Midwest Manufacturing News • Nov 23 • CNC Jig Grinder Offers Flexibility

The high-performance Mitsui Seiki J350G jig grinder offers a combination of application flexibility, accuracy, reli- ability and operator-friendly operation, the company reported.

“The machine’s grinding infeed stroke is the largest available among competing machines, with a U-axis range of -3 mm to +50 mm relative to the spindle center,” said a company spokesperson. This provides the flexi- bility to grind small and large diame- ter 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 com- ing 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” 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 meth- ods.

“Jig grinders are the most common machine type in small shops and large factories. Our CNC J350G provides the ability to grind a wide variety of fea- tures automatically, without changing wheels,” said Bill Malanche, Mitsui Seiki USA COO. “It provides the flexi- bility required in today’s manufactur- ing environment.”

To maximize 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 maximize positioning accuracy. The machine bed consists of a thick, rigid casting supported by three level points, offer- ing consistent perpendicularity and parallelism. Built-in, custom-designed HEIDENHAIN scales contribute to +/- 0.0007 mm accuracy on the X-, Y- and Z-axes.

Table longitudinal travel (X-axis) is 500 mm, transverse travel (Y-axis) is 300 mm and quill travel (Z-axis) is 100 mm. Maximum distance from the table surface to the grinding spindle nose is 450 mm. The machine’s work surface is 700 mm x 350 mm and permissi- ble table load is 300 kg. Table and saddle maximum rapid feed rates are 2,000 mm/min and grinding feedrates are variable from 0.1 mm/min to 2,000 mm/ min. The standard high-fre- quency spindle motor operates from 9,000 RPM to 45,000 RPM. Spindle motor options include an air-turbine motor with 75,000 RPM capability.

The machine’s 3 sq. m (2,220 mm x 2,610 mm) footprint is 50% smaller than that of the previous model, maximizing floor space efficiency. A standard total en- closure machine cover permits easy op- erator access while addressing safety and environmental concerns.