Energy Consumption and CO2 Footprint – Comparison of Selected Furnace and Case-Hardening Concepts

Case hardening is an important process step in gear manufacturing. As it is performed in high temperature furnaces, it is a highly energy intensive process. Nowadays, there are two common process routes, gas carburizing and low-pressure carburizing (LPC). For both processes there is a variety of different equipment types available on the market such as batch furnaces, automated multi-batch furnace lines or continuous pusher type furnaces. But which of them provides the lowest carbon footprint? What are the future energy sources for heating industrial furnaces?

This presentation shows a comparison of energy consumption and carbon footprints for the case hardening process of a typical gear part. The case depth and carburizing temperature are kept constant while only the equipment type varies. Both gas and electrically heated atmosphere furnaces are compared to LPC furnaces in this study. New heating concepts such as hybrid furnaces with both gas and electrical heating installed together in one furnace as well as hydrogen heated furnaces are discussed. Depending on the local electricity mix, differences between countries are highlighted. A short introduction into low-NOx (Nitrogen oxides) clean combustion is given.