Article From: 9/17/2012 Production Machining, Chris Felix, Associate Editor
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What tooling do a multi-spindle automatic, a CNC lathe and a vertical machining center have in common? The answer is S-pads. S-pads can be shared between many brands of machines, whether the master collet is mounted directly in a machine spindle (single or multiple), in a collet adaptation chuck, or in a collet block. And pads can be considerably faster to change from job to job than collets.
Hardinge Style-S master collets use interchangeable pads. The S-pads can be changed without removing the master collet from the spindle, thus reducing change-over time. On an eight-spindle automatic, all the pads can be changed in 15-30 minutes as compared with the 2-3 hours it would take to change the solid collets. The dovetail anchor design securely holds the pad in place and cannot be dislodged under normal use. This design eliminates any pressure on the clamp.
Style-S master collets and pads were designed to eliminate issues created by pre-existing master collet designs. When loading bars, the rugged shoulder of the pad locates against the front of the groove in the master collet. There are no set screws or clamps to be damaged or loosened. When a part is machined, the working forces are against the rear shoulder of the pad that is located against the rear shoulder of the groove in the master collet. The clamp that holds the pads in the collet floats longitudinally, ensuring that there is never any pressure on the clamp. There are no holes in the OD of the master, or on the ID of the pads, resulting in maximum bearing on the workpiece and the spindle collet seat.
Hardened pads are available in round, hex and square with smooth or serrated order holes and can be custom-made for extruded stock. Style-S master collets and pads can be a good fit when other quick-change systems cannot be used because of budget restrictions or tool clearance issues.
The Style-S master collet, although originally designed for multi-spindle automatic screw machines, offers many benefits to the CNC lathe and vertical machining center operator as well. The collet pads can be changed more quickly than a standard collet, the cost is lower, and the pads require much less storage space. Standard S-pads from Hardinge are hardened and ground for a long life. Semi-hard and soft emergency pads can be bored to size on the machine for the best possible concentricity. Hardinge has a dedicated S-pad manufacturing cell enabling the company to maintain stock availability on more than 1,000 sizes of S-pads, in a variety of styles.
The S-pads are available in S10 through S50 sizes to fit Hardinge style-S master collets used in screw machines and CNC lathes. Style-S master collets designed for Hardinge collet-ready CNC lathes are available in 16C, 20C, 25C, B42 and B65. HCAC collet adaptation chucks are available for chuck-style lathes to accept Style-S master collets and pads. S-pads can also be used in the FlexC collet blocks, as well as 16C collet blocks, for three- and four-axis milling applications. The company provides stock delivery of the most popular sizes and quick turnaround for decimal sizes and specials. Pads are available in round, hexagon and square with smooth or serrated order holes and special shapes.