Links to all courses

3 - σ control limits for R-chart are given by -

E (R) + 3σR

E (R) is estimated by R̄ (R-bar) and σR from

σR = C.E (R) = CR̄

where C is the constant depending on n.

So, UCL

= (1 + 3C)R̄ = D

LCL

= (1 - 3C)R̄ = D

The values D

However, the control limits for R-chart can be obtained directly from the assumed or known value of σ as follows:

UCLR = D

LCLR = D

Where, D

3 - σ control limits for R-chart are given by -

E (R) + 3σR

E (R) is estimated by R̄ (R-bar) and σR from

σR = C.E (R) = CR̄

where C is the constant depending on n.

So, UCL

_{R}= R̄ + 3CR̄= (1 + 3C)R̄ = D

_{4}R̄LCL

_{R}= R̄ - 3CR̄= (1 - 3C)R̄ = D

_{3}R̄The values D

_{3}= (1-3C) and D_{4}= (1 +3C) have been tabulated for different values of n from 2 to 25.However, the control limits for R-chart can be obtained directly from the assumed or known value of σ as follows:

UCLR = D

_{2}σLCLR = D

_{1}σWhere, D

_{1}and D_{2}are tabulated for different values of n from 2 to 25.
## No comments:

Write comments