Industrial Oven Control System

I designed and built a Raspberry Pi-based control system to retrofit a 240V, three-phase, 15 kW industrial curing oven, replacing its obsolete standalone PID controller and mechanical timer with a fully programmable, networked controller. Safety drove the design, so I left the independent hardware high-limit completely intact and wired the Pi’s master contactor in series with it, guaranteeing that the hardware can always override the software. I engineered the low-voltage interface between the Pi and a Watlow solid-state power controller through a MOSFET driver stage, and rather than simple on-off switching the software delivers heat with time-proportioned control, easing the six heating elements toward setpoint so the oven follows smooth, repeatable temperature curves. At the heart of the system is a profile engine that runs editable ramp-and-soak recipes, holding controlled ramp rates as the oven climbs, settling into PID-tuned soaks, and constantly watching the rate of temperature change to catch a thermal runaway before it can become unsafe. Redundant dual thermocouples are cross-checked against each other so a single failing sensor cannot mislead the controller, and the thermal behavior of every run is captured on live and historical trend charts. I wrote the full stack in Python with a FastAPI control loop, a PySide6 touchscreen interface at the oven, and a browser-based web app backed by SQLite, adding PDF and Excel run reports, barcode part tracking, power-loss resume, and secure remote access. The system is deployed and running in production on the shop floor, auto-booting on power-up and updating itself from a code repository.