Page 1
Page 1
IRG-WOEM OECD
European Tribology Research Group Conference
The IRG-WOEM OECD Group held their 27th meeting from September 30th to October 1st at the Federal Institute for Materials Research and Testing (BAM for Bundesanstalt Fur Materialforshung und-prufung) in Berlin, Germany. The acronym for the group means: Industrial Research Group, Wear of Engineering Materials – Office of European Common Development. Essentially, the group was started to address common tribology problems and research among European countries. Somehow the group expanded so that there are country representatives in the USA and other non-European countries. The group has undertaken projects in the past, like interlaboratory wear tests, but in the last decade or so, the group meets about once every two years and attendance is usually 20 to 40 people. There were about 25 people in attendance at BAM.
The hosting IRG member was Dr. Ing Mathias Woydt and he started the program of 22 technical presentations by attendees with an overview of BAM. The organization was formed about 1880 as a testing organization for German rulers at the time. They tested materials of construction and materials for military use. Mathias pointed out that some very famous material researchers worked at BAM including Stribeck of Stribeck Curve fame and Martens who identified the hard phase in steel that was named after him: martensite. Mathias even passed around August 1888 journals containing some of Marten’s work. He was also interested in tribology. One journal contained a detailed drawing of one of his wear testers. Mathias also mentioned that Stribeck invented the 52100 alloy steel that has been the basis for most rolling element bearings for many decades.
The current mission of BAM is materials research as well as testing. There are a number of campuses in Berlin and their budget is about 100 million Euros. Our meeting was held in Fabeckstrat campus, a former American hospital. The technical program was followed by a tour of their tribology labs. They have some very unique capabilities including wear testers that work up to 1400oC and down to 4.2oK. They have high and not-so high vacuum tribometers and many special pin-on-disk and conforming surface wear testers as well as commercial testers such as SRV and Amsler machines. Of course, they have complete analytical capabilities to identify friction and wear byproducts.
The technical sessions were in three categories:
- Tribotesting
- Tribotesting out of usual scales
- Wear mechanisms and modeling
The following are some of the “notes” I made during the presentations. The complete presentations will be posted on the group’s web site.
- The static coefficient of friction of skin varies from 0.22 to 2.1; the kinetic varies from 0.9 to 3.6 and anatomical location makes a difference.
- Nickel matrix cermets Ni/CrC are being studied as replacements for WC/Co because of the economic and availability problems with tungsten and cobalt.
- Ecole Centrale de Lyon has the capability to perform wear tests of tribocouples immersed in automotive fuels. They are studying fuel pump materials at present.
- The tribology community needs to develop tribocoatings to allow sliding components in MEMS and NEMS. Currently, they can only get motion through the use of flexures.
- Many people are using diamond scratching devices to simulate abrasion by a single asperity on hard particles. However, diamonds wear and need frequent checks for flat spots.
- Friction measurements obtained on mass-loaded tribometers need to be corrected for increases in force due to inertia effects. One way to address this problem is to vary the mass in tests and use the slope of the friction force versus normal force plot as the coefficient of friction for the system.
- MOMs (metal-on-metal couples) are still being researched for orthopedic prosthesis to solve the particle problem with metal-on-plastic devices.
- Abrasion occurs in MOM’s.
- Partial slip fretting (5 to 10 µm promotes fatigue (pitting) while gross slip (>25 µm) fretting produces wear.
- Nano-fretting is a new type of fretting obtained by vibrating nano-indentors during indentation.
- Some triboelements like 10 m diameter dam bearings need large scale tests (1.5 GPa normal force) because edge effects occur at high load and not on low-load bench tests.
- Ceramic-on-ceramic hip and knee replacements produce the least particles and osteolytis.
- Eighty percent of all cutting tools are PVD or CVD coated, but only 2% of wear parts are coated; why?
- If you replace the top ball in a 4-ball test with a hardened steel cone, you end up with a pitting test.
- Anti-wear additions in automotive oils do not work on PVD/CVD coatings.
- Thermal sprays now include nanoparticles that stay “nano” in the deposit.
Overall, this meeting of the IRG-WOEM OECD Group was very successful. Our BAM hosts were most gracious; the facilities and food were excellent. The conference secretary, Amilcar Romalho (University of Coimbra) did a great job in coordinating the event and the group president, Ian Hutchings (Cambridge University) stated that the group will meet again within the next two years – someplace.
ASTM G2 Meeting, November 20-21
St. Louis, MO
The ASTM G2 Committee on Wear and Erosion had their Fall 2008 meeting at the ASTM Committee week in St. Louis, Missouri in the U.S.A. The following is a synopsis of what transpired at the various subcommittee meetings and some comments of news and announcements from ASTM staff.
- Abrasion Activities:
The St. Louis meeting was chaired by Steve Shaffer (Battelle). Steve identified the standards that need ballot action:
- G171 scratch testing – Peter Blau, technical contact..
- G 65 dry sand rubber wheel abrasion test – Mike Anderson, Falex, technical contact.
- G174 loop abrasion test – Ken Budinski, Bud Labs, technical contact.
Peter described needed changes to the G171 standard and said that it will be reballoted in the next main and subcommittee ballot.
Mike Anderson stated that the rubber wheel used in G 65 is still a problem. The sole supplier of the special rubber has decided to not supply any G 65 wheels in the future. Brian Merkle (Nanosteel) made a slide presentation on a significant study on the G 65 test outlining potential sources of error and variability. His paper will be posted on the G 2 website under additional information.
Steve Shaffer obtained a commitment from Akron Rubber to make wheels to the G 65 formulation for $475.00 (for two). Mike Anderson will follow-up on this lead and will possibly buy some wheels to evaluate. There are other issues with the G 65 spec, such as, sand flow and Durometer tolerances, but rubber availability needs priority attention.
Ken Budinski reported that he revised the G 174 standard and it can be reballoted at will.
- Erosion activities:
Paul Swanson, Consultant, chaired the St. Louis meeting. Subcommittee activity is still centered around possible revisions to the G 32 vibratory horn cavitation standard. Scott Hummel proposed a virtual meeting of the cavitation task group before the spring meeting to address the issues on a case-by-case basis. Paul Swanson will work with ASTM Staff Manager, Kate McClung, to make the virtual meeting happen.
- Computerization activities:
Chair, Greg Dalton, Tribsys, was not in attendance and Scott Hummel reported for Greg. The G 163 standard on data acquisition is in need of review for reapproval and Greg will do this review. Greg is also chairing a workshop on data acquisition for the 2010 Jacksonville meeting.
- Friction activities:
Chair, Ken Budinski, reported that the rolling friction standard passed committee ballot without negatives and editorial comments will be included in the published version. It will be ASTM G 194.
There were two negatives on the friction energy dissipation standard ballot. The ballot was withdrawn and another draft that addresses the negative issues will be balloted before Spring.
A vehicle rolling friction test was discussed, but the consensus was that user interest should be acquired before progressing. The proposed test is described in the Miscellany section of Wear News.
Three standards were reviewed for reapproval:
G 115 friction testing methodology
G 143 capstan friction
G 164 paper clip surface lubricating test
All are okay for reapproval except G 115 which needs ASTM to provide schematics of friction tests developed since the last reapproval. Kate McClung will try to get a listing of appropriate additions.
- Non-abrasive wear activities:
The meeting was chaired by Mike Anderson (Falex). Peter Kindersley started the meeting describing a new galling tester that he developed that rotates on an annular test specimen against a fixed annular specimen under forces that result is apparent contact pressures up to 2,500 psi. The 90o rotation can be repeated to make it a wear tester and testing can be done at cryogenic temperatures and up to 1,000o C. Peter will champion a new standard using this testing device.
Mike reported that a standard has been drafted on a 3 disks-on-flat test that can be run on the Falex Multispecimen Tester. Three pins (like a milk stool) rub on a counterface disk at 30 psi contact pressure. The draft is almost ready for subcommittee ballot.
Scott Hummel (Lafayette College) reported that the ballot to withdraw the G 98 galling standard received six negatives. Scott will try to revise the standard to make it more technically acceptable and ballot it for reapproval.
- Additional standards:
Mike Anderson reported that the corrosion and wear synergy standard, G 119, is being revised for reapproval by Margart Stack, University of Strathclyde. G 137 and G 176 plastic block on ring tests will be balloted for reapproval and Peter Blau is planning round-robin tests on the G 181 piston ring test.
Ken Budinski reported that a new standard on fretting wear and fretting corrosion is ready for subcommittee ballot.
Scott Hummel reported the new galling test has been approved and it has the identification ASTM G 196.
Peter Blau presented a progress report on interlaboratory testing related to the G 181 piston ring on cylinder wear test. Peter has 7 labs lined up and he will supply test specimens and instructions for testing. Tests will be in progress on Plint reciprocating machines by February, 2009.
- Terminology activities:
Subcommittee Chair, Peter Blau, wordsmithed a new definition for “wear” to be balloted for inclusion in the G40 definition standard:
Wear – progressive loss, damage, or displacement of material due to relative motion between solid surfaces and a contacting substance or substances.
The definitions for galling, rolling resistance, scratching, and abradant will also be balloted.
Rolling Resistance of Automobiles
For the past five years or so, the ASTM Friction subcommittee has been working on the development of a standard rolling friction test method. A sphere/spheroid (golf ball, soccer balls, lacrosse ball, ball bearing, orange, etc.) is placed at the top of an angled ramp on a rolling surface of interest and released. The rolling resistance of the test couple is calculated as the ramp height divided by the rolling distance traveled x 100.
Golf ball on 2” high turf = 60
Golf ball on a dry green = 10
Billiard ball on billiard cloth = 9
6mm-diameter ball bearing on a granite surface plate = 4
The theory being the test method is that the potential energy of the spherical shape on the ramp (mass x height) is equated to the distance traveled times the retarding force (rolling resistance).
The test method was recently approved for spheres, but an obvious application of the test concept is to evaluate the rolling resistance of wheeled objects like automobiles. A vehicle with low rolling resistance should produce better gas mileage; it takes less energy to roll it on the pavement.
In response to the current escalating gasoline prices, an informal rolling resistance test was conducted on four vehicles; the purpose of the test was to see if it is repeatable, and if there are significant differences between different vehicles.
Our exploratory test was conducted on the morning of July 4 on a hill not used much on a holiday. The procedure was to align the front bumper of the vehicle with a bridge abutment with the engine running in neutral. The operator then abruptly released the brake and we measured the distance rolled. Each car was tested three times. All of the vehicles had the same tire diameter and all tires were inflated to their recommended maximum working pressure. The test results are presented in Figure 1:
The average distance traveled by the four vehicles varied from 550 feet to 635 feet; about a 15% difference. There was a difference between vehicles. Contrary to what one might expect, the lightest vehicle “won”. The heaviest vehicle had the most potential energy based upon mass times height. Could it be that rubber/roadway slip and real areas of contact is more important? Maybe some readers care to comment on our results as well as the viability of the test method. Send comments and suggestions to Ken Budinski.
Acknowledgements: the test participants were Mark Kohler, Robert White, Brian Kohler, and the author.
Regards,
Ken Budinski
Technical Director
Bud Labs
Miscellany/Announcements
- Standards, henceforth, will be classified by their use of SI units:
SI only, English + SI equivalents, SI + English and both are standard. The units used must be specified in the scope.
The goal is hard metric, but they realize that some materials are made only to English dimensions (like 1 ft x 1 ft floor tiles).
- ASTM has hired an outside vendor to create online abstracts of standards for sale.
- Negatives can now be resolved on-line.
- ASTM will arrange virtual meetings on an 888 phone number for task groups and subcommittees whose attendance at a meeting could be a financial challenge. Participants call the phone number and use their computers to view documents.
- There is a new award (President’s) for outstanding service in the 1st five years of membership (not retroactive).
- Future meetings:
Spring 2009June 24 – 25
Norfolk, VA (USA)
Marriot (with D2)
Fall 2009November 2 – 3
Battelle Memorial Institute
Columbus, OH (USA)
Spring 2010May 20 – 21
Las Vegas, NV (USA)
(after STLE)
Fall 2010December 9 – 10
Jacksonville, FL (USA)
(includes a workshop on data acquisition)
- New friction book:
A second edition of past G2 chairman, Peter Blau’s book on “Friction, Science, and Technology” has just been published by CRC Press ( Of course it is a must-have for all designers, engineers, and tribologists.
- New Secretary:
Mike Anderson of Falex Corporation has assumed the position of Committee Secretary.
- Upcoming meetings:
The appended list of upcoming wear meetings is graciously supplied by Peter Blau.
NOTE:Wear News is the informal account of ASTM G2 Committee activities and related tribological activities. Article contributions by others are encouraged.
Send them and other inquiries to:
Ken Budinski
Bud Labs
904 Ridge Road West
Rochester, NY 14615 (USA)
Page 1
Wear News is the informal account of ASTM G2 Committee activities and related tribological activities. Article contributions by others are encouraged.
Page 1
Page 1