Measurement system analysis in angle of repose of fertilizers with distinct granulometries

Abstract

This research presents an experimental study for measurement system analysis of angle of repose in fertilizers with variable granulometry (1.5 mm < d50 < 5.0 mm). In the literature, there are different procedures for determining this angle of repose, which often result on a variety of measurements for one measurand. Thus, the main objective of this work is to propose a method for measurement system validation of angle of repose. The statistical validation was based on Nested Gage Repeatability and Reproducibility (NGR&R) and the experiment was conceived through a technical apparatus built to measure the angle of repose of fertilizers. Experiments was conducted by using available resources in a typical industrial laboratory of fertilizer characterization. Among the measuring procedures, the fixed funnel has been used and an image analyzer software has been adopted to gather the data. The experiment was planned with 3 (three) operators, 10 (ten) samples with distinct granulometries and 3 (three) replicates. The result analysis has shown that the measurement error through the first measuring procedure was deemed unacceptable. After investigating the root cause of measurement error, a new standard measurement procedure was proposed. The new procedure was able to measure the angle of repose precisely, reducing measurement error from 59.93% to 4.82%.