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Comparison of Centrifugal & Sand Casting

   

Centrifugal Casting is the preferred method of producing rotor end rings for A.C. induction motors. O.E.M.s specify this manufacturing method for optimum quality.

 

At Tallman We:

  • Specialize in high conductivity grade centrifugally cast copper as well as controlled conductivity grades.
  • Can supply chrome copper when increased strength and high conductivity is required.
  • Can supply rotor end rings rough or finish machined to your specifications.
  • Meet the exacting standards of the major North American O.E.M.s.
  • Also supply to the rebuilt market.
  • Furnish complete Quality Assurance documentation as required.
  • Are competitive on both production and low volume requirements.
  • Can offer expedited service normally at no extra charge for breakdown requirements.

   

Improper Cooling Can Cause Lance Tip Wear

   

Port erosion is affected by the grain size of the copper. A smaller grain size in the copper lance tip will assist in minimizing the rate of port erosion.  tallman's fine grain copper is produced by a proprietary process that does not significantly reduce the thermal conductivity of the copper.

   

Copper oxides are concentrated along the grain boundaries. These oxides when exposed to high concentrations of oxygen at elevated temperatures, which occur when a lance tip is under-blown, will react with the oxygen and cause cracks to form and propagate along the grain boundaries.

   

A coarse grain structure that is typical of a sand cast lance tip has less grain boundary area per square mm and thus has a higher concentration of copper oxides along the grain boundaries. This coarse grain structure leads to more severe cracking and a faster rate of crack propagation.

   

A finer grain structure that is typical of a centrifugal or forged lance tip impedes crack propagation because of the number (density) and shape of the grains.

 

   

Difference between tallman's fine grain copper (top photograph) and a standard coarse grain sand cast copper (bottom photograph).


tallman centrifugal lance tip removed from service after 1163 heats (Steel Plant, India - September 2001)

 

 

   

   

   

     

©2007. A.H. Tallman Bronze Company Limited . All rights reserved

2220 Industrial Street . Burlington . Ontario . Canada . L7P 1A1

p.905.335.3491    f.905.335.5896

Last Updated:   January 3, 2007

     

e-mail: tallman@tallman-bronze.com

    

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