Most high-quality 3D printer filament manufacturers provide a technical data sheet for each of their filaments that contain some of the critical technical information about the material, including its mechanical properties, thermal properties, and electrical properties, to name a few. The technical data sheet gives designers the information they need when designing products; these include, material strength, flexibility, durability, and heat resistance. ZABFAB has created a guide to all of the most common properties of materials used in 3D printing. We provide overviews on the various properties, how the materials are tested to determine these property values, and how these values can be interpreted so you can make the best material selection. For more information on material brands, check out our 3D printing materials guide, our ZABFAB materials page, or contact us!
Tensile strength (or ultimate tensile strength) is defined as the capacity of a material or structure to withstand loads tending to elongate, per industry standard ASTM D638. Ultimate tensile strength is measured by the maximum stress that a material can withstand while being stretched or pulled before breaking. The higher the value (usually in PSI or MPa), the stronger the material. Carbon fiber and glass fiber reinforced composite materials offer much higher tensile strengths than regular 3D printer filaments, learn more about composite materials here.
Tensile Strength at Yield
Tensile strength at yield can be defined as the stress a filament can withstand without permanent deformation. The higher the yield strength, the stronger the material.
Tensile elongation is the stretching that a material undergoes as it is pulled in tension and is commonly expressed as a percentage. In other words, it is a ratio between increased length and initial length after breakage of the tested specimen at a controlled temperature. The higher the percentage value from the industry standard ASTM D638 test, the more flexible the material.
Tensile Modulus (Young’s Modulus)
Young’s modulus can be defined as the measurement of the stiffness of a solid filament. It defines the relationship between stress(force per unit area) and strain (proportional deformation) in a material in the linear elasticity regime of a uniaxial deformation. The higher the value of the Young’s modulus, the stiffer the material. Likewise, the lower the value, the more bendable the material.
Flexural strength can be defined as the extent to which an object or any material may resist breakage when bent, according to industry standard test, ASTM D 790. The higher the value, measured in PSI or MPa, the stronger the filament.
Flexural Modulus can be defined as a physical property denoting the ability for a material to bend. The higher the value, measured in PSI or MPa per industry standard ASTM D 790, the less bendable the material.
The impact strength of a 3D printer filament is typically measured using the Izod notched impact test per industry standard ASTM D256. The test measures the amount of energy lost per unit of specimen thickness at the notch. A higher value means that more energy was lost from the testing apparatus and absorbed by the material, and thus, a tougher and more durable material.
Hardness is a measurement of the resistance to localized plastic deformation induced by either mechanical indentation or abrasion. Typical tests include the Shore D hardness test ASTM D 785, which is typically used with rubbers or plastics, and the Rockwell R hardness test ASTM D 2240, which is generally used with metals. Higher numbers on the scale indicate a greater resistance to indentation and thus harder materials. Lower numbers indicate less resistance and softer materials.
Surface resistance is used to measure the electrical resistance of a material. Metals, generally have low resistance and are therefore used as conductors, whereas ESD materials resist the flow of electricity. The higher the value of the exponent, the higher the resistance.
The flammability rating is used to determines the material’s tendency to either extinguish or spread a flame once the specimen has been ignited. The value on the UL 94 scale typically begins with a V- and a digit (i.e. V-1); the lower the value of the digit, the less flammable the material.
Melt Flow Index
The melt flow index can be defined as the measurement of the mass of material that extrudes from a nozzle over a given period at a constant temperature, typically measured in grams/10 minutes, per ASTM D1238. The higher the weight of material pushed through the extruder at the end of the test, the easier the material flows when melted and the higher the melt flow index.
Density can be defined as ratio between mass and volume of a material, in other words, how much mass a material has per volumetric unit as measured per industry standard ASTM D792. The density of a material determines its weight and is therefore a critical property to consider when designing for an application in which weight is a critical factor. The denser a material is, the more it will weigh. A material with high strength and low density will have a high strength to weight ratio.
Heat Deflection Temperature
Heat deflection temperature (HDT) can be defined as the temperature at which a polymer or plastic sample deforms under a specified load per industry standard, ASTM D648. This is a critical property to consider because if the application requires a product to maintain its strength and structure while exposed to heat, then a heat resistant material is required. A higher HDT value will indicate a more heat resistant the material.
Glass Transition Temperature
Glass transition temperature can be defined as the gradual and reversible transition in amorphous materials, from a hard and relatively brittle “glassy” state into a viscous or rubbery state as the temperature is increased. This value will be higher than the HDT temperature and is also a critical value when evaluating the thermal properties of materials.
Coefficient of Thermal Expansion
The coefficient of thermal expansion is the amount to which a material changes in size as a result of a change in temperature. It is an important property to consider when 3D printing, as materials that are more prone to change in size when heated will exhibited higher residual stress and warpage. ABS, for instance, has a high thermal expansion coefficient of around 100 ppm/k and exhibits a high degree of warpage that must be managed through the product design and machine parameters. In contrast, the metal invar has the lowest coefficient of any metal at 1 ppm/k.