Wherever two systems do not talk to each other, a spreadsheet grows. Engineering exports, work preparation pastes bits in, purchasing filters, and after a few months there is a file nobody ever actually designed: it simply grew. It is called "orderlist_final" and three versions of it are in circulation.
This article is not a plea to abolish Excel; it remains a tool, and often a good one. What you will get is the honest story about Excel between your CAD and ERP: where the file is a perfectly good link, where it quietly stacks up risk, and how to decide when an integration should take over from the spreadsheet. Even if you export with a toolbox like Thundercad, that question stays relevant, because even a tidy export file is still a file.
Why spreadsheets grow everywhere
A spreadsheet is rarely born out of laziness, and almost always out of a gap between systems. The ERP has no concept of saw lists, planning wants an overview per week, the customer asks for a list in their own format. Excel fills that gap within fifteen minutes: no request to IT, no project, no waiting. That is its strength, and you should not argue it away.
The problem is never the first spreadsheet. The problem is what happens next: the file grows formulas, then a tab per department, then a copy per person. What started as a handy helper quietly becomes infrastructure: an entire process depends on it, except nobody has ever treated it as infrastructure.
A familiar example from machine building: the list work preparation uses to pass saw lengths to the sawing station. It started as one planner's little helper, and by now it is the only place where that information exists. A macro hangs off it that only runs on his PC, and nobody else dares to touch the file.
Where Excel is a perfectly good link
Some flows are simply best served by a file, certainly in a smaller team:
- One-off analyses. Adding up weights, comparing a quote, finding out which purchased parts come back most often: export, sort, done and delete.
- Small volumes at low frequency. A list that goes out once a month with twenty lines does not justify an integration project.
- Structured handover with a fixed template. A BOM export that looks exactly the same every time and is read in at the receiving end instead of retyped. With Export BOM from Thundercad you pull the bill of materials from Inventor straight into your own Excel template, with every column exactly where the receiver expects it.
- Checks and reporting. A pivot on failure costs or ordering behaviour does not need to be a dashboard.
The common thread: Excel is strong as a carrier, a file that moves data from A to B or answers a one-off question. It becomes fragile the moment it is the place where data is created, edited and stored all at once. A saw list that is exported fresh from the model every week is a carrier. The same list in which someone then manually corrects lengths that never make it back into the model is a second truth in the making.
Where the risks quietly pile up
Formulas nobody knows anymore. The builder has left, the successor dares not touch anything and nobody knows whether the surcharge in column K is still correct. The file works, until one day it does not, and there is no error message: just a wrong number.
Manual copying. The moment someone types lines from the file into the ERP, a second truth is born that quietly drifts away from the first. We wrote about that earlier in One source of truth: your BOM into purchasing and ERP without retyping.
Versions by mail. The file leaves as a copy, and from that moment every receiver works in a private reality. "Which version do you have?" is the most expensive sentence in this whole process.
Silent breakage. Someone sorts a range instead of the whole table, a filter is still on while copying, a column shifts. The file still looks trustworthy; that is exactly the danger. The twelve missing lines only surface on the shop floor, when the material is not there.
Not sure whether your BOM export is a reliable carrier? Set up your own template and export a real order; you will see immediately where the manual work still sits.
Try 30 days freeWhen do you replace the spreadsheet with an integration?
Not every spreadsheet has to go. Use this framework per flow, not for "Excel" as a whole:
| Signal | Why it matters |
|---|---|
| The handover recurs weekly or more often | Every repetition pays for the manual work again and raises the odds of a mistake |
| Several people edit the same file | Clashing versions and overwrites become a matter of time |
| The receiving end retypes the content | That is where the second truth is born, with detective work to follow |
| Mistakes reach the shop floor or a supplier | The damage shifts from irritation to failure costs |
| The file doubles as an archive | A spreadsheet has no revision control and no memory |
If two or more signals apply to the same flow, that is the flow to tackle: first standardise the export, then replace the retyping at the receiving end with your ERP's import function. What that ladder looks like, from file to full integration, is described in Connecting Inventor to your ERP: where do you start?. Replace the riskiest link first; the rest may stay as long as it works.
Rules to keep Excel healthy
As long as the file has a role, a few agreements keep the risks small:
- One location per file: on the network share or in the document system, never as a copy by mail.
- Export instead of edit: when in doubt about the content, run a fresh export rather than repairing the file.
- Freeze the template: the column layout is a contract with the receiver, so changes only happen in consultation.
- State the source: which assembly and which revision produced this list, and who ran it.
- Give every structural file an owner who is allowed to clean up and improve it.
Frequently asked questions
Is an ERP integration not simply always better than Excel?
No. An integration needs setup and maintenance, and only earns itself back on flows that run often and where mistakes hurt. For one-off analyses and the occasional list, a file remains the fastest and perfectly acceptable option. Decide per flow, not per belief system.
How do I stop versions being mailed around?
Agree on a single location and from now on mail a pointer to the file rather than the file itself. Whoever needs the list then always fetches the current version. Combine that with the source line at the top and most of the version mess disappears by itself.
My ERP only accepts one fixed import format. Is that a problem?
No, that is actually helpful: a fixed format is a clear contract. Point your export at it once, for instance with the custom template of Export BOM, and every list goes straight in without shuffling columns. You can test it on a live order with the free trial month of Thundercad.