Team Members: Suraj Bhogal, Jeremy Faludi, & Myles Iribarne

 

This project was completed during Spring 2013 when taking the graduate-level course ME 290I: Sustainable Manufacturing. The goal of this work was to compare the environmental impacts of producing a control part using additive manufacturing and conventional machining to determine which is more or less ‘sustainable.’ The technologies studied included Fused Deposition Modeling (FDM), PolyJet, and CNC. To evaluate the environmental impacts, we conducted a life cycle assessment (LCA) using SimaPro LCA software. This work can be used to enable informed decisions about which technology to purchase or use, and so that the manufacturers of these technologies can understand their priorities for improving environmental impacts.

 

 

Three LCAs were performed, each with multiple scenarios, comparing a Haas VF0 CNC mill to a Dimension 1200BST FDM machine and an Objet Connex 350 inkjet machine. The LCAs were conducted using the ReCiPe Endpoint H methodology in SimaPro LCA software. The scope of this analysis was cradle-to-grave; it included the embodied impact of the tools themselves (raw materials and manufacturing), transportation of the machines to and from UC Berkeley, energy use during the processing of parts, energy use while idling and in standby, material used in the final parts, waste material generated during processing, cutting oil for the CNC mill, and disposal of both process material waste and the machines themselves.

 

 

The manufacturers were not willing to release the bills of materials of these machines with weights listed, as they believe that the mass of steel, glass, and plastic in their machines is “proprietary” information. This can be estimated by disassembling the machines and weighing all components, then entering the data into the LCA software with estimates of materials and the manufacturing processes used to make each part.

 

To assess the embodied impacts of the machines, we measured the dimensions & calculated the masses for 50-60 different parts on the Objet Connex 350 & FDM machine. For the CNC we were able to use existing work.

Because there are many differences between these tools and how they manufacture parts, it is important to make an apples-to-apples comparison when conducting this analysis. Therefore, the functional unit was chosen to be one “job” comprising of the manufacturing of two different parts in plastic--one with complex curvature as people often make by additive manufacturing, and one with simple planes and holes as people often make with traditional milling machines. Both parts are shown below as printed by the Objet.

 

As mentioned previously, the LCA compares the CNC, inkjet, and FDM machines across three different scenarios: Minimal utilization (1 job/wk) idling; Minimal utilization (1 job/wk) at low power; and Maximal utilization (running 24 hrs/day, 7 days/wk). The results below compare the impacts of each machine, for each scenario, in ReCiPe endpoint H points per year per job (one pair of parts).