With the .15 release of Factorio, nuclear power has been added. With this, came uranium ore. I just began harvesting some uranium with my electric drill, and noticed that there is a purple progress bar:

Purple progress bar

On electric mining drills that aren't working on uranium, this bar isn't here. I don't think it has to do with the speed modules that are inserted either (the bar doesn't seem to move any differently with or without them). What does it indicate?

This is game version 0.15.5 if that helps.

  • In the previous version it represented "increased output upgrade" - when the bar made it to the end, you'd get one free product. Maybe it's due to those upgrades? Commented May 1, 2017 at 2:03
  • @BlueRaja-DannyPflughoeft I don't think it has to do with the speed modules upgrades. I've edited that into my post. I don't see any difference in progress with the purple bar with the modules inserted. Just the green bar moves faster as expected.
    – Timmy Jim
    Commented May 1, 2017 at 2:06
  • 1
    It's for the productivity module, not the speed module. Commented May 1, 2017 at 4:36
  • 1
    Do you have any of the new mining productivity upgrades? That's my first suspicion, but you said it's not on other electric drills.
    – mmatthews
    Commented May 1, 2017 at 15:53
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    Sorry I was unclear, there is also a research that increases mining productivity.
    – mmatthews
    Commented May 1, 2017 at 16:00

1 Answer 1


Version 0.15 introduced a new line of upgrades, called Mining Productivity. Researching these upgrades have a similar effect to using Productivity Modules, in that each miner will have a purple bar that slowly fills up, producing an additional ore when it fills up.

I haven't tested to see if burner drills receive the upgrade as well, but all electric drills are affected.

  • And pumpjacks also get this bonus. Commented May 22, 2017 at 11:39
  • Same for assembly machines (1 and 2 at least). I've seen this myself.
    – Tim S.
    Commented Jan 4, 2018 at 20:11

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