Ametek BROOKFIELD CT3, Operating Instructions Manual

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AMETEK Brookfield Page 37 Manual No. M08-372-F1116
IV. TEST METHOD DEVELOPMENT
The measurement results provided by the CT3 Texture Analyzer will be dependent on several factors
relating to the sample, the test probe, and the test parameters. A variation on any of these elements
may result in a change in measurement results. For good test repeatability, it is suggested that a
clear and complete test method be developed. The following sections describe these elements.
Brookfield suggests that your method development include some trial and error testing to determine
the best test method for your sample material. Brookfield offers a texture day training course for
anyone wishing assistance with texture analysis methods.
IV.1 Sample Preparation
The measurement of texture using the CT3 Texture Analyzer requires contact between the test
probe and the sample. The shape and surface of the sample may affect the measurement results.
Consider for example an orange: the test of a peeled orange will likely give a different result from
the test of a single wedge from the same fruit. This is likely the same for any bulk material when
compared to a neatly prepared cube of material. Consideration should be given to the preparation
of the sample to facilitate repeatability of the test. For example, a material that has a flat surface
offers a consistent interface with the probe even if the material is not centered in the test fixture.
If your test sample is uneven, part of the test method could be to cut, shape or modify the sample
such that the sample is flat; consider, for example, the difference between a loaf of bread versus a
slice of bread.
IV.2 Test Probe / Fixture
The CT3 Texture Analyzer may be used with a wide variety of probes and fixtures. Brookfield offers
a set of standard items while also providing special design services. Each type of probe offers benefits
for certain sample types. The following table provides some basic guidelines. Although this table
represents our general experience, it is important to note that there are few established standard
tests for physical measurements of texture. The main objective is to characterize your material in
a way that best represents its perception by human senses. This is the essence of texture analysis.
Probe Type Typical Application
Cylinder well defined samples with uniform surfaces,
general purpose, TPA (texture profile analysis)
Sphere samples with small scale variations on surface,
general purpose
Cone samples with rigid outer layer. Also used for
penetrometry and spreadability
Wire used for cutting or slicing samples such as cheese
Magness Taylor used for puncturing, often used for determining
ripeness of fruit/vegetables
Extrusion Cell samples that can be made to flow, general purpose
Shear blades meat tenderness
Table IV.1