Job shop production is a challenge for scheduling.
Here are three ideas for job shop scheduling and scheduling for Engineer-To-Order and customized products.
Each of these ideas can be realized with an automated Excel tool. Give feedback in the comments, we can develop a tool for you and add it to the download page.
Job shops and other suppliers of customized products need production scheduling. Demand can be more uneven and unpredictable than repetitive manufacturing.
As well as the uncertainty of which product will be in demand, there is also uncertainty of what materials it will require and how much work is needed from which work centers.
Products that are highly customized usually carry critical due-dates. Customers depend on getting the order on time – they often do not have an alternative supply.
A simple truth about capacity planning is that predictable production performance arises from a simple calculation. This compares minutes and hours of work in a product with hours of available capacity. A process routing is the starting point, yet Engineer-To-Order products have no standard process data.
How to generate routing data inside the fulfillment cycle?
There are three alternative approaches to job shop scheduling, scheduling customized products and any other manufacturer who have no standard process data.
1.Scheduling Engineering in Pre-Production
In highly engineered systems, there is usually a lot of design and product/system engineering before work is released to manufacturing.
The order confirmation point can sit anywhere on a line that stretches from defining the solution to production.
The main application for scheduling is production. But why should we limit it to this? In many cases, engineering work that goes into a solution is value-added. It requires skilled, finite resources and is under time pressure.
Integration between engineering and production leads to predictable delivery and cost performance. There is no justification for silos between sales, engineering and manufacturing. In this view, engineering can be seen as another work operation that feeds production.
The scheduling of pre-production generates routing data for production. Engineering outputs are dependencies. The product of upstream engineering is an input for work centers at downstream production.
In some cases, this is not just analogy. Bills of Material can include documents and certificates that are required to ship or release work into manufacturing. QA/QC and regulatory documentation generates before and during the manufacturing process.
Before engineering builds scheduling data for production, you need to start with some token data. Process families give estimated times that support an initial scheduling run. Then when engineering operations are completed, it revises the scheduling for downstream production. Estimate assumptions should be checked carefully, else this feedback loop gets unstable.
Most job shops and ETO manufacturers have order configuration software. This system is usually connected to the generation of drawings and Bills of Material. Less common is an integration to routings and process definition. Fewer companies truly integrate work-flow between engineering and production.
If you did do this, imagine the benefit? Faster Request-for-Quote (RFQ), better capable-to-promise, management of engineering constraints, eliminated silo-thinking and even (dare we say it…) design-for-manufacturing and concurrent engineering!
2. Job Costing and Configuration
A good costing process has the same granularity as capacity constraints.
What do I mean by this? If you have constraint work centers, then job costing should drill down to hours and minutes at each of those work centers. Any constraint to revenue and cash-flow needs to be properly sized up in the cost of sales.
So it should be simple, right? The job costing process already generates the level of precision that you need for process routings.
In practice, configuration and costing do not always align with process definition. They should do but they don’t.
The obstacle may be technical (system doesn’t support it), accounting (cost pools too broad) or organizational (silos, overly optimistic costing assumptions). Either way, it could be that the order configuration process needs to be
thrown out enhanced and highly specific calculations on cost and capacity made to fit. By the way, spreadsheets are great for doing this.
It doesn’t have to be an all-or-nothing process. Improve configurator inputs, enhance the logic or extend the functionality with an open, Excel-based system.
And measure estimates against actuals to constantly improve the process. A closed feedback loop of measurement can deliver twin improvements in higher costing accuracy and better production capability.
3. Automated Calculation from Master Data and History
This option is trickier, but offers strong advantages based on a scientific approach. The premise is that process routing data be derived from order parameters.
This means that given a BOM and some values from configuration, you can calculate the routing result.
Now clearly this depends on the complexity of product engineering. Manufacturers of products customized from a base model have a good chance of making this work. Suppliers of highly engineered solutions will not want to fully automate this process.
We can simplify the process by breaking it down into constituent parts. A process routing for a job shop (or anyone else) comprises of work sequence and content. The sequence of operations that each product requires is a starting point for a process family.
In many job shops, there are a limited number of work center sequences. Putting aside the actual time at the process and comparing only the operation sequence, new products will fall into one of a manageable number of process families.
Manageable means dozens at the most, not hundreds or thousands. Interrogate the order history and see how many different sequences have been produced in the last few years. What relationships there might be between product family and unique sequence?
Is it possible to select the right process family from a list at order entry? Maybe it could be done by process of elimination. This is a nice application of the suggestion of smart drop-down boxes that can be powered by the INDEX function.
Once the operation sequence is set, the next step is work content. This is trickier and requires a flexible configuration tool that can handle many variables in a linear calculation.
In theory, all work times relate to order parameters like this: ax + b = c. x is the volume, a and b are parameter values. To state this another way, all standard times have a variable component and a fixed one.
Job shop and engineer-to-order manufacturers regularly accept demand for products that they have never made before. This rarely means that they accept demand for product with no similarity whatsoever to previous orders . The production and order history can show correlation between order attributes and production requirements .
Data analysis can discover adaptable rules that link order parameters with a prediction of resource requirement. When put together with the material structure in the BOM, it is possible that information exists to make calculated predictions of working time.
Try it, test it and see if any patterns emerge that are useful to the scheduling process.
How to Put These Ideas Into Action
The theory is nice, but how do we make it happen?
Our job shop and engineer-to-order clients often come to us with configuration, costing and production capability problems. We solve these problems with real Excel-based solutions based on their business requirement.
You understand that we can’t show you client examples. but we can do the next best thing. If you let me know which of these ideas fits the best with your job shop scheduling or Engineer-To-Order business, we can build a demonstration system for you.
This will be free from confidential client data, but a true example of what works in the real world. We might even give away a download version to our subscribers.
This is what you have to do. Firstly, if you have not already done so, sign up as a subscriber for free. This will open in a new window, so you can do it now.
Next, tell me in the comments which of these ideas for building routing data fits the best with your business:
- Schedule Engineering in Pre-Production
- Job Costing at Configuration
- Automated Calculation from Master Data
Give us more detailed comments and help us give you something of value.