* If you are having trouble viewing this e-mail, click here.
* To make sure you continue to receive our e-mails in your inbox (not sent to bulk or junk folders), please add newsletter@vacaeronews.com to your address book. Click here for more information.
* At VAC AERO International Inc., we practice permission-based marketing. To unsubscribe, please click here.
* To log on to the VAC AERO web site, please click here.
|
November 2008 |
905-827-4171 |
|
|
|
|
|
|
Maintenance Procedures for Vacuum Furnaces Part 3 - Minimizing Outgassing
|
 |
Whenever the door to a vacuum furnace chamber is open, humidity from the air will enter the chamber and condense in a very thin film on the chamber walls or be absorbed into the hot zone materials.
When the chamber is subsequently evacuated (before heating) and the furnace internals are exposed to this lower pressure, “outgassing” of the entrapped moisture will occur. If sufficient moisture has been entrapped (such as in very humid environments), the outgassing effect will slow the pumpdown process and may even give the appearance of a malfunction in the pumping system. Eventually, the outgassed moisture will be pulled out of the chamber by the pumping system and evacuation rates will improve. This same effect will be apparent when oily or contaminated workloads are placed in the furnace. It may be more pronounced in furnaces with graphite-based hot zone insulation materials. READ MORE
This is the third in a series of four articles on Vacuum Furnace Maintenance. (read part 1) / (read part 2) |
|
|
Preparation for Vacuum Brazing - Part 3
|
 |
Clean, oxide-free surfaces are essential to achieve sound brazed joints.
Uniform capillary action will occur only when all grease, oil, dirt and oxides have been removed from both the braze alloy and base metal prior to brazing. The length of time that cleaning remains effective depends on the material involved, atmospheric conditions, storage techniques and the amount of handling that may be involved. It is recommended that brazing be performed as soon as possible after the material has been cleaned. The selection of a cleaning technique depends on the nature of the contaminant, the base metals involved and the joint design. The same cleaning practices used for vacuum heat treating (ie. manual cleaning, vapour degreasing, etc.) are applicable to vacuum brazing. READ MORE
This is the third in a series of four articles on Vacuum Brazing Tecniques. ((read part 1) / (read part 2)
|
|
|
|
