Hybrid 3D Printer-CNC Machine Offers a Cut Above the Rest
Michael Molitch-Hou posted on September 12, 2016 | 8407 views

At the International Manufacturing Technology Show (IMTS) in 2014, one news story swept the floor, that of the first car to be 3D printed, assembled and driven off the showroom floor of the event—all within 48 hours. The car, developed by Local Motors and its cocreation community, was 3D printed on Cincinnati Inc’s Big Area Additive Manufacturing (BAAM) system, a massive 3D printer relying on technology licensed from Oak Ridge National Laboratory and capable of extremely high throughput.

Perhaps a lesser known star of the show was a CNC router from Thermwood Corporation. Purchased by Local Motors just before the event, the Thermwood 5 Axis Model 70 10x15 CNC router took the 3D-printed auto chassis and trimmed it down to net shape so that the wheels could be thrown on, the engine thrown in, and the car driven off of the showroom floor.

Thermwood has just unveiled the LSAM, the first extrusion 3D printer with built-in CNC machining capabilities. (Image courtesy of Thermwood.)
Thermwood has just unveiled the LSAM, the first extrusion 3D printer with built-in CNC machining capabilities. (Image courtesy of Thermwood.)

Two years have passed since that day and Thermwood’s CNC technology is back in the 3D printing space and bigger than ever. The 40-year-old CNC equipment manufacturer has announced the release of the Large Scale Additive Manufacturing (LSAM) system, so far the only extrusion-based 3D printer with built-in CNC capabilities.

Building the LSAM

In an interview with Jason Susnjara, vice president of Marketing for Thermwood, Susnjara discussed the history of the company and the details that led up to the production of the LSAM. “We’ve been manufacturing CNC routers for over 40 years now,” Susnjara said. “We’re probably one of the only manufacturers that not only builds the machine but also the controller itself. So, that gives us great functionality and the ability to update and add new items and features throughout these 40 years that we’ve been in business.”

After the IMTS event, Susnjara said that a company in Indianapolis reached out to Thermwood with the idea that the firm should build its own 3D printer. Beginning in October 2014, Thermwood began work on developing the LSAM machine, based off of one of its existing CNC router designs, a high wall system with a moving gantry. Susnjara explained, “Through a few iterations and after a few hiccups, we have now come out with the LSAM machine.”

The LSAM 3D prints an object to near net shape before a CNC router trims the part to net shape. (Image courtesy of Thermwood.)
The LSAM 3D prints an object to near net shape before a CNC router trims the part to net shape. (Images courtesy of Thermwood.)

Thermwood added a high power extruder gantry to the system, which deposits thermoplastic material onto a stationary substrate. Once that was assembled, a CNC gantry was added, giving the LSAM two different gantries, one for 3D printing and one for CNC routing. Objects are 3D printed to near net shape and, once the material cools sufficiently, the router can pass by and shave the print to provide a refined finish.

LSAM vs. BAAM

Despite this author’s initial understanding, the BAAM system from Cincinnati Inc does not feature an integrated CNC router. In fact, Susnjara believes that Thermwood’s system is the only extrusion-style 3D printer with built-in CNC capabilities, though hybrid systems exist that 3D print and machine metal.

Other differences with the BAAM include the extruder. Whereas the BAAM system can print 80 pounds of material per hour, Thermwood has three different printheads that are capable of deposition rates of 150, 300 and even 500 pounds per hour. The material is heat dried and transported automatically to the machine’s hopper, which feeds the material into the extruder.

A built-in roller on the LSAM’s extruder compresses the material as it’s printed. (Image courtesy of Thermwood.)
A built-in roller on the LSAM’s extruder compresses the material as it’s printed. (Image courtesy of Thermwood.)

Additionally, the BAAM system features a ring-shaped mechanism for compressing the material as it’s printed, while the LSAM uses a servo controlled wheel that follows behind the deposited plastic, packing it down. Susnjara said that Thermwood has “found this to be extremely beneficial as far as getting any air pockets out and creating a nice bond between layers.”

The BAAM system also relies on a moving printbed for control over Z-axis height, unlike the LSAM, which has a fixed bed and raises the extruder or router. While the BAAM is available with a print volume of 20 ft x 7.5 ft x 6 ft, the printing envelope of the LSAM is 10 feet wide and 10 feet tall, but the bed can be extended up to 100 feet or higher, if needed. “If you’re looking at windmill blades or the wings for drones, things of that nature,” Susnjara said, “we can go beyond 100 feet if needed to where we can print that long of a structure.”

The LSAM can be made to extend to over 100 feet long. (Image courtesy of Thermwood.)
The LSAM can be made to extend to over 100 feet long. (Image courtesy of Thermwood.)

Due to the size and the dual gantry system, the LSAM machine can even simultaneously trim parts with the CNC gantry and 3D print with the extruder gantry. It’s possible to imagine the system 3D printing one Local Motors car and moving on to a second while the CNC router comes in and begins refining the surface finish of the first.

Massive Tooling

Though possible, not every Thermwood customer will be using the LSAM to 3D print blades for giant wind turbines. Instead, Thermwood aims to tackle the toolmaking industry.

Making a mold is a labor- and cost-intensive process that, in the case of very large molds, requires gluing multiple components together before machining them with a CNC router. Throughout the process, at least one person is involved in every step, but teams of multiple people are more often required.

Susnjara pointed out that with the LSAM, the sole machine operator did not have to be present for the majority of the process. “Just looking at our preliminary numbers now, we’re looking at a 50 to 70 percent reduction of cost printing compared with the traditional method of creating patterns,” he said.

To create molds and other tooling, the ability of the roller on the LSAM extruder to drive out air pockets is key. “The plan for this is not to actually print a final part; it’s to print tooling, molds, masters, fixtures, and other items and some of those molds or patterns that have to go into an autoclave need to be air pocket free, so that’s one of the things we’re striving for,” Susnjara explained.

That's also one of the reasons that Thermwood is striving to increase the carbon fiber content in the system’s feedstock. Currently, the LSAM 3D prints using industrial pellets from Techmer PM that have a ratio of 80 percent ABS plastic and 20 percent carbon fiber. To increase the rigidity within the parts, the company plans to increase the ratio of thermoplastic to carbon fiber even more. Future materials will include pellets made up of 50 percent polyphenylene sulfide (PPS), an engineering-grade thermoplastic, and 50 percent carbon fiber. To print such a material, Thermwood will have to up the melting temperature of its extruder, which currently heats up between 350 and 400 °F. Printing the PPS composite requires temperatures between 600 and 650 °F.

3D Printing Gets Industrial

As GE’s recent 3D printing acquisitions indicate, the world of 3D printing is no longer about prototyping. The technology has truly entered an industrial manufacturing phase, in which 3D printing is used to produce industrial-grade end parts.

For this reason, companies like Thermwood and Cincinnati, which have rich histories of producing manufacturing equipment, have entered the field with massive, highly capable systems that meet the needs of large manufacturers, such as those in the aerospace industry. Needless to say, traditional 3D printer manufacturers will have to keep up, which is why Stratasys unveiled its new industrial 3D printing equipment and EnvisionTEC showcased its enormous composite 3D printer at RAPID 2016.

Thermwood stands out as the only maker of a hybrid extrusion and milling system and will certainly continue to do so, but, as the industry heats up, so will the competition.


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