How to calculate the value add time?

[rufeng]

I am preparing the IQF six sigma exam and get the question below:

A factory loads explosive into rockets. The rockets move through production in a cart containing 20 rockets. The process steps are; cleaning, pouring, cooling, drilling, and painting. There are two operators at the cleaning station, and one operator at the remaining stations. The time to process cycle times for a single rocket are:

cleaning 2 minutes
pouring 2.2 minutes
cooling 1.7 minutes
drilling 2.2 minutes
painting 1.8 minutes

What is the value add time (percentage) if a rocket takes 7.7 hours to move through production?


I added the time requested for each step (2+2.2+1.7+2.2+1.8) and divided the total by (7.7*60). The result is 2.14%. Is this the correct way to calculate it? It is independent to the # of rockets in the cart and the # operators in each step, right?

Thanks for the help.

 

[Miner]

You are on the right track, but did not go far enough.

Look at the six operations. Which add value for which a customer would be willing to pay?

Pouring explosive? Yes, otherwise it would not function.
Drilling? Probably, depending on why you are drilling. If it serves some functional purpose, yes.
Painting? If for cosmetic or corrosion prevention, probably. However, think of the liquid fuel tank of the space shuttle. They stopped painting it because it served no functional purpose and added weight.
Cleaning? No. That's your problem, not mine.
Cooling? No. I get no functional benefit from that.

You will always get differences of opinion on what constitutes Value Add. But use the mathematical approach that you used before, but only include the Value Add operations.

 

[DanteCaspian]

Value added time = what the customer cares about; is willing to pay for.