High-Volume, Flexibility are New Quality Standards

July 10, 2006
As the expectations rise, fettling systems get more productive, flexible, and precise in the task of cleaning high volumes of castings.

The earliest refrigerators got the job done: they kept food from spoiling, even if by today’s standards they were rather ineffective. No chilled water through the door, no attached freezers or automatic icemakers, and no zoned cooling for fresh vegetables or meats and cheeses. You might make a similar observation about fettling systems. As the capabilities grow more sophisticated, the expectations increase, too.

"Fettling" is the process of cleaning all manner of imperfections from finished cast parts. As castings become more highly engineered, standards for product quality rise, and that includes the surface finishes. The standards for perfecting those finishes are rising, too.

Because product quality is the driving concern, it’s no surprise that automotive castings are in the vanguard of this trend. Maus S.p.A., an Italian machine-tool builder represented in North America by Reich Cos., offers a line of high-production fettling machines tailored to the automotive sector, where high efficiency and high-volume loading/unloading transfers between simultaneously working cells (up to 300 parts/hour) are as much a performance standard as finished product quality.

These machines are designed to be flexible and reconfigurable as the parts in production change. Maus also designs the systems for fettling of interior cavities, using specially shaped tools.

Also, Maus designs fettling machines specifically to cut risers on iron casting. Such equipment is conceived for sturdiness and durability, to remove risers from workpieces up to 220 lb, cutting, fettling, and finishing the part in a continuous cycle.

For jobbing foundries, fettling machines are designed for low- and medium-volume operation with the same options for flexibility and high throughput, and minimal changeover. Maus recently introduced its SAM 300 model, part of a four-axis, CNC series that handles workpieces measuring 100 to 2000 mm (4 to 78 in.) in diameter and weighing 3 to 600 kg (6 to 1,320 lb.). Cycle times vary from 30 sec to 5 minutes, depending on the complexity of the casting.

When the SAM series machines are in operation, the workpiece is clamped to a custom fixture mounted to a standard machine table. The table has XYZ linear movement, and one rotational axis movement. The table moves the workpiece around the fixed position tooling, while the next workpiece is fixed to the transpallet as the first workpiece is being machined.

Each workpiece is laser-gauged and compared with pre-programmed values tuned to a pre-fettled part that is used to set the cutting program. All parameters are monitored and adjusted in real-time during the process.

The OEM trailer business unit of Webb Wheel Products Inc. in Tell City, IN, manufactures brake drums and hubs it supplies to heavy-duty trailer manufacturers. It operates 16 Maus machining centers to turn, drill, grind, and mark ductile- and gray-iron castings.

Webb Wheel’s castings are manufactured into brake drums in over 400 styles, ranging in sizes from 12.2536.00 to 18.0038.00 in.; vented and ribbed transit drums; BTS drums up to 16.5038.62 in. for use with Lynnfin brake turbines; trailer, drive and steering axle hubs; standard and ABS rotors, plus spoke wheels of many types.

Each of the Maus machining cells at Webb Wheel is controlled by a Siemens Sinumerik 840D CNC that monitors axis movement, spindle movement, rotary table positions, transfer lines, ancillary robotics, CMM probing and laser detection orientations. Also, each machining cell can be programmed with the entire work-cycle program for the particular hub or brake drum being produced, sequentially. "When we change production on the cell, we simply create screens for the operator," says Maus marketing manager Sandra Selwan. "On these screens, the operator can answer ‘yes or ‘no,’ in most cases. The standard program on the Siemens CNC interprets the answers and predisposes the cell for the new part." In terms of logistics, David Link, Webb Wheel’s v.p. - manufacturing notes the particular value of the CNC remote controller — a handheld device that allows the operator to interact with the host control panel from various locations on the cell.

Webb uses Maus MTV high-volume machining cells and Maus MTC vertical turning centers with 36-position tool changers, for its hub and brake drum production. The combination reportedly brings valuable flexibility to the Tell City plant, while reducing response times for special orders.

New Options in Vertical and Horizontal Machining

Toyoda Machinery is introducing a new line of vertical machining centers, horizontal machining centers, and grinding technology. Toyoda, one of the world's largest machine tool makers, builds finishing systems used by component suppliers and OEMs in the automotive, aerospace, and general manufacturing segments.

  • Toyoda’s new AF-Series vertical machining centers are being promoted for high-speed machining applications. With cast iron bases and columns, they will offer accurate and long-term service. Their direct-drive 12,000-rpm, temperature-controlled spindles are paired with the Fanuc 18i-MB controls for finishing complex cast shapes.
  • The new BM-1200 vertical machining center delivers superior performance for heavy-duty machining of ferrous materials. The iron base is paired with four Y-axis box guideways to eliminate saddle overhang, and an extra-wide column expands machining capability. Numerous high-torque and direct-drive spindle configurations are available in CAT 40 or CAT 50 tapers.
  • The fast, powerful FH450-S is a 40-taper horizontal machining center with work envelope that's larger than comparable machines, but with a streamlined enclosure that minimizes the floorspace it occupies. It increases product throughput by linking a high-speed spindle with faster non-cutting operations, for cycle times up to 30% faster. Its modular design means it fits flexibly into various manufacturing settings.
  • SelectG is an economical universal grinder designed for flexible, precise, small-lot work. The machine’s wheel-head rotates from 90° to 60° to accommodate a straight or angled wheel, so manual changeovers are simpler. Single-machine capabilities are expanded without the added cost of a full CNC-controlled wheel-head or a second dedicated grinder.