Manufacturing Line Case Study
A study of a manufacturing line using Flexsim Simulation Software
Operating a manufacturing line is always a challenge. Ensuring the rules for operation, staffing levels, and production capacity are all in sync with the business plan is no simple feat. Facing these challenges, a large manufacturer turned to Flexsim to develop a simulation model as a way of addressing these questions.
Issues to Solve
This manufacturer wanted to know how to best operate a new manufacturing line and answer specific questions regarding staffing, changeover times, and buffers.
The new manufacturing line required operators with different skill sets. At question was how many of each operator would allow for the highest throughput.
Also, production is done in batches and every time a batch is completed some of the production equipment requires a changeover in order to run the next batch. The manufacturer wanted to minimize lost production time due to changeovers and so they wanted to know when to start the changeover process.
Lastly, the product is manufactured on one main line until it reaches a point where the product is assigned to one of three branch lines. Each of these lines has a slower production speed than the main line. Therefore, the manufacturer wanted to know how to assign product to and how much buffer to have in front of each branch line.
The initial simulation model had one tech and one operator. They both repaired down equipment and did changeovers. However, the operator’s first priority was to repair down equipment. This meant that if the operator was doing a changeover and a repair job was generated and the tech was busy, the operator would interrupt the changeover to perform the repair job. This created a lot of inefficiencies for the operator when it was doing a changeover because it would get interrupted and leave to repair the down equipment and then return to finish performing the changeover. This would happen many times while the operator was performing a changeover and so the operator would waste a lot of time walking back and forth between the changeover it was performing and the repair jobs it would perform. This caused changeovers to take longer and in turn caused system throughput to decrease.
Therefore, another simulation model was created that had two techs and one operator. In this model tech1 and the operator performed repair jobs and tech1 and tech2 performed changeovers. Once a tech started performing changeovers it continued until all the changeovers were completed. This modification to the changeover process minimized walk time for both techs and in turn led to an increase in system throughput.
In order to minimize lost production time due to changeovers it was determined that one of the three branch lines would shut down and the changeover process begun while a batch was still being processed on the main line. The model was set up so that the shutdown point within the batch was variable as was the batch size. This allowed the manufacturer to analyze how different shut down points with different batch sizes impacted system throughput.
To determine buffer sizes, the queue capacities before each branch line was set to a large number in order to see what the maximum queue content would be under different operating scenarios.
By having Flexsim develop a simulation model of their new production line the manufacturer was able to test different operational schemes in a virtual world. This allowed the manufacturer the capability of analyzing different modes of operation for the new production line before investing large amounts of money in new equipment.
The simulation model developed by Flexsim also demonstrated that having one tech and one operator working on the production line would cause changeovers to last longer than needed and in turn would cause the production level to be decreased.
Model and case study completed by Bill Strong. Bill is a simulation engineer with Flexsim Software Products and can be reached at [email protected] or 801-224-6914.