STATISTICAL QUALITY CONTROL OF CHEMICAL COMPOSITIONS AND HARDNESS VALUES OF GREY CAST IRON IN FOUNDRY SHOP – AJAOKUTA STEEL COMPANY LIMITED (ASCL)

Summary

Statistical Quality Control (SQC) analysis deals with quantitative data; it is also a scientific method of analyzing
masses of numerical data so as to summarize the essential features and relationship of data in order to generalize
from the analysis pattern behaviour, particular outcome or future tendencies. This research work focused on the
use of statistical quality control to determine the chemical compositions and hardness values of grey cast iron in
the Foundry Shop with a view to detecting and eliminating non -random (sporadic) variations in production
process. The process monitored the performance of the Chemical compositions and hardness values of grey cast
iron periodically by examining sample units of output. The analyzed samples and data collected for critical
characteristics were determined to ascertain if they shifted away from the purely random pattern. Ten samples
were collected and analyzed with a SPECTRO Analytical Instrument in the Quality Control and Materials
Analysis in the Foundry Shop of the Company, the chemical compositions were determined and the same
samples were also used for hardness values which were also determined with the use of Brinell Machine in the
Mechanical Repair Shop of the company. Two control charts (X and R) were used to determine the performance
and to indicate if the process remained in control and where there are variations, these will serve as early
warning system for the information of the management that something odd has probably happened to the
production process.

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