The new high-performance Mitsui Seiki
J350G jig grinder offers a combination of application flexibility, accuracy, reliability and operator-friendly operation. The machine’s grinding infeed stroke is the largest available among competing machines, with a U-axis range of -3 to +50mm relative to the spindle centre. This provides the flexibility to grind small and large diameter holes, as well as multiple features, using a single wheel in a continuous, automatic mode.
According to Japanese company Mitsui Seiki, many legacy jig grinders are currently coming offline in shops and manufacturers are looking to replace them with those featuring advanced CNC controls. To that end, the J350G’s Fanuc 31i-B control has a 15in touch panel LCD screen and is preloaded with ‘G-MAPS’ conversational-style programming software. The control also permits easy manual programming via graphic icons, data entry, or conventional methods.
Bill Malanche, Mitsui Seiki USA chief operating officer, said: “Jig grinders are the most common machine type in small shops and large factories — most have at least one. Our new CNC J350G provides the ability to grind a wide variety of features automatically, without changing wheels and has the flexibility required in today’s demanding manufacturing environment.”
To maximise accuracy, the X and Y axes of the J350G are hand-scraped and incorporate needle roller bearings. Left and right slide ways are V-F flat shaped, and the Y-axis (spindle head motion) is V-V shaped to maximise positioning accuracy. The machine bed consists of a thick, highly rigid casting supported by three level points, assuring consistent perpendicularity and parallelism. Built-in, custom-designed Heidenhain scales contribute to +/-0.0007mm accuracy on the X, Y and Z axes.
The X, Y and Z-axis travels are 500 x 300m x 100mm and the maximum distance from the table surface to the grinding spindle nose is 450mm. The machine’s work surface is 700 x 350mm and permissible table load is 300kg. Table and saddle maximum rapid feed rates are 2,000mm/min and grinding feed rates are variable from 0.1mm/min to 2,000 mm/min. The standard high-frequency spindle motor operates from 9,000-45,000rpm. A variety of spindle motor options include an air-turbine motor with 75,000rpm capability.
The machine’s 3m2
footprint is 50% smaller than that of the previous model, maximising floor space efficiency and a standard total enclosure machine cover permits easy operator access while fully addressing safety and environmental concerns.