Client request
A physics lab needed a compact vacuum oven with a relatively large chamber that could reach 500 °C while maintaining pressure down to about 850 mTorr. There was no commercial unit available in the lab, so a custom system was required.

Design & build
A laboratory vacuum oven has been designed and built that meets these requirements. The main design decisions were:

A rectangular sheet-metal housing was designed in SolidWorks to support the chamber, insulation, and electrical components. The body was fabricated, bent, welded, and painted in the workshop based on these drawings.

A cylindrical 316 stainless-steel chamber (~5 mm wall thickness) has been installed inside the housing to provide chemical resistance and long-term corrosion protection. A port at the top of the chamber was included for a thermocouple to directly monitor internal temperature.
Band-type electric heaters have been mounted around the chamber wall to provide uniform heating up to 500 °C.
The chamber has been wrapped with rock-wool insulation to reduce heat loss and prevent the external body from overheating.
An electrical control system has been implemented using a contactor, fuse, and programmable temperature controller to regulate the set-point and heater power.
A vacuum line has been added using a cross-shaped steel connection welded to the chamber, with one valve connected to the vacuum pump, a second valve for venting, and a vacuum gauge on top to monitor pressure.
After final assembly and installation in the lab, the oven has been tested at different temperatures and pressures and has reliably reached 500 °C and ~850 mTorr.

Issue resolved
Initial tests showed that the three small clamps on the chamber lid could not maintain a stable vacuum. These clamps have been replaced with larger, stronger ones, which has eliminated the leakage problem and allowed the system to hold vacuum consistently during operation.

Final look:

Vacuum Oven for Lab