Ac 2007-1520: Determining Process Capability of an Industrial Process in Laboratory Using Computer Aided Hardware and Software Tools

Quality means suitability for use and it is inversely proportional to variability of product, service, people, processes, and environment. However, it is the dynamic state that is associated with each of the above and that meets or exceeds expectations of a customer. Quality improvement is therefore the progressive reduction of variability. The gradual reduction of process and product variability can be done by successive determination and removal of the causes responsible for the variability. For a process industry, causes of product variability happen generally due to two reasons: (1) The process itself (2) Personnel that runs the process. Whatever the reasons are -in order to rectify, they need to be determined. Since product and process variability can be described in statistical terms, determination of this in quantitative form using statistical methods will point us to the obvious direction of rectification. Process Capability is a measure of the uniformity of a process output. To estimate this, engineering and statistical analyses have to be launched. If a process is determined to be incapable of producing product within the required specification, Statistical Process Control (SPC) will not fix it or control it; however, it will exhibit that the process is incapable. Often time’s workers are blamed for their poor workmanship even when the process machinery is incapable of producing the product to meet the newer and tighter specification. In such situation management tend to think, what can go wrong with the process? The thing the workers need to do is to run the machinery and produce the product of required specification. It is like someone have given you felt-tip pen having one millimeter thick tip and tell you to make a 0.1 millimeter thick line on a paper. No matter how hard you try it is quite impossible to do so. Similarly if a process is incapable of meeting the standard, no matter how well one tries to control it, it will not produce the product of desired specification. Determination of Process Capability is not hard, but it is frequently overlooked. It should be done first in any quality improvement program. It must be repeated on a periodic basis to ensure that the process stay fit to produce product of desired specification. If the process is incapable, then it is management’s responsibility to either improve the process or accept poor quality product. The workers cannot be held responsible for failure to meet standards, if they do not have any means to achieve those specifications. Process Capability of a certain process is determined by collecting a set of data sample of an output product specification from the process that is under optimal control. Then calculating the upper and lower natural tolerance limits that is within 6σ (6-sigma, σ = standard deviation) spread in the distribution. In other words collected data samples should reveal that the product specification is within 6σ distribution limit. If μ (mu) is the target specification, then the 99.73% of the product produced by the process under investigation must fall within μ +3σ and μ -3σ. If so, the process is said to be capable. If it is not within these two limits, the process is not quite profitable and is a candidate for improvement. This paper analyses and outlines the procedure for the determination of Process Capability of an industrial process in a laboratory using computer hardware and software tools. In order to communicate the understanding of process capability determination to the students we have prepared a statistical software tool coupled with a digital micrometer that is interfaced with the software tool through USB port for collecting data samples. After collecting a set of data sample students will then use the statistical software tools to determine the process capability of the industrial process that produced the product. Data collected from an industrial process can also be entered manually in to the statistical software tools to determine the process capability, normal distribution charts, process capability ratio, X-bar, and R-charts. Determination of process capability and generating statistical charts using software and hardware tools are part of a process control course.