Line Balancing using Capacity Study Data and Work Sharing Among Sewing Operators (Question answered)

A few days back, I received an email from one of the OCS readers. He asked a couple of questions to clarify the calculation used in Line Balancing and shared a document. I am sharing the line balancing sheet and capacity study data. He found the guide from another website, but calculation methods are not explained in detail – so he wants some clarification from me. 

I sent the answers to him and sharing the same here for you. I thought you might have the same question. Let’s learn the line balancing topic today. Read my answer below. To understand the below questions, you need to read the line balancing table thoroughly.

In previous articles, I have written the line balancing method using skill matrix and capacity study. You can refer to those articles for more clarification.

OCS Reader wrote

“The table below is obtained from some resource on the internet. It is not clear to me the calculation. It is on line balancing topic. Given benchmark target is 200 pcs.

Image-1: Line balancing using capacity study data

Image-2: Balancing process 

On the source I got the document, it says for the line to be balanced, operator # 7 should work for 50 minutes and should help operator # 8 for 10 minutes. Now my question is:

Question-1: Why operator # 7 helps operator # 8 for 10 minutes? Why not for 8 minutes, why not for 12 minutes, etc.?

Answer: 

You can allocate an employee for a second process#8 as many minutes as needed to meet the hourly target. Though in the example it is suggested for 10 minutes for balancing. Actually, the engineer who made this document has calculated balancing with 7 minutes allocation for the second process (#8). 7 minutes is enough for making 201 pieces on the operation#8

Question#2: If operator# 7 works for 50 minutes on his main operation, his output (balanced capacity) will be 200 but inside the table, the calculation says 212. How that is calculated?

In 60 minutes production =240 pc

Therefore, in 50min operator will produce = (50 x 240) /60= 200 pcs

Answer: 

As I said in the above question, the employee worked 7 minutes for the process#8. Ans she worked 53 minutes for process#7. Calculate using 53 minutes of work on operation#7, you will get 212 pieces of production.

Production quantity in 53 minutes will be = (53 x240)/60=212 pieces 

Question-3: 

In the remaining 10 minutes, he helps in operation# 8. According to the calculation formula, in 10 minutes worked, the operator can produce 30 pcs i.e.

In 60 min production qty =180 pcs

therefore, in 10 min production quantity will be = 30 pcs

Operator# 8 has a capacity of 180pcs per hour and when operator # 7 helped him for 10 minutes, the output will be 180+30=210 pcs. But this figure also doesn’t match with the data inside the table.  It shows the produced quantity is 201 pieces. How that is derived?

Answer:
The operator#7 worked for 7 minutes and she produces 21 pieces
Combined production of operation#7 and #8 in process#8 = (180+21) = 201 pieces.

So, the given document has correct information. Only the comment added like 10 minutes work shared by operator#7 creates confusion.

I hope I have answered all these questions and able to clarify your confusion on understanding the calculation in the given document.