Application of Statistical Process Control Technique for Evaluating Machine Capability: A Case Study

Deros B. M.

Department of Mechanical and Materials Engineering, Faculty of Engineering,

Universiti Kebangsaan, Malaysia E-mail: Địa chỉ email này đã được bảo vệ từ spam bots, bạn cần kích hoạt Javascript để xem nó.

Rahman M. N. Ab

Department of Mechanical and Materials Engineering, Faculty of Engineering,

Universiti Kebangsaan, Malaysia

Ismail A. R.

Faculty of Mechanical Engineering, Universiti Malaysia Pahang

Yee L. W.

Department of Mechanical and Materials Engineering, Faculty of Engineering, Universiti Kebangsaan, Malaysia

Zain R.M.

Department of Mechanical and Materials Engineering, Faculty of Engineering, Universiti Kebangsaan, Malaysia

QC 29

Abstract

This paper discusses the use of statistical process control (SPC) for evaluating production machinery capability and efficiency of production machineries in Malaysian manufacturing companies.

The case study was conducted at three manufacturing companies’ coded names: company A, B and C. In the first part of the case study, the authors had gathered the profile of the three companies’, general requirements in quality management, general information about SPC and its application at each company.

Having done that, later the authors investigated each company’s past experienced in implementing SPC in their production department.

First, in Company A the authors had found that the manufacturing processes for making base plates are still in control. In company A, the high speed milling machine used is very capable of producing consistent frame lengths for the base plates because the process capability indexes (Cp = 2.62 and Cpk = 2.27), which are more than 1.

 In company B, the manufacturing process for printed circuit board (PCB) was found to be out of control. In company B, the authors had not studied and calculated its process capability index because the manufacturing process was already out-of-control. In other words, it is already very obvious that the machine used in the manufacturing process for PCB was not capable.

Meanwhile company C, which is currently producing compressed pill tablet seems to be in control. However, the study found that the pill tablet compression machine capability index at Cp = 1.16, seems to be capable of producing pill tablets with hardness within the upper and lower control limits. In this case, the process is not centred because Cpk = 0.93 is less than 1 and thus the distribution of pill tablets hardness are not following the normal distribution.  

Keywords:

Statistical process control, Process capability, Machine capability, Manufacturing company