I’ve been watching this great new show on Spike called “Coal”. It documents the trials and tribulations of a group of miners and supervisors at a coal mine in West Virginia. It’s exciting TV because you realize just what these men are risking to support their families. It seems to be an incredibly dangerous profession, but I definitely understand why they’re willing to sign up. In a state where the median household income is about $36,600 (2009), a coal miner starting salary is on average $60,000.
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)|
For the “Coal” mine, they could have used the aforementioned causes like generator failure and conveyor belts. Whenever the drill wasn’t running, they could log the cause and note the minutes they lost. Their pareto should have showed them what that “hired gun” figured out – that their generator was too small. In an industry where minutes cost you thousands of dollars in lost production, measuring and understanding your downtime seems critical.
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.