The histogram for the whole process reveals that high
frequency size of 62.500-62.250 being manufactured near the
lower tolerance level (Fig 2). This shows the product is
experiencing some problem in any one of the production line,
while the other two processes are normal.
When X-R chart was plotted, some production lines were
moved out of control for all the three sizes (Fig 3). Hence these
out of control process were to be controlled.