If a machine cannot make parts that meet specifications $($USL and LSL$),$ what can be done to improve this situation:

Question $5$ options:

Do a $100\%$ inspection to separate good from bad parts and rework parts that can be corrected

Perform controlled experiments to determine the main sources of variation and try to solve them

Ask the customer to relax the specified limits$,$ i$.$e$.$ make the $($USL $$ LSL$)$ difference larger

Shift production to a different $($better$)$ machine, i$.$e$.$ decrease standard deviation $\backslash$sigma

Everything mentioned here