Honing Capabilaity

"One Source — Many Solutions" takes on added meaning at MAG with the addition of honing capability on MAG's automotive industry machines, according to the company. This new machining center solution provides a complete process, potentially eliminating secondary honing machines for the manufacture of engine cylinder and crankshaft bores.

MAG says it is one of the leading providers of systems for high-volume production of engine and powertrain components, and has always approached this business emphasizing complete, customized solutions. Those solutions are now even more complete with the addition of honing capability on MAG machining centers. This means that every process, from the machining of castings to the finishing of cylinder and crankshaft bores, can now be conducted on CNC machining centers. The new process uses a combination of fine-drilling and honing on a single machine. The optimization and interlinking of the two operations brings about a significant reduction in cycle time.

"During the past few months, our experts have been working on finding a solution to the specific requirements for machine kinematics, the machining spindle, tools and the control and regulation concept," explained Dr. Tobias Abeln, Engineering Manager at MAG's Eislingen operation. "We have now reached the point where we can produce bore geometries and surface finishes to the same quality as when using conventional honing machines, and we can do so in a distinctly shorter period of time with significantly lower costs."

Honing is always required when bores must meet high-end requirements for size, cylinder form and specific surface parameters. One of the primary application areas is the finishing of cylinder and crank bores made of cast iron, aluminum alloys and ferrous layers. In volume production, these features are typically finish machined on special honing machines in a secondary operation.

MAG's goal, of course, was to integrate this bore finishing operation on a single machine, which required overcoming the hurdles of adding the honing process management functions to a machining center. By executing fine-drilling and honing operations on a clamped workpiece, the universal-jointed honing tool connection required for compensating any differences in positioning can be dispensed with. This eliminates high-cost hinged tool connections, and tools can be changed quickly and automatically with tool orientation unaffected by position and gravitational force.

The necessary modifications on the basic machining center are relatively few. These included integration of in-process air gaging technology and an electromechanical actuation system for the spindle, using a push-pull rod, needed to actuate the honing tool. This spindle is also designed for other applications that require a geometrically-specific cutting edge, such as valve-seat machining (e.g., turning of valve seats on CNC machines) and the machining of bores with defined contours (e.g., boring of 3-D contours).

Honing capability adds a small cost premium to the machining center, but it is comparatively small when taking into account that separate honing machines and their coolant supplies are eliminated from the manufacturing line. That's not all. Because of the energy-optimization features of the new Specht generation, savings up to US$76,000 can be achieved over a comparable system with separate honing machine, at an annual production volume of 500,000 units.