Operational Efficiency = Sustainability Improvements | Lessons from the shop floor - Part 7

Mindset Change Towards Sustainability

Operational Efficiency and Sustainability Improvements are two sides of the same coin when it comes to shop floor operations. Sustainability responsibility has typically (and unfortunately) fallen to either a sustainability champion or left to grand/CAPEX heavy projects such as solar installations, brand new recycling systems, etc. However, sustainability improvements can and should start at the shop floor that translates to both immediate returns and savings while improving carbon emissions instantaneously.

OEE Improvement = Sustainability Improvements

Let's go on a thought exercise and take a random CNC lathe or milling machine for example that can consumes roughly 1kWh during normal operations. A 1 hour of machine unplanned downtime translates to 1 hour of idle machine electricity consumption. Studies have shown that the actual cutting activity of a CNC isn't the biggest energy consumer, it's the coolant systems, pumps, setup, etc. that go around the process that can account for 60% or more of the energy used. These systems would still need to be kept active and ready for operations even though no cutting is happening.

So if we were to continue with our rough back-of-the-envelope calculations, 1 hour of idle machine electricity consumption, at half power usage of normal operating condition would be equivalent to 0.5kWh energy wasted each time a machine goes down and is not utilized for 1 hour while remaining powered up. Now let's assume average electricity costs run 0.16 USD/kWh and the potential carbon footprint of that 1kWh averages to be 0.85 pounds of CO2.

0.5kWh that could have been saved translates to: $0.08 savings & 0.425 pounds of CO2 saved. Now, this doesn't seem like much at all, however, if we scale this to 10 machines, with a unplanned rate of it happening once a week for each machine, we're looking at:

0.5kWh * 10 Machine * 52 Weeks/Year = 260*$0.08 = $20.80 & 221 pounds of CO2/Year!

Note that this is just the electricity impact of the machine itself, we haven't even measured the cost of the labor, facility (lighting, air conditioning, etc.), equipment leveraged to get this equipment running again. These all add to the overall cost & carbon impact.

To put this in context, let's take a daily situation like commuting to work by car. Taking some averages in account based on the US Environmental Protection Agency (EPA)'s research: Average Fuel Efficiency = 22 miles/gallon and Average Mileage of 11,500 miles/year gives us about 8887g or 19.6lbs of CO2/gallon, for the average gasoline car.

With the savings above from the CNC machine of 221 pounds, we can estimate that:

221/19.6 * 22 miles = ~248 miles of driving. Which is quite the distance.

Factory downtime cannot be overlooked, as these numbers add up and can easily translate to immediate dollar-savings and CO2 savings if we focused on improving OEE. Now these are very rough calculations and your specific facility and equipment can be quite different, but it's clear - improve OEE, improve carbon emissions, period.

Quality Improvement = Sustainability Improvements

Scrap & Rework not only takes time and materials out of the system, but delays delivery and consumes labor and equipment resources. At times, a rework of a part can be equivalent if not more than the effort/time/energy it takes to make a new one!

Taking the same rough math from above, assuming a typical part coming out of a CNC machine takes 1 hour to produce. In the case a rework is needed, let's assume it takes an additional 30 minutes of machining/additional operations for repair, we're looking at again:

1kWh for 30 minutes of CNC Machine Usage = $0.08 and 0.85 pounds of CO2 wasted per unit reworked. We haven't even included the labor costs and facility costs yet. Not to mention the risk of customer return/reputation hit for poor delivery (in case this was a returned part).

Ensuring tight quality control throughout the process from digital checklists and automated inspection ensures that this cost and CO2 savings can immediately be recognized.

Recognize, Internalize & Publicize!

When we're all busy fighting fires on the shop floor, we tend to always be worried about maximizing savings and efficiency which is a great thing. However, we need to recognize that each operational efficiency improvement, whether it's OEE, yield, MTBF, etc., translates to improving CO2 and direct dollar-savings.

Let's internalize this within the organization and get everyone excited that each small improvement is better for the enterprise's bottom line and for the earth. When we can measure these results, let's get it out into the open and share it with the world. We don't need to let big CAPEX sustainability improvement grab the headlines all the time, our individual and small shop floor contributions adds up to significant savings for the world's fight towards sustainable manufacturing!