Block 5 - lecture 4

Question 1

u chart?

Answer 1

count of nonconformities per unit that works for varying subgroups

Question 2

what chart is the u chart mathematically equivalent to?

Answer 2

the c chart

Question 3

typical minimum number of subgroups needed?

Answer 3

25 subgroups

Question 4

basic steps to create and use a u chart?

Answer 4

• collect data
• find trial central line and control limits
• discount subgroups with assignable causes
• find revised limits

Question 5

where are the control limits positioned relative to the central line?

Answer 5

3 standard deviations away

Question 6

what subgroup sizes can be used for c charts and u charts?

Answer 6

c charts - fixed, single unit

u charts - can be variable

Question 7

nonconformity classification?

Answer 7

nonconformities or nonconforming units classified on severity

Question 8

three classes that can be used for nonconformity classification?

Answer 8

1. critical (unsafe, will affect usage)
2. major (might affect usage)
3. minor (won’t affect usage)

Question 9

Demerits?

Answer 9

a way for classification to effect a control chart

Question 10

equation used for demerits?

Answer 10

D=WcUc + WmaUma + WmiUmi
W is the weight per classification
U is the count of nonconformities

Question 11

give a typical example of the weightings for demerits?

Answer 11

critical = 9
major = 3
minor = 1

Question 12

how to graph data with classifications?

Answer 12

• separate graphs initially

- combine the central lines using the formula