Purdue CMSC, in collaboration with Purdue Silicon Detector Laboratory (PSDL), is designing, prototyping, testing, and fabricating composite support structures for CERN’s Large Hadron Collider (LHC) CMS and ATLAS experiments. This is part of the particle collider’s High Luminosity upgrade, with installation of final components in 2026-27. The Thermwood LSAM 105 Additive Printer and five-axis LSAM Trim router at the Purdue LSAM Research Laboratory have enabled rapid large-scale printing and machining of trimming fixtures for the high precision composite tube structures. The 1m long, 208mm radius trimming fixture was printed on the LSAM with Acrylonitrile Butadiene Styrene (ABS) reinforced with 20% by weight of carbon fiber.
This 914mm long prototype of the CMS upgrade inner tracker support tube will allow project partners at national labs, universities around the world, and CERN to begin installation tests of their structural and detection components. Individual components installed into this support tube are expected to be positioned within +/- 0.5mm or less, so accurate machining of interface features is critical. This kind of precision at large scale is made possible, economical, and convenient with the aid of systems like LSAM.
Printing Details
Since critical surfaces would be machined later, and to increase production speed for the prismatic geometry, the tool was split into two vertically-printed segments. The halves were bonded with adhesive and dowel pins for joint strength and stability.
Machining Details
The faces that would become the trimming fixture base were machined to the flatness required for fixturing later. The printed, bonded fixture was then mounted on pedestals in the LSAM Additive Trimmer and the surface was machined to fit the nominal inner surface shape of the composites half-cylinders to be trimmed. Edge finding and reference features were machined into the trimming fixture to allow proper centering of the cured composite part.
Using this printed and machined fixture, the composite part edges were trimmed, interface holes drilled, mating surfaces machined flat and a scarf joint for joining the two half cylinders was created. The precision trimmed composite halves were then able to be bonded together.
Final Result
The final tube, 3.2m long, has to support 140kg of mass while only allowing sub millimeter deflections to occur. Purdue CMSC and PSDL will also be designing, fabricating, or testing other composite support structures for the CERN LHC upgrade as small as 0.5mm sheet goods and as large as 2.4m x 5m sandwich panel tubes. It is planned for the LSAM system to be utilized to create tooling and some final components for these other structures.
About CMSC
The Composites Manufacturing and Simulation Center (CMSC) of the College of Engineering and the Purdue Polytechnic are located in over 30,000 square feet of the Indiana Manufacturing Institute building. CMSC consists of faculty experts in composites manufacturing, a professional staff of doctoral degree engineers, a support staff and research students in doctoral, masters and bachelor’s degree programs of the Schools Aeronautics and Astronautics, Chemical Engineering and Materials Engineering, as well as, the Department of Aviation Technology in the Polytechnic.
A comprehensive set of laboratories is available at the IMI for the study of composites manufacturing processes, characterization of composite materials, and the validation of simulation software essential to the development and verification of the digital twin concepts in composite manufacture and performance. Focus specialties include extrusion deposition additive manufacturing, composites autoclave processing of continuous fiber systems, compression and injection molding of discontinuous fiber composites, prepreg impregnation, infusion molding, sheet forming, complex mold-forming and hybrid continuous/discontinuous fiber systems. Workflow simulations are being developed to provide for end-to-end digital twins of these manufacturing processes. Accordingly, manufacturing informed performance predictions are a direct outcome of these workflow analyses.
About Thermwood Corporation
Thermwood has also become the technology and market leader in large scale additive manufacturing systems for thermoplastic composite molds, tooling, patterns and parts with its line of LSAM (Large Scale Additive Manufacturing) machines that both 3D print and trim on the same machine. These are some of the largest and most capable additive manufacturing systems ever produced and are marketed to major companies in the aerospace, marine, automotive and foundry industries as well as military, government, and defense contractors.
This content was first published on the Thermwood website.