Cobalt Alloy Scissor Blades for Molten Glass

In specialized sectors such as pharmaceutical vials, food-grade condiment bottles, and high-end cosmetic containers, demands for surface smoothness and uniform light transmission in glass bottles are exceptionally stringent. As the initial critical process preceding bottle forming, the cutting quality of molten glass droplets directly determines whether hidden defects—such as striated shear marks or internal microcracks—appear on the bottle body, ultimately impacting product transparency and yield rates.

The temperature of the molten glass shearing process is about 1000°C. The silica in the molten glass exhibits strong abrasive properties, and the high-frequency cutting cycle ranges from 300 to 500 times per minute. Traditional high-speed steel and standard cemented carbide scissor blades remain highly prone to failure under these conditions: high-speed steel softens and deforms above 600°C, resulting in "striated shear marks" that directly compromise the glass's purity and transparency; standard cemented carbide begins to exhibit intergranular adhesion failure around 1000°C. Compounded by frequent tool changes due to rapid wear, this not only reduces production capacity but also risks introducing impurities via tool debris. Metal migration triggered by high-temperature oxidation further forms internal crystalline defects, compromising light transmission uniformity and increasing scrap rates.

Cobalt alloy scissor blades, with their simultaneous resistance to high temperatures, wear, and corrosion, emerge as the core solution for ensuring the premium quality of glass bottles.

Exceptional Red Hardness

Even when directly contacting molten glass at 1000°C, cobalt alloy shears maintain stable hardness at HRC 38–44 without annealing, softening, or deformation. Their clean, precise cutting eliminates striped shear marks. Consistent cutting accuracy prevents stress concentration during subsequent forming, reducing microcrack risks and ensuring uniform light transmission across the entire bottle body.

Exceptional Wear Resistance

Silica abrasives in molten glass, combined with high-frequency impacts at 300–500 times per minute, limit the lifespan of high-speed steel scissor blades to only 8–12 hours. Frequent blade changes not only cause production line downtime but may also introduce debris impurities during replacement, forming internal "stone-like" defects in the glass. Cobalt alloy scissor blades effectively resist abrasive wear and fatigue, significantly extending their service life compared to traditional high-speed steel.

Superior Corrosion Resistance

In high-temperature environments, oxidation of conventional blades causes metal elements like chromium and iron to migrate into molten glass, forming internal crystalline inclusions or compromising light transmission uniformity. Cobalt alloy scissor blades feature a Cr₂O₃ oxide film that acts as a protective barrier, completely isolating the blade substrate from chemical reactions with molten glass and preventing metal migration. Their excellent corrosion resistance makes them fully compatible with molten glass cutting applications.

If you are a glass bottle manufacturer seeking high-end transformation, consider using cobalt alloy scissor blades. Cobalt alloy achieves exceptional red hardness through multi-element synergistic strengthening, delivers outstanding wear resistance due to its composite structure, and offers superior corrosion resistance, bolstered by its high chromium content. Whether mass-producing pharmaceutical vials or precision-manufacturing high-end cosmetic bottles, cobalt alloy scissor blades consistently deliver stable cutting performance. They transform the extreme conditions of molten glass processing into a quality advantage, empowering enterprises to establish core competitiveness in premium markets.