Sakai aluminium Corporation

Refining"Cojunal®"

Cojunal® is an aluminum refining technology based on the principle of segregation and solidification, which we were the first company in the world to successfully commercialize. The Cojunal® refining plant produces 99.99% to 99.999% (4N to 5N) pure aluminum ingots from 99.9%(3N) pure ore. The refined ingots are used as raw materials for high-purity aluminum products such as aluminium foil for electrolytic capacitors.

Melting and Casting

The raw materials are melted in a melting furnace, and the molten metal which has had its composition adjusted in a holding furnace is poured into a mold where slabs (rectangular-shaped ingots) are cast semi-continuously. Before casting, the molten metal is dehydrogenated using GBF® and filtered to remove non-metallic inclusions.
*GBF® (Gas Bubbling Filtration) is a molten metal dehydrogenation and inclusion removal technology using inert gas blowing developed by our company.

Hot Rolling

A slab heated to a high temperature is repeatedly rolled to a thickness of about 3 to 8 mm, and then wound into a coil. By using an emulsion that combines cooling and lubricating properties as the rolling oil, stable dimensional accuracy and excellent surface quality can be obtained. Based on the technology and know-how cultivated over many years, we are working to further improve the quality level and develop new products.

Cold Rolling

After hot rolling, the coil is rolled at room temperature to make it even thinner. Automatic thickness control (AGC) and automatic shape control (AFC) are used to produce high precision, high quality sheet coils with minimal thickness variation and width distortion. This is one of the most important processes that greatly affects the quality of the final product, and we are constantly making improvements.

Foil Rolling

After cold rolling, the coil is rolled at room temperature in order to make it even thinner to achieve the final product thickness. In addition to ensuring dimensional accuracy through automatic thickness control (AGC) and automatic shape control (AFC), this is an important process that determines surface quality, and our facilities are filled with a wealth of know-how in both hardware and software.

Slitter

This is the process of cutting the pre-washed coil into pieces of the specified size and winding them. By optimizing the blade design and cutting conditions, sharp cuts are achieved in a wide range of alloys and thicknesses. The slitter is installed in a cleanroom to prevent contamination by foreign substances. In addition, surface defect detectors are used to detect and remove abnormalities such as holes, scratches, and stains.

Annealing (Foil)

This is the process of heat-treating coils that have been cut by the slitter in an inert atmosphere. To meet the high quality requirements for the surface oxide film and crystal grain structure of the aluminum foil, production is carried out under optimal conditions with thorough controls. We often use bell-type furnaces, which have excellent airtightness and energy efficiency.

High-purity Aluminium Foils

High-purity aluminium foil for electrolytic capacitors

Tension Leveler

This process corrects the distortion and warpage of sheets by repeatedly bending the coil while applying tension after cold rolling. Since the coil is processed in a continuous manner, it is more productive than a stretcher that tensions and straightens the cut sheet. A washing system is installed before the leveler to prevent foreign substances from entering the leveler rolls and causing surface defects due to the accumulation of dirt.

Shearing

Coils are continuously processed into cut sheets of predetermined dimensions. The width and length are cut by the shear force generated by sandwiching between the upper and lower two blades. By adjusting the clearance and angle of the two blades, the cutting surface can be finished in a straight line with a sharp cut. Also, dust prevention is thoroughly implemented to prevent foreign matter from entering the product.

Annealing (Sheets)

This is the process of heat-treating cut sheets and coils after shearing. In order to stably produce products that meet high quality requirements (mechanical properties, formability, etc.), we set optimal conditions and conduct thorough facility and condition management.

Aluminium Sheets

High heat conduction, high strength material ST60: heat dissipation sheets for PCs and car navigation systems, cases and buttons for smartphones and cell phones, etc.