filling out our Ask an Expert form at www.IpsenUSA.com/Ask-an-Expert.