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SPRING 2019

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Distributor's Link Magazine Spring 2019 / Vol 42 No2

168 THE DISTRIBUTOR’S

168 THE DISTRIBUTOR’S LINK SPIROL HOW TO CALCULATE THE ESTIMATED FATIGUE LIFE OF A DISC SPRING from page 146 FIGURE 4: EXCERPT FROM SPECIFICATION CHART IN SPIROL’S DISC SPRING CATALOG Example 2 Estimate the fatigue life of the same DIN EN 16983 Series B Group 2, DSC 50 x 25.4 x 2 Disc Spring with a preload of 25% of its initial height with a final position at 50% of its initial height. The maximum differential in stress occurs again at location III. Referencing the fatigue life chart in Figure 5 and plotting 430 N/mm² on the X-axis and 810 N/mm² on the Y-axis, the intersection of the lines is slightly below the 2 million cycle line; therefore the estimated fatigue life is over 2 million cycles. These examples highlight how a reduction in deflection results in an increase in fatigue life. Life charts are based on laboratory testing performed on single Discs at room temperature. Testing is done at a frequency that does not result in heat buildup. Test Discs are lubricated and tested on polished anvils; actual fatigue life is likely to be different than values estimated in the fatigue life charts. These charts are valid for single Discs and stacks of a maximum of (10) Disc Springs in series. Discs Springs stacked in parallel will have reduced fatigue life due to heat buildup resulting from friction. MAXIMUM DIFFERENTIAL STRESS, N/mm² FIGURE 5: ESTIMATED FATIGUE LIFE FOR DSC 50 X 25.4 X 2 DISC SPRING IN EXAMPLE 2 Summary FATIGUE LIFE CHART: GROUP 2 1.25mm ≤ t ≤ 6.0mm MINIMUM TENSILE STRESS, N/mm² Deflection range of the Disc Spring determines its fatigue life. Increasing final load increases stress in the Disc Spring resulting in lower fatigue life. Increasing preload reduces deflection resulting in increased fatigue life. The guidelines provided in this paper are general in nature. Testing is necessary under actual conditions to verify fatigue estimates. SPIROL INTERNATIONAL CORP.

Navy SEAL…Army Ranger… Air Force Tactical Controller… Ultra-marathoner. That can only describe one man: David Goggins. The Specialty Tools and Fasteners Distributors Association, (STAFDA) will welcome him to its 43rd Annual Convention & Trade Show, November 10-12, at the Music City Convention Center in downtown Nashville. Goggins will address STAFDA attendees during his keynote presentation at the General Session on Monday, November 11, which is also Veteran’s Day. Soldiers are the toughest breed on the planet, but this man is the toughest among them. He fought for America for 21 years, has completed over 60 ultra-marathons, triathlons, and ultratriathlons, setting new course records and regularly placing in the top five. That’s why he’s dubbed the toughest man in the world and Outside magazine calls him the “Fittest (Real) Man in America.” Sadly, poverty, prejudice, and physical abuse colored his childhood, but through self-discipline, mental toughness, and hard work, Goggins transformed himself from a depressed, overweight young man with no future into a U.S. Armed Forces icon and one of the world’s top endurance athletes. He has a huge Instagram following and is one of the country’s most sought after speakers: from addressing Fortune 500 companies, to sports teams, and on November 11, STAFDA members. Goggins is all about shutting up the voice in your head that says “I can’t do this.” He has some of the most motivating and “hair-on-the-back-ofyour-neck” raising stories but his big message is that the only person in control of your destiny is YOU. STAFDA’s 43rd Annual Convention & Trade Show in Nashville is for members only! Registration materials will be mailed to all members in late June; online registration opens on Monday, June 24, at 8:00am (Central) from the members-only section of www.stafda.org. For more information contact STAFDA by Tel: 1-800-352-2981, Fax: 262-784-5059, Email: info@ stafda.org or visit them online at www.stafda.org. THE DISTRIBUTOR’S LINK 169

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