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Explain the 7 tools of statistical process control?

Statistical process control:

Statistical process control (SPC) is a method of quality control which uses statistical

methods. SPC is applied in order to monitor and control a process. Monitoring andcontrolling the process ensures that it operates at its full potential. At its full potential, the

process can make as much conforming product as possible with a minimum (if not an

elimination) of waste (rework or trash). SPC can be applied to any process where the

"conforming product" (product meeting specifications) output can be measured. Key tools

used in SPC include control charts; a focus on continuous improvement; and the design of

experiments. An example of a process where SPC is applied is manufacturing lines

Objective analysis of variation

SPC is a valuable process because it allows examination of specific parts of a process. In

particular, it looks at the parts that may conceal sources of variation in the quality of the

product. The examination involves objective analysis rather than subjective opinion. SPC

also allows the strength of each source of variation to be determined numerically. If sources

of variation are detected and measured, they may be amenable to correction. In turn,

correction of variations may reduce waste in production and may improve the quality of the

product that reaches the customer. SPC must be practiced in 2-phases, where in first phase of

SPC to establish the process initially and after that in second phase during the production run.

In the second phase, we need to decide the period to be examined, depending upon the

change in 4-M conditions and wear rate of parts used in the manufacturing process (machine

parts, Jigs and fixture and tooling standard.

Statistical process control (SPC) is a method of quality control which uses statisticalmethods.

SPC is applied in order to monitor and control a process. Monitoring and controllingthe process ensures that it operates at its full potential.

At its full potential, the process can make as much conforming product as possiblewith a minimum (if not an elimination) of waste (rework or trash).

SPC can be applied to any process where the "conforming product" (product meetingspecifications) output can be measured.

Key tools used in SPC include control charts; a focus on continuous improvement;and the design of experiments

The Seven Tools of Quality

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1. Control chart

2. X-Bar and R Charts

3. Pareto chart

4. Flow chart

5. Cause and effect diagram

6. Histogram

7. Scatter diagram

The Pareto graphically summarizes and displays the relative importance of thedifferences between groups of data. A Pareto chart can be constructed by segmenting

the range of the data into groups.

A flowchart is important project development and documentation tool.It visuallyrecords the steps, decisions, and actions of any manufacturing or service operation

and defines the system, its key points, activities and role performances.

A histogram is used to graphically summarize and display the distribution of aprocess dataset. It can be constructed by segmenting the range of the data into equal-

sized bins (segments, groups, or classes). The vertical axis of the histogram is the

frequency (the number of counts for each bin), and the horizontal axis is labeled with

the range of the response variable.

Cause and Effect DiagramA problem is systematically tracked back to possible causes. The diagram organizes the

search for the root cause of a problemA similar diagram can be used to systematically search

for solutions to a problem.

Scatter chartsIt is similar to a line graph except that the data point are plotted without a connecting line

drawn between them. Scatter charts are suitable for showing how data points compare to

each other. At least 2 measured objects are needed for the query (one for x-axis and one fory-axis)

Control ChartsA broken line graph illustrates how a process behaves over time. Samples are periodically

taken, checked, or measured, and the results are plotted on the chart. The charts can show

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how the specific measurement changes, how the variation in measurement changes, or how

the proportion of defective pieces changes over time

X-Bar and R ChartsThe most commonly used of the control charts and the most valuable.They are ideal toolsto improve product quality and process control and help to drastically reduce scrap and

rework while assuring the production of only Satisfactory products.They can be used for

controlling every step of production process, for the acceptance/ rejection of lots, and for

early detection of equipment or process failure

Limitations

SPC is applied to reduce or eliminate process waste. This, in turn, eliminates the need for the

process step of post-manufacture inspection. The success of SPC relies not only on the skill

with which it is applied, but also on how suitable or amenable the process is to SPC. In some

cases, it may be difficult to judge when the application of SPC is appropriate.