CONTROL CHARTS APPLYING A SEQUENTIAL TEST AT FIXED SAMPLING INTERVALS chosen betw cen 0.1 further see Chaudhry and Higbie (1990) on whether the chart should be tuned for vide an illustration of the use of the SPRT chart using simulated data. ca A manufacturer of thrust washers is makin Step 5.Determine the SPRT chart contro entrated efforts to control the parameters g and h.The chart parame which as occa onally been inflated in the pa obtained d h ATS/d Step 6.Evaluate the Tsperformance of arget value for average washer thickness iso SPRT chart ca tained using Figures 4-9.which are plotsof SSAT at=0.00005 inches.Presently,the company is washers every two hour is int d in for shifts in of interest and used to de- Xchart.The ide SPRT chart will creasing the mean time to signal so that the costs o prod are reduced Step 7. Adiust n that is effective to rework nonconforming washers.Prelim initially chosen from Steps 1-6 may not nary stu SPRT ha times If the SSATS at 6 is not sho enough. hav e a relatively W FAR. will perform well fo control ASN should be from the and ed x char should be considered of decreasing the in cordingly,the sampling intervals are chos to be control ATS. =a us,it hours (Step D). ont n to he 3000 (Sten 3)and is cho and for the sar and/or the in- e 0.15 (Step 4). That is, 2.0 achi .sampling cost d FAR. D.Once every 2 hours washers are sampled sequen dkmdmpaatspTmo The nex section ides an illust ially,one washer at a the washers rt SPRT bei An Illustration From Figures 2 and 3.respectively,for0.15 an n- ontro parameters (Step 5) SPRT ch ers are manfactured using a punching operation on canvas ma SPRT ch stripping.punching.baking.and shipping.The im mances (Steps 6 and 7).Using Figure 2.it can be sitive to iameter.I ciaAg very sensitive to the Vol.29.No.1.January 1997 Journal of Quality Technology Reproduced with permission of the copyright owner.Further reproduction prohibited without permission.Reproduced with permission of the copyright owner. Further reproduction prohibited without permission