Spc For Short Production Runs

n

&

!2:3

2 3 4 5 6

1.88 1.02 .73 .58 .48

o o o o o

~

3.27 2.57 2.28 2.11 2.00

· Table 2 Table of constants used to calculate controllimits.

7.

Draw the appropriate center lines and controllimits on the Nom-i-nal X-bar and R charts and then interpret the finished Nom-i-nal chart (Fig. 5).

1<--- PartA --->1<---- Part B - - - - - -1-

1 1

1

1

1 1

1

X 1 NOMINAL 1-----

1

,1

1 1

CL

1

1

1*

1 1

1

R

---->

1 -

-

-

- - - - -1- -

LCL

1

-

-

- - - - -1- -

UCLR

-

1 1 1

1 1 1

1

1 1

1-

= =

CL - A 2R

D4R

1 1

~-------------------------------Fig. S The Nom-i-nal X, R chart with controllimits added. There is one imponant assumption with this chart. It assumes the process variation (60') of all part numbers are approximately equal. lf one is too large compared to the rest, it cannot be plotted on the same Nom-i-nal chart.

5