The paper summarizes the experiences acquired from on-line acoustic emission
monitoring (herafter AE) of heavy castings during their manufacturing (solidification and following
cooling in the mould). They are usually monitored elastic waves generated above all by stress
changes in the solid state. In order to exactly determine plastic-elastic transition state the
investigation was focused on raising the sensitivity of detection. The suitable experimental
technique is discussed in the first part of this article. The main problem of the measurement by high
temperatures was solved by using waveguides. It is very important in this case to select useful
signal sources from mechanical and electromagnetical disturbances. Some laboratory experiments
were done for studying the signal origin in the first state of solidification.
The results from on-line monitoring of two types cast rolls during manufacturing were
compared. Each type of casting has its typical AE histogram. For the quality evaluation ( in our
case) is significant the time period of approximate 5 days after pouring . The time delayed stress
induced cracking generates high level AE signal in this time period and the presence of such signal
indicates defective product. The study of high temperature tensile tests, structural phase
transformation and solidification processes using AE is very important for analysis of AE sources.
The use of the laboratory results for the AE source analysis on real products will be subject to
futher research.
Reducing non-productive time of mud pump with acoustic emission monitoring techniques on fluid end parts
