The manufacturer of a power tool company needs your help with selecting an appropriate material for tool casings which would minimize the embodied energy per unit volume. Which of the following most correctly summarizes the choice given that the dimensions of the casing, including the thickness, are fixed?
Embodied energy per unit volume
107 W-alloys
Ti-alloys Tin Ni-alloys Tungsten carbides Pb-alloys 106 Aluminum nitride Mg-alloys Stainless/Cu-alloys PEEK steels Y PTFE Al-alloys Silicone Silicon carbide Epoxies PMMA Alumina Low alloy steels PET PS PVC. Silicon 105 Carbon PE Nylons/Silica steels Cast PCABS glass irons Polyester pp Borosilicate PLA glass Soda-lime-glass
CFRP
GFRP
SMC
Paper and/cardboard
Polymer foams
104
Brick-
Hardwoods Softwoods Bamboo Hybrids
Concrete Ceramics
103
Metals
Polymers
(Link)
O Glass fiber reinforced polyester (GFRP) has a high embodied energy but this is compensated by its very low density, resulting in a low mass component, and hence lower energy than expected.
O Cast irons appear to have more embodied energy than many polymers but this is only an artifact of their higher density, and if you exploit their higher modulus and toughness to use less material you might have a saving in energy terms.
O Acrylonitrile butadiene styrene (ABS) offers a low embodied energy per unit volume compared to most materials, although there are alternative polymers that are better by this metric. ABS would be chosen if its toughness and ease of moldability were seen as significant benefits. Alternate ceramic and hybrid materials look attractive but only if you ignore practical issues of production and damage tolerance.
O Die-cast aluminum is a very good choice. While the embodied energy per volume is higher than some other materials, its high stiffness lets us make the case thinner and use less material. The casting process is suitable for making a complex shape without further processing.