The Hardinge Group Blog

As parts get more and more complex, you will see part tolerances get tighter than ever. We’ve all seen the (+ -) .0001” size on a turn or bore, but what about concentricity? Quite often, it’s a call out that’s just plain missed. Catching the spec is one thing, meeting it is another.

Here’s some helpful ideas.

First of all, concentricity starts with “round” features. Remember, you cannot check for concentricity between two journals; maybe the spec is .0003” if one of the journals has .0004” run out in itself.

Second, boring the spindle tooling while positioned in the spindle, especially for the 2nd chucking, is a must. If you’re talking .001”, probably not needed, but if the print calls for .0004” concentricity or less, bore the spindle tooling and your success rate goes up.

Third, for the most demanding concentricity specifications, machine all the critical features together. This trick is pretty well understood in this industry but be careful, it’s not a 100% guarantee. There are a lot of factors that affect concentricity, Example: Balance, tool pressure, excessive part clamping pressures, to name a few….…

We are often asked the question What makes a “high-performance” turning center a high performer from our customers?

The Answer:

It’s having the latest technological components designed into and built into the machine. This way the entire structure becomes a single harmonious entity. Plus including other factors that few builders offer, such as a collet-ready spindle for direct use of a collet (no spindle adaptation chuck), allows the workpiece to be gripped and machined as close to the spindle bearings as possible.  In fact, gripping a part with a collet is the preferred method for high-precision machining. This ability further enhances the tolerance and surface finish capability and allows effective turning of hardened metals, further reducing or eliminating costly grinding operations. A high-performance machine also has features such as linear scales, unique ESA precision tooling and top plate system, Harcrete polymer composite filled in strategic areas of the cast iron base, high grade linear guides, ball screws and guide trucks. Plus the collet-ready spindle is driven by a perfectly matched motor and drive system for optimum speed and torque. High-pressure and through-spindle coolant capabilities help during the machining process to keep chips flowing away from the machining area, while maintaining proper cutting temperature.

A machine’s design should also included the latest software design platform and FEA (finite element analysis) techniques to accurately depict the structural deflection, stress levels, thermal response and vibration response of the assembled components and the assembled machine. Extreme-case loadings should also be used to verify adverse machining conditions. Every machine produced receives laser calibration to the X and Z-axis to ensure positioning accuracy and straightness. Accuracy certification is included as assurance of machine accuracy. Size repeatability, surface finish quality and thermal stability are a hallmark for Hardinge RS-Series turning centers which truly is a High-Performance turning center.