How tensile strength relates to 3D printing

Whether prototyping or producing final parts, the ability of a part to bend or hold firm depends on the chosen material’s tensile strength.

A fundamental property of many materials, tensile strength, is an indicator of what a material might do under or supporting a load. On a material data sheet, you will often find this information at the top as one of the first listed features. Also on a data sheet, you will see this information represented with a stress/strain curve.

Information about whether a material will bend or hold a load is only one factor to consider when choosing a material for 3D printing. A material’s toughness is also important in combination with tensile strength. For example, hardened glass has a tensile strength of 175 MPa and 3003 Aluminum has a tensile strength 110 MPa. Now, which one would you use to print a socket wrench? In this case, examining the toughness in addition to the tensile strength will give you a better choice.

Metal materials are assumed to have high tensile strengths. Polymers and other plastics may require some research, especially for desktop 3D printers. Plus, there are a number of variations of polymers for 3D printing specific to a 3D printer model that can offer tensile strength higher than that used for traditional injection-molding.

Some of the more commonly used polymer materials for 3D printing and their tensile strengths:

ABS, 33MPa, 4,700 psi
Nylon, 48MPa, 7000 psi
PLA, 50MPa, 7250 psi
PC, 68MPa, 9800 psi
PEI, 81MPa, 11,735 psi

Other popular materials include:
–ASA (Acrylonitrile styrene acrylate) —an alternative to ABS but with better weather resistance. It is widely used in the automotive industry.
–PPSF/PPSU (polyphenylsulfone), a material that offers good mechanical performance with high temperature and chemical resistance.

ABS is used in a variety of objects. This engineering-grade material can be sanded, finished, and painted. It is often chosen for 3D printing as it suits the need for end-use parts.

A number of nylon materials are available. Thus, most general tensile strength numbers for this material are estimated. For example, Nylon 910 is estimated to have a tensile strength of 7000 psi, but there is also Nylon 6 and Nylon 12 at more than 10,000 psi. Check vendors data sheets to get more information.

PLA (polylactic acid), with its tensile strength of 7250 psi, is considered a strong material but it will degrade when exposed to light. While often used in 3D printing applications, it is not recommended for load bearing designs.

PC (polycarbonate) is strong and heat resistant. When 3D printing with it, it is recommended that the bed be heated to 145 degrees Celsius or higher. The print heat should be at 290 degrees Celsius or higher. This material is best printed in an enclosure to avoid warping. This material also has a high glass transition temperature.

PEI is polyetherimide resin and more commonly known as Ultem. SABIC developed a family of PEI products after it acquired the General Electric plastics division in 2007. Ultem is known for its high tensile strength and its ability to handle high temperatures.

There are hundreds of materials suitable for 3D printing. It’s best to check with the 3D printing vendor or the material developer to find the right material for your 3D printing needs.

Part orientation plays a role in tensile strength. Parts built in the Z direction may exhibit less strength than parts build in the X and Y directions.