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Panasonic Cordless Tools Energy Article

“ECO” & “Go Green”, phrases that manufacturing now uses to describe the reduction of energy usage and changes their making to lessen the damage to our planets environment. In the plan to reduce energy usage manufacturers are reviewing the compressed air system to reduce energy costs. During the compressed air system review, manufacturers have found that air tools consume a large amount of energy. To support their findings, below is an excerpt from the Compressed Air Challenge showing just how inefficient a compressed air tool is to run.

“Compressed air is one of the most expensive sources of energy in a plant. The over-all efficiency of a typical compressed air system can be as low as 10%-15%. For example, to operate a 1-horsepower (hp) air motor at 100 pounds per square inch gauge (psig), approximately 7-8 hp of electrical power is supplied to the air compressor.” quoted from www.compressedairchallenge.org Compressed Air Tip Sheet #1

Inefficient air tools have manufacturers looking at alternate types of tools to reduce their energy usage and CO2 Emissions. Panasonic’s Assembly Tools provide a new option for achieving these goals using cordless tools.


For more information click on the Energy Savings Calculator arrow


How Much Can I Save By Switching to Cordless Tools?

To calculate the savings of running cordless tools vs air tools we will just take the yearly cost of running the cordless tool from the cost of running the air tool.

Total Energy Saving by Running Cordless Tools

Yearly cost to run air compressor for air tool - $272.65 /yr

Yearly cost to run cordless tool - $7.39 /yr

Possible savings in energy by running cordless tools
$272.65 /yr - $7.39 /yr = $265.26 /yr

Total money saved by running cordless tools (not including air leaks) $265.26 /yr

In a true comparison not counting maintenance costs, the air tool cost $480.86 a year when including compressor standby time and air leaks.

Calculate the yearly cost to supply the air leaks in the plant.
3,080 kwh/yr x $.07 /kwh = $215.60 /yr

Total money wasted to compressed air leaks $215.60 /yr.

Total Potential Savings of $486.86

To help explain the cost effectiveness of Panasonic’s Assembly Tools compared to compressed air tools we’ve created a scenario along with the math to show how much a manufacturer could save by using cordless assembly tools.

Example Application

A manufacturer is putting together 120 parts per hour and each part requires 2 fasteners. They are running 2 shifts, 8 hours each, 5 days a week and with two weeks of shutdown. This manufacturer has the perfect compressed air system for this tool application, an 18.6 CFM VSD compressor with 100% efficiency fully loaded and 20% energy usage unloaded. The compressor is set to turn on at the start of the shift and turns off at the end of the shift. Due to the frequency of the fasteners the compressor is unable to shut down.

Manufacturers Fastener / Part Data

Time to Rundown Fastener (sec) – 2
Number of Hours in a Day – 16
Number of Days in a Year – 250 (5 days/wk x 50 wks)
Number of Fasteners per Day – 1920

Tools in comparison: Panasonic Cordless Pulse Tool Vs Compressed Air Pulse Tool

  • Cordless Tool Specs
    • 620 Fasteners per Charge
    • 0.132 kwh Charge Mode
    • 0.035 kwh Standby Mode
    • 60 min Charge Time
  • Pulse Tool Specs
    • 18.6 CFM

Rules of thumb

To show an example of the cost comparison between cordless tools and air tools we need to use a couple of rules of thumbs. To conduct your own savings, replace the examples below with actual data to obtain a more accurate savings for your plant.

  • For every horsepower an air compressor produces on average 4 scfm (rotary screw type).
  • Average US electrical cost is $.07 per kwh for manufacturers.
  • Compressed air systems waste on average 20% to leaks.
  • Compressor uses on average 20% of compressor bhp completely unloaded (VSD type / use 25% for Modulation or Load/Unloaded type compressors).

Energy Consumption of Air Tools

To calculate the cost of running an air tool we need to break out the energy usage. During the rundown, lets state that the tool uses 100% flow during the entire rundown and no flow when the tool is not in use. While running the fastener the tool uses 18.6 scfm fully loading the compressor for 2 seconds and there are two fasteners every minute. While the tool is not in use, the compressor only uses 20% of the full load brake horsepower. Lets’ do the math…

Cost to run air compressor during fastening process.

Calculate the runtime per fastener in minutes.
2 sec ÷ 60 min = .033 min per fastener

Calculate the runtime hours per day.
1920 fasteners/day x .033 min/fastener ÷ 60 min = 1.06 hr/day

Calculate the BHP required to run air tool CFM then convert to KW.
(18.6 cfm ÷ 4 cfm (/hp) ÷ 0.9 m.e.) x 0.745 watts (/hp) = 3.85 kw

Calculate the total kwh used per day.
1.06 hr x 3.85 kw = 4.08 kwh/day

Calculate the total kwh used per year.
4.08 kwh x 250 days = 1020 kw/yr

Calculate yearly cost to run air compressor during the fastening process.
1020 kw x $.07 /kwh = $71.40 /yr

Cost to run a perfectly sized air compressor for just the tool in standby

Calculate total time the compressor is running in standby.
16 hrs (both shifts) - 1.06 hrs (fastening time) = 14.94 hrs/day

Calculate the unloaded CFM, BHP required and convert to kw.
((18.6 cfm x 20%) ÷ 4 cfm (/hp) ÷ 0.9 m.e). x 0.745 watts (/hp) = 0.77 kw

Calculate total kwh used per day.
14.94 hr x 0.77 kw = 11.5 kwh/day

Calculate total kwh used per year.
11.5 kwh x 250 days = 2,875 kw/yr

Calculate yearly cost to run air air compressor in standby.
2,875 kw x $.07 /kwh = $201.25 /yr

We’ve just calculated the cost to run the air tool for each stage. To calculate yearly costs, we simply add the cost to run the compressor during the fastening process with the cost of running the compressor in standby.

Total Energy Cost to Run Compressed Air Tool

Yearly cost to run air tool during fastening process - $71.40 /yr

Yearly cost to run air compressor in standby - $201.25 /yr

Total yearly cost to run air compressor for air tool
$71.40 /yr + $201.25 /yr = $272.65 /yr

Total energy cost to run air tool $272.65 /yr

Energy Consumption of Cordless Tools

Calculating the cost of cordless assembly tools is the same as calculating an air tool without the conversion steps for CFM to BHP and BHP to KW. The charger only takes an hour to charge a battery consuming 0.132 kwh and when the charger is in standby it’s only uses 0.0032 kwh. If you were to leave the charger plugged into the wall for a year without charging any batteries the charger would only cost about $0.22 to run.

Cost to charge the battery

Calculate the number of charges per day.
1920 fasteners/day ÷ 620 fasteners/charge = 3.1 charges/day

Calculate daily kw usage of charger during charging.
0.132 kwh x 3.1 charges /day = 0.41 kwh to charge/day

Calculate the total kwh used per year to charge the batteries.
0.41 kwh/day x 250 days = 102.50 kwh

Calculate yearly cost to charge batteries.
102.50 kw x $.07 /kwh = $7.18 /yr

Cost to leave charger plugged into the outlet

Calculate total time charger is in standby.
24 hrs/day - 3.1 hrs charging time = 20.9 hrs in standby/day

Calculate daily kw usage of charger in standby.
0.00035 kw x 20.9 hr = 0.0073 kwh

Calculate the total kwh used per year in standby.
0.0073 kwh/day x 365 days = 2.66 kwh

Calculate yearly cost to charge batteries.
2.66 kw x $.07 /kwh = $0.19 /yr

To calculate the yearly cost of running a cordless tool we just add the yearly charging cost with the cost to leave the charger plugged into the outlet.

Total Energy Cost to Run Cordless Tool

Yearly cost to run cordless tool during fastening process - $7.18 /yr

Yearly cost to leave charger plugged in standby - $0.19 /yr

Calculate the yearly cost to run a cordless tool.
$7.18 /yr + $0.19 /yr = $7.37 /yr

Total energy cost to run cordless tools $7.37 /yr

Leaks

“Leaks can be a significant source of wasted energy in an industrial compressed air system, sometimes wasting 20-30% of a compressor’s output. A typical plant that has not been well maintained will likely have a leak rate equal to 20% of total compressed air production capacity.” quoted from www.compressedairchallenge.org Compressed Air Systems Fact Sheet #7

The Compressed Air Challenge and CAGI (Compressed Air and Gas Institute) both state on compressed air systems older than five years have at least 20% of system capacity wasted to leaks. A company with a proactive maintenance routine using an ultrasonic gun to find and fix leaks can achieve better results which we recommend. If a manufacturer replaces an air tool with a cordless tool we also recommend terminating the compressed line at the header to eliminate possible air leaks. Here’s an example of potentially how much it cost to leave the compressed air line connected to the header.

Calculating Compressed Air Leaks

Calculate the running time of the compressed air system.
2 shifts/day x 8 hr/day = 16 hrs/day

Rule of thumb 20% of compressed air system lost to air leaks.
18.6 cfm compressor at full capacity x 20% average leaks in system = 3.72 cfm

Calculate BHP needed to keep up with air leaks and convert to kw.
(3.72 cfm / 4 cfm (/hp) / 0.9 m.e.) x 0.745 watts (/hp) = 0.77 kw

Calculate total kwh used per day for air leaks.
16 hr/day x 0.77 kw = 12.32 kwh/day

Calculate total kwh used per year to supply air leaks.
12.32 kwh/day x 250 days/yr = 3,080 kwh/year

Calculate the yearly cost to supply the air leaks in the plant.
3,080 kwh/yr x $.07 /kwh = $215.60 /yr

Total money wasted to compressed air leaks $215.60 /yr.

Environmental - CO2 Emissions

A growing concern about global warming and the EPA (Environmental Protection Agency) placing more stringent guidelines on CO2 Emissions has manufacturers looking for ways to improve their electrical usage.

“The combustion of fossil fuels to generate electricity is the largest single source of CO2 emissions in the nation, accounting for about 40% of total U.S. CO2 emissions and 33% of total U.S. greenhouse gas emissions in 2009.” quoted from www.epa.gov Greenhouse Gas Emissions

Utilizing the calculations above we’ll help show you how converting just one tool and eliminating the compressed air line (air leaks) can significantly reduce CO2 Emissions.

Calculating CO2 Emissions

Total kwh to run the air compressor for the tool w/o air leaks = 3,895 kwh

Total kwh to run the compressor to supply the air leaks = 3,080 kwh

Total kwh to run a cordless tool = 104.33 kwh

Potential kilowatt-hours savings converting to a cordless tool per year
3,895 kwh + 3,080 kwh -104.33 kwh = 6870.67 kwh /yr

Calculate total CO2 Emissions reduction for converting to a cordless tool per year 6870.67 kwh x 681 g of CO2/kwh x 0.002205 lbs/g / 2000 lbs/ton = 5.16 tons

Run cordless tools and reduce your carbon footprint by 5.16 Tons