Industrial Heating

40 MAY 2015 ■ IndustrialHeating.com

A

condition-based maintenance strategy for vacuum
pumps used in vacuum furnaces is enabled by a vibration
monitoring system. This allows company maintenance
departments to proactively participate with efficient
and predictive allocation of resources because they will now
focus more on planned downtimes instead of troubleshooting to
recover from unplanned downtimes.

Vacuum in Heat-Treatment Applications
Vacuum furnaces are utilized for a broad application range
these days.
One driver for vacuum furnaces is the increasing demand
coming from the aerospace and automotive industries, where
modern components need to fulfill standards that can only
be reached by vacuum heat treatment. Unexpected furnace
downtime creates high costs because each production step is
just-in-time.
Va r iou s heat-treatment applications create different
challenges for the utilized vacuum systems. One could cluster

the applications roughly in three different groups.

• Standard applications (e.g., tempering, annealing,
  hardening): Media entering the vacuum system are mainly
  air and humidity. Only the smallest amounts of other
  vapors or particles can be expected.


• Medium applications (e.g., brazing, soldering, nitriding):
  Furnace outgassing contains aggressive vapors such as f lux
  agents and ammonia. Significant amounts of vapors with
  potential to condense inside the pump can be expected.


• Harsh applications (e.g., sintering, MIM, carburizing):
  The furnace outgassing contains particles and vapors that
  tend to crack and build layers inside the vacuum pumps.

While all types of vacuum pumps typically perform well in

standard applications, it is important to select the right vacuum-

pump system for medium and harsh applications to have the

ability to handle the specific outgassing. The risk of unexpected

furnace downtime can be reduced by selecting the right pump

type supported by an efficient and reliable maintenance strategy.

Thomas Knecht – Oerlikon Leybold Vacuum
GmbH; Cologne, GERMANY

Dry-compression vacuum pumps represent a perfect  t in
supporting medium to harsh conditions in vacuum heat-
treating applications by o ering low operating costs and
high reliability.

Condition-Based Maintenance

Strategy for Dry Vacuum

Pumps in Furnaces

VACUUM/SURFACE

TREATING

Fig. 1. Layout of the DRYVAC screw pump featuring rotors with progressive pitch profile and integrated, frequency-converter-driven high-efficiency motor