A process in the manufacturing industry is unique because the process needs the combinations of manpower, raw materials, machines, and methods. In order to improve the qualitylevel of products, the capability of the process plays an important role in themanufacturing industry.
Rezaie, K. 6. The process capability indices(PCIs) is also known as process capabilityanalysis which is widely used in manufacturing industry.
The PCIs isused to measure the ability of the process to meet the requirements of thecustomers which are also known as specification limits. The analyst used PCIsto control and monitor the performance of the process in the manufacturing industry. Besides, the PCIs can use to improve the performance of the process by reducing the variation of theprocess.
JH, S. et al. 3.The process capability analysis can be presented graphically by usinghistogram and probability plot.Montgomery, D.
C. 5. The graphics can determine whether the process iswithin specification limits (SLs) or not. Steiner, S. et al.
9. Thehistogram is the easiest and clear method to determine the performance of the process. If the process is incontrol and the data is normally distributed, the potential capability analysiscan be used to improve the quality of the process. Spano, A.
8. The PCIs is used tocompare the output of in control process with the SLs by 6 sigmas. PCIs are quantitative measures based on the performance and potential of theprocess. By doing so, the process can meet the requirements of the customers.Rezaie, K. et al. 6. The process of the manufacturingindustry is considered as capable when the process is under control.
Spano, A.6. The automotive industry was applying the PCIs in Japan and United States(US). The process capability with sampling properties and estimation proceduresis measured to determine the normality of the process and the process is instatistical control or not. Kane, V.E. 4.
The PCIs had been used inmanufacturing industry in quantitative measure form to ensure the performanceof the process. The cost spent in the process of rework and scrap will causethe loss of the industry. Hence, the high-qualityproduction should practice in industry and try to meet the requirements. JH, S.et al. 3.
According to the requirements of thecustomers with the costs that needed to spendby the suppliers, the suppliers still need to set the suitable cost for theirproduct and ensure that the products are under tolerance limits. If the process capability of the process is undercontrol by the suppliers, we can try toimprove the quality of products or the process by out of control action plan(OCAP). The process capability indicescan help to analyze the capability andtry to predict the machining process that can meet the expectations andtolerance limits of the customers.
The process capability indices consist of , , and . Abhijit S. et al., Montgomery, D. C.
1, 5. The valuewill represent the performance of process. Table 1 summaries the six qualitycondition with its value.?hsan K.2.Table 1: Quality conditions and value Quality condition value Super excellent 2.00 ? Excellent 1.67 ? ? 2.
00 Satisfactory 1.33 ? ? 1.67 Capable 1.00 ? ? 1.
33 Inadequate 0.67 ? ? 1.00 Poor < 0.
67 In manufacturing process, value is used to identify the variation of thecharacteristics of the product within SLs that set by the engineers or thedesigner. Rupesh C. et al. 7.
Although many manufacturing industry had use value to determine the process capability ofthe process, but value cannot used to determine whether theprocess is off-centering and we do not know the actual performance of theprocess. Thus, the value is used to indicate that the process isin the SLs. The and always used in manufacturing industry in orderto determine the number of the product that within the specification limits andensure the process is well perform. ?hsan K.2. and have the same statistical properties. Sincethe consists of the and , most of the manufacturingindustry will used instead of and . The value widely used in manufacturing industry.
The value can assume the normality and independencyof the target value, T. If the sampling distribution had skewed slightly or offcenter slightly, the process can still considered as capable. Zhang, N.
F. et al. 10. Since thereare many manufacturing industry had uses the process capability, there are manystudy that try to use the capability indices to determine the performance ofmachining process. More undertakings have been given to utilizations andinvestigations of process capacity indices. Abhijit S. et al.
, JH, S. et al., Rezaie, K. et al. 1, 3,6.
In the future, the manufacturing industry might implement the capabilityindices to determine machining process performance.