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Control charts help identify when a process should be investigated in order to find and eliminate special-cause variation. The table below gives long-term DPMO values corresponding to various short-term sigma levels. [21] [22] These figures assume that the process mean will shift by 1.5 sigma toward the side with the critical specification limit.
The process capability index, or process capability ratio, is a statistical measure of process capability: the ability of an engineering process to produce an output within specification limits. [1] The concept of process capability only holds meaning for processes that are in a state of statistical control. This means it cannot account for ...
Control charts are graphical plots used in production control to determine whether quality and manufacturing processes are being controlled under stable conditions. (ISO 7870-1) [1] The hourly status is arranged on the graph, and the occurrence of abnormalities is judged based on the presence of data that differs from the conventional trend or deviates from the control limit line.
Simple example of a process control chart, tracking the etch (removal) rate of Silicon in an ICP Plasma Etcher at a microelectronics waferfab. [1] Time-series data shows the mean value and ±5% bars. A more sophisticated SPC chart may include "control limit" & "spec limit" % lines to indicate whether/what action should be taken.
The process capability is a measurable property of a process to the specification, expressed as a process capability index (e.g., C pk or C pm) or as a process performance index (e.g., P pk or P pm). The output of this measurement is often illustrated by a histogram and calculations that predict how many parts will be produced out of ...
A control chart can be useful during the Control stage to assess the stability of the improvements over time by 1. serving as a guide to continue monitoring the process and 2. providing a response plan for each of the measures being monitored in case the process becomes unstable. Standard operating procedures (SOP's) and Standard work
In process improvement, SIPOC or suppliers, inputs, process, outputs and customers (sometimes in the reversed order: COPIS) is a tool that summarizes the inputs and outputs of one or more business processes in table form, with each of the words forming a column in the table used in the analysis.
Process capability is the ability of a process to produce output within specified limits. [1] To help determine whether a manufacturing or business process is in a state of statistical control, process engineers use control charts, which help to predict the future performance of the process based on the current process.