Overview of Common Vacuum Furnace Equipment

Vacuum furnaces are available in numerous styles and sizes and come in both standard and custom configurations. They are designed to process an almost limitless number of both semi-finished component parts as well as raw materials using a diverse set of thermal processes in equipment available from a wide variety of different equipment manufacturers located around the world.

The intent here is to provide a brief overview of some of the more common designs and applications found throughout the heat-treatment industry. The hope is that the reader will come away with an understanding that there is a vacuum furnace solution to virtually any design, application or specification encountered.

Why Vacuum?

Historically, vacuum heat-treating applications were classified in one of four areas, namely processes that could be:

• Performed using no technology other than vacuum
• Done better in vacuum from a metallurgical perspective
• Done better in vacuum from an economic standpoint
• Done better in vacuum from a surface enhancement perspective

Today, given the demands for productivity and flexibility vacuum heat-treatment has been the preferred choice by the heat-treat industry. This is due to a number of reasons, not the least of which is that the technology (and hence the end result of the heat treatment process) now rests in the machine and not with the individual operating it. The drivers for vacuum technology are:

• Process control (i.e., accuracy)
• Process repeatability,
• Up-time reliability
• Adaptability to new materials, new processes and new recipes
• Integration with manufacturing
• Reduced environmental impact.

All of these factors have resulted in a strong economic advantage for vacuum processing driven by higher productivity, less distortion and decreased cycle times.

Vacuum Furnace Design

The main components of a vacuum furnace (Fig. 1) include, but are often not limited to, the following subsystems:

Vacuum vessel (aka shell)