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also, some asked me about the bronze.
i am not using the UNI5275 which is used by Anomino. its known in italy.
the bronze i use is German RG7 based on DIN EN 1982. its used for high stressed machines. so its not soft, but bronze is never strong as steel.
but the most important point why i use this bronze is, it is seawater resistant.
so please dont get fooled always by big brand marketing.
Hey Kenzo,
From my rudimentary research the alloy you are using, RG7 DIN EN 1982, is know by C93200 or SAE 660 in North America. It is a standard bearing bronze, and contains nominally 7% Tin, 6-7% Lead, and 3-4% Zinc, remainder Copper.
From http://www.concast.nl/elcas/index.php?page=brons/brons&lg=eng:
"[RG7 is the] Most common used bronze alloy, also called bearing bronze. Suitable for bearings with middle duty load, good sliding and dry running properties and good machinability. Main purposes: bearings, slide strips and valves. RG7 has a very good lubricant structure."
From http://www.anchorbronze.com/c93200.htm:
Mechanical Properties
M07 - As Continuous Cast
Hardness* Brinell Hardness (500 kg load) 65
Tensile Strength** KSI 35 min
Yield Strength ** KSI (0.5% Ext. under load) 20 min
Elongation** % in 2 inch 10 min
**Test values are nominal approximations and depend on specimen size and orientation.
Whereas the UNI5275 is known as C95500 or C95520 (heat treated version, TH04) in North America and contains no lead, being an Aluminum Nickel Bronze.
From http://www.nbmmetals.com/downloads/NBM_C95520.pdf:
Room Temp Tensile & Hardness Data
TENSILE STRENGTH (KSI) MIN 125
YIELD STRENGTH (KSI) MIN 95
ELONGATION IN HD MIN 2%
BRINELL (3000 KG) 262
That is heat treated. Not sure if the bronze can be in this condition prior to machining. I think it can be, but set-up would differ accordingly.
The non-heat treated, as cast version, C95500, has these properties.
From http://www.anchorbronze.com/c95500.htm:
Mechanical Properties (as cast)
M07 - As Continuous Cast
Hardness* Brinell Hardness (3000 kg load) 190
Tensile Strength** KSI 95 min
Yield Strength ** KSI (0.5% Ext. under load) 42 min
Elongation** % in 2 inch 10
**Test values are nominal approximations and depend on specimen size and orientation.
The composition of C95500, C95520 is nominally 11% Aluminum, 4-5% Iron, 5% Nickel, Max 3.5% Manganese, remainder Copper (with some additional minor constituents).
Also from the pdf linked to above:
Typical Uses
Oil & Gas
Rock Bit Bearings, Bushings, & Washers, BOP Parts,
Wellhead Components
Aerospace
Landing Gear Bushings and Bearings
Automotive
Bearings, Off-Highway Truck Bushings, Forming Roll
Bearings
Marine
Pump Parts, Bushings
Industrial
Cams, Shafting, Hydraulic Bushings for Earth Moving
Equipment, Valve Balls, Cryogenics, Drill Guide Bushings
Military
Tank Track Bearings, Bushings, Aircraft Components"
And from http://www.anchorbronze.com/c95500.htm:
Applications
Valve guides and seats in aircraft engines, corrosion resistant parts, bearings, bushings, gears, worm gears, pickling hooks and baskets, agitators.
That website also lists the machinability of C93200 (=70) and C95500 (=50) compared to free cutting brass (=100), so the C93200 is easier to machine.
You can draw your own conclusions about which alloy provides which benefits for this application. Not saying there is a wrong or right alloy here, or one is better than another, just showing the different compositions and properties.
With the C95500 and C95520 you can see a big difference in mechanical properties between the as cast and heat treated versions of this alloy.
What I haven't found is a good comparison of these two alloys in terms of salt water corrosion, but they both are listed as corrosion resistant alloys.
Lukas