We consider ourselves fortunate to offer the North American casting industry the ingenuity behind the melting furnaces developed by Nippon Crucible Corporation. It all began several years ago with the introduction of the Jet Melter® furnace, followed by the subsequent evolution into the Freedom Furnace.
What’s so innovative? Ask a furnace operator. The Freedom Furnace has reduced holding chamber cleaning frequencies from once per shift to once every 6 months. In one case seen by the author this was extended to an 18-month period to verify the technology of a new furnace.
Cleaning the dross from melting and holding furnaces is a necessary part of the overall maintenance regime required to ensure the best quality metal and the longest possible life for an expensive asset. Cleaning the holding chamber is a tough and uncomfortable task for furnace operators and anything that makes this task easier and less frequent has significant effects on both operator and furnace efficiency as well as overall operating and energy costs.
Extending the cleaning cycle from every shift to every six months may seem too good to be true, but in fact, is made possible by world-class engineering of the holding chamber and burner design. The resulting outcome:
- Removes or reduces the amount of oxygen present in the holding chamber by separating the melting, holding and pocket chambers to avoid air ingress.
- Avoids surface impingement on the metal bath by strategically locating burners.
- Runs burners as close to stoichiometric as possible.
- Avoids air flow into the chamber when burners are off or idling on low fire.
This patented development has created significant savings in energy, operator time and effort and very importantly, metal loss and metal quality and consequent cost savings for the foundry by:
- Reducing operator time to clean the holding bath.
- Avoiding excessive production downtime for cleaning
- Improving metal quality through reduced inclusions from cleaning
- Reduced metal loss from oxidation (dross) removed during cleaning.
- Better energy efficiency from closed holding chamber
- Reduced flux usage in cleaning the holding bath.
The accompany series of images documents that the amount of dross produced during continuous aluminum melting remained virtually the same over the course of 18 months.
