At a customer site, a three-hour drive away, a packaging machine stands still. The field service engineer is on the phone with work preparation: which bearing sits in the tensioning station, and under which number can he order it? On the other end of the line somebody scrolls through a four-hundred-line production BOM, past positions like "plate left" and "arm assembly complete". Ten minutes of searching later there is still no answer, and the machine is still down.
The problem is not that the information is missing. The problem is that a production BOM was made for a different purpose. A good spare parts list from your Inventor data is a document of its own, with its own rules: orderable units, recognizable descriptions, marked wear parts. And the beauty is that it comes from exactly the same source as your production BOM; with tooling like Thundercad you extract it without maintaining anything twice.
The technical side of that export, the template and the columns, was covered earlier in BOMs from Inventor to Excel: always in your own template. This article is about the content: what makes a service list different, and how do you keep it current?
A service list is not a production BOM
The production BOM follows the build order: subassemblies, semi-finished items, phantom parts that only exist to keep the structure consistent. For the workshop that is exactly right. For the engineer at the customer site it is noise. He searches by breakdown and function, not by build order. A welded frame that consisted of fourteen parts in production is one piece after welding: loose part number seven can no longer be supplied, so it does not belong in his list. And a description like "bracket left v2" is perfectly clear internally, but means nothing to somebody who only knows the machine from the outside.
On top of that, the production list contains everything, while service only needs a fraction. The service engineer replaces bearings, belts, gears, sensors and guides; in practice he never replaces the frame or the cladding. A service list showing all four hundred lines buries the thirty that matter.
What the service engineer actually needs
A usable service list answers three questions at every breakdown: what is it, can I order it, and how many are in the machine? Concretely, that means per line:
- The orderable unit: the level at which you can supply, such as a complete tension roller instead of loose inner rings and bushings.
- A description in functional language, free of internal abbreviations: "guide roller infeed belt" instead of a drawing code.
- The quantity per machine, so one order covers all positions at once.
- A marker for wear parts, where possible with an indication of the replacement cycle based on experience.
- Your article number plus a reference to position or drawing, so identification remains possible in case of doubt.
None of this is new information: it already lives in your models, iProperties and assembly structure. It has just never been exported from this point of view.
Choose per branch: loose part, assembly or kit
The hardest decision is the level. Do you supply the bearing, or the complete roller with the bearing in it? The answer depends on what the engineer can do on site: swapping a roller works next to the machine, pressing a bearing does not. Choose the service level deliberately per branch of the assembly and mark that one level, not everything below it. Frequently requested wear parts can also be bundled into a service kit per maintenance interval: one article number, one order, no debate about what belongs in the box.
Record that choice as a property of the part itself, not in a separate list next to it. That is the same discipline as separating make, buy and standard parts: decide once per article, and every next list benefits automatically. How to set up such a classification is described in Make parts, buy parts and standard parts: cleanly separated in your BOM.
Once the marker is in your parts, the list itself is no longer work. Thundercad exports BOMs into your own Excel template, including a separate service template with only the columns the field engineer needs.
Try 30 days freeOne source, two lists
The biggest pitfall is a service list somebody maintains in a spreadsheet, detached from CAD. That list is outdated at the first design change, and nobody notices until the wrong part sits on the pallet. So keep one source: the assembly. The production BOM and the service list are two views of that same source, with different filtering, different columns and different language. With Export BOM you push the bill of materials of an assembly straight into Excel in your own template; include the service marker and the functional description as columns, and after the export the service list is only one filter step away.
Store the service list per delivered machine in the project file, next to the drawing package. Service often starts years after delivery; the question then is not "what is our current design", but "what is actually installed at this customer".
Keeping it current after delivery
Machines live long and designs keep moving. Two agreements keep the service list reliable. One: at every release of a change you regenerate the service list from the assembly, just like the drawing set; because the markers live in the parts themselves, that is minutes of work. Two: when you replace a part with an improved design, note the succession on the new line ("replaces article ..."), so an engineer holding an older list still ends up at the right part.
If service grows into a serious branch of the business, this data will sooner or later move into the ERP system. Even then the approach stays the same: the model is the source of structure and properties, the ERP handles stock and delivery times, and the list per machine remains the link between those two worlds.
Frequently asked questions
Does the service list belong in Excel or in the ERP system?
Start in Excel, per delivered machine, stored with the project file. That is set up quickly and readable for everyone. As soon as service becomes structural and you start stocking wear parts, the articles naturally grow into the ERP; the assembly in Inventor remains the source of the structure even then.
How do I prevent the service list from going stale?
By never editing it by hand. The list is regenerated from the assembly at every release, so changes in parts and markers travel along automatically. A manually adjusted export is a dead-end branch by definition.
How much extra work is this per machine?
Most of the work sits in marking wear parts and service levels once; as an estimate, count on half a day for an average machine. After that, every list takes only minutes. Want to experience how that export works? Try Thundercad free for 30 days.