Modelling Multi-Step Manufacturing with Raw Material, By-Products, and Machine Capacity

[mayankkulkarni-ctrl]

Hi,
I would like some guidance on modelling a complete manufacturing flow in frepple.

My Manufacturing Scenario
I want to manufacture Product A, which is completed only after passing through 4 sequential operations:

Operation 1
Operation 2
Operation 3
Operation 4

Additionally:
-I purchase Raw Material RM-A from Supplier A
-RM-A is consumed in Operation 1
-The output of Operation 1 flows into Operation 2
-Then continues to Operation 3
-Then Operation 4
-After Operation 4, I get my final Product A

So the flow is:
Supplier → RM-A → Op1 → Op2 → Op3 → Op4 → Product A

Additional Complexity

In Operation 1:
-A by-product (let’s call it Product B) is also produced
-That by-product may either:
-----Be stored as a separate item
-----Or be consumed in another operation
I also want to model 2 additional items created during intermediate operations (similar to by-products), and link them correctly in the flow.

My Questions

1. Operation Materials Configuration

How should I configure operation material correctly?
Should RM-A be consumed only in Operation 1?
Should intermediate outputs be modeled as separate items between each operation?
Or should only the final operation produce Product A?

What is the recommended modeling approach for:
Raw material input
Intermediate WIP items
By-products

2. By-Product Modeling

If Operation 1 produces:
-Main flow output (to Operation 2)
-Plus a by-product
-How should I define this in operation materials?

Should I:
-Add two outputs in Operation 1?
-Use negative quantity for consumption and positive for production?
-Create separate buffers?

3. Machine Capacity & Timing
   a. I want to:
   -Define exact machine run times
   -Define machine capacity
   -Control utilization
   -See accurate resource loading in the plan

b. How should I configure:
-time per vs fixed time
-Load quantity
-Resource capacity per day/hour
-Calendars

c. So that when I run the plan:
-I see realistic machine utilization
-I know exact production duration
-I understand bottlenecks clearly

4. Best Practice Question

For a 4-step sequential routing with:
-Purchased raw material
-Intermediate outputs
-By-products
-Machine capacity constraints

What is the recommended modelling structure?
-Routing with suboperations?
-Multi-level BOM?
-Combination of both?

If there is a minimal example or best-practice reference for such a setup, that would be very helpful.
I want to model the system in a way that reflects real manufacturing behaviour and gives accurate machine utilization when planning.
Any guidance would be appreciated.

[jdetaeye]

Should RM-A be consumed only in Operation 1?

Any operation can consume it. It's also ok to consume the same item multiple times during the same supply path.

Should intermediate outputs be modeled as separate items between each operation?
...
What is the recommended modelling structure?
-Routing with suboperations?
-Multi-level BOM?
-Combination of both?

You can choose the approach.
As a rule of thumb:

• follow the data structure you have in your ERP and the planner's practice
• if you physical store the intermediate item in a warehouse -> use intermediate items
• if the intermediate item can be used to produce multiple end items -> use intermediate items
• if manufacturing orders of OP1, OP2 and OP3 are always directly linked to each other (ie have identical quantity and ideally back to back times) -> use a routing without intermediate

By-Product Modeling
-Use negative quantity for consumption and positive for production?

Yes, that's the approach. By-products are bit trickier to plan. If not absolutely necessary for your plan, avoid them.

[jdetaeye]

This is not an issue/bug, but a question/discussion.