Stick-Slip in Dairy Powders During Shear Testing

Tuesday, November 9, 2010: 9:08 AM
251 B Room (Salt Palace Convention Center)
Guillaume Brisson1, Payel Bagga2, Alan Baldwin2 and Clive E. Davies3, (1)Riddet Institute, Massey University, Palmerston North, New Zealand, (2)Fonterra Research Centre, Palmerston North, New Zealand, (3)School of Engineering and Advanced Technology, Massey University, Palmerston North, New Zealand

In an investigation of the flow properties of skim milk powder, whole milk powder and cream powder, shear test measurements were made at 25C, 30C and 37C, using an annular cell. In all experiments, both for angle of wall friction where a sample of wall material was sheared against a powder bed, and in measurements for powder flow parameters where a bed of powder was sheared until it failed, the trace, after failure, exhibited the oscillations characteristic of stick slip friction. Observed amplitudes were highest at the higher normal stresses used, and temperature had little effect on the behaviour of the skim milk powder, which had a fat content of 1%, compared to 26% and 55% for the whole milk powder and cream powder respectively. There appears to be a strong correlation between amplitude and period of oscillation. Some implications arising from different ways the raw data might be interpreted are discussed.

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See more of this Session: Characterization and Measurement in Powder Processing
See more of this Group/Topical: Particle Technology Forum