AAT3D In SME Article About On-Machine Metrology
In the cornfields of southern Indiana, Thermwood Corp. is making unique large-scale additive manufacturing (LSAM) equipment. LSAM machines produce large- to very-large sized components from reinforced thermoplastic composite materials, creating industrial tooling,
masters, patterns, molds and production fixtures used in the aerospace, automotive, foundry, and marine industries.
The LSAM process is a unique mix of machine design and material science. Workers lay down a large bead of thermopolymer at room
temperature. The company describes this as essentially an exercise in controlled cooling—polymer cooling, not print head output, determines print speed. Print head output determines how large a part can be printed in the layer time available. LSAM print heads are
available that can print well over 500 lb. (228 kg) per hour, which makes very large parts possible.
Thermwood makes LSAM machines in work area sizes from 10 × 10′ (3.05 × 3.05 m), up to 10 × 100′ (3.05 × 30.5 m). The machines both print and trim thermopolymer components.
The process is dubbed vertical layer printing (VLP). Using large print beads plus Thermwood’s patented compression wheel, it creates solid, fully fused, virtually void-free printed structures. These structures can sustain a vacuum in a pressurized autoclave at elevated temperature without the need for expensive coatings.
In 2019, Boeing, on behalf of the Air Force Research Laboratory (AFRL), contacted Thermwood, based in Dale, Ind., to evaluate LSAM’s ability to reduce the time and cost of fabricating autoclave-capable tooling to make composite aerospace components. The initial demo tool would be for fuselage skin for an AFRL concept.
LSAM’s main attraction for autoclave tooling was speed—the ability to produce a complete tool in days compared to the weeks or months required with conventional machining. The LSAM equipment also could print large components, thereby reducing assembly time and
cost. Thermwood LSAM machines print, trim, and probe. CAPPSNC software feeds
metrology data back to the NC controller and adjusts work offsets and other
machine parameters as they change.
Measuring and machine adjustment becomes automatic. (All images provided by Thermwood Corp. and Applied Automation Technologies)
On-Machine Metrology Drives Efficiencies In Large-Scale AM
Boeing and AFRL 3D-printed a section of a large tool to evaluate LSAM functionality. The mid-scale tool (4′ [1.22 m] in length vs 10′ [3.05m] for the final tool) was printed on Thermwood’s LSAM demonstration machine using a 40-mm print core running 25 percent carbon fiber reinforced polyethersulfone (PESU).
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