No matter which traditional planning methods manufacturers use, the schedules generated by capacity-loading software often lead to frustration.
This is because the majority of shop production scheduling software allocates capacity in a way that doesn’t align with actual execution priorities. Using the due date to sequence jobs from earliest to latest, these systems take all of the operations for any given work order into account and shove each one into capacity, regardless of whether or not that particular operation may or may not be the best one to be working on at that point in time.
The end result is a capacity-loading exercise completely disconnected from shop floor reality. Due dates change? Forget about it. Machine goes down? Sorry, partner. Outsourced operations? Good luck.
Thankfully, there’s a better way to approach shop floor production capacity: enabling better flow. Not only does this method of managing production better reflect how a shop floor should operate, it also leads to more orders getting completed in less time and more profit coming in.
Current Approaches to Shop Floor Capacity
Like most manufacturers, you are likely forced to view shop floor production capacity through a lens of either infinite or finite capacity based on how ERP and production scheduling programs are designed, limiting your shop to four possible approaches to shop floor capacity, each with its own set of challenges.
Infinite capacity loading ignores all constraints and assumes that you will have all the time, materials, and personnel needed to complete a job on time. Obviously, this rarely happens in reality, leading to inaccurate and unmanageable production schedules. That being said, infinite capacity does have some value when it comes to seeing how overloaded you are in a particular work center.
On the flip side, finite capacity loading lets you set your shop floor capacity constraints, then only loads the number of jobs that can be worked on at any given time. While this is a more accurate reflection of true shop floor capacity, it isn't reflective of how execution actually happens. A capacity-loading program loads all the operations of a particular order at the same time. In reality, at any single work center, several jobs are evaluated to determine which job's operation to do next. Just because a certain job's upstream operation recently completed — as placed in a capacity-loading schedule — does not necessarily make that the most important job to work on next.
Backward loading assumes that you need to finish the work order on the day (or the day before) it’s due. Starting with the last step, it then sequences each operation needed to complete the job to determine the last day you can start the job and still deliver it on time. If you are already late starting the job, forward loading (the next option) will need to be used instead. Backward loading leaves no buffer time to account for variability, so if something happens along the way, then the job will be late.
Starting with the first step, forward loading sequences each operation needed to complete the job, beginning today and extending as far into the future as necessary. Forward loading tells you how long it will take to complete a job regardless of the due date, and can better accommodate buffer time. However, it often leads to flooding WIP with too many jobs, leading to delays.
Why You Need to Go With Better Flow
Clearly, these approaches to shop floor production capacity all have their drawbacks. But there’s nothing wrong with these methods, per se: they do exactly what they were designed to do. The problem isn’t with these approaches to capacity, it’s that the whole system of managing production based on capacity loading is broken to begin with.
Better shop floor production management starts (and ends) with better flow. The prioritization mechanism in Protected Flow Manufacturing™ (PFM) is purposely blind to capacity in favor of executing what needs to be done first based on real-time factors, such as the relative lateness, the complexity of operations, and the variables that might derail production along the way.
The result is a production planning and execution system that focuses on speeding up the flow of information and materials throughout your shop.
With PFM, manufacturers can:
- Simulate shop floor operations to determine exactly how changing a variable might affect future capacity
- Pinpoint future bottlenecks that will delay production
- Control how much work goes into WIP to prevent overloading
- Drop expedited orders into sequence without disrupting other jobs
- Anticipate and account for variability on the shop floor
- Maintain visibility into where an order is and how it’s progressing at all times
Rather than operating at the discretion of a capacity-loading exercise, PFM gives your shop floor the actionable intelligence it needs to achieve true visibility into priorities and deliver jobs on time.