Question

Question: Twelve additional samples of curetime data from the molding process were collected from an actual production run. The data from these new samples are shown below. Update your control charts and compare the results with the previous data. The X -and R-charts are drawn with the new data using the same control limits established before. Comment on what the new charts show.

Short answer

Answer

The data shows the range and mean for 25 samples whereas also shows the values of the average of mean and range. Where the X bar is 30.40289 and the Range bar is 5.932155 (as shown in the table).

Step-by-step solution

Calculating the upper control limit and lower control limit of X-bar

As given,

A2 = 0.73

D3 = 0

D4 = 2.28

N = 4

Calculating the upper and lower limits of X-bar -

Where,

$\stackrel{=}{X}$= 30.40289

$A_2$= 0.73

$\stackrel{-}{R}$= 5.932155

The formula is given below-

Upper Control Limit =$\stackrel{=}{X+}{A}_2\stackrel{-}{R}$

= 30.40289 + (0.73 x 5.932155)

= 30.40289 + 4.33047

= 34.73

The formula is given below

Lower Control Limit =$\stackrel{=}{X-}{A}_2\stackrel{-}{R}$

= 30.40289 - (0.73 x 5.932155)

= 30.40289 - 4.33047

= 26.07

Calculating the upper and lower limits of R-bar

Given,

A2 = 0.73

D3 = 0

D4 = 2.28

Calculating the upper and lower limitsof R-bar

Upper Control Limit =$D_4\stackrel{-}{R}$

= 2.28 X 5.932155

= 13.53

Lower Control Limit =$D_3\stackrel{-}{R}$

= 0 X 5.932155

=0.