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I-MR Chart — Tablet Press Weight

Twenty-six hourly tablet weight checks from a rotary press, where Cpk 1.23 sits well above Ppk 0.86 because a punch-wear drift over the final shift makes the press unstable rather than incapable.

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Tablet weight — press 2, product MTX-500I-MR chart · 26 points · mg · all 8 Nelson rulesI chart — individual readings245250255151USL 257.50UCL 256.20CL 250.62Target 250.00LCL 245.03LSL 242.50MR chart — moving range of 20246UCL 6.861CL 2.100LCL 0.0001234567891011121314151617181920212223242526Out of control — 3 of 26 points flagged by rules 1, 5.Cp 1.34 · Cpk 1.23 · within-subgroup sigma 1.86 mg · 115 PPM expected out of specPp 0.94 · Ppk 0.86 · overall sigma 2.67 mg · 6,164 PPM observed-spread estimateMarginally capable — Cpk sits between 1.00 and 1.33. Quoted from an unstable process, so treat it as provisional.Rule 1 · Individual value at point 11 = 244.90 — 1 point beyond a 3σ limitRule 5 · Individual value at point 12 = 245.80 — 2 of 3 points beyond 2σ on the same sideRule 1 · Individual value at point 26 = 257.60 — 1 point beyond a 3σ limit

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title "Tablet weight — press 2, product MTX-500"
chart i-mr
unit mg
spec lsl: 242.5 usl: 257.5 target: 250
# One composite of twenty tablets weighed every hour across three shifts.
value 251.7
value 249.4
value 248.5
value 246.7
value 251.7
value 250.8
value 249.2
value 250.9
value 248.1
value 248.9
value 244.9
value 245.8
value 250.5
value 248.8
value 251.5
value 252.7
value 251.2
value 253.2
value 249.5
# Punch wear from hour 20: the fill cam is no longer holding the setting.
value 253.0
value 253.3
value 252.1
value 252.1
value 251.2
value 252.7
value 257.6