At our company, it is policy that the engineering BOM must match the job BOM. So if an order requires something special, it will have a specific part and BOM for that order and a job will be created off of that. While networking recently, someone brought up that their company will not create special BOM’s, rather they will manipulate the job BOM by adding the special material. This threw up a red flag to me as I always thought the Engineering BOM must match the job. This creates a scenario where the BOM of part 12345 may vary from one job to the next which seems wrong to me. But besides it just feeling “wrong” I can’t think of a good reason why this is bad practice. Any thoughts are welcomed!
That’s up the business to decide. And if you have revision change, you’ll have some overlap as to the engineering change that happened after a job was release, and a new job was made.
Some companies have materials that are different for certain properties (like length or size) but can be subbed out because they get cut anyways (think beams, or pipes, or sheet metal). So they manipulate them on the jobs to account for using different part numbers.
Other companies have make to order where the engineering BOM is a starting point, but the specific order has requirements that don’t match up. And if they are all custom, they may not want to bother with part master record for every part they sell, as they will never use it again anyways.
So there are lots of situations where the job might not match the engineering BOM. It really depends on the company business model and policies.
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There are a lot of reasons a Job bill could vary from the Eng. BOM. One simple example, which we’ve run into over the past few years due to supply chain slow down issues… a BOM that requires 1.75" round bar stock (for example) as a raw material.
When running the job, we don’t have inventory of 1.75" round bar stock, but we have 2" diameter in inventory. We could substitute that raw material on the job and with a little more time in the lathe… we still get the correct end result.
Obviously not ideal (higher raw material cost, additional machining costs, etc.)… but if you’re in a pinch… it works.
So… the job BOM is different from the Eng. BOM. The Eng. BOM should still call out 1.75" round because if we ever want to make that part again, that’s the ideal raw material to start with. But that specific Job BOM will show that in that case we started with 2".
another reason why the job’s BOM would not match the Enginering BOM is if there is a problem on the job… for example, you get 1/2 way through the process, and someone breaks something on the job. At this point, you might modify the BOM on the job to incorporate a substitute material to repair what is already in WIP. Also, remember that the BOM/BOO in the JOB incorporates the entire design of the product… both the materials, AND the operations. And SOMETIMES, companeis will change the bill of operations to change HOW something is made (Send to outside processing instead of inside manufacturing). as a result of that change the BOM or BOO might change slighly.
anyway… it is VERY common practice to have a slightly different BOM/BOO on the job than in the Engineering BOM/BOO…
HOW TO STOP THIS FROM HAPPENING: well… you CAN limit changes in the job…
- create a security group that is something only “Engineers” can access
- create a limiation on the business object in Jobs that would prohibit changes,
- OR use a BPM that prohibits changes to the JobMtl/JobOpr unless you are an “engineer”.
but even with the above idea… if someone creates a job while the part is under Revision A, and then enginering changes the BOM/BOO (rev B) there WILL be a difference. the Job always has a “copy” of the BOM/BOO that is taken as a snapshot when the job is created.
Thank you @Banderson, @dcamlin, and @timshuwy for the replies. It makes sense that certain things cause a material in the job to change based on certain circumstances. In this case, I am particularly interested less about specific material changes, and more about varying the job BOM of a finished good from one job to the next under the same part number. For example… If we make worktables that can be ordered with fixed height, mechanical lift, or electric lift, my employer would say all three work tables needs specific part numbers with an EBOM, and they will be ordered as those part numbers. The other company would have 1 part number that represents the work table and they will manually adjust the job if a customer wants an alternate lift instead. I imagine there would be financial impacts to this method, especially if there are cost standards on the EBOM.
The basis of my question is that we do a ton of custom work and I am curious if there are certain scenarios where it makes sense for us to just manipulate the job rather than always doing special EBOM’s.