Interview first published in the January–February 2021 issue of 3D ADEPT MAG, then online in May 2021. Prepared in collaboration with Thermwood; roles, equipment and market assessments reflect that period.
Large-format additive manufacturing draws on expertise in polymer processing, machine control and machining. Thermwood’s experience in CNC equipment provides one example of this industrial background.
Dennis Palmer, then Thermwood’s vice president of sales, discusses the company’s Large Scale Additive Manufacturing (LSAM) systems and their applications.
Thermwood’s manufacturing background
Thermwood supplies large-format equipment and services using chopped-fibre-reinforced polymer pellets. Its CNC background extends to the 1970s; the original article’s claim that only three companies served this market was not supported by a defined market study.
Thermwood’s initial business consisted in extruding plastic parts. “Due to various reasons, the product changed and new markets required three dimensional thermoformed parts to be trimmed. There was nothing on the market to meet our needs for this application, therefore Thermwood designed and built the very first CNC router. We make our own machine control system, and also developed 3rd generation cabinet design software for the woodworking industry”, Palmer outlines.
By the time of this interview, the company had built around five decades of experience in manufacturing equipment. That experience informs its approach without guaranteeing suitability for every application.
Thermwood is based in Dale, Indiana, and supplies equipment to woodworking and other manufacturing industries.
Its CNC capabilities also serve aerospace, marine, automotive, plastics and defence applications, where trimming and machining can complement additive production.
Thermwood’s LSAM approach combines large-scale polymer deposition and CNC trimming. The operations may be organised differently across machine configurations.
Anyway, today we have discovered a company that supplies machines, parts and service to various branches of the U.S. government as well as to U.S. defense contractors. As per the words of Palmer, 2020 saw a busy team supplying “machines to companies that were manufacturing COVID PPE products, as well as to industries [that provide items in need to those that elected to remain] home and not spend their money on vacations”; industries that provided items such as motor homes, marine products and off-road vehicles. Furthermore, as AM received positive media hype in 2020, this also helped the company maintain “a large backlog of orders for [its] Large Scaled Additive Manufacturing (LSAM) systems.”
Existing and emerging applications
Although it was first seen as a process for concept modelling and rapid prototyping, AM in general has rapidly expanded to include applications in many sectors of activity. Despite their potential, it should be noted that all additive manufacturing technologies do not advance at the same pace.
As far as “Large Scale Additive Manufacturing” process is concerned, our expert states that it is still an emerging market.
“The machine has proven its worth in our current target markets, but only time will tell what future market sectors will be able to utilize the near net shape printing capabilities”, the Vice President of Sales confirms. Current markets that already adopt LSAM include aerospace, automotive, marine and foundry. As a matter of fact, multiple machines from Thermwood are currently installed in several facilities across these industries.
Among the numerous applications that have been achieved using Thermwood’s LSAM, the largest part to date the machine has ever 3D printed was a display. The enterprise’s representative explains that it “was designed utilizing 225 printed blocks that were assembled to create a 93’ tall structure with the base being approximately 30’ in diameter.” (That translates into a 28m structure with 9m in diameter).
Moreover, among the numerous applications that have been made public, marine applications have increasingly raised a key interest within the manufacturing field.
A yacht-hull mould demonstrator
Marine tooling illustrates the use of fibre-reinforced polymers in large-format AM. It does not, by itself, establish that the resulting material or tool is recycled or readily recyclable.
The manufacturer’s documented yacht-hull mould demonstration explored printing the mould directly rather than first making a master pattern.
For a proposed 51-foot hull mould (about 15.54 m), Thermwood printed a 10-foot test section (about 3.05 m). This demonstrated a section and assembly approach, not completion of the entire 51-foot mould.
The design incorporated curved rocker supports to improve access during layup.
The printed pieces, about five feet tall (1.52 m), were joined chemically and mechanically with polymer cables into two mould halves. Rockers allowed tilting by about 45 degrees, with wedges holding the position. After curing, the halves could be separated to release the hull.
The pieces were printed and trimmed on an LSAM MT 1010 with a 10 × 10 ft envelope, using carbon-fibre-reinforced ABS. Thermwood selected it for its properties and comparatively low cost among reinforced thermoplastics.
The demonstration also had material limits: Thermwood reported that some thermoset solvents attacked ABS and that protective-coating performance changed with curing temperature. The application therefore requires compatibility testing; it does not validate every resin or production tool.
As Palmer points out, “the LSAM can process parts from virtually any thermoplastic composite material used, including high temperature materials that are ideal for molds and tooling that must operate at elevated temperatures. LSAM’s unique printing capabilities produces parts that are fully fused, vacuum tight and virtually void free”.
This performance statement is Thermwood’s assessment. Material compatibility, porosity, vacuum tightness and service temperature must be established for the actual process and tool.
Technical challenges and process control
It is often said that AM of composite materials poses three main challenges: the problem of the homogeneous distribution of reinforcement material in the matrix, the availability of the raw material in a proper form and its imperfections while looking at the chemical variations of the feedstock materials as well as the selection of the ideal process parameters to manufacture these composite materials.
Hybrid equipment does not remove the need to control feedstock, fibre distribution, temperature and process parameters. The significance of each challenge depends on the material and application.
During the 2021 interview, Thermwood identified reducing the operator’s need to monitor and adjust printing temperatures as an area of development.
“Currently a thermal imaging camera is utilized, but this still requires the operator to manually change settings during the print process. Even though modifications are rarely needed, an operator needs to be in place when control parameters need to be modified. We anticipate the operator’s participation will be greatly reduced by LSAM control capabilities”, the VP of Sales explains.
Large components can require hours or days of printing and trimming. The Thermwood Mobile App described in this interview was intended to help operators follow machine status, programme progress and error messages; it did not remove responsibility for process supervision.
Outlook at the time of the interview
Thermwood’s long outstanding business has demonstrated that the company has “the experience, the ingenuity and the building blocks to address Large Scale Additive Manufacturing.” From the M400 – the largest machine it has ever built to increase LSAM production, to the LSAM MT or even the LSAM 1010 3D printers, the company is ready to meet the increasing production demand of companies with very bold manufacturing goals.
The machine portfolio and development plans described here are those discussed in 2021, not a statement of current availability.
This content has been written in collaboration with Thermwood.
This dossier was first published in the January-February issue of 3D ADEPT Mag
THE 3D ADEPT WEEKLY NEWSLETTER
The industry moves fast. Stay ahead.
Every week, the latest additive manufacturing news, in-depth features and real-world applications, straight to your inbox. Plus, be the first to know when a new issue of 3D ADEPT Mag is out.
Free · One email a week · Unsubscribe anytime
Clicking loads our email provider’s sign-up form, including its analytics and Google’s anti-bot protection. You’re only subscribed if you complete the sign-up. Read our privacy policy.