Keystone Resource
Moving from spreadsheets to MRP without stopping production
What to fix before an MRP implementation starts, in what order, and where these projects commonly fail.
This is a first draft awaiting review by somebody who runs a factory. It is published as a working document rather than as advice.
Most factories running on spreadsheets are running well. The sheets have been refined over years and encode a great deal of knowledge about how the business actually works. That is worth respecting, because it is also why replacing them is harder than it looks.
What actually goes wrong
Failures in these projects tend to be the same few things, in the same order.
- Part data that was good enough for a person is not good enough for a calculation. A bill with two lines missing works fine when a planner knows to add them.
- Nobody agreed what the opening stock was, so the first MRP run is wrong and confidence goes immediately.
- The old system stays alive “just for now”, and for a fortnight nobody knows which is right.
- Training was given by module rather than by role, so people learned screens instead of their job.
A sensible order
Do the data before the software. Parts, then bills, then routings, then suppliers and lead times. Every one of those can be improved while you are still running on spreadsheets, and every one of them makes the implementation shorter.
Count the stock properly and agree it. Not approximately. The first run after go-live is what everyone judges the system on.
Pick a go-live date with a fallback, and tell everyone what the fallback is. A cutover nobody is frightened of goes better.
Keep the spreadsheet for one thing
There is usually one calculation in the sheet that the new system does not do, and that is fine. Keep it, deliberately, and write down why. What causes trouble is keeping the whole thing informally as a shadow system.
What to measure afterwards
Do not measure success by whether people like it in week two. Measure the things that were broken before: how often a job stops for material, how long it takes to answer a traceability question, and how far actual job cost sits from the quote.
Take those measurements before you start. Otherwise you will have no way of showing what changed.
What this does not cover
Every factory is different, and the sequence above assumes you are replacing spreadsheets rather than an existing MRP system. Migrating from an older system brings its own problems, particularly around historical records.
How an implementation runs · An MRP implementation checklist
Next step
Show us how your factory runs
A walkthrough starts with your orders, your production flow and your material problems. We follow one of your jobs through the system rather than presenting a feature list.