Inthis essay I will be covering the statistical process control system. Thestatistical process control system, or SPC for short, is basically a qualitycontrol & improvement strategy information system. The statistical processcontrol system is a data driven, graphic centered, process oriented operatorrun system designed to implement timely corrective action & also a way toidentify quality problems & challenges. In this essay I will cover the main features & uses of thestatistical process control system. There are several reasons of why manycompanies use the statistical process control system.
The main tool of the statistical processcontrol system is the control chart, which users with access can view &change attribute data & variable data as they see fit. Typical users will initiate the use of controlcharts & other SPC techniques to reduce variation & to enhance themanufacturing process. Many times, the companies will use the statisticalprocess control system to satisfy the customer requirements or to meet certaincertification requirements. Characteristicsof the Users of the System The typical users of the statisticalprocess control system are engineers & technicians. The engineers basically use the statisticalprocess control system to manipulate data & view trends within the data.
What separates the statistical processcontrol system from other quality related data systems is basically a greateremphasis on the participation & role of the process users, more real timedata analysis & preventing problems instead of explaining why theyoccurred. Featuresand Usage of the System One of the main features of thestatistical process control system is the control chart. It is basically a graphical representation ofwhat is going on in a process. It is agraphical tool used to distinguish between inherent & assignablevariation.
The SPC system incorporatesthe control chart with center line, upper limit, & lower limit functionswhich can be manipulated by the user. The control chart basically shows changes in data pattern as well as thecauses of the changes in data. Thecontrol charts have a center line, upper limit line & lower limit line. Thecenter line function is basically the process average or expected value. Theupper & lower limit values can also be changed by the user if they see fitto do so. The users can signal the need for corrective action by measuring theprocess sample in accordance with the control plan. They then can use therecord function by recording the data on the control chart & plot pointsthat need further attention. Other users then can log in to the SPC system,view the control chart & compare any individual readings to thespecifications that are previously noted on the control chart.
The variables& attributes functions are other features that users can view & changevia the SPC system. The variables function basically are characteristics thatusers can measure, weight, or change. The attributes function is used for usersto focus on defect & classification. Other functions of the statisticalprocess control system are the “In control” & “Out of control” statusoptions.
If data listed on the controlchart are within the upper & lower limit lines, the process is listed to be”In control” and is capable of producing within the control limits. If the data is plotted outside of either theupper limit or lower limit lines, it is process is listed to be “Out ofcontrol”. The In control & Out ofcontrol status can also be viewed as functions due to the fact that users canmanually change the status of a process as In control or Out of Control at anygiven time. An example of a user changinga process status to Out of control would be if there is scheduled work to bedone to a manufacturing tool.
The tool would be listed as Out of control, andwould not start any manufacturing process until the user logs back in and listsit as In control. Impactof the System The impacts of the statisticalprocess control system can be great at my organization. My organization, being that I currently workat Intel, relies greatly on the SPC system. This is due to the fact that thatalmost all the wafer manufacturing tools & equipment are integrated to thestatistical process system.
The positive impacts of the statistical processsystem would be that with certain users being able to change the data on aparticular control chart, that user can potentially improve the quality of theoutput product. This would basically result in not only improved quality butpotentially higher revenues, reduced costs, increased productivity, lowerrework issues, lower scrap costs & lower warranty costs all of which wouldbasically result in increased profits. The negative impacts of the statisticalprocess control system would be that at any given time, if data listed on acontrol chart is above the upper level limit or lower than the lower levellimit, a process or tool would be “Out of control”. This means that the process or tool wouldessentially be in a down state. At Intel if a process or tool goes down, thatis basically wafers that are not being processed for output. This in turn wouldresult in a loss of wafers in process, and in a manufacturing environment, ifthere is no output the company is basically losing money. Another negative impact would be that if thestatistical process control system goes down, for example if it fails to loadvia the intranet, the fabrication plant would potentially be at a stand stilluntil it comes back up. This would result in a huge loss due to there being nooutput throughout the down time.
Conclusion In conclusion, I will state that thestatistical process control system is a complex program that while the cost of runningit is high, the return investment to the company utilizing it is potentially higher. The knowledge & information created withthe statistical process control system does prove to be successful. The system does require good coordination and cangreatly improve a company’s product output through user controlled & analyzeddata. With the use of the statistical process control charts, engineering IT candetermine where the process will be out of control at a future point and can thenquickly respond with the steps needed to find a solution.