A recent episode really stood out in mind. The team was having average production on dayshift but was failing to meet their targets on the night shift. The mine operators were scratching their heads and wondering why they weren't hitting their targets on the off-shift. Whenever the drilling machine (continuous miner I think is what they called it), wasn't running, they weren't adding any value. A variety of things were causing the drill not to run - e.g generator failure, pump failure, conveyor belts jamming, ventilation fans shutting off, etc.
The mine's solution to their problem was to bring in a "hired gun" - a contractor to take over as the shift supervisor and solve the problems. After a couple of shifts, he quickly identified the generator failure as their biggest source of downtime. When the drill was run too fast, it would bind up and kick the generator, effectively shutting down the mine for 15 minutes. This would happen several times during the night shift due to an inexperienced drill operator, costing the mine thousands. This very observant "hired gun" was able to identify this fairly obvious root cause but it seems the mine would have benefited from a lean tool called Lost Time Analysis.
In Lost Time Analysis (LTA), you track production time (planned and unplanned) you lose to a bunch of different causes. Typical causes are like "machine down", "tooling change", "absenteeism", or "preventative maintenance". You can assign codes for each cause like 01 is machine down, 02 is tooling change, etc. Whenever the machine - whatever machine you are tracking - isn't adding value, you log the time you lost and assign it to the appropriate cause code. After a set period of time, management or engineering paretos and reviews the data with the team. The team might see that they are spending an excessive amount of time on tooling changes so maybe its time for a changeover reduction event.
|Lost Time Analysis might have looked like this for the mine (simplified obviously)|
Have any insight on what kind of systems they use in the mining industry or have any past experiences in your industry with lost time analysis? Please share.