60 Case Shafting Catalog Section Inch/Metric - Thomson - #5

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158 www.danahermotion.com Surface Finish Surface is the key factor affecting travel life, load levels, frictional resistance, and smoothness of travel. Thomson 60 Case shafting is centerless ground for a consistent smooth and industry leading cataloged surface finish of 8 Ra max. Excellent surface finish and hardness maximize the efficiency and life of linear bearings, shaft riding seals, and overall visual appearance. When 8 Ra is not good enough we can provide 6 Ra surface finishes at an additional cost. Smoother equals longer bearing life. Roundness Shaft roundness is vital for linear race applications such as spindles and guide rods where accuracy, life or precision is paramount. Roundness ensures uniform distribution of bearing loads for maximized bearing life, longer travel life and improved positional accuracy. Shafts that look round can be deceiving to the eye and anything but round when properly evaluated, using precision tracing techniques. Thomson 60 Case shaft roundness is within 0.000080” for Class L, S, D, M and .000050” for Class N. Our leading competitors don’t catalog roundness and some are .0002”. Rounder equals longer bearing life. These two graphs taken from a roundness trace display the major roundness difference between Thomson 60 Case LinearRace shafting products and competitor shafting. Straightness Straightness is the most vital parameter to positioning accuracy for a linear ball bushing system. Thomson 60 Case shafts are straight within 0.001” per foot cumulative (TIR .002”) when shipped from the factory. Handling or machining of shafting can cause the material to bend once they leave the factory. When straightness is critical let Danaher Motion provide the special machined shaft; let us machine and straighten the shaft for you using our proprietary straightening and measurement techniques. Our leading competitor does not catalog straightness. Straighter equals higher precision. 60 Case LinearRace shafting is inspected to ensure that it meets the highest quality standards. Standard straightness for all 60 Case LinearRace shafting is .001 inch per foot (25mm/300mm) cumulative .002 inch (50mm) TIR, with special straightness of .0005 inch per foot (12 mm/300mm) cumulative .001 inch (25mm) TIR available. Cylindricity Cylindricity is a measure of the degree of conformance of the outside surface (diameter along the length of the shaft) to a true cylinder. True conformance (high cylindricity) ensures the benefits of roundness, diameter and straightness are present over the shaft length, or working surface, and not just in a particular location. This ensures uniform distribution of bearing loads, increases load capacity in the working area of the bearing, maximizes bearing life, and increases travel life. Taper is a component of cylindricity and all Thomson 60 Case shafts are produced with a maximum taper of 1/2 the diameter tolerance over the entire length of the shaft. In linear bearing applications, taper found in competitor shafting can cause one portion of the linear bearing to be loaded higher than the other. This can cause dramatic reduction in travel life or load capacity. As taper increases, balls go in and out of preload causing premature wear and reduction in travel life. Low Load High Load Outer Race Outer Race Clearance A 0.2 L L 0.2 L B 60 Case LinearRace Competitor Shafting Introduction