en.Wedoany.com Reported - Mitsui Seiki USA has introduced the PJ 303X five-axis ultra-precision vertical machining center, equipped with an automation system that delivers the highest accuracy and versatility when machining workpieces up to 230mm (9 inches) in height, 280mm (11 inches) in diameter, and 20kg (44 lbs) in weight. This system is suitable for machining critical components such as lens molds, medical products, EDM electrodes, and fuel cell assemblies. From September 14 to 19, 2026, visitors can watch live demonstrations at Booth 338700 in the South Hall of McCormick Place in Chicago.
Although the industry generally believes that Mitsui Seiki machine tools are primarily used for heavy cutting of large critical components, the PJ303X is specifically designed for precision machining of small parts, with positioning accuracy and repeatability reaching ±0.001 mm. High-speed linear motors drive the X, Y, and Z axes, with travels of 300 mm (11.8 inches), 325 mm (12.8 inches), and 200 mm (7.9 inches) respectively, and rapid traverse speeds of 20 m/min (66 ft/min). In applications requiring tight tolerances and complex geometries, the linear axes can feed material at extremely low feed rates approaching 0.1 mm/min, enabling operators to machine fine features and perform finishing processes. The PJ 303X provides precise rotary axis control at the low-speed end, achieving smooth five-axis interpolation on critical features, improving surface finish and dimensional accuracy. The absolute glass scale feedback system determines the exact axis position for each job, enabling full closed-loop control without the need for additional programming after each startup.
A 50,000 rpm, HSK-E25 taper spindle provides high-speed machining capability. Advanced spindle thermal displacement technology is standard, including a symmetrical gantry column structure that adapts to thermal deformation fluctuations and a thermal compensation mechanism for the spindle/spindle head.
Operator-friendly features include a 15-inch color touchscreen that can be moved to the most convenient position. The control system is the new FANUC F31i-B5 equipped with an i-H Pro control panel. The machine's two-stage rotating door provides a wide field of view and setup access. The automatic tool changer can accommodate up to 24 tools, with a maximum tool diameter of 40mm (1.57 inches) and length of 100mm (3.9 inches).
Yasuhide Akimoto, Executive Vice President of Mitsui Seiki, stated that the design of the PJ303X combines ultra-precision machining with modern automation strategies. For medical, optical, and advanced technology manufacturers, it offers a scalable platform that delivers uncompromising accuracy, process stability, and production efficiency while meeting the industry's most stringent quality requirements.
