A process is in statistical control with and
The control chart uses a sample size of n = 3.
Specifications are at 42 ± 4. The quality characteristic
is normally distributed.
What conditions should we check to ensure that conclusions from
a capability analysis are correct?
Estimate the potential capability of the process.
Estimate the actual capability of the process.
How much improvement in ppm could be made in process
performance if the mean could be centered at the nominal
value?
Statistical Process
Control is a critical part of tracking performance, and evaluation
of process capability is an important element to track the need to
closely monitor.
Using the table
below and the attached X-bar, S charts, determine the process
capability indices for the process (Cp,
Cpk),
and evaluate whether the process is capable for average surface
roughness (Ra) for the inner diameter of
tubing. If
not, what change(s) should be made next to get
Cpk
≥
1.33? The
specification requires...
Explain the difference between process capability and
statistical control.
Suppose that a process with a normally distributed output has a
mean of 50.0 cm. and a variance of 3.61 cm. If the specifications
are 51.0 +/- 3.75 cm.,
a. Compute Cp and Cpk
b. What are your conclusions about this process?
Statistical process control charts:
A. display upper and lower limits for process variables or attributes and signal when a process is no longer in control.
B. display the measurements on every item being produced.
C. are a graphic way of classifying problems by their level of importance, often referred to as the 80-20 rule.
D. indicate to the process operator the average outgoing quality of each lot.
E. indicate to the operator the true quality of material leaving the process.
Statistical process control
explain the types of control charts available for analysis, the
basis under which their limits are defined and change, the types of
analysis that lead to decisions of controlled or not-controlled,
and the types of risks associated with different sample sizes and
limit settings. In particular, describe what it means statistically
to declare that a process is not in control.
a process in statistical control has a mean of .3119
and specification limit of .307 to .317. if the standard deviation
of the process is .0013, what percent of the process output is
expected to be below the specification limit?