What is it: Individual X and Moving Range Chart (IX and MR Chart). This chart is similar to the X-bar and R chart, except this chart is used when the subgroup sample size is one.
Why use it: IX and MR Chart — Monitors single samples, not subgroups as the X-Bar and R Chart complete.
Where to use it: Is used when a subgroup size average isn't pratical, feasible, or cost effective. I used when tests are expensive or take a long time to perform. For continuous flow processes, not for discrete part manufacturing if possible.
When to use it: Control charts are generally used in a production or manufacturing environment and are used to control, monitor and IMPROVE a process.
How to use it: A control chart is a graph or chart with limit lines, called control lines. There are basically three kinds of control lines:
The purpose of drawing a control chart is to detect any changes in the process that would be evident by any abnormal points listed on the graph from the data collected. If these points are plotted in "real time", the operator will immediately see that the point is exceeding one of the contol limits, or is heading in that direction, and can make an immediate adjustment. The operator should also record on the chart the cause of the drift, and what was done to correct the problem bringing the process back into a "state of control". Please refer to the attached template package for further information.
Important Information: The moving range can be relatively slow to signal an out of control condition. The distribution of the individual X control chart needs to be nearly normal.