Monday, August 22, 2016

Bearing Design Guide: Chapter Four: LOAD SPEED CATAGORIES AND USAGES-Day 1

          This chapter will be broken down into 5 different sections and I will be posting a new Blog post every day this week. The sections are as follows:

  1. High-Lead Tin Bronzes: High-speed, low-loads
  2. Leaded tin bronzes: Medium-load, medium-speeds
  3. Tin bronzes: Low-speed, high loads
  4. Aluminum bearings: High-loads, low-speed
  5. Manganese bronzes: Extreme high-loads, low-speed
So....sit back, fasten your seat belts and enjoy the ride!



The bronze alloys are categorized by their most desireable properties they offer for specific applications.

High-lead tin bronzes: High-speed, low-loads

          The lead content is above 12% and higher and are best suited to meet high surface speeds but with low loads since they are considered to be more plastic in nature, conform readily to imperfections of mated parts, do not require a hardened shaft and have the least galling tendencies.
          The design working load of these alloys can be taken at 1500 PSI and can accommodate surface speeds through 1000 fpm.

                    The permissable static load can be taken at 6000 PSI.

                    The average physical properties are:
                    Brinell hardness 50 to 60 BHN
                    Coefficient of friction (dry) .15
                    Minimum recommended shaft hardness 165 BHN
                    Maximum operating temperature 450 ° F

   CDA             Tensile Strength PSI             Yield Strength PSI          Elongation %          BHN
    943                         21000                                    15000                                 7                         42
    941                         25000                                    17000                                10                        53
    938                         25000                                    16000                                 8                         53

Principle uses: Turbine bearings, compressors, pumps, rotors, seals and where loads are free from  shock and impacts, where lubrication is less than ideal and speeds well over 70 fpm.

Well...that's it for our first section.  Until next time my metal loving friends...

 Next Up: Chapter 4: Load Speed and Usages-Leaded Tin Bronzes: Medium-load, Medium-speeds



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