Since 2009, when the main patent for portable 3D printers expired, 3D printing has exploded into an industry of its own. As a result, 3D printers are one of the defining products of our time.

Currently, 3D printers are being used to create nearly anything you can fathom —instruments, camera equipment, medical models, phone and personal technology accessories, home decor, toys and fashion, just to name a few things. Its applications are nearly endless. Theoretically, 3D printing can manufacture any solid object. While some limitations in technology prevent printing at certain sizes and with certain materials, research and development is advancing the capabilities quickly.

The most popular type of 3D printing is fused deposition modeling (FDM). Also referred to as fused filament fabrication, fused deposition modeling works by melting and extruding a spool of plastic filament through a nozzle as it moves up, down and across specified XYZ coordinates.

Creating a product using an FDM process looks something like this:

  • A 3D model is generated using CAD software.
  • The CAD model is exported as a stereolithography file (.stl format), then imported into slicing software.
  • The file is broken into layer slices, and specific tool paths are generated.
  • The design is sent to the printer.

Within minutes — or perhaps hours or days, depending on part size and complexity — the part is produced via additive manufacturing.

Creating Heat for 3D Printing

When it comes down to it, fused deposition modeling is all about the heat. 3D objects are fabricated via the melting, shaping and cooling of plastic.

A few key components create and manage heat within an FDM printer:

  • Extruder.
  • Print bed.
  • Layer-cooling fan.

A closer look at each will explain how they affect print outcome.

Extruder. The extruder is where most of the printer’s technology is located. It is composed of a cold end, which pulls filament through the system, and a hot end, which melts the filament as it is extruded.

Within the extruder’s hot end is the heating block. Typically, this is made of aluminum and is heated by a heater cartridge. The heating element melts the filament as it passes through the thermal tube and reaches the nozzle.

Also within the extruder is a heat-sink fan. This cooling element helps keep heat from entering parts of the extruder that need to stay at lower temperatures.

Another element of the extruder that is worth mentioning is the thermistor or thermocouple. This piece senses and helps regulate the temperature of the hot end.

Print Bed. The print bed is the surface on which filament is deposited in a specified shape during the printing process. Most print beds are heated to prevent the plastic from cooling too quickly and creating product warp. Print beds typically are kept somewhere between 122 and 212°F (50 and 100°C). The specific temperature requirement depends on what type of filament is used.

Some printers do not have heated beds. These machines are limited in the materials they can print with. Also, materials may not stick to these beds as well, and the fused parts are more likely to pop off mid-print.

Layer-Cooling Fan. The layer-cooling fan cools plastic after it leaves the nozzle. This element helps the product being created keep its shape as it is printed.

Keeping Heat in Check: Dealing with Heat-Related Problems

Because 3D printing is so dependent on heat, any temperature issues can easily disrupt the entire process. Common issues encountered in 3D printing include:

  • Heat creep.
  • Warping and bending.
  • Melted or deformed prints.
  • Cracks in the sides of taller prints.
  • Bowing or curving near the bottom of prints.
  • A blurry or undefined first layer.

Manufacturers may encounter such problems as a result of non-ideal temperatures.

3D printing

As 3D printing research and development continues, refined technology advances to offer even more precise control over higher temperatures, yielding high quality prints with difficult-to-work-with materials.

Heat Creep. Heat creep occurs when heat gets spread irregularly through the hot end of the extruder. This happens when the filament is cooled as it extrudes, and heat rises up the thermal-barrier tube. This will cause filament to heat and swell too soon and stick to the walls of the thermal-barrier tube. Heat creep can cause blockages that halt printing, and such blockages are difficult to clean out.

Polylactic Acid (PLA)

  • Extruder Temperature: 401°F ±27°F (205°C ±15°C)
  • Print-Bed Temperature: 104°F ±27°F (40°C ±15°C)

Acrylonitrile Butadiene Styrene (ABS)

  • Extruder Temperature: 446°F ±18°F (230°C ±10°C)
  • Print-Bed Temperature: 194°F ±27°F (90°C ±15°C)

Polyamide (Nylon)

  • Extruder Temperature: 491°F ±27°F (255°C ±15°C)
  • Print-Bed Temperature: 158°F ±27°F (70°C ±15°C)

Polyethylene Terephthalate (PET/PETG/PETT)

  • Extruder Temperature: 473°F ±18°F (245°C ±10°C)
  • Print-Bed Temperature: 140°F ±27°F (60°C ±15°C)

Acrylonitrile Styrene Acrylate (ASA)

  • Extruder Temperature: 482°F ±18°F (250°C ±10°C)
  • Print-Bed Temperature: 194°F ±18°F (90°C ±10°C)

Polypropylene (PP)

  • Extruder Temperature: 482°F ±18°F (250°C ±10°C)
  • Print-Bed Temperature: 230°F ±18°F (110°C ±10°C)

Thermoplastic Elastomer (TPE)

  • Extruder Temperature: 428°F ±18°F (220°C ±10°C)
  • Print-Bed Temperature: 86°F ±18°F (30°C ±10°C)

Thermoplastic Polyurethane (TPU)

  • Extruder Temperature: 482°F ±18°F (250°C ±10°C)
  • Print-Bed Temperature: 122°F ±18°F (50°C ±10°C)

Wood Filaments

  • Extruder Temperature: 428°F ± 54°F (220°C ±30°C)
  • Print-Bed Temperature: 86°F ±18°F (30°C ±10°C)

Polycarbonate

  • Extruder Temperature: 554°F ±36°F (290°C ±20°C)
  • Print-Bed Temperature: 266°F ±27°F (130°C ±15°C)

Polyvinyl Alcohol (PVA)

  • Extruder Temperature: 392°F ±18°F (200°C ±10°C)
  • Print-Bed Temperature: 104°F ±27°F (40°C ±15°C)

As a result, thermal-barrier tubes often are designed to help prevent heat creep. Notches or threads in the tube help keep heat from sneaking into spaces where it does not belong. Beyond that, there are a few preventive steps that can be taken to prevent heat creep. First, ceramic insulation tape should be added around the heater block. Second, when it is not printing, avoid leaving the printer heated. Third, avoid using low-end filament that can expand irregularly. Finally, if possible, always unload the filament when finished printing.

Warping and Bending. Product warp happens when plastic cools too quickly after extrusion. Because plastic shrinks a bit when it cools, fast cooling can cause the plastic to curve as it hardens.

Warping can be prevented by keeping the plastic just below melting temperatures on the print bed. If warping occurs, the print-bed temperature most likely needs to increased.

Melted or Deformed Print. When designs come out looking saggy, too much heat is to blame. FDM printing requires a fine balance between a temperature that provides good flow and a temperature that ensures quick solidification.

To correct melted-looking prints, adjust the temperature settings. First, make sure that the temperature is within the proper parameters for the material. Next, try reducing the nozzle temperature 9°F (5°C) at a time.

Cracks in the Sides of Taller Prints. Sometimes, when taller pieces are created in 3D printers, cracks can appear between some of the higher layers. This is because these layers are too far removed from the heat of the print bed. After extrusion, the filament cools too quickly and is not as adhesive as it should be. This causes small spaces, or cracks, to show up between layers.

To keep filament from cooling too quickly, try increasing the extruder temperature by about 18°F (10°C).

Bowing or Curving Near the Bottom. Bowing or curving near the base of printed objects occurs when the weight of the model presses down on bottom layers before they have adequately cooled.

Filaments

Filaments come in different colors and textures and offer effects ranging from glow-in-the-dark to the look and smell of wood.

This deformation of bottom layers is remedied by ensuring quicker cooling. This can be achieved by lowering the temperature of the print bed by 9°F (5°C) at a time until desired results are reached.

Blurry and Undefined First Layer. Sometimes, the first layer can come out blurry. When this happens, angles seem undefined, and the lines of filament look sloppy. This is usually because the print bed is too hot, and this causes the plastic to lose its shape.

The solution to this problem is probably pretty obvious. It may be necessary to reduce the temperature of the print bed 9°F (5°C) at a time until desired results are achieved.

Temperature Limitations of Materials

There are several options for filament. Filaments come in different colors, textures and offer effects, ranging from glow-in-the-dark to the look and smell of wood. An important part of mastering the use of these varying materials is understanding the specific temperature requirements for each material. Not paying attention to these parameters can lead to any of the temperature-related issues already mentioned.

Higher Temperatures Equal Greater Possibilities. When 3D printers can maintain higher temperatures during production, more filament options become available. However, operating at higher temperatures requires specific technology within the 3D printer.

For example, quite often, extruder hot ends are comprised of both metal and polyether ether ketone (PEEK) or polytetrafluoroethylene (PTFE). While PEEK and PTFE provide excellent insulation, they limit hot-end temperatures to no more than 464°F (240°C). When all-metal hot ends are used, however, temperatures can effectively be maintained over 572°F (300°C). This opens the door to utilizing a whole slew of different materials.

New developments in FDM technology are paving the way for even higher temperatures during 3D printing. Last year, one 3D printer manufacturer introduced a line of high temperature printer components that allow hot ends to reach temperatures above 752°F (400°C). The print beds on those same units can reach temperatures above 392°F (200°C).

As 3D printing research and development continues, refined technology continues to offer even more precise control over higher temperatures. These advances are yielding high quality prints with difficult-to-work-with materials. We are excited to see what the future holds for 3D printing. Who knows what materials we will be able to print with 10 or 20 years from now.