What Is The Minimum Number For Worker To Supervisor Ration In Manufacturing Industry

in a manufacuring industry what is ratio for workers and supervisors?
behind how many workers we appoint 1 supervisor?

Dear Mr. Sachin
Before i answer to your query, i want you to understand the ROLE OF SUPERVISOR in your organisation based on REQUIREMENTS or KPA and KPI. An individual taking charge as SUPERVISOR should have an ABILITY to handle his TEAM, UNDERSTAND HIS TEAM MEMBERS and guide them towards RIGHT PATH.
"SUPERVISOR" means NOT JUST SUPERVISING TO WHAT EXTENT INDIVIDUALS ARE CARRYING OUT OR DELIVERING THEIR RESPONSIBILITIES AT WORKPLACE WITHIN STIPULATED TIME FRAME. Its something more than SUPERVISING where you have to find out SUPERVISORY SKILLS in your SUPERVISORS.
Based on my views, you are requested to define the ratio and please try to avoid ASSIGNING EXCESS WORKLOAD to any of your SUPERVISOR, beyond their CAPACITY, which may SLOW DOWN - PRODUCTIVITY.
With profound regards

for example we have 14 shift supervisors in our foundry in one shift we have capacity of 18 ton melting. you just tell me in moulding section one supervisor can handle 20 workers?

Dear Mr. Sachin
I regret as I can't answer your query because you can only judge your supervisor's caliber and much more as i am not available ONSITE to advice you THE BEST SOLUTION.
How much distance does a supervisor need to travel to monitor 20 workers? This is routine job and has to be performed within 8hours/shift. Kindly study about this
Evaluate PAPER WORK to be carried out before end of the shift
Based on these points, you can decide further. You can enhance RATIO gradually if supervisor has less workload.
With profound regards