Printer specific energy protocol:MOST

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Introduction

MOST performs tests to measure the energy required to produce a 3D print in units of kWh/kg, termed specific energy. This data is useful when performing economic and environmental life-cycle analysis of printed parts. See for example:

• Environmental life cycle analysis of distributed 3-D printing and conventional manufacturing of polymer products
• Environmental impacts of distributed manufacturing from 3-D printing of polymer components and products
• Life-cycle economic analysis of distributed manufacturing with open-source 3-D printers

Following is the protocol used for collecting this data.

Equipment

• RepRap 3D printer and host computer
• kW-hr monitor such as the commercial Kill-A-Watt power monitor (The precision of the Kill-A-Watt is around 0.01 kWh)
• Timepiece if printer host does not display print duration

Method

1. Plug the power monitor into an outlet and plug the printer's power supply into it.
2. Chose an open source digital design that will weigh more than 50g when printed. (Small prints can consume less than 0.01kWh.)
3. Ensure heaters (hot end, heated bed, etc.) are at room temperature.
4. After slicing the model and just before printing it, record:
   1. print description
   2. nozzle diameter (mm)
   3. print T (C)
   4. heated bed T (C)
   5. print speed (mm/s)
   6. starting kWh
5. Print the model.
6. When the print is complete, record:
   1. ending kWh
   2. actual print time
   3. weight of the print (kg) see; Digital mass protocol:MOST

Reporting

1. Calculate the energy consumed by subtracting the starting kWh reading from the ending kWh reading.
2. Group the data by print speed and nozzle diameter.
3. Create a scatter plot with power consumption (kWh) on the ordinate and printed part weight (kg) on the abscissa. A data series should be created for each group of print speed and nozzle diameter. For example, if one series of prints was performed at 60 mm/s with a 0.5mm nozzle and another at 30mm/s with a 0.5mm nozzle, two data series would be required.
4. Add a trendlines to the plot and display the equations.
5. Record the slope of the trendline(s) as the specific energy and the intercepts as warming and idle energy.