Grinding Journal - Summer 2007 - (Page 11)

Summer 2007 (commonly called a “dog bone” outside Dirats Laboratories). The blank may be cut from the sample material with wire EDM or abrasive waterjet. But to create the final form the blank must be ground, and with a minimum of residual stress, which would affect the test results. Minimizing stress is also critical because Dirats Laboratories must be able to duplicate the specimen exactly, even if the subsequent job is months later. Otherwise the test results can not be compared. Geometric tolerances are not particularly tight and the specimen only has to fit the testing stand. But it’s a challenge to duplicate the metallurgical properties of a series of parts, especially when they are hard to machine. That’s a major reason Dirats Laboratories has its own machine shop in the first place. And it’s a major reason a Studer S31 cylindrical grinder is at its heart. As stable as a Swiss mountain and as accurate as William Tell The Swiss obsession with accuracy might even predate William Tell’s legendary 14th century marksmanship (he shot an apple off his son’s head with a crossbow). Let’s just say it runs deep at Studer – based in Thun, Switzerland. The Studer S31’s unique GRANITAN base dampens any vibration. Its proven knobbed guideway system virtually eliminates “slip-stick.” The FANUC 21i control and glass scales on the X & Y axes assure precise positioning. Every aspect of the grinding process can be monitored and controlled, like achieving a constant wheel speed through a grind. Coolant delivery is excellent. And key components are manufactured to the highest tolerances. For example, the roundness of the workhead spindle is accurate within 0.000,004 inches (0.0001 mm) and the conical tolerance over 10 inches of taper is 0.000,08 inches (pictured to the left) The Studer S31 grinds the midsection of a test bar and then the groove in one setup, thanks to a rotating head with twin spindles. Besides flexibility, it’s the rock-solid repeatability of the machine that gets top billing. Grinding Journal 11

Table of Contents Feed for the Digital Edition of Grinding Journal - Summer 2007

Contents My Thoughts Exactly When Lives Are at Stake Walter Consolidating Production The Art of Grinding: Knowing the Source of Grinding Errors and How to Fix Them The How and Why of Conventional Vitrified Grinding Wheel Selection Grinding Glass Flat Problem Solver

Grinding Journal - Summer 2007

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