You are encountering quality control problems with your production line, and need to monitor your factory’s processes.  The Statistical Process Control can help you find out if changes have occurred within your company’s production in your absence.  Many companies are already using various SPC methods, such as control and management charts for different purposes.  SPC methods such as those mentioned above can reduce the chances of variation occurring within your production lines, and improve the overall manufacturing process.  SPC can also help you meet customer satisfaction and certification standards.

Each process has one or more outputs.  Each output, in turn, has its own attributes that can be measured.  The idea that these said attributes can have two sources of variation, namely, natural/common and assignable/special causes, is the basic principle of Statistical Process Control.  If variation within a processes’ attributes is within the range of variation from natural or common causes, then that process can be said to have ‘statistical control’.  The worker using SPC tracks down some variations that need to be controlled.  When variability exceeds the natural cause range, then these should be identified and corrected.

SPC’s value comes from its ability to analyze a process and the causes of variation using objective analysis instead of opinionated reasoning and allow these causes to be measured numerically.  Problems that occur within production can then be identified and fixe, reducing waste and total production time, as well as the probability that defects can ever reach the customer.  Other quality control methods such as inspection, which use resources to find and fix problems only after production, would seem inferior to these kinds of methods.  Moreover, since there is a smaller chance that a product will have to be reworked, the whole production process’ precision is improved.

The SPC is a valuable instrument in maximizing the amount of valuable information that you can use in making critical management decisions.  SPC methods provide further understanding of your business’s baselines, positive insight for improving your processes, value communication, and process results.  SPC gives you analyses in real time so that you can easily establish controllable baselines for your processes.  SPC provides objective and logical analysis instead of making subjective, opinion-based decisions so that you can readily control processes, set and improve the capabilities of your processes and focus your business on the areas that need to be improved upon.

In spite of these benefits, SPC provides merely a tool to identify variation sources within the manufacturing process, and cannot stand alone.  It is the worker’s responsibility to take note of variation within production and take necessary measures; positive changes in the production line should be included fully into the system, otherwise eliminated.   One primary method of SPC is the implementation of control charts.  Two control plans can then be utilized, namely ‘variable information control plans’, which measures the defect’s length, weight, or width, and ‘attribute information control plans’, which counts the number of faulty objects.  The latter is the more practical choice, since it precisely determines variations within production.  First, the control chart should be set up, to confirm that the process is being analyzed.  Next, identify the procedure that you wish to inspect.  Then collect the data from the process and plot the data on the control plan.  Finally, interpret the control plans to determine whether the process is controlled or not.  The worker can then take action based on the results of the control plan.

When using Statistical Process Control methods, a few things should be remembered:

• Do not assume which control plans the processor programs are using and train the workers at using and implementing the Statistical Process Control.
• You should always consider conducting a process ability study.
• For precise results, use the correct type of control plan for the process you are studying.
• Use random tests in analyzing your process, or use a sample size to identify changes in the procedure.
• Management charts should not have requirement limits.
• Review your control plans on a shop floor from time to time with the workers.
• Don’t use control charts just to please your customers.
• Do not plan the control chart data after the process has begun.