Job sequencing: From a chaotic production schedule to 100 % ODT

The due date is the most important criterion for most job shop planners to prioritize their jobs. The job closest to the due date is scheduled first. In this blog post, we showcase through a practical use case (video) how utilizing a criterion other than the due date can greatly enhance the efficiency of your job sequencing process. You will also receive strategic insights for additional improvements in job sequencing.

Some general, theoretical preliminary remarks

This is the third of a series of articles about job sequencing in HMLV production environment. First, we analysed the strategies used to prioritize the jobs. Then we summarized the functional options that our just plan it software offers for priority-based job shop scheduling. In this article, we will use a use case to demonstrate how to gradually move from a chaotic production schedule to a schedule with an optimal job sequence that does not exceed delivery dates. 

Use case: scheduling a large number of jobs for on-time delivery

This use case was recently presented by my colleague Elmar. In the video, he shows in a very impressive way how you can achieve a production schedule that is free of conflicts, even when you have to schedule a large number of jobs. He uses some strategies that he has developed in his consulting work as a scheduling expert. He is also the "inventor" of our production scheduling software, just plan it, which is specifically designed for HMLV production. 

From chaos to a conflict-free schedule in several steps

Here are Elmar's recommendations:

Pro Tip first: use the 20/80 rule. This means identifying the 20% most important jobs and excluding them from automatic rescheduling (just plan it offers a pin function for this case). Experience has shown that this number is manageable and can be scheduled without conflicts. As they are the most important orders for you, whether for reasons of due date, order volume, customer importance, or other reasons, you are already on the safe side when you focus on them.

The remaining 80% of jobs are a volatile mass, for which you can easily calculate an optimal sequence with the help of automatic scheduling and additional fine-tuning under the premise of delivery dates. First, use the "automatic sequence number calculation" function to immediately obtain a solid priority list of orders. You will witness that the due date as the criterion to calculate the sequence numbers, is less effective, than the maximum remaining cycle time that a job has to the due date. 
For an explanation of how this criterion, called MaxBuffer is calculated, please read this blog post.

After the initial sequence calculation, manually fine-tuning the calculated sequence. Firstly, use the resource view to identify bottlenecks, where planners often have alternatives available to them to increase capacity at this point in the short term, for example by outsourcing. 
Secondly, look out for orders that do not run through the bottleneck. These can usually be pushed further back in priority. just plan it offers an automatic calculation of the critical sequence number for this purpose.

You can see everything live in the video

In the video, Elmar demonstrates and explains in detail the individual steps described above for optimized sequence scheduling. Enjoy watching it. If you have any further questions, please do not hesitate to contact us.