University of Pittsburgh Awarded Grant to Improve 3D Printing of Tungsten Carbide

Carbide Parts provided by General Carbide Corporation (photo chredit University of Pittsburgh)

My alma mater in home town Pittsburgh continues its research in additive manufacturing. One of its latest projects involves evaluating the effectiveness of binder jet 3D printing technology to produce robust tungsten carbide parts. Researchers hope that binder jet-based 3D printing will overcome a challenge often encountered in fusing layers by “energy beam-based 3D metal printing” which can cause part failure due to rapid heating and cooling.

Pitt’s industry partner is General Carbide which is located in Pennsylvania. While the partners don’t specifically identify the 3D printer being used, researchers can be seen gathering around an ExOne (headquartered close to Pittsburgh) printer, so that would be a logical choice. Good luck Panthers.

3D Printing (Additive Manufacturing) is a Family of Technologies

When we talk about 3D printing, it is a catch-all phrase that encompasses several distinct technologies, each with its own strengths.  Here are some comparisons of additive manufacturing options in plastic, metal and composites:

3D Printed Plastics

Fused Deposition Modeling (FDM)

Learn more about FDM

Standard Materials: ABS

Relative Cost: ★★☆☆☆

Machine Finish: ★★☆☆☆

ABS Prime Finish: ★★★★★

Typical Lead Time:  2-5 Business Days

Specialty Materials: PC, nylon, ULTEM and many more (See FDM page)

Relative Cost: ★★★★☆

Machine Finish: ★★☆☆☆

Typical Lead Time: 3-7 Business Days

FDM Pros: Very high accuracy on large parts, diverse materials, rigid and tough, fast turnaround, sparse fill for light weight with high part volumes

FDM Cons: Striated machine finish, low resolution on features under 0.030"

Polyjet (Objet) Printing

Learn more about Polyjet

Standard Materials: Acrylic and polypropylene-like

Relative Cost: ★★★☆☆

Machine Finish: ★★★★★

Typical Lead Time:  2-5 Business Days

Specialty Materials: ABS-like, various elastomers and digital materials (See Polyjet Page)

Relative Cost: ★★★★☆

Machine Finish: ★★★★★

Typical Lead Time: 3-7 Business Days

Polyjet Pros: Top quality detail, best surface finish, clear material option, embedded textures, fine features, single piece mechanical assemblies

Polyjet Cons: Resins - not industrial thermoplastics, lower heat resistance, better for smaller parts

Selective Laser SIntering (SLS)

Learn more about SLS

Standard Materials: Nylon and glass filled nylon

Relative Cost*: ★★★☆☆

Machine Finish: ★★★☆☆

Typical Lead Time:  5-10 Business Days

Specialty Materials: Rubber (TPU), carbon filled nylon and other composites (See SLS page)

Relative Cost: ★★★★☆

Machine Finish: ★★★☆☆

Typical Lead Time: 5-10 Business Days

SLS Pros: Real thermoplastic and thermoplastic composites, uniform matte finish, great thermal and mechanical properties

SLS Cons: Large and thick parts can warp, longer production lead times, porous material, low resolution on features under 0.030"

*In volume SLS can become one of the least expensive printing processes.

Large Format 3D Printing

Learn More about Large Format 3D Printing

Standard Materials: Epoxy infused Acrylic

Relative Cost*: ★★★☆☆

Machine Finish: ★★★☆☆

Typical Lead Time:  5-10 Business Days

Specialty Materials: Sand (Sand Casting), Low Ash Burnout Resin (Investment Casting)

Relative Cost: ★★★☆☆

Machine Finish: ★★★☆☆

Typical Lead Time: 5-10 Business Days

Large Format Pros: Largest build size of any 3D printers, cost effective for large parts, casting patterns and molds without any additional tooling

Large Format Cons: Not as durable as SLS or FDM, not intended for small objects, longer production lead times compared to smaller printers

3D Printed Metals

Note: 3D printed metals tend to be 5 to 10 times the cost of 3D printed plastics and are often more expensive than machined metals.

Direct Metal Laser Sintering (DMLS)

Learn more about DMLS

Standard Materials: Aluminum, stainless steel, tool steel and titanium

Relative Cost: ★★★★★

Machine Finish: ★★☆☆☆

Typical Lead Time:  5-15 Business Days

Specialty Materials: Cobalt chrome, inconel, (nickel alloy) and more (See DMLS page)

Relative Cost: ★★★★★

Machine Finish: ★★★☆☆

Typical Lead Time: 5-15 Business Days

DMLS Pros: Stronger than cast parts, works with exotic and expensive to machine metals, can make parts that are otherwise not manufacturable

DMLS Cons: Limited part size (generally under 10"), rough finish, lower tolerance than machining, generally more expensive than machining

Printed Metal

Learn more about Printed Metal

Standard Materials: Stainless steel bronze alloy

Relative Cost: ★★★★☆

Machine Finish: ★★☆☆☆

Typical Lead Time:  10-20 Business Days

Specialty Materials: None

Relative Cost: N/A

Machine Finish: N/A

Typical Lead Time: N/A

Printed Metal Pros: Half to a third the cost of typical DMLS parts, beautiful bronze polish look, easily plated, larger bed than DMLS

Printed Metal Cons: Single available material, low strength to weight ratio for metal, long lead time relative to other 3D technologies

3D Printed Composites

Colorjet Full Color Composite

Learn more about Colorjet

Standard Materials: Full color composite

Relative Cost: ★☆☆☆☆

Machine Finish: ★★★☆☆

Typical Lead Time:  2-5 Business Days

Specialty Materials: None

Relative Cost: N/A

Machine Finish: N/A

Typical Lead Time: N/A

Full Color Composite Pros: Full gradient of 390,000 colors, generally least expensive material, fastest way to make large models, very rigid

Full Color Composite Cons: Features thinner than 0.100" can be brittle, does not have the flex of real plastic

What's the Difference Between Selective Laser Sintering (SLS) and Selective Laser Melting (SLM)

Samples of metal printed parts

What's the difference between Selective Laser Sintering (SLS) and Selective Laser Melting (SLM)?  Here's one of the better descriptions I've found that explains it:

"Selective Laser Sintering and Direct Metal Laser Sintering are essentially the same thing, with SLS used to refer to the process as applied to a variety of materials—plastics, glass, ceramics—whereas DMLS refers to the process as applied to metal alloys. But what sets sintering apart from melting or "Cusing" is that the sintering processes do not fully melt the powder, but heat it to the point that the powder can fuse together on a molecular level. And with sintering, the porosity of the material can be controlled.

Selective Laser Melting, on the other hand, can do the same as sintering--and go one further, by using the laser to achieve a full melt. Meaning the powder is not merely fused together, but is actually melted into a homogenous part. That makes melting the way to go for a monomaterial, as there's just one melting point, not the variety you'd find in an alloy. To nutshell it, if you're working with an alloy of some sort, you'll go SLS or DMLS; if you're working with say, pure titanium, you'll go with SLM."

So in lay terms, SLM is stronger because it has fewer or no voids which helps prevent part failure but is only feasible when using with a single metal powder.

RapidMade works extensively with SLS and DMLS processes.  To learn more, click here or contact us.

Original release: http://www.eurekalert.org/pub_releases/2014-06/dlnl-lrd061614.php

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"Cool" Ultrasonic Additive Manufacturing "Foils" Its Competition.

Photo Credit: Plant Services/Fabrisonic

Additive manufacturing technologies are evolving at such a rapid pace that it sometimes feels like a full-time job keeping up with new innovations.  Recognizing that each 3D printing process has its own strengths, weaknesses and applications, practitioners and researchers alike are inventing alternative methods "to get the job done."  Ultrasonic Additive Manufacturing (UAM) is one of the more recent technologies to be adopted.  The following is an excerpt from an article in Plant Services that describes UAM in greater detail...

"One of the newest alternatives to conventional metals and thermoplastics printing is the Ultrasonic Additive Manufacturing (UAM) process. Developed by Fabrisonic, this process takes thin metal foils on the order of 6 to 10 thousandths of an inch thick and typically 1 inch wide, and ultrasonically welds those together in a brick-laying pattern to build up a near-net-shape item.

" 'All of our machines are actually 3-axis CNC mills," says Mark Norfolk, President at Fabrisonic, "so we use the additive piece to get near-net shape, and the subtractive piece to get the exact-fit finished tolerance that you need out of the part. We’re welding with ultrasound, which is unique to our process and which happens essentially at room temperature, so we don’t have to worry about a lot of metallurgical interactions.' "

"The solid-state nature of the final printed product is a key advantage of the UAM process, as it bonds dissimilar metals without creating brittle inter-metallics (see Figure 2), and enables the embedding of electronic components including microprocessors, sensors, and telemetry into solid metal parts."

" 'For example, in aluminums, we see peak temperatures in the range of 200 °F, so we’re not changing the metal at all," says Norfolk. "We can also combine dissimilar materials since we’re doing this at so low a temperature. Taking ultrasound and vibrating the metals back and forth and essentially scrubbing off the oxide layer, with a little bit of temperature and a little bit of pressure, we get a solid-state metallurgical bond.' "

Selective Inhibition Sintering Seen as Affordable Metal Printing Technology

Wrench printed by SIS (Photo Credit:  3DPrint.com)

Many consider the affordable 3D printing of metal to be a breakthrough that would allow greater adoption of additive manufacturing for end-use parts.  According to 3Dprint.com, researchers at the University of Southern California are working on a novel approach to that end:  Selective Inhibition Sintering (SIS) which inhibits powder from melting, instead using it a mold:

"Using this new technique, a machine first lays down a layer of metal powder on a print bed. At this point a commercial piezoelectric printhead deposits a liquid solution which acts an an inhibitor, preventing the metal that it is sprayed upon from melting once it’s heated. The printhead, which is similar to that found in an inkjet printer, only sprays in an area which represents the boundary of the actual print. Where this solution is sprayed, the metal clumps together and hardens.  Layer by layer, more metal powder is deposited, and more of the inhibiting agent is sprayed onto the print bed. The boundary of the object slowly is built up, with metal powder inside.  It basically becomes a mold filled with pristine metal powder. When complete the entire print is then melted at a high temperature, leaving behind a solid object encased inside the inhibitor shell, which is then easily removed."

SIS is being touted as an affordable alternative to other metal printing processes because:

• It relies on printhead technology which is seen as cheaper
• It builds only the boundary of an object and is therefore faster.
• Unused powder can still be reclaimed since the inhibitor is made from sucrose which can be dissolved in water.

While not yet perfected - part shrinkage and inhibitor application problems have occurred - researchers are encouraged by their preliminary results. 

Is Additive Manufacturing Another Gold Rush?

Sometimes the frenzy around 3D printing reminds me of  the Gold Rush... Additive manufacturing (AM) has a lot of value in and of itself, but, like the Gold rush, it is also having a transformative impact on its environment.  

Consider these similarities:

Challenges over land claims surfaced during the Gold Rush which prompted the establishment of property rights.  Many would argue that similar problems will arise from 3D printing's impact on intellectual property and patents.

Once the gold that was easiest to retrieve was gone, The Gold Rush encouraged technological innovation that enabled miners to extract more of the precious metal from the riverbeds and ground.  Almost daily, we read about advancements in AM - both in material applications and printing processes which in some cases are creating precious metals.

As the Gold Rush continued, only larger organized enterprises remained profitable.  While we are not there yet, we've seen a fair number of mergers and acquisitions for a relatively young industry.

Secondary industries fared well, if not better, than the miners themselves.  Merchants, shippers, lodgers and entertainers thrived when most miners failed to make money.  Today, an increasing number of 3D printing supplies, trade shows, conferences, publications, certifications, and courses are being offered.

San Francisco and California grew significantly from the influx of 49ers  The establishment of AM Centers of Excellence in Youngstown and Detroit may well reverse the population loss of the Rust Belt region. 

The Gold Rush spurred an economic boom.  Many industry experts and government officials believe AM will boost the U.S. economy by bringing back manufacturing. 

Let's just hope that we don't see some of the problems (environmental damage, human rights issues) the Gold Rush created.