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External processing in SAP MES


Hi Experts,

can anyone explain what is the bet Praxis to handle External Processing (external operations) in SAP MES system? Is it supported in SAP MES system and how to handle such cases with standard MES system solution?

Thank you for your answers.

Best regards


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I do not understand your question. Can you provide more details on what external operations you wish to execute? Also what did you mean by 'bet Praxis'?

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Answers (4)

Answers (4)

Hello Darko,

before getting to your specific question, let me quickly set the scene for the other commenters here.

Currently there are two major ways to get external support for manufacturing operations, which are subcontracting and external processing. The first option expects to work from one material to another and is handled via purchasing and logistics on the ERP level (e.g. see "subcontracting stock" and the surrounding processes).

However, it is not always feasible to plan for these material numbers and the required master data, and thus there is the second option of external processing. Here, you mark selected operations within the routing for external processing a a certain vendor, and the tricky part is, that we are now handling WIP and no stock. This makes it harder to process from a logistical point of view, e.g. creating shipping documents etc. This is the reason why many customers try to cover as much as possible with option 1, subcontracting, especially if the intermediate products have to cross national borders (quite common in central Europe).

But external processing doesn't require a dedicated material number for the intermediate products that are being externally processed, which allows for more ad-hoc decision where to execute certain operations in case of capacity constraints. So, with option 2 it is easier to handle unplanned external support, but even on the ERP layer this process is not fully covered and many extensions were built in customer implementations.

Now, to get back to the question how we can handle these options in SAP ME or DMC.

For option 1, this is almost trivial, as it can be handled by ERP, but there should be some considerations regarding traceability and genealogy. It would be a shame if the high resolution information based on the SFC data model is softened by external handling.

Now, for option 2, there is not a standard feature in our solutions, but there are certain patterns or best practices, some of which can be combined:

  • Give POD access to the supplier to process the external operations directly in the system. (I understand this is not feasible in most cases due to effort on the supplier side or system access guidelines. However SAP DMC makes this easier, being a SaaS offering.)
  • Introduce outbound (packing and sending) and inbound (receiving back to the own shop floor) operations for the internal staff to guide them through the process and filter out the external operation in the interface. (There are options to automatically confirm the external operations with the GR against the service PO for the operation. Other project implementations have built logic in ME to auto-complete the operation upon receiving the processed SFCs.)
  • In order to ease the logistical processing, there are custom options to create EWM Handling Units which correspond to ME/DMC SFCs. These HU (that do not contain real stock, only WIP) can be used to generate the shipping objects in EWM/TM.

I hope this helps you going forward, but feel free to contact me for further support.

Best regards, Michael


Hi Darko, I believe based on your response, you are sending only one operation as external processing, and I believe this is a typical subcontracting scenario for an Production Order Operation. I believe as the operation 0020 is done outside of your company, it's best to use external processing in the operation, create Purchase Req, convert to Purchase Order, send the components to the subcon vendor, receive it with respect to PO (which will post a material document with link to your production order) and continue with next operation internally. This operation shouldn't be sent to MES layer as it's external. Hope this helps.




Hi Mike,

thank you for your asking and try to help me.

Our case is as follow:

We have one routing (Single Linear routing) created in SAP ERP system and transferred to MES system. Operation 0010 and 0030 are our internal operation and operation 0020 (control key PP02) is external operation which must be done out of our company. This means when operation 0010 is finished our product must be sent out of our company (for example painting) and this is happening everything in step 0020. After external operation was done the product is sent back to our company and we start with operation 0030.


Must operation 0020 be completed manually from ME side or is there any automatically process on SAP MES side to complete external operation 0020? Is there any documentation or guidelines for SAP MES maybe?


I hope it is more understandable now.

Best regards


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I think this is more of an S/4 issue than an ME issue. You should read up on subcontracting in S/4.