Question

A textile mill wishes to establish a control procedure on flaws in towels it manufactures. Using an inspection unit of 50 units, past inspection data show that 100 previous inspection units had 850 total flaws. What type of control chart is appropriate? Design the control chart such that it has two-sided probability control limits of α=0.06, approximately. Give the center line and control limits.

Answer 1

Answer:

•A c-chart is the appropriate control chart

• c' = 8.5

• Control limits, CL = 8.5

Lower control limits, LCL = 0

Upper control limits, UCL = 17.25

Step-by-step explanation:

A c chart is a quality control chart used for the number of flaws per unit.

Given:

Past inspection data:

Number of units= 100

Total flaws = 850

We now have:

c' = 850/100

= 8.5

Where CL = c' = 8.5

For control limits, we have:

CL = c'

UCL = c' + 3√c'

LCL = c' - 3√c'

The CL stands for the normal control limit, while the UCL and LCL are the upper and lower control limits respectively

Calculating the various control limits we have:

CL = c'

CL = 8.5

UCL = 8.5 + 3√8.5

= 17.25

LCL = 8.5 - 3√8.5

= -0.25

A negative LCL tend to be 0. Therefore,

LCL = 0