The TPU (thermoplastic polyurethane) is a type of elastomeric material used in 3D printers to produce flexible and resilient objects.
A little further explanation is needed regarding the Shore scale. The Shore scale, used to measure the hardness of elastomeric materials like TPU (thermoplastic polyurethane), is an indication of the material's resistance to the penetration of an indentation point into a surface. In the context of 3D printing, the Shore scale is often used to describe the hardness or softness of TPU, and thus its elasticity.
Typically, TPU used in 3D printing has a hardness ranging from about 85A to 95A on the Shore A scale. A lower value indicates greater flexibility and softness, while a higher value indicates greater rigidity.
Technical and mechanical characteristics of TPU
Flexibility and Elasticity: TPU is known for its flexibility and elasticity, making it ideal for printing parts requiring a certain degree of deformability and restoration to their original shape. These properties make it suitable for producing gaskets, sheaths, protective gear, and other items that need to adapt to irregular surfaces or withstand mechanical stresses.
Strength and Durability: TPU also offers good impact resistance, making it suitable for producing components that must withstand mechanical stresses without breaking or deforming excessively.
Transparency: TPU is available in various transparency options and can be easily colored with pigments to achieve a desired range of colors.
Ease of Printing: Despite its elastomeric nature, TPU can be successfully printed with many 3D printers. However, it requires some adjustments to settings compared to rigid materials like PLA or ABS. For example, you need to use an extruder and hotend capable of handling lower temperatures, generally between 200°C and 230°C. Additionally, it's advisable to use a flexible print surface or adhesive coatings to improve material adhesion to the print bed.
Density and Infill: Due to its elastomeric nature, TPU tends to deform more easily than rigid materials during printing. Therefore, it's recommended to use a higher infill density (e.g., over 20-30%) to achieve greater structural stability.
Chemical Resistance: Generally, TPU can offer good chemical resistance in many applications, but it's important to consider the specific requirements of the application and the chemicals involved to ensure optimal performance and durability over time.
Printing Tips for TPU
Nozzle Temperature: The nozzle temperature should typically be between 220°C and 250°C. This range allows the TPU to melt properly and flow through the nozzle without risking clogs or other temperature-related issues.
Heated Bed Temperature: Although TPU can be printed without a heated bed, many users prefer to use one to improve material adhesion to the print bed and prevent warping. If using a heated bed, the temperature should generally be set between 40°C and 60°C. This helps maintain the material's temperature during printing and reduces the risk of deformations.
Printing Speed: The printing speed of TPU should be set to relatively low values compared to other materials like PLA or ABS. A printing speed between 20 mm/s and 40 mm/s is commonly recommended to ensure good print quality and reduce the risk of issues like stringing.
Cooling: During TPU printing, it's important to monitor the printer's cooling system to avoid excessive cooling of the material during extrusion. Excessive cooling can cause layer adhesion issues and deformations of the printed model. In some cases, it may be necessary to completely deactivate the cooling system to achieve better results.
Post-Processing: After printing, it's important to let the model cool completely before removing it from the print bed, as TPU can be more prone to deformations if handled prematurely. Once removed, the printed model may require some post-processing to remove any strings or filaments and to refine the surfaces if necessary.
It's important to note that the hardness measured on the Shore scale is just one of many factors influencing the properties of printed TPU. Other factors, such as the material's chemical composition, printing conditions, and model design, can significantly affect the performance and characteristics of printed TPU. Therefore, it's advisable to conduct tests and experiments to determine the best combination of printing parameters and TPU type to meet the specific requirements of the application.
Suggested brands
TPU is one of those materials that is relatively challenging to print and produce. The quality of raw materials, precision in diameter, and spool winding are crucial for achieving excellent results. That's why my recommendation always falls on ColorFabb or Fiberlogy filaments sold by Prusa Research.
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