CNC Jig Grinder offers flexibility and accuracy

The high-performance Mitsui Seiki J350G jig grinder is said to offer a combination of application flexibility, accuracy, reliability and operator-friendly operation.

The machine’s grinding in-feed stroke is one of the largest available among competing machines, with a U-axis range of -3mm 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 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 15-inch 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.

“Jig grinders are the most common machine type in small shops and large factories. Most have at least one. Our CNC J350G provides the ability to grind a wide variety of features automatically, without changing wheels,” said Mitsui Seiki USA chief operating officer Bill Malanche. “It provides the flexibility required in today’s manufacturing environment.”

To maximise accuracy, the X- and Y-axes of 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.

Table longitudinal travel (X-axis) is 500mm, transverse travel (Y-axis) is 300mm, and quill travel (Z-axis) is 100mm. Maximum distance from the table surface to the grinding spindle nose is 450mm. The machine’s work surface is 700mm x 350mm and permissible table load is 300kg. Table and saddle maximum rapid feed rates are 2,000 mm/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 rpm – 45,000 rpm. A variety of spindle motor options include an air-turbine motor with 75,000 rpm capability.

The machine’s 3m2 (2,220mm x 2,610mm) footprint is 50 percent smaller than that of the previous model, maximizing floor space efficiency. A standard total enclosure machine cover permits easy operator access while fully addressing safety and environmental concerns.

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