BOM Redlining: Adding Colour to Your BOM!

BOM Management is without doubt one of the fundamental components of PLM. So much so, that BOM Management is not discussed as a separate functionality or module at all, when we talk about SAP PLM. Part of the reason could be that the functionality is mostly already present in ERP, and therefore can  be readily consumed by PLM users. Nevertheless, SAP PLM does have something in addition - BOM redlining! This interesting tool came about with Enhancement Pack 6, and the good thing is that it is almost entirely out-of-the-box, i.e. it doesn't require any special configuration.

So what exactly is BOM redlining? Imagine a BOM with most items in the familiar grey/blue colour, but some standing out in red or green. What could it be? Now think of the word redlining - it typically means adding a transparent layer over a drawing, etc., and writing something over it. Right? So there you are - BOM redlining lets you create a layer over the original BOM where you can make changes without changing the underlying BOM. You create redlining to suggest changes to a BOM such as addition or deletion of items, changes in quantity, etc. Depending on the changes you are suggesting, the items become red, yellow or green. The redlining can then be reviewed by someone and approved. All that you have to do then is click on Apply button, and voila! the original BOM is changed as per the suggestions in the redlining. You can even insert items for which you haven't yet created material masters. For that you have time till you are actually applying the changes to original BOM.

When do we use BOM redlining? One may think that question is already answered - whenever we plan a change in a BOM, we can use this feature. But there is a catch. What if you are using CAD integration? Would you implement a change in BOM through just the redlining without making any changes to the geometric models in CAD? This may be possible for some items, for example, consumables and variable length items. But in majority of the cases, one would imagine that a change in BOM would necessitate some or the other change on CAD side. In this scenario, the change must start with the CAD model and copied to the engineering BOM from within Engineering Control Center. For recording a suggestion, you can always use the comment option in the viewer. Incidentally, that is also called 'redlining'. Should we then use BOM redlining in process industries? Not really, because there the changes would first be implemented in a recipe. I can think of 2 scenarios where BOM redlining can be used. First, in complex multilevel assemblies, there could be some subassemblies that are not maintained in CAD. Second, for changes in manufacturing BOM which are done independent of engineering BOM. You make such changes in mBOM and then in Product Structure Synchronization (PSS) decide intelligently which of these changes should be accepted or overwritten in the next round of BOM syncing.

You can create a redlining for a BOM by clicking on the 'Redlining' button in the BOM screen. But matters get slightly confusing here. You always land at the default redlining that is called REDLINING1. You need to click on the 'Create' button to create a new redlining which then becomes available via a dropdown. I think this is not very intuitive and hopefully we will see some improvement soon. A BOM redlining can be added to an Engineering Record, though that is not strictly required.

Incidentally, BOM redlining has a very different meaning in some other (non-SAP) PLM applications. There it means comparison of a BOM between two revisions where the result shows up something similar to the redlining in SAP PLM, namely, rows of items with colours based on whether the items are present, absent or different between the two BOMs being compared. SAP PLM users can use the BOM comparison feature from ERP, which uses mathematical icons to show equivalence between rows of BOMs being compared, but it would be a good idea for SAP to reuse underlying code of redlining for a BOM compare function in web UI, in future. 

Finally, an interesting titbit: If you look at IMG for BOM redlining, you realize that it is a special case of a generic object called redlining. Which means you can extend redlining function to other objects. But SAP strongly recommends against using it for any other standard objects than the BOM. All you have in IMG is a couple of BAdIs with standard code, which you can extend, for example, to add fields to be displayed, etc. 

Do share your thoughts!