1. PROCESOS INDUSTRIALES EN EL ÁREA DE
MANUFACTURA
SPC
CONTROL ESTADÍSTICO DEL PROCESO
LIC. EDGAR GERARDO MATA ORTIZ
LAKSMI RODRIGUEZ CORTEZ
DANIEL AGUILERA MUÑOZ
3°C

2. Laksmi: What is the variability in processes?
Dany: Variability is a kinf of small changes that
are involuntary and unavoidable in the process.
Laksmi: ¿Can be represented as the varibility?
Dany: The variability can be represented
numerically. With the variance calculation and
graphically with a histogram.
Laksmi: The rules attempt to distinguish unnatural
patterns from natural patterns based on several
criteria:
Dany: The absence of points near the centerline
Laksmi: The absence of points near the control
limits

3. Dany: The presence of points outside the control
limits.
Laksmi: Other unnatural patterns
Dany: What are the rules nelson?
Laksmi: Nelson Rule 1
One point is more than 3 standard deviations
from the mean.

4. Dany: Nelson Rule 2
Nine (or more) points in a row are on the same
side of the mean.
Laksmi: Nelson Rule 3
Six (or more) points in a row are continually
increasing (or decreasing).

5. Dany: Nelson Rule 4
Fourteen (or more) points in a row alternate in
direction, increasing then decreasing.
Laksmi: Nelson Rule 5
Two (or three) out of three points in a row are
more than 2 standard deviations from the mean in
the same direction.

6. Dany: Rule 6
Four (or five) out of five points in a row are more
than 1 standard deviation from the mean in the
same direction.
Laksmi: Nelson Rule 7
Fifteen points in a row are all within 1 standard
deviation of the mean on either side of the mean.

7. Dany: Rule 8
Eight points in a row exist with none within 1
standard deviation of the mean and the points are
in both directions from the mean.