Conventionally, at aluminum foundries and diecasters, operators’ attention has focused on improving the energy efficiency of furnace melting chambers, often overlooking waste created in the next process stage: the holding chamber used to control metal purity. Nonferrous furnace designs have treated holding chambers as containment vessels, failing to address their ability to control gas content that may form inclusions. This oversight promotes quality issues to surface in the holding bath that can lead to downstream compromises in final casting integrity.
Redefining melt purity
Nippon Crucible’s proprietary metallurgical technologies are globally recognized by OEM and Tier 1 manufacturers, like Toyota. Its patented Freedom® shaft melter offers metal holding technology that maintains precise atmospheric control, achieving residual oxygen levels of 2% or less (targeting 1.0%.) Operating at a controlled ambient temperature of 770ºC, the holding chamber creates an optimal environment that actively prevents the formation of inclusions and gas absorption. It’s an innovative approach that transforms the holding chamber from a passive storage space to an active quality control component.
In contrast to conventional systems that expose holding chambers to contamination from exhaust gases and ambient air, the Freedom® shaft melter’s independent chamber design achieves previously unattainable levels of melt quality. It consistently delivers K-mold ratings of Rank A (K value < 0.1) and a hydrogen gas content of 0.2 cc/100 g Al or less — metrics directly linked to superior casting quality and reduced defect rates.
Controlling oxygen concentration is critical for melt quality. Complete isolation of the chamber prevents exhaust gas infiltration, and a specialized dam at the inflow effectively blocks aluminum dross migration from the melting chamber, preserving melt cleanliness without requiring special treatment. In practice, even after six months of continuous operation without cleaning, the oxide film on the molten metal surface remained manageable at just 3- to 5-mm thick – and the adhered dross was soft enough to allow easy removal from the furnace walls.
In addition to those document quality improvements, the holding technology realizes temperature stability within ±3ºC at the tapping point, thanks to the independent chamber design. Its thermal efficiency is measured at 50% or greater due to an integrated heat exchanger, compared to 40% or less in conventional furnaces.
The Freedom design offers a melting yield of 99% or higher due to improved efficiency and reduced dross formation.
Thermal efficiency and energy management
The system’s advanced thermal management maintains consistent molten metal temperatures between chambers, significantly reducing the load on the holding chamber burner. An integrated heat exchanger maximizes heat recovery from exhaust gases, resulting in superior thermal efficiency of 50% or greater—a notable improvement over conventional furnaces that operate at 40% or less.
The Freedom® shaft melter design minimizes maintenance requirements while enhancing operational efficiency:
- Reduced cleaning requirements in the holding chamber due to superior oxide control
- Lower aluminum loss through reduced dross formation
- Enhanced melting efficiency with minimal unmelted metal residue
- Improved working environment through advanced atmospheric control
- Consistent melt quality without the need for special treatments.
For automotive OEM and Tier 1 manufacturers needing exceptionally clean aluminum for structural and safety-critical components, the Freedom® shaft melter provides unequaled control over critical quality parameters. Manufactured and serviced exclusively by SINC Thermal in the United States, this system represents significant progress in aluminum melt management technology, offering measurable improvements in quality, efficiency, and operational performance.