SABIC
SABIC and Local Motors have determined that up to 100% of the material from the post-production of large format additive manufacturing (LFAM) parts can be reused in LFAM and other processes.
The companies have reached this conclusion after carrying out a feasibility study which analysed the printability and mechanical properties of SABIC’s LNP THERMOCOMP AM reinforced compound after being printed, reclaimed, ground and reprocessed into pellet form. They embarked on this study in a bid to identify a ‘feasible path to circularity and an extended lifecycle for materials’ used within the LFAM space. Having concluded the research, the partners believe more work is required to fill existing gaps in the process chain for reusing LFAM scrap and is calling on other LFAM companies to join their ongoing efforts.
Reclaiming parts and scrap of LFAM post-production is considered to be a complex process which includes locating, collecting and transporting large parts to a facility with the capacity to clean, cut, regrind and repurpose the material. There is also the potential degradation of LFAM materials as it moves through multiple heat cycles.
In the SABIC-Local Motors study, the companies assessed six variations of the LNP THERMOCOMP AM compound, with samples containing, 0, 15, 25, 50, 75 and 100 per cent reprocessed content. Each sample was used to print a single-wall hexagon and was monitored for changes in throughput and melt flow rate on SABIC’s Big Area Additive Manufacturing machine from Cincinnati Inc. All samples are said to have printed well, with a smooth and shiny surface, and straight, even layers that demonstrated no issues with material flow. To evaluate the mechanical properties, specimens were cut from each hexagonal part, before being tested for tensile properties using Test Method D638 as a guideline and flexural modulus using a three-point bend test following a modified ASTM D-790 test method. The results showed ‘excellent tensile properties’ in the part samples containing smaller percentages of regrind, ‘incremental declines’ in the samples that included larger percentages of regrind, and a 20 per cent reduction in tensile properties in the X direction and 15 per cent in the Z direction in the 100% regrind sample. For flexural properties, the same gradual trend occurred, with flexural modulus declining by 14 per cent in the X direction and 12 per cent in the Z direction for the sample containing 100 per cent regrind.
Though highlighting the reusability of LFAM shavings and parts, the partners believe the existing gaps in the recycling value chain need to be filled before the process can become viable. Counting this study as the ‘first steps in finding a circular solution for the LFAM industry’, SABIC is soon to complete a report containing detailed data from the study, and has suggested a ‘large, collective effort by the LFAM community’ is required to devise an economical method of collecting scrap and converting it to a reusable form.
“As adoption of large format additive manufacturing accelerates, it is essential to find sustainable alternatives to landfilling large, printed parts,” commented Walter Thompson, Senior Applications Development Engineer, SABIC. “SABIC and Local Motors have investigated the practicality of using mechanically ground scrap material and end of life parts generated from LFAM. Our study showed great potential for reusing these materials and marks a first step in supporting reuse within the value chain.”
“Building next-generation vehicles means embracing next-generation manufacturing processes,” added Johnny Scotello, Director of Technical Product at Local Motors. “We’re proud to work with SABIC in making large format additive manufacturing more sustainable. Bringing value to scrap or end-of-life parts is a difficult challenge, but the results of this study point to a bright future for sustainable, circular products.”
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