As the metals industry moves toward more sustainable production, induction furnaces are a top choice for energy efficiency and lower emissions.
To perform at their best with longevity, induction furnaces rely on ramming mass linings that resist heat and wear.
Incorporating boron into ramming mass formulations strengthens the lining, extending the furnace’s service life and reducing operational downtime.
What is ramming mass?
Ramming mass is a monolithic refractory used to line induction furnaces for melting steel and recycled scrap metal.
It is a mixture of raw materials such as silica, alumina, or magnesia and binders such as boron. Most formulations are silica-based and are compacted or “rammed” around the induction coil. This process creates a seamless, joint-free lining that protects the coil from molten metal.
Compared to brick or castable refractories, ramming mass offers several advantages:
- Faster installation and sintering to reduce downtime and accelerate production
- Smooth, crack-resistant surfaces for consistent melting and longer lining life
- Efficient heat transfer to improve energy use and furnace performance
Ultimately, the effectiveness of ramming mass depends on how well its ingredients bond and endure extreme heat—qualities that boron significantly enhances.
How boron works in ramming mass
Boron is an important additive in ramming mass formulations because it:
- Enhances thermal shock resistance
- Improves sintering behavior
- Supports structural stability
Together, these properties help the lining maintain strength through repeated melt cycles.
During mixing and ramming, boron acts as a dry binder, helping silica grains pack tightly and evenly. This creates a smooth, dense lining—key for efficient heat transfer and reduced wear.
As the furnace temperature rises (around 500-700° C), boric oxide—whether added directly or formed from boric acid—reacts with the silica grains to create a borosilicate glass phase. This glassy phase flows into microscopic gaps and pores between the grains, sealing the structure into a dense, cohesive layer.
During normal heating and cooling cycles, the boron-rich glass phase flexes with temperature changes, absorbing stress and preventing cracking that can lead to downtime.
Why refinement matters
Impurities in ramming mass formulations degrade performance and lining durability. Contaminants can shorten operating life and cause more frequent maintenance.
U.S. Borax products are refined to remove these impurities and ensure consistent quality.
| Contaminant |
Effect |
Manufacturing impact |
| Iron (Fe) |
Increases eddy current losses, creating localized hot spots near the coil |
Wastes power and may lead to overheating or uneven melting |
| Sodium (Na) |
Lowers the refractory’s softening point |
The lining may slump or deform during extended high-heat cycles |
| Sulfates (SO4) |
Promotes porosity during firing |
Molten metal and slag can penetrate and weaken the lining |
| Chlorides (Cl) |
Causes uneven melting in the glass phase, resulting in bonding issues |
Leads to patchy erosion and premature wear |
Learn more about boron in metallurgy
Choosing the right borate for ramming mass
Two U.S. Borax products are well-suited for refractory formulations:
Many scrap metal manufacturers and pre-mix ramming mass producers prefer boric oxide for ramming mass formulations because it has been shown to increase lining life by 10-20%, depending on furnace design and scrap composition. Because boric oxide contains no water, it leads to denser ramming mass liner, longer service life, and fewer shutdowns.
Picking the right mesh size depends on your manufacturing environment.
- 60-mesh: Fine, uniform dispersion for rapid melting and even sintering
- 4-mesh: A coarser grade option that offers flexibility for localized milling to achieve the desired PSD, while being more resistant to caking during extended storage periods
U.S. Borax: Your refractory solutions partner
Refined borates add lasting value as they help extend lining life, reduce maintenance costs, and improve operational efficiency.
At U.S. Borax, we manage the full value chain—from boron minerals to quality boric oxide—ensuring stable feedstock, consistent quality, and trusted supply for the refractory industry.
Our technical experts work directly with you to optimize ramming mass formulations and match specific process or equipment requirements.
If you’re ready to enhance your ramming mass, contact our team.
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