Application linkage are the variation of the process that

Application of Process Capability Indices to Measure Performance of Manufacturing Process


Kwek Yan Ping

We Will Write a Custom Essay Specifically
For You For Only $13.90/page!

order now

Faculty Applied Science and Technology, University Tun Hussien Onn Malaysia, Malaysia


[email protected]


The process capability indices (PCIs) are used to evaluate and monitor the process of manufacturing industry. The PCIs that used in the manufacturing industry are , ,  and . The machine capability is calculated by  and  which is in short period. The PCIs are important in manufacturing industry.

Keywords. Process capability indices; Machine capability.


A process in the manufacturing industry is very unique because the process needs the linkage of manpower, raw materials, machines, and methods. The linkage are the variation of the process that are hard to control. In order to improve the quality level of products, the capability of the process plays an important role in the manufacturing industry. Rezaie, K. 6. The process capability indices (PCIs) is also known as process capability analysis which is widely used in manufacturing industry. The PCIs is used to measure the ability of the process to meet the requirements of the customers which are also known as specification limits. The analyst used PCIs to evaluate 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 the process. JH, S. et al. 3.

The process capability analysis can be presented graphically by using histogram and probability plot. Montgomery, D. C. 5. The graphics can determine whether the process is within specification limits (SLs) or not. Steiner, S. et al. 9. The histogram is the easiest and clear method to determine the performance of the process. If the process is in control and the data is normally distributed, the potential capability analysis can be used to improve the quality of the process. Spano, A. 8. By referring to the histogram, we can determine whether the process is off centering or not. The PCIs is used to compare the output of in control process with the SLs by 6 sigmas. PCIs are quantitative measures based on the performance and potential of the process. By doing so, the process can meet the requirements of the customers. Rezaie, K. et al. 6.


The process of the manufacturing industry 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 procedures is measured to determine the normality of the process and the process is in statistical control or not. Kane, V.E. 4. The PCIs had been used in manufacturing industry in quantitative form to ensure the performance of the process. The numerical data will help the person in charge can modify the process by using more efficient methods. The cost spent in the process of rework and scrap will cause the loss of the industry. Hence, the high-quality production should practice in industry and try to meet the requirements. JH, S. et al. 3. The PCIs is the best method to maintain the quality of the product.

According to the requirements of the customers with the costs that needed to spend by the suppliers, the suppliers still need to set the suitable cost for their product and ensure that the products are under tolerance limits. If the process capability of the process is under control by the suppliers, we can try to improve the quality of products or the process by out of control action plan (OCAP). The process capability indices can help to analyze the capability and try to predict the machining process that can meet the expectations and tolerance limits of the customers. The process capability indices consist of , ,  and . Abhijit S. et al., Montgomery, D. C. 1, 5. The  value will represent the performance of process. Table 1 summaries the six quality condition with its  value. ?hsan K.2. The different  value will represent different quality condition.

Table 1: Quality conditions and  value

Quality condition


Super excellent

2.00 ?


1.67 ?  ? 2.00


1.33 ?  ? 1.67


1.00 ?  ? 1.33


0.67 ?  ? 1.00