The balance between the number of shifts in your line design comes down to resource utilization versus operations costs. In a One-Shift scenario the fixed asset utilization is the lowest. Only 1/3 of the capacity of the fixed assets are being utilized. For 2/3s of the day, they sit idle. A one-shift line design requires more floor space than any of the alternatives. On the plus side, you would normally find most support activities available during the first shift. Plus, working only one shift allows for the most additional capacity for growth. A one-shift line design tends to be the preferred path for high growth industries or factories with low fixed asset investment.
As you start increasing the number of shifts, your fixed asset utilization improves and your cost of operation increases. You will need to add supervision, material handling and other support activities to multi-shift factories.
A three-shift option is rarely recommended, as it provides no headroom for growth. Three shifts would be typical of a stable industry where there is a very high fixed asset investment. Maintenance and training are also more challenging with three shifts. If you are currently running three shifts, now is a great time to evaluate that strategy, and possible reduce it to two.
WHICH SHIFT IS MORE PRODUCTIVE?
Since we’re talking about shifts, a question that is often asked is “Which shift is more productive?”
There is no one answer to this question, and it will depend on your particular environment. There are some general comments that we can make, however.
First shift will often have more experienced workers, since most people prefer to work during the day, and more senior people would get those jobs. If support from engineering and other front office services are needed, these people are also typically there during the day. On the downside, there may be more distractions during the day, with engineers wanting to use valuable resources, and more material movement activity, which can affect productivity.
On the Second and Third shifts we often find less experienced operators and newer people, so if high skills are required this can reduce productivity. The front-office staff is usually not there. On the plus side, it is quieter and there are fewer distractions, and the operators may be able to get more done.
Also, if the Second and Third shift operators are newer, they may feel that they have something to prove, and set a faster working pace than the first shift.
The bottom line is that we have seen higher productivity on both the First Shift, and on the other shifts, depending on the environment and company culture. Knowing this may help you to decide on any changes to your current shift strategy.