Statistical Process Control

Standard Operating Procedure for inline Q. A, using Statistical Process Control charts OBJECTIVE To remove or minimize, cost of hapless quality. SCOPE This procedure is applicable for all kind of critical points for which variable charts ar being made to know about the butt stability. RESPONSIBILITY 1) Q. A. coach-and-four Q. A. Manager is responsible for allotting the critical points in a particular product to in line Q. A. s. 2) A. Q. M. A. Q. M. is responsible for carrying out the SPC effectively in their given lines.He is too responsible to assist the in line QAs in case of any difficulty. 3) In Line Q. A. s In line Q. A. s are responsible to fill the variable chart correctly and take appropriate actions required after depicting the charts. PROCEDURE ? One Variable chart is to be prepared against each critical point. ? Take 5 samples at random produced in a particular hour and experience measuring critical points on each sample. ? Write down the measurement difference as pe r the size-measurement specification given on variable chart in the period of that hour. After the pentad pieces are inspected, find out the median and range of these five readings by the interest method. o Arrange the data in ascending order and write down the third no. in the median array for that particular hour. o To calculate range note down the difference between the upper limit reading and minimum reading of that particular hour. Write it down in the range array. ? Calculate Upper Control delimit and Lower Control Limit by using the following formula o Calculate X Bar for previous days 8 hours reading by following formulaX1+X2+X3+X4+X5+X6+X7+X8 X = 8 Where X1 .. X8 are the median readings for previous day 8 hour. o Calculate R for previous days 8 hours reading by following formula R1+R2+R3+R4+R5+R6+R7+R8 R= 8 Where R1 .. R8 are the range readings for previous day 8 hour. o UCL and LCL for median chart will be calculated by the given formula __ UCL = X+0. 691* R LCL = X-0. 691 * R o UCL and LCL for Range chart will be calculated by the given formula UCL = 2. 14 * R LCL = 0 * R ? Now once limits of median chart as well as range chart are calculated start marking the points of median and range on the median and range graph respectively that to corresponding to that particular hour. ? If any point is found to lie outdoors the control limits, immediate action should be taken to bring the process in control. ? One point should be kept in mind that process should lie somewhere near central line. It means your process is stable and predictable.