Material to slide on Stainless Steel
Material to slide on Stainless Steel
(OP)
I have the following problem:
A slab gate (in a dam outlet) is guided by bronze guide plates sliding on stainless steel guides. The gate jerks when it is operated, and I suspect this is caused by galling between the two materials.
Does anyone have any suggestions on what material to use in stead of bronze. The contact pressure is about 20 MPa and the relative movement is slow.
Thanks
Christian
A slab gate (in a dam outlet) is guided by bronze guide plates sliding on stainless steel guides. The gate jerks when it is operated, and I suspect this is caused by galling between the two materials.
Does anyone have any suggestions on what material to use in stead of bronze. The contact pressure is about 20 MPa and the relative movement is slow.
Thanks
Christian





RE: Material to slide on Stainless Steel
RE: Material to slide on Stainless Steel
RE: Material to slide on Stainless Steel
RE: Material to slide on Stainless Steel
RE: Material to slide on Stainless Steel
cheers
joro
RE: Material to slide on Stainless Steel
RE: Material to slide on Stainless Steel
RE: Material to slide on Stainless Steel
cheers
G
RE: Material to slide on Stainless Steel
Would this be too simple a reply?
RE: Material to slide on Stainless Steel
RE: Material to slide on Stainless Steel
What is causing the problem, I dont know for sure but I want to bet my few cents on lack of lubrication system spelled "bad maintenance". The guys are probably not following any maintenance schedule specified by the designer. The another possibility is poor construction where the contracter has not adhered to the specified tolerances. So I urge you, not to blame the material, but to do a little bit of investigation on what the real cause of the problem is.
RE: Material to slide on Stainless Steel
Just to add a little information on the design of the system. There is no lubrication between the materials, the bronze strips on the stainless steel actually form the liquid seal.
The observation that the actuator could cause the problem is possible, but there are definite signs of galling (visual). The friction was such that the bolts holding the bronze strips sheared off.
Anti galling coatings could be a solution. To change the design of the system will be very expensive (the gate is situated 80m down an intake tower).
As a matter of interest, the dam is Sterkfontein Dam in South Africa.
Cheers
Christian
RE: Material to slide on Stainless Steel
You might try Nitronic 60 for the stainless elements. Here is some data:
NITRONIC 60 Wear and Corrosion Resistant (UNS S21800) Registered trademark of ARMCO ADVANCED MATERIALS CORPORATION
This alloy provides a significant lower cost way to fight wear and galling compared to Nickel or Cobalt based alloys. Its uniform corrosion resistance is better than 304 stainless in most environments. The yield strength of Nitronic 60 is nearly twice that of 304 and 316 stainless steels. Chloride pitting resistance is superior to that of type 316 stainless; Nitronic 60 provides excellent high temperature, oxidation resistance and low temperature impact.
Applications using Nitronic 60 are valve stems, seats, and trim, fastening systems, screening, pins, bushings and roller bearings, pump shafts and rings. Other uses include wear plates, rails guides, and bridge pins. Call High Performance Alloys for an Armco brochure on either of these Nitronic high performance stainless steel alloys.
NITRONIC 60 TYPICAL CHEMISTRY
C Cr Fe Mn N Ni Si
.005 17 63 8.0 .13 8.5 4.0
NITRONIC 60 TYPICAL ANNEALED AND COLD REDUCED MECHANICAL PROPERTIES
(1"annealed bar and 1.75" 50% cold reduced bar, smaller bar can be produced to even higher strengths)
UTS KSI YS KSI ELONGATION R/A HARDNESS
103-195 60-153 64-20% 74-57% B95-C38
Here is a Ryerson link:
http://www.ryersontull.com/stocklist/RedbookServlet?COM=GetTable&ID=1587
RE: Material to slide on Stainless Steel
RE: Material to slide on Stainless Steel
RE: Material to slide on Stainless Steel
RE: Material to slide on Stainless Steel
www.ghardapolymers.com
RE: Material to slide on Stainless Steel
1. Thordon is marketed by Thordon bearings, Inc. 3225 Mainway, Burlington, Ontario, L7M 1A6. It's claimed by the maker to be the best material for service in highly abrasive environments with minimal boundary lubrication. This material is a monolithic polymer of proprietary formulation, and I don't think it's available as a reinforced polymer, but check with them if you want a reinforced material. Thordon is used as a bearing shell liner in water-lubricated propeller shaft bearings (known in the maritime trade as "cutless" bearings). Another application is in water-turbine shaft bearings, where the operating conditions are similar to propeller shaft bearing conditions.
Thordon has a website at:
http://www.thordon.com/
2. Another material is called "Orkot", sold by the Orkot Corporation, 2535 Prairie road, Unit D, Eugene OR 97402. It consists of a woven-glass fiber reinforcement that's embedded in a graphite-filled polymer matrix. The operating conditions and applications are similar to those in 1. above.
Here is an excerpt from an Orkot ad:
"Orkot is a thermoset composite material reinforced by impregnating fabric with thermosetting resins. The result is a material with excellent strength, impact resistance and dimensional stability. The precise formulation of Orkot can be varied to suit specific applications, but all grades have outstanding chemical and mechanical properties. An extremely low coefficient of friction, high PV limit, and superior wear performance makes Orkot a supreme bearing material, particularly when working with heavy loads. With virtually no water absorption or swelling in water, Orkot is a perfect material choice for wet applications. Orkot is commonly used for Offshore Marine bearings, bushings, thrust washers, wear pads and wear rings."
Orkot is marketed by San Diego Plastics who have a comprehensive website at: http://www.sdplastics.com/orkot.html
This site has all you need to evaluate the material for your application.
These materials are used in applications very similar to yours (water-immersed, high-pressure, boundary lubrication, slow speed) and I believe they're both very good candidates.
RE: Material to slide on Stainless Steel
RE: Material to slide on Stainless Steel
You do not indicate the size or weight of the gate nor the load against it. It would seem that the use of some of the plastics mentioned would have problems over time under some load conditions depending on the load conditions.
Just my thoughts.
Griffy
RE: Material to slide on Stainless Steel
RE: Material to slide on Stainless Steel
Jim Treglio
Molecular Metallurgy, Inc.
RE: Material to slide on Stainless Steel
RE: Material to slide on Stainless Steel
http://www.waukeshafoundry.com/antigall.htm
We used this as a rotor in a volumetric piston pump for years and worked perfect
RE: Material to slide on Stainless Steel
Lets regress a little.
You might give these people a call. Lignum Vita guides maybe the ticket.
http://www.woodex-meco.com
RE: Material to slide on Stainless Steel
Hardness (HV 0.05): 4000 +/- 400
Friction Coefficient: 0.45
Good Luck,
Ken
Pulse Designtech