X̄-S Chart — Moulded Boss Diameter
Fourteen subgroups of nine mouldings with limits from A3/B3/B4, showing a tool-wear drift that rules 1, 3 and 5 catch and a Cpk of 0.90 against a 12.40–12.60 mm print tolerance.
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title "Boss diameter — tool 4, cavity 2"
chart xbar-s
unit mm
spec lsl: 12.40 usl: 12.60 target: 12.50
// Nine shots per hour, measured on the CMM. n = 9 puts this on an
// X̄-S chart: the range loses efficiency once subgroups get this wide.
subgroup 12.541 12.503 12.544 12.457 12.513 12.513 12.513 12.498 12.511
subgroup 12.490 12.527 12.519 12.534 12.561 12.586 12.542 12.514 12.528
subgroup 12.531 12.522 12.484 12.518 12.533 12.493 12.543 12.498 12.511
subgroup 12.508 12.521 12.538 12.527 12.465 12.523 12.535 12.530 12.540
subgroup 12.537 12.545 12.523 12.524 12.531 12.499 12.535 12.529 12.558
subgroup 12.529 12.535 12.546 12.574 12.541 12.527 12.524 12.533 12.525
subgroup 12.515 12.563 12.558 12.510 12.562 12.495 12.537 12.521 12.480
subgroup 12.514 12.528 12.533 12.550 12.555 12.549 12.529 12.525 12.571
subgroup 12.543 12.557 12.523 12.511 12.560 12.514 12.558 12.540 12.534
subgroup 12.532 12.553 12.544 12.551 12.493 12.575 12.543 12.556 12.540
subgroup 12.552 12.544 12.552 12.521 12.525 12.577 12.532 12.564 12.539
subgroup 12.569 12.570 12.546 12.576 12.549 12.528 12.588 12.559 12.560
subgroup 12.577 12.585 12.580 12.590 12.603 12.540 12.553 12.482 12.548
subgroup 12.531 12.567 12.572 12.556 12.558 12.573 12.600 12.603 12.565