1. What is your analysis of the bag weight problem?
The problem begin when Wet-Land Drilling, Inc. had filed a complaint that the bags it received from Bayfield were short-weight, according to previous send the weight of the bags used to be 50 pounds, however the new arrivals show a weight of 47.5 pounds per bag, causing a conflict to the company. The company present the problem as a increased of demand, hiring new employees with a lack of training, new employees occupy the night shift, where old employees check the production, however the double checking of the bag still a problem to the company. First of all we need to analyze and find the errors the process could have, caused by the increased of demand and a lack of control due the old employees, for the analysis I will use the Statistical Process Control (SPC).
¨Statistical process control (SPC) involves using statistical techniques to measure and analyze the variation in processes. Most often used for manufacturing processes, the intent of SPC is to monitor product quality and maintain processes to fixed targets. Statistical quality control refers to using statistical techniques for measuring and improving the quality of processes and includes SPC in addition to other techniques, such as sampling plans, experimental design, variation reduction, process capability analysis, and process improvement plans.¨(reliability.sandia.gov, Statistical Process Control)
We have and average of 50 pound from older shipment, this is the correct weight that the bags should have so, X=50, also we have a standard deviation of 1.2 which is also the desired level, so o=1.2, for the determination of the bags we need to resolve this formula [pic] 0.489 and a 99.73% confidence interval Z = 3: UCL= x+ 3σx=50+3 x 0.4899=51.4697
LCL= x – 3σx=50-3 x 0.4899=48.5303
The Percentage of Bags with Average Weight within Control Limits (Per Shift)
Day Shift = 23 bags/24 bags = 96%
Afternoon/Evening Shift = 12 bags/24 bags = 50%
Night Shift = 12 bags/ 24 bags = 50%
2. What procedures would you recommend to maintain proper quality control? I recommend making a constant control, trying to make the double checked of the bag weight, also is important for the company to create a mean and range charts guide, that will help the employees to make the control of the bags, this also will help bag packers to make and extra control to the bags, avoiding any errors in weight. Is important to buy scales in the production area and in the bag packers area, the scale will be accompanied by the mean and wage charts, reducing the errors of weight. Also use camera in the areas and training process fro new employees about the doze and the mean and wage of every bag.
reliability.sandia.gov, Statistical Process Control, retrieved 12 August 2010, from http://reliability.sandia.gov/Manuf_Statistics/Statistical_Process_Control/statistical_process_control.html