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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