3-D printing parts manufacturing is definitely coming of age in a way that's highly disruptive to traditional manufacturing. Global expenditures from the recent February Inside 3D Printing Conference & Expo on desktop and industrial printers will grow from $12 billion in 2017 to $25 billion by 2022.

Rapidly maturing 3-D-printed parts are moving forward into end-use applications such as athletic shoes, car bodies and even rocket engine components. Manufacturers from across all industrial segments are expanding their 3-D printing programs based on new, high-speed process development, software advances and tailored materials improvement.

Stated simply, 3-D printing is now easier to implement on the manufacturing floor alongside traditional industrial processes in an increasingly cost-effective manner. Over the next 3-5 years it will cross the threshold from advanced to conventional and enter mainstream manufacturing. It will develop in parallel against a continuing back drop of increased custom, just-in-time end-use products.

Let's now take a closer look at seven key trends that currently define this disruptive 3-D printing environment.

1. 3-D printing is currently being used by roughly 66 percent, or two-thirds of all U.S. manufacturers, most frequently as a prototyping tool.

It has basically remained pretty steady over the past two to three years. However, some important shifts are underway. A greater number of manufacturers are using 3-D printing for starting point prototyping (33 percent), end-use part production (7 percent), or in both ways (14 percent), according to a review by the Plastics Institute of America (PIA). Simultaneously over the past two to three years fewer manufacturers (18 percent) are deciding how to use the technology versus tinkerers (30 percent).

2. High-volume manufacturing is strongly expected for 3-D printing.

A greater number of manufacturers (45 percent) versus two to three years back (39 percent) anticipate that in three to five years hence 3-D printing will be mainly used in high-volume part production. Most manufacturers (65 percent) still currently hold the belief that 3-D printing will center on low volume part production, with this metric being down from two to three years back (76 percent).

3. Manufacturers hold the belief that 3-D printing will focus more on aftermarket parts versus new, first time end uses.

Roughly half of all U.S. manufacturers (51 percent) will focus on aftermarket parts, down from two to three years back (60 percent).

4. The manufacturing of outdated or old parts will be an important priority for 3-D printing.

Over the next three to five years, manufacturers (66 percent) say 3-D printing will be used to make old, obsolete parts down from two to three years back (73 percent).

5. 3-D printing technology will be embraced in practice by a majority of U.S. manufacturers.

Currently manufacturers (65 percent), by PIA survey strongly hold that over the next three to five years half of all U.S. industrialists will integrate 3-D printing into their operations versus the case two to three years back (52 percent).

6. Part quality and lower cost remain barriers to 3-D printing acceptance.

Manufacturers (50 percent) rated part quality followed by lower part cost as their major concerns, and this remains unchanged at present.

7. Intellectual property and supply chain redesign remain the top two threats to 3-D printing use in manufacturing.

Both threats remain constant at 25 percent each. Other threats are now starting to emerge such as (1) lower need for 3-D printed part transport, (2) trained technologists availability and (3) redesigned and different customer relationships.

3-D printing plastic material selection grid. (Image: Stratasys).

Continuing, 3-D printing thermoplastics include such materials as acrylonitrile butadiene styrene (ABS), polycarbonate (PC) and Ultem polyetherimide (PEI). Fused deposition modeling (FDM) 3-D printing technology is primarily used with these resin systems.

These types of materials are generally considered engineering-grade materials, but in 3-D printing use can experience a 20-30 percent drop off in properties as compared to injection-molded parts due to inherent layer-to-layer adhesion strength weakness as parts become more complex. FDM type thermoplastics find broad use in prototype parts to specialized end-use applications in medical and aerospace.

Key properties for use here are good flexural modulus, tensile strength and impact resistance. Other base resin systems such as Nylon 12 and ASA (Acrylonitrile Styrene Acrylonitrile) also find property use in this regard.

Specialty compounded FDM materials include ABS ESD7 (electrostatic dissipative) to prevent static electricity build up on plastic part surfaces, PC-ISO (meets both International Standards Organization 10993-1 and USP Class VI standards) for biocompatible medical sterilization applications, ABS-M30i for medical, pharmaceutical and food packaging, and Ultem 9085 FST (flame, smoke, toxicity) certified thermoplastic for aerospace application development.

3-D printing industry FDM process schematic. (Image: Plastics Institute of America).

FDM is the most common form and industrially functional 3-D printing process, pioneered by equipment supplier Stratasys in the early 1990s. Stratasys still maintains a strong patent position in this technology. Entry-level FDM type competitive equipment suppliers have proliferated significantly since the 2008-2010 period using a similar to Stratasys type technology, commonly referred to as freeform fabrication (FFF), but market visible in a basic form due to the continuing strength of the existing Stratasys patents.

The basic FDM process starts by (1) melting a thermoplastic filament via a heated extrusion head, (2) depositing the heated filament a layer at a time onto an application build platform based on 3-D modeling data supplied to the printer extrusion head, and (3) allowing each layer to harden as it is placed down to maximize layer to layer bonding, that is in turn critical to maximizing finished product physical property performance.

The FDM and FFF processes generally need support structures for parts involving overhanging geometries. In FDM, a secondary water-soluble material allows these support structures to be easily washed away, whereas this remains a limitation in the more basic FFF process. As a rule of thumb, FDM produces more accurate finished parts versus FFF, with both these processes requiring extensive post processing steps.

3-D plastic filament spools. (Image: Plastics Institute of America).

Next, in terms of an advanced 3-D printing application example, let's take a look at what's developing with polyetheretherketone (PEEK). Solvay Specialty Polymer's 3-D printable KetaSpire PEEK compound grade has been specified for the Polimotor 2 engine's fuel intake runner part that uses reinforced, filament fusion, technology and is manufactured by Arevo Labs. The major outside advisor for the Polimotor 2 project is legendary engine designer Matti Holtzberg of Composite Castings LLC (West Palm Beach, Florida).

3-D printed KetaSpire KT-820 PEEK fuel intake runner. (Image: Solvay).

Intake runners are found in racing and street vehicles and are a transition part from the engine cylinder head and integrated into the plenum chamber. The intake runner injects gasoline in the air stream as it enters the engine and directly affects vehicle horsepower. Other PEEK features include:

  • 50 percent lower part weight versus original aluminum intake runner
  • 10 percent carbon fiber reinforced KetaSpire KT-820 PEEK used
  • excellent automotive fuel chemical resistance
  • mechanical toughness at 240 degrees C (464 degrees F) continuous use temperature
  • fuel intake runner temperature range of 150 degrees C (302 degrees F)
  • 3-D filament fusion process bonds successive layers into the complex finished shape
  • Digital CAD design eliminates mold cost and time to build
  • Software for 3-D printing process control optimizes desirable mechanical properties

3-D printing — although in its plastics industry end-use product infancy is a disruptive, technology driven innovation that will change the face of manufacturing in the coming years, provided additional plastic material development takes place. 3-D printing technology will change manufacturing by:

  • Minimizing or requiring no assembly
  • Making product variety and quantity free
  • Reducing with CAD files the skill in manufacturing
  • Lead time reduction or elimination
  • Design requirements being limited by one's imagination
  • In many cases portable and compact technology
  • Product complexity is free
  • Increased material choices

In 3-D printing, products are built layer by layer versus the use of a mold or machining from a larger material block. It dramatically decreases time from design to manufacturing, transfers power to designers, and generates products with radically new forms with less waste and at extremely lower cost compared to manufacturing as we perceive it today.

The growth of 3-D printing plastic materials is entering an important 3-5-year development phase where it is evolving from highly publicized prototypes and molds/tooling to end use industrial and consumer products.

3-D printing global market penetration. (Image: Plastics Institute of America).

In conclusion, 3-D printing plastic materials find their major use in prototyping parts, the manufacture of standard, straight forward fixtures and jigs, and have limited traditional end-use applications. More 3-D printing plastic material development is needed by major resin and specialty compound suppliers to expand the range of options available. In this regard, more partnerships between plastic material and 3D equipment suppliers needs to take place.

Potentially utilizing 3-D printing plastic prototypes as true emerging end-use application development routes will bring resin and 3-D equipment suppliers together. Further supply chain adaptation by both parties is the key.