The majority of materials consist of various particle types of different shapes and sizes. When classifying these particles, the main objective is calculating how much of each type is present in your sample. Laser Diffraction or Light Obscuration can offer a basic particle size distribution which only provides size information. This may be sufficient when dealing with a uniform mixture, but what happens when you carry particles of similar sizes that are different shapes?
If this scenario sounds familiar, then a method that can analyze both particle shape and size is essential.
A number of industries will analyze particle shape as part of their quality processes due to the fact shape impacts the performance of raw materials and/or the quality of the final product. Characteristics such as texture, solubility, flowability and reactivity can all be influenced by the shape of the particles. Here are a few examples of how particle shape analysis is used to guarantee both product and process quality.
Verifying Uniform Particle Shape for Process Efficiency
Column chromatography is employed across a range of industries to divide and purify complex mixtures. Uniform shape and size of column packing material produced tighter column density control, and in turn, improved column performance. Utilizing flow imaging techniques, it is possible to analyze column packing material to confirm particle uniformity.
The images below were captured from a column packing material batch analysis conducted using the FlowCam, a flow imaging microscope.
Round, adequate particles are displayed on the left, and less round, inadequate particles on the right. The analysis determined that across all 9,261 particles imaged, stored and measured, 8,921 of them (97.26% by volume) were acceptable and 340 of them (2.74% by volume) were unacceptable.
Image Credit: Yokogawa Fluid Imaging Technologies, Inc.
The analysis took just under a minute with the batch passing as more than 95% of the particles had an acceptable shape. One major benefit of the FlowCam system and paired VisualSpreadsheet® software is that it is possible to sort images easily and quickly by acceptable and unacceptable characteristics. You can then, in short order, extrapolate the statistically significant findings to the larger population of material.
Measuring Particle Surface Roughness for Quality Control
Superabrasives are being largely used in applications for cutting, grinding, and drilling of hard materials. Particles with a smooth and uniform finish are amongst the most effective. In the example below, a batch of micronized diamonds were analyzed using a FlowCam to establish if the manufacturer's specifications were met: a minimum of 95% of the diamond particles need to have a smooth and uniform surface.
The images below display the result of the batch analysis of the micronized diamonds utilizing VisualSpreadsheet Software. The images from the set on the left have comparatively smooth perimeters with rounded edges, whereas the images displayed in the set on the right are more angular. VisualSpreadsheet enables the creation of particular filters to help categorize images predicated on various parameters, including aspect ratio, equivalent spherical diameter, sphericity, volume, etc. This way images can be rapidly sorted for the content analysis of your sample, allowing you to identify if it meets or falls short of the specifications. For instance, the percentage of angular particles was below 5%, meaning this batch of diamonds was within the range of set specifications.
Image Credit: Yokogawa Fluid Imaging Technologies, Inc.
To determine particle surface roughness, a range of morphological characteristics can be used. Some of these particle measurements include circularity, edge gradient, aspect ratio and perimeter. The FlowCam's VisualSpreadsheet can even measure the irregularity of a particle's surface due to the inclusion of a roughness measurement in the software.
Identifying Different Particle Types for Process Evaluation
To analyze wash water, an electronic device manufacturer makes use of the FlowCam. The devices are washed and rinsed to eliminate traces of fibers, metals and plastics that can appear throughout the manufacturing process. It is crucial that the wash water contains a minimum number of specific particle types, such as fibers, plastics and particularly metals, which could suggest problems in their production, and cause potential device failures.
A variety of particles were discovered in the wash water, including long and skinny fiber particles, translucent metal shavings and more opaque plastic particles. VisualSpreadsheet facilitates the creation of libraries predicated on particle attributes. Each run was filtered automatically by particle type, and the relative volume percent, either particles/ml, or particles per million, all counted in real time. The images below demonstrate how the sample was sorted by different particle type. With the FlowCam, the manufacturer can identify and quantify particles found in the wash water rapidly and establish areas in the manufacturing process that may require immediate attention.
Image Credit: Yokogawa Fluid Imaging Technologies, Inc.
This information has been sourced, reviewed and adapted from materials provided by Yokogawa Fluid Imaging Technologies, Inc.
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