Continual Improvement (Total Quality Management)
1. Introduction
Statistical process control refers to a statistical method used to separate variation produced b y special causes and varation produced by natural causes. This is done so that it is possible to eliminate the special causes and to establish and maintain consistency in the process, allowing the process to be improved.
A Process refers to everything that is done in a workplace. Multiple factors affect these processes and they are usually refered to as the Five M’s. The Five M’s are, the Machines employed, Materials used, the Methods(manuals for labour) provided, the Measurements taken, and the Manpower(workers) who operate the process. When all Five M’s are conformed(no misadjustments in the machines, no flaws in the material, work instructions are precisely followed and are totally accurate, people(manpower) following the work instructions properly and with full concentration), special causes are eliminated and the process will be in statistical control.
However, this does not mean the output from the process are 100% perfect. There is still natural variations which may affect the output of the process. Natural variation is expected to account for roughly 2,700 out-of-limits parts in every 1 million produced by a 3-sigma process, 63 out-of-limits parts in every 1 million produced by a 4-sigma process, and so on.
1.2 History of SPC
SPC(Statistical Process Control) originated as far back in 1931, when Dr Walter Shewhart wrote a book, The Economic Control of Quality of Manufactured Product. He is a statistician from Bell Laboratories which was the first to realise that data could be retrieved by industrial processes themselves. By using statistical methods, these data could then signal that the process is in control or affected by special causes(unnatural causes, predictable variation). (history of SPC)
1.3 Benefits of SPC
Implenting SPC is essential in a company’s manufacturing process. It benefits the process by reducing
Statistical process control refers to a statistical method used to separate variation produced b y special causes and varation produced by natural causes. This is done so that it is possible to eliminate the special causes and to establish and maintain consistency in the process, allowing the process to be improved.
A Process refers to everything that is done in a workplace. Multiple factors affect these processes and they are usually refered to as the Five M’s. The Five M’s are, the Machines employed, Materials used, the Methods(manuals for labour) provided, the Measurements taken, and the Manpower(workers) who operate the process. When all Five M’s are conformed(no misadjustments in the machines, no flaws in the material, work instructions are precisely followed and are totally accurate, people(manpower) following the work instructions properly and with full concentration), special causes are eliminated and the process will be in statistical control.
However, this does not mean the output from the process are 100% perfect. There is still natural variations which may affect the output of the process. Natural variation is expected to account for roughly 2,700 out-of-limits parts in every 1 million produced by a 3-sigma process, 63 out-of-limits parts in every 1 million produced by a 4-sigma process, and so on.
1.2 History of SPC
SPC(Statistical Process Control) originated as far back in 1931, when Dr Walter Shewhart wrote a book, The Economic Control of Quality of Manufactured Product. He is a statistician from Bell Laboratories which was the first to realise that data could be retrieved by industrial processes themselves. By using statistical methods, these data could then signal that the process is in control or affected by special causes(unnatural causes, predictable variation). (history of SPC)
1.3 Benefits of SPC
Implenting SPC is essential in a company’s manufacturing process. It benefits the process by reducing