Presentation is loading. Please wait.

Presentation is loading. Please wait.

ChemTrak SPC Training 1.1 ChemTrak7 SPC Training Control Chart Details Distribution Chart Details Step 1 : Stay Inside the Control Limits Impact of tests.

Similar presentations


Presentation on theme: "ChemTrak SPC Training 1.1 ChemTrak7 SPC Training Control Chart Details Distribution Chart Details Step 1 : Stay Inside the Control Limits Impact of tests."— Presentation transcript:

1 ChemTrak SPC Training 1.1 ChemTrak7 SPC Training Control Chart Details Distribution Chart Details Step 1 : Stay Inside the Control Limits Impact of tests that are outside of limits Step 2 : Adjust the Limits with Experience Living with the manufacturer’s TDS Squeezing some more margin Step 3 : Show Some Improvement Scrolling back to show the old days 1

2 ChemTrak SPC Training 1.1 Control Chart Details USL (Upper Specification Limit) (0.85) from manufacturer’s TDS Starting date for Control and Distribution Charts. LSL (Lower Specification Limit) (0.65) from manufacturer’s TDS UCL (0.81) and LCL (0.75) must be set by you to keep test results far away from USL and LSL so Cpk > Ending date for Control and Distribution Charts. Each vertical line is 1 day. Chart covers ~ 4 months. Use the scroll bar on the Test Log to move dates. Vertical bars show range of daily test results. One test on this day. Test below LCL and post-add value at UCL. Range of test results this day. 2

3 ChemTrak SPC Training 1.1 Distribution Chart Details USL, UCL, LCL and LSL on vertical axis 131 readings just below the UCL 5 readings just above the UCL 27 readings below the LCL Cpk = 0.82 for the time period from 11/14/11 to 3/5/ samples during time period from 11/14/11 to 3/5/12 If 3σ tail is too near the USL, “Check UCL” will show. Cpk should be at least 1.33 µ (average value of all readings) is Maximum value on the horizontal axis is set by the maximum count (131 in this example). Other bar lengths are relative to the maximum. If 3σ tail is too near the LSL, “Check LCL” will show. 3

4 ChemTrak SPC Training 1.1 Step 1 : Stay Inside the Control Limits Too many results below the LCL This is the worst result in the past 4-month period. Note: Cpk =

5 ChemTrak SPC Training 1.1 Step 1 : Stay Inside the Control Limits Too many results below the LCL Without this one test result... … Cpk improved to

6 ChemTrak SPC Training 1.1 Step 1 : Stay Inside the Control Limits Now there are no results below LCL With all of the low test results removed … … 0.91 < 1.33 so process still not under control. … Cpk improved to

7 ChemTrak SPC Training 1.1 Step 2 : Adjust the Limits with Experience Current experience shows σ = and µ = oz/gal TDS Sets USL at 0.85 oz/gal and 0.8 oz/gal is optimum. For Cpk = 1.33, if µ = 0.80 then σ = (0.85 – 0.80) / 4 = For Cpk = 1.33, if µ = 0.79 then σ = (0.85 – 0.79) / 4 = So, we must decrease the UCL, but not below 0.8 oz/gal, and we must increase the LCL to reduce σ from to ~

8 ChemTrak SPC Training 1.1 Step 2 : Adjust the Limits with Experience Lower the UCL to 0.8 and raise the LCL to 0.76 oz/gal. After 4 months, the Cpk is improved from 0.82 to even with 7 readings < LCL. This is a huge improvement, the tank control looks good, and yield has increased. The cost of this improvement is more frequent testing and smaller, more frequent adds. 8

9 ChemTrak SPC Training 1.1 Step 3 : Show Some Improvement To show your continuous improvement, scroll down to an earlier date. Note where the limits changed, the wider spread, and the old Cpk. 9

10 ChemTrak SPC Training 1.1 Step 3 : Show Some Improvement Then scroll back to the top... a tighter spread and a better Cpk. … you can show 10

11 ChemTrak SPC Training 1.1 Step 3 : Show Some Improvement + opportunity to improve for the next audit. 11


Download ppt "ChemTrak SPC Training 1.1 ChemTrak7 SPC Training Control Chart Details Distribution Chart Details Step 1 : Stay Inside the Control Limits Impact of tests."

Similar presentations


Ads by Google