Thermwood PH50 Head Successfully Tested

After recently announcing our line of LSAM (large scale additive manufacturing) machines, Thermwood has now built and tested a high output version of our PH Series composite thermoplastic 3D print head.

At a print rate of 500 lbs/Hr, our newest and largest print head, the PH50 is more than three times faster than even our current PH15 print head (which we believe is currently the highest output composite thermoplastic print head available).  

The Thermwood-designed PH series print head uses three servo drives in a unique configuration.

The advantages of this new design include:

• a highly accurate print bead, the ability to change bead size while printing
• high output print rates
• better fusion between printed layers
• a virtually void-free printed structure

Thermwood has been operating the PH15 print head on the development version of our large scale additive manufacturing machine, called LSAM (L-Sam). The PH15 features a maximum print output rate of 150 Lbs/Hr when running a 20% carbon fiber filled ABS material. Our newest, and largest print head, the PH50, has been successfully bench-tested at a print rate of slightly over 500 Lbs/Hr running the same material.

A New Way to 3D Print

Fast print rates make possible all new ways to 3D print. The maximum print rate on a particular part is dictated not by the output of the print head, but instead, by cooling. When a layer is printed it must be allowed to cool sufficiently to stiffen enough to support the next layer but should not be allowed to cool so much that it doesn’t fuse properly with the next layer. This means that, although you may be able to print much faster, with most materials, you must wait at least 1 ½ to 2 minutes before you can print another layer. This would tend to make high output print heads unnecessary except for really large parts, but there are situations where this is not the case. 

At times, parts are printed as completely solid structures. When this occurs, bead length adds up quickly. A 5 foot by 5 foot solid layer requires 375 feet of bead length with a 0.800” bead width. Even with a 125 foot per minute print speed (which is the print speed of the PH50 at full output), it will require at least three minutes to print that layer. While this is still within a good layer to layer working time, it is clearly not overly fast. 

Some parts which are printed vertically are so long that they must be printed in multiple sections which are then bonded together. With a fast enough print head and large enough table, all sections can be printed at one time rather than printing them one at a time. In this approach, you print a layer on one part, then move to the next and the next, until you have printed that layer on all the parts. Then, you return to the first part which should then be ready for another layer. You can also mix different types of parts and print them all at the same time, rather than one at a time.  With additive manufacturing technology today, this is the only way to speed up production rate. This approach makes fast print heads and large table sizes not only practical but quite desirable. 

Thermwood's PH Series Print Head Design

Thermwood’s PH Series print head design uses a servo-controlled plastic extruder with a specially designed, patented plasticating screw to heat and soften the composite thermoplastic material. It then uses a servo-controlled fixed displacement polymer pump to deliver the softened material at a precisely controlled rate to the print nozzle. This dual-servo, two-step approach to generating the print bead eliminates a variety of problems encountered when trying to use just an extruder to print and generates a highly controlled material flow rate which results in a highly accurate and controllable print bead size. 

Thermwood’s PH Series system generates a relatively large print bead, applied at high speed. The print head is slaved to machine speed so as the machine speeds up and slows down, the output of the print head automatically adjusts to keep the size of the print bead consistent and accurate. This print speed control is automatic and doesn’t need to be incorporated into the CNC print program, greatly simplifying programming. An additional feature of this approach is that the print program can vary the size of the print bead during printing, something Thermwood has found to be a valuable capability. 

Once the bead has been applied, the PH Series print head uses a unique servo-controlled compression wheel to flatten and fuse each new print layer to previous layers. This wheel is the third servo in the PH series print head and can be instructed to automatically track machine motion. 

Since it tends to squeeze out any air that might otherwise be trapped between layers during printing, Thermwood has found that this compression wheel results in superior bonding between printed layers and a virtually void free printed structure. 

Another Unique Feature

A unique aspect of this new print head design is that, unlike machine motion, the three servo drives in the print head are not machine axes. Thermwood’s print gantries have six servo drive systems, but only three of them are axes. A machine axis needs to be programmed. The servo drives in the print head have their own unique, independent, self-operating intelligent control functions, which they continuously perform without specific ongoing CNC program commands.

The CNC program simply tells them to perform their function and they do it without further specific instructions, even if those functions require them to interact with the machine program, machine motion or each other. For example, simply turn on the print function and move the machine and the print head will print the proper size bead as the machine moves, automatically adjusting for acceleration, deceleration and different machine speeds. Engage the compression wheel and it follows machine motion automatically. During printing, a delicate balance exists between the extruder and polymer pump in the print head. Achieving and maintaining this balance during all aspects of operation is also automatic. 

PH50 Successfully Operated at Full Output

Currently, the new PH50 print head has successfully operated at full output in a static position. Thermwood is replacing its 10x10 foot LSAM development machine with a 10'x20' foot demonstration machine to verify and demonstrate operation of this new head at full print speed. Thermwood believes that 10'x20' is as small a machine as is practical for this high output print head. LSAM machines are available with table lengths of up to 100 foot or more. Thermwood is confident that technology in the PH Series print heads could be used in even higher output print heads should a need ever develop.  

For More Information

The Thermwood line of LSAM machines are available now, and you can get more information and see videos of these new heads in operation here

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Thermwood LSAM Now Available 

After an extensive development program, Thermwood Corporation, (Dale, Indiana, USA), has announced it is now offering a line of Additive Manufacturing Systems for the production of large to very large reinforced thermoplastic composite parts. Thermwood’s new machine line, called LSAM (pronounced L-Sam, short for Large Scale Additive Manufacturing), uses a two-step, near-net-shape production process. 

Two-Step Near Net-Shape Production Process

First the part is 3D printed, layer by layer, to slightly larger than the final size, then it is trimmed to its exact final size and shape using a CNC router. The process operates in free space and does not require molds or tooling.  

 
  

Thermwood’s target market for this new equipment is the production of tooling, masters, molds, fixtures, patterns and plugs for a variety of industries including aerospace, automotive, boating, foundry and thermoforming. In addition, Thermwood believes it will find additional applications as various industries become aware of the substantial benefits of large part additive manufacturing. For tooling, the primary benefits of this approach are a substantially lower cost and a dramatically shorter build cycle. 

Print and Trim on the Same Machine 

 

Thermwood’s high wall, overhead gantry LSAM machines feature a ten foot wide, five foot high work envelope. Length of the work envelope can be as short as ten foot but as long as 100 foot or more. Machines include both a print gantry and a second trim gantry which is actually a five axis CNC router. Both gantries operate over the entire table surface. With this configuration, all functions needed to make parts are performed on the same machine. 

Thermwood’s print gantry features an advanced, Thermwood-developed, vertically-mounted PH Series print head that melts and precisely meters the polymer bead. It can process filled thermoplastic composite materials at temperatures up to 650 ^o F. Advantages of this unique triple servo design include a much more accurate print bead, the ability to change bead dimensions while printing, the ability to print at high output rates, better fusion between printed layers and a superior void free printed structure. 

Highest Output Rate Head Available 

Thermwood currently offers the PH15 Print Head on it LSAM machines. The PH15 prints at rates up to 150 lbs/hr which Thermwood believes is the highest output rate available today. Although Thermwood believes the PH15 is appropriate for many current tooling applications, they are actively developing even higher output versions of the PH Series Print Head. 

The size and typical geometry of parts to be printed, the number of part to be printed at the same time and the overall size of the machine will dictate how large a print head is appropriate. PH Series Print Heads include the ancillary systems required to dry and transport material from storage to the print head. 

The trim or subtractive gantry is a five axis CNC router system equipped with a 12HP (3,000 to 24,000 RPM) Automatic Tool Change Spindle and a ten position automatic tool changer. The vertical Z axis stroke is enhanced, so that the router head can machine from the print table surface to a point completely over the top of a printed part. The machine is also equipped with an automatic tool length measurement system and Thermwood’s patented impact resistant head. The machine uses Siemens Intelligent Servo Drives throughout, for both printing and trimming.  

 

Each gantry has its own, free standing Thermwood high performance Q-Core CNC Control for movement. The print gantry also includes an integrated print head control to manage melt, pressure and metering functions. Special control functions, not normally part of a CNC control, have been developed to operate the servo drive print head and bead compression wheel. These functions automatically perform tasks that would otherwise need to be incorporated in the CNC print program. This simplifies 3D print programming. 

Exciting New Manufacturing Revolution

“This is exciting”, says Thermwood’s founder and CEO, Ken Susnjara. “We are at the beginning of what appears to be a revolution in manufacturing and we look forward to the new challenges and incredible possibilities that this type of transformational change brings”. 

 

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Thermwood Corporation, a major U.S. based manufacturer of CNC routers, has embarked on a program to develop Large Scale Additive Manufacturing (LSAM) which can perform both the “additive” and “subtractive” functions on the same machine. This approach, called “near net shape”, uses a high volume thermoplastic printer to quickly create a part that is nearly, but not exactly, the final net shape. A “subtractive” function then machines the part to the exact final net shape. In its final form, Thermwood’s system will perform both the “Additive” and “Subtractive” functions on the same machine.

MeltShape Technology 

Thermwood's MeltShape wheel is servo controlled to precisely follow machine motion

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Both vertical walls and horizontal slabs were successfully built during initial testing

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A more complex pattern was also created and trimmed as part of the testing process

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Thermwood’s development system has performed well during initial additive testing. It has been tested through its entire operating range. This startup effort included initial validation of an all new “MeltShape Technology”. Melt shaping promises enhanced control of layer shape and improved bonding between layers. This new patent pending approach uses one or more shaping wheels to shape, form and compress the hot plastic melt as it is being extruded, insuring that each new layer is the proper shape and thickness and that it bonds firmly to previously applied material.  Melt shaping offers a new and promising technique in the advancement of large scale additive manufacturing. 

Featuring an extruder from American Kuhne

Kevin Slusarz, American Kuhne vice president of process technology, assisted with the start-up effort.  American Kuhne, a Graham Group Company, supplied the custom extrusion system for Thermwood’s development machine. The extrusion system performed flawlessly during initial testing. Extruder controls are designed to smoothly network and integrate with the machine control. “We are quite pleased to have a partner like American Kuhne as part of this development program” says Ken Susnjara, Thermwood’s CEO. 

20% Carbon Graphite Filled ABS

The material processed during startup testing was a 20% carbon graphite filled ABS from Techmer ES. Thermwood is in discussions with other material supplier to test their material in this new application. 

MeltShaping Approach 

Thermwood’s melt shaping approach to adding material offers several significant advantages. Because layers are rolled together, rather than tamped together, air between layers is squeezed out during the additive process, so it is much less likely that air becomes trapped between layers. This was borne out during initial testing which produced virtually void free walls. This addresses the problem of trapped air delaminating layers when a part is processed through a heated autoclave, which is a common requirement for aerospace parts and patterns.  

Full Six Axis Articulated Additive Deposition Head 

This approach uses a melt shaping wheel that interact with the extruded thermoplastic bead while it is still hot and pliable. The shaping wheel is servo controlled so it can track the direction of machine motion. The Thermwood machine is a full six axis system, five axes to position the head in any orientation and the sixth axis to align the shaping wheels to the machine motion direction. Thermwood has added a software feature to its Q Core CNC control called “Tangential Following” which automatically keeps the shaping wheel aligned with the direction of machine motion without the need for six axis programming. This eliminates the need for a specialized CAD/CAM system to handle the sixth axis and allows the use of virtually any five-axis CAD/CAM system to program machine motion. 

Multiple Shaping Modules

Thermwood envisions different shaping wheels, each imparting specific characteristics to the hot plastic bead. 

Further Details

Because of its five axis head configuration, material can be applied at an angle or onto a curved surfaces in addition to traditional horizontal layers. This capability opens new processing possibilities and supports free form additive manufacturing techniques not currently possible. 

Thermwood’s initial test machine, which can print parts up to ten foot by ten foot by five foot thick, is expected to be fitted with a five axis “subtractive” gantry trim system in the next few months at which time all functions can be performed on the same machine. 

Ongoing Development

Thermwood Corporation, a leading U.S. based manufacturer of CNC routers, has announced a program to develop a 3D Additive Manufacturing System, capable of making large carbon graphite reinforced composite thermoplastic components.

Near Net Shape Approach

Thermwood’s systems utilizes a “near net shape” approach where a relatively large extruder, mounted to the machine, is used to heat, melt and deposit, or “print”, carbon graphite filled thermoplastic material to quickly create a structure which is almost, but not quite the exact final shape. That structure, when it cools and hardens is then five axis machined to the final net shape. 

Up to Sixty Feet Long

These new systems will be based on Thermwood’s Model 77, semi-enclosed, high wall gantry machine structures, which are currently offered in sizes up to sixty feet long. For the plastic extruder, Thermwood turned to American Kuhne, the preferred provider of engineered solutions for plastic, rubber & silicone extrusion, who developed a custom system, which integrates tightly, both mechanically and electronically, with Thermwood’s CNC machine. This allows not only the machine but also the plastic extruder to be controlled and managed by a central CNC control, insuring smooth integration and increasing both capability and flexibility. 

Optional Additive and Subtractive on the Same Machine

With the addition of a second gantry, both the “Additive” and “Subtractive” processes can be performed on the same machine. The second “Subtractive” gantry will be offered as an option. Companies that already have five axis machining capacity and want to work with Additive Manufacturing may only require “Additive” machine capability as they can use existing equipment for the “Subtractive” part of the process. 

Full Six Axis Articulated Additive Deposition Head

Thermwood’s systems will feature full six axis articulated additive deposition head, allowing it to build layered structures on both a horizontal plane as well as planes canted in any direction up to ninety degrees from horizontal. Management believes this capability will be important as technology advances and more complex structures are required. 

Further Details

Thermwood’s initial development machine, which is nearing completion, can make parts up to ten foot by ten foot by five foot high, is equipped with a 20HP, 1 ¾ inch diameter, 24-1 L/D extruder and support equipment capable of processing over 100 pounds of material per hour. Despite the relatively heavy weight of the extrusion system and head, which are both mounted on and move with the machine, the machine generates impressive performance with high acceleration rates and high feed rate capability. 

Ongoing Development

This is an ongoing research and development program and Thermwood Management cannot say when commercial systems might be available to the market, but they believe this technology represents a major opportunity and that “Additive Manufacturing” will become a significant factor in the future of manufacturing. Thermwood believes it is in a unique position to pursue this emerging technology since, at one time, it was a plastic processing company that operated large plastic extruders in a production environment. Thermwood is already a major manufacturer of the “Subtractive” machinery part of the equation and this same technology is the basis of the “Additive” equipment.

Thermwood also designs, builds and programs its own sophisticated CNC controls which it can tailor to any new requirements and also has experience developing sophisticated design and CAD/CAM software packages which are also an important part of this new technology.