What is a Bottleneck
A bottleneck is the operation in a production line that has the lowest capacity and therefore limits the output of the entire line. In simple words, the bottleneck is the slowest process. The line can never produce more than what the bottleneck can produce, no matter how fast the other operations run.
How to Identify a Bottleneck
The bottleneck is usually the operation with the highest work content, the longest cycle time, or the most waiting in front of it. Look for a pile of work-in-progress (WIP) in front of one workstation. That is a strong sign of a bottleneck. You can also calculate the cycle time of every operation and find the highest one.
Practical Example 1 — Sewing Line
A sewing line has 5 operations. Their cycle times in seconds are: 40, 45, 62, 50, and 42. The bottleneck is operation 3 with 62 seconds. If we balance perfectly at the average, the line could produce at a 47.8 second cycle. The gap from 62 to 47.8 is the opportunity lost.
Practical Example 2 — WIP Pile
A supervisor notices 200 pieces waiting in front of a side seam operator while other operators have almost empty baskets. That side seam operation is the bottleneck. Adding a helper or splitting the operation reduces waiting dramatically.
Practical Example 3 — Cutting Section
The cutting section can cut 1200 pieces per day. The sewing floor can sew 1500 pieces per day. The cutting section is the bottleneck. Adding one more cutting table raises the whole factory output by 300 pieces per day.
Practical Example 4 — Finishing Bottleneck
In finishing, 800 pieces come in and 700 pieces go out because ironing is slow. Ironing is the bottleneck. Adding 2 more ironing stations or reducing iron time by 10 percent fixes the line.
Causes of Bottlenecks
Common causes are unbalanced operations, one slow operator, machine breakdown, long setup time, missing material at the station, and poor workstation layout. Sometimes the bottleneck shifts after it is fixed, so bottleneck analysis must be continuous.
How to Fix a Bottleneck
Split the operation into two, add a helper, add a second machine, improve the method, reduce handling time, or move work to a less loaded operator. Train the operator on the bottleneck. If the bottleneck is machine-based, consider a faster machine or parallel machines. After fixing, re-measure because the bottleneck moves to a new operation.
Theory of Constraints
Eliyahu Goldratt's Theory of Constraints says every system has at least one bottleneck. The goal is to exploit the bottleneck fully, subordinate everything else to it, and then elevate its capacity. Do not improve a non-bottleneck, because it will not increase the line output.
Common Mistakes
Many supervisors try to speed up every operator. This only builds more WIP in front of the bottleneck and does not increase output. Others improve the fastest operator, which has no effect. Good IE practice is to focus on the bottleneck.
When to Use It
Bottleneck analysis is essential in sewing lines, cutting, finishing, washing, packing, and any flow-based production. Use it daily in line balancing and weekly in capacity planning.