Detailed scheduling & finite capacity scheduling

Key steps in detailed scheduling  

Inputs and outputs of detailed scheduling:

Challenges in detailed scheduling 

Typical examples of factors that complicate detailed scheduling:  

1. 1. Dependencies: One task in the production process can only be completed after the task before it is completed.  

E.g. an insulation panel needs to be covered with foil after the production.  

In this case, if there is a change needed in the production step, then the schedule for the foil-covering also needs to be adjusted. 

Many products have several dependencies and this makes scheduling changes very difficult.  

1. 2. Machine downtime/maintenance 

• Unexpected breakdowns can disrupt schedules -> as mentioned hereabove for flexibility purposes when changes in priorities arise, you might consider the amount of breakdowns based on historical cases 

• Proactive maintenance schedules should be considered to avoid unrealistic overloading 

1. 3. Conflicting production priorities 

• Trying to execute for high-priority orders when regular orders have already been scheduled and commitments have been made (it’s not just pure scheduling that is tricky but also internal communication and priority assignments) 

• Order changes: finite capacity scheduling can reallocate resources dynamically but may push lower-priority tasks to later slots. A new order or high-priority order might impact the schedule for days or weeks to come 

• Similar tasks sharing the same resources 

1. 4. Human resource constraints: employee availability, skill sets, and work hours must be factored into schedules 

1. 5. Regulatory and quality control (especially crucial in industries like pharmaceuticals and food): ensure production processes comply with legal and safety standards, including post-production checks. It is not always considered as part of detailed scheduling but if this also includes several steps and impacts the availability timeline of the product, then it’s wise to incorporate this step into the scheduling.  

Example for an insulation manufacturing company 

A company produces two types of insulation materials: fiberglass sheets and spray foam. See the earlier sections for the high-level production plan on a monthly/quarterly level, the master production schedule on a weekly level, and the material requirements on a weekly level based on the MRP.  

Now, we’ll look deeper at the daily production scheduling for the fiberglass products. 

Inputs into the detailed production schedule: 

The 1,500 units/day daily capacity for the machine is considering 24hours of non-stop production (meaning 62.5 units/hour, the number sometimes being a little higher and sometimes a bit lower, hence the acceptable comma number), with no setup times and quality checks. In the detailed schedule, this is considered more carefully than in the previous planning steps and we see that there is a capacity issue that wasn’t considered at the higher levels of planning.

Detailed scheduling plan for week 1 considering the finite resources

Analysis of week 1 schedule 

Machine utilization: continuously used, and 512,5 units short for FG-30mm.  

This is due to the fact that set-up times and quality checks weren’t considered at the highest level of planning. 

GANTT chart example for the full week:

Production scheduling Gantt chart example