Michael Southan, Mathew Rees, Robert Quodling, Daniel Skylas

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Achieving NATA Accreditation of Laboratory Test
Milling

• Michael Southan, Mathew Rees, Robert Quodling,
  Daniel Skylas
• John McCorquodale, Brian Osborne

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Introduction

• Flour yield is the most important quality target
  for wheat breeders large investment is at risk
  if milling potential is not accurately measured
• The Buhler MLU 202 laboratory mill is most
  commonly used to measure milling potential
• Samples are milled under constant settings
• Allows direct comparisons of flour yields and
  flour relevant for chemical analysis and end
  product testing

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Introduction

• Laboratory milling is an analytical method that
  should, like any testing method, be subject to
  technical accreditation to ISO/IEC 170252005
  standard which in Australia equated to NATA
  accreditation

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Buhler Test Mills

• Direct correlation of Buhler test mill flour
  yields and commercial milling yields is difficult
• FMCA report by Greer et al 1977 observed that
• Buhler test mills have an inherent limited
  reduction capacity - ie low flour yields.
• Entoleters and bran finishers increased flour
  yield and commercial relevance.

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Buhler Test Mill
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Buhler Test Mill
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Sources of Error in Test Milling

• Sample non-homogeneity
• Inadequate or excessive sample preparation
  (cleaning)
• Non-uniform conditioning
• Variation in lab temperature and humidity
• Poor maintenance of milling equipment
• Sub-optimal mill settings, and
• No standardisation of methods

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Increasing Test Mill Efficiency

• Test Mill overhaul

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Increasing Test Mill Efficiency

• New felt seals

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Increasing Test Mill Efficiency

• Repairing wear

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Increasing Test Mill Efficiency

• New bearings

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Increasing Test Mill Efficiency

• Reduction rolls re-ground

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Increasing Test Mill Efficiency

• Stainless steel stock trays for more efficient
  cleaning

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Increasing Test Mill Efficiency

• Replacement of sieve chains with rubber sieve
  cleaners
• More efficient sieve cleaning - greater area of
  sieves cleaned

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Increasing Test Mill Efficiency

• Plastic sheeting on sifter boxes for protection
  when cleaning

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Increasing Test Mill Efficiency

• Fan exhaust outlet was repositioned to allow
  ducting and a sock to be added so that dust could
  be collected more efficiently

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Increasing Test Mill Efficiency

• Reconfiguration of entoleters which were mounted
  on back of mill and controlled with a frequency
  inverter

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Increasing Test Mill Efficiency
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Measuring Test Mill Performance
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Measuring Test Mill Performance
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Measuring Test Mill Performance
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Measuring Test Mill Performance
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Measuring Test Mill Performance
B3
B1
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Measuring Test Mill Performance
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Measuring Test Mill Performance
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Measuring Test Mill Performance
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Conclusions

• The first ever NATA accreditation of laboratory
  test milling has been achieved
• Test mill maintenance and efficiency is critical
  for high performance and productivity
• Laboratory test mill optimum roll gaps need to be
  identified experimentally - a systematic approach
  to determining optimum roll gap settings has been
  developed
• Milling Quality Index provides a mechanism for
  determining the optimum balance between flour
  yield and flour quality irrespective of mill set
  up