Machinery Lubrication magazine published by Noria Corporation
Issue link: https://www.e-digitaleditions.com/i/1378657
and greater skill. Factoring in size, color, heat tinting, slide orientation, texture and count, plus an array of other features in the same debris field, is the tribologist's task. Yet, we don't really have many formally trained tribologists in condition monitoring. e recently published standard ASTM D7684, Microscopic Characterization of Parti- cles from In-Service Lubricants, went far to add greater granularity and guidance, as shown in the examples below from its classification grid: • Color and texture: pitted, striated, smeared, tempered, colors from transmitted and reflected light • Shapes: platelet, ribbons, chunks, spheres, etc. • Composition: ferrous, cupric, sludge, dust, etc. • Wear modes: abrasion, mild sliding, severe sliding, rolling contact (subsurface spall) • Two-dimensional aspect ratio (minimum to maximum) and particle size distribution Even with the help of D7684, many lab analysts fail to connect the dots between wear debris characterization and the needed main- tenance response. Often, connecting the dots requires the aid of careful machine inspection and findings from other condition monitoring methods (vibe, etc.). Introducing the WPCD Table The discussion that follows offers some valuable tips on how to get more condition monitoring value from wear particle analysis and identification. A high percentage of wear particles found in in-service lubricating oils are produced from pure sliding contact (abrasion and adhesion), rolling contact (Hertzian) or various mixtures of the two. erefore, this article will focus specifically on particle gener- ation mechanisms from machine surfaces in various states of rolling and sliding contact. To streamline the discussion, I'm not going to include the following types of particles, which will be addressed at a later time: • Laminar particles. Reworked by over- rolling. • Cutting wear particles. Usually, the result of hard particles interposed between sliding surfaces. • Spherical particles. A complex and still generally misunderstood subject. • Break-in particles. An artifact of running in new machines (gears primarily). • Soft particles. Also known as varnish potential. • Terrain dust. is is a huge topic — the cause of wear but not the product of wear. Table 1 shows five Contact Dynamics Zones. e top zone is 100% rolling contact, and the bottom is 100% sliding contact. e three middle zones are binary mixtures of the two. I have added examples of where they might be found in common machines. ese zones also appear on the Wear Particle Contact Dynamic (WPCD) table in Table 2. e five columns across the top of the WPCD table are Wear Protection States, ranging from no protection to high protection. Based on the well-known Stribeck Curve (AK A the ZN/P curve), these states are directly influenced by oil viscosity, surface speed, contact load and ZONE ROLLING CONTACT SLIDING CONTACT EXAMPLE LOCATIONS A 100% 0% Rolling cam follower, roller bearing (load zone), spur gear pitch line B 75% 25% Rolling-element bearings, most gear-mesh contacts (root to tip), hydraulic pumps (rotating), screw compressors, some mechanical couplings C 50% 50% D 25% 75% E 0% 100% Sliding cam follower, pump swash plate, bearing cage, piston/cylinder, worm gearing, journal bearings, chains Table 1 Example locations of contact dynamics zones in lubricated Machines. ML GROUP PUBLISHER Brett O'Kelley - bokelley@noria.com SENIOR EDITOR Jim Fitch - jfitch@noria.com EDITORS Nick Holder - nholder@noria.com Marissa Menge - mmenge@noria.com Hayden Beeson - hbeeson@noria.com Kate Perryman - kperryman@noria.com TECHNICAL WRITERS Wes Cash - wcash@noria.com Bennett Fitch - bfitch@noria.com Matthew Adams - madams@noria.com Devin Jarrett - djarrett@noria.com Travis Richardson - trichardson@noria.com Paul Farless - pfarless@noria.com CREATIVE DIRECTOR Josh Couch - jcouch@noria.com GRAPHIC ARTISTS Patrick Clark - pclark@noria.com Matt Berkenbile - mberkenbile@noria.com ADVERTISING SALES Brett O'Kelley - bokelley@noria.com MEDIA PRODUCTION COORDINATOR Sheryl Adekoya - sadekoya@noria.com CORRESPONDENCE You may address articles, case studies, special requests and other correspondence to: Editor MACHINERY LUBRICATION Noria Corporation 1328 E. 43rd Court • Tulsa, Oklahoma 74105 Phone: 918-749-1400 Fax: 918-746-0925 Email address: editor@noria.com MACHINERY LUBRICATION Volume 24 - Issue 3 May - June 2021 ( USPS 021-695) is published bimonthly by Noria Corporation, 1328 E. 43rd Court, Tulsa, OK 74105-4124. Periodicals postage paid at Tulsa, OK and additional mailing offices. POSTMASTER: Send address changes and form 3579 to MACHINERY LUBRICATION, 1328 E. 43rd Court, Tulsa, OK 74105-4124. SUBSCRIBER SERVICES: The publisher reserves the right to accept or reject any subscription. Send subscription orders, change of address and all subscription-related correspondence to: : Noria Corporation, 1328 E. 43rd Court, Tulsa OK 74105-4124. 918-749- 1400 or Fax: 918-746-0925 Copyright © 2021 Noria Corporation. Noria, Machinery Lubrica - tion and associated logos are trademarks of Noria Corporation. All rights reserved. Reproduction in whole or in part in any form or medium without express written permission of Noria Corpo- ration is prohibited. Machinery Lubrication is an independently produced publication of Noria Corporation. Noria Corporation reserves the right, with respect to submissions, to revise, republish and authorize its readers to use the tips and articles submitted for personal and commercial use. The opinions of those interviewed and those who write articles for this magazine are not necessarily shared by Noria Corporation. CONTENT NOTICE: The recommendations and information provided in Machinery Lubrication and its related information properties do not purport to address all of the safety concerns that may exist. It is the responsibility of the user to follow appro - priate safety and health practices. Further, Noria does not make any representations, warranties, express or implied, regarding the accuracy, completeness or suitability of the information or recommendations provided herewith. Noria shall not be liable for any injuries, loss of profits, business, goodwill, data, interruption of business, nor for incidental or consequential merchantability or fitness of purpose, or damages related to the use of information or recommendations provided.