20k 178 mm dia unshaped cyl horn driven at nonaxial resonance with excessive joint loss (HRD-073-4) FEA - see Black 3-ring "Cyl horn" notebook P&G 20k eared 1-slot 4.5" wide bar horn with excessive joint loss FEA - see Black 3-ring "Bar horn" notebook 20k square spool with joint galling FEA - see Black 3-ring "Bar horn" notebook https://tributek.us/product/high-pressure-silicone-ultrasonic-stack-grease/ The Great Ultrasonic Stack Joint Debate: Who should you listen to? (Tom Kirkland, Tributek) http://archive.plasticsdecorating.com/articlesdisplay.asp?ID=111 Pig horn (4 or 6 tip horns on mother horn) Significantly better performance when reduced joint contact area. Branson SN_proj E:\websites\usr\_design_info\Fatigue\Branson\SN_proj\Lovett3.90 - reducing xdu contact dia with 40 kHz SN horn reduced joint temp (16.5mm = best) Torques Sonics and Materials - 'Model 1098 press (20 khz)'.pdf (p. 13) <-- need actual article in References http://www.dukane.com/us/se_stackarticle.htm Reconditioning surfaces Sonics and Materials - 'Model 1098 press (20 khz)'.pdf (p. 20) 400 or finer grit, figure-8 stroke pattern http://www.emersonindustrial.com/en-US/documentcenter/BransonUltrasonics/Plastic%20Joining/Ultrasonics/Technologies/TL-3_Horn_Troubleshooting.pdf 400 grit, linear stroke pattern Interface washers http://www.emersonindustrial.com/en-US/documentcenter/BransonUltrasonics/Plastic%20Joining/Ultrasonics/Technologies/TL-13_Acoustic_Interface_Washers.pdf (I have this pdf) Find picture of spanner fixture (S&M?) Dukane has a stainless steel tool vise (Part No. UFTV20.) for clamping 20kHz boosters and transducers to facilitate disassembly of stubborn components without damage. (p. 17) http://www.dukanestore.com/Tooling-Vise--20-kHz_p_59.html Branson image p. 35 (Branson - '250 - 450 Sonifier, Analog Cell Disruptor User's Manual, Rev. C (2011)'.pdf) https://tributek.us/product-category/sonication-parts-supplies/page/2/ In general, can the static tightening (axial) force at a joint be made large enough so that the static transverse frictional break-away force is sufficiently large that no joint slippage can occur (hence no fretting)? If so, should joints be assembled without lubricants? Molykote -- Follow up with Keith Anderson ========================================= E. C. Fitch, Tribolics, Inc. - Fretting Wear in Lubricated Systems (http://www.machinerylubrication.com/Read/693/fretting-wear) Because virtually all machines vibrate, fretting occurs in joints that are bolted, pinned, press-fitted, keyed and riveted; between components that are not intended to move; in oscillating splines, couplings, bearings, clutches, spindles and seals; and in base plates, universal joints and shackles. Fretting wear is a surface-to-surface type of wear and is greatly affected by the displacement amplitude, normal loading, material properties, number of cycles, humidity and lubrication. Fretting wear occurs as a result of the following sequence of events: 1. The applied normal load causes asperities to adhere, and the tangential oscillatory motion shears the asperities and generates wear debris that accumulates. 2. The surviving (harder) asperities eventually act on the smooth softer surfaces causing them to undergo plastic deformation, create voids, propagate cracks and shear off sheets of particles which also accumulate in depressed portions of the surfaces. 3. Once the particles have accumulated sufficiently to span the gap between the surfaces, abrasion wear occurs and the wear zone spreads laterally. 4. As adhesion, delamination and abrasion wear continue, wear debris can no longer be contained in the initial zone and it escapes into surrounding valleys. 5. Because the maximum stress is at the center, the geometry becomes curved, micropits form and these coalesce into larger and deeper pits. Finally, depending on the displacement of the tangential motion, worm tracks or even large fissures can be generated in one or both surfaces. Changes in the normal load generally affect fretting wear. Although equipment users often presume that high normal loads will dampen vibration sufficiently to reduce fretting, the increase in contact area produces more surface interaction which tends to outweigh this effect. Consequently, increasing load or unit pressures tend to generate higher wear rates as Figure 3 shows. Lubricant Influences on Fretting Fretting seems to progress more rapidly in friction couples that have smooth surface finishes and close fits. Lubricants do not penetrate wear areas with small clearances (described as close fits). In addition, the smooth finish eliminates lubricant-retaining pockets between the asperities in rougher surfaces. Under these conditions only boundary lubrication condition, the continuous interaction of oil wetted surfaces, can be achieved. Lubricants are not always successful because the reciprocating action squeezes out the lubricant film and does not allow it to be replenished. In general, the purpose of the lubricant in most fretting situations is to prevent oxygen from reaching the fretting surface and the wear debris. Liquid lubricants with effective metal deactivator additives can help to reduce the effect of fretting but will not likely stop fretting altogether. This article originally appeared as a chapter in E.C. Fitch's book, Proactive Maintenance for Mechanical Systems. 1992. =========================================