Finding the right material for your specific 3D printed part requires the balance between several important factors. In this guide, we share with you some fundamental of material properties for choosing the right material for your design.
Our goal is to communicate these simple concepts to you without making it a graduate level engineering course.
Let’s check them out
Fundamentals
Elastic Modulus – How Stiff Is The Part?
Elastic modulus is the material’s strength to combat elastic deformation under stress load. Flexural modulus simply measures the material’s tendency to bend.
High flexural modulus often describes materials like metal, diamond and other hard things.
Low flexural modulus describes elastic materials like rubber and plastics.
Share modulus describes the materials physical properties to share stress like cutting
Elongation – Ability To Stretch & Bend
Elongation describes the material’s strength to survive stretch before breaking
Things that typically crack or break right away after getting bend are brittle materials. They feature low elongation material properties such as glass, brittle plastics, ceramics.
Ductile materials can stretch several times before breaking, such as rubber band, daily consumer grade plastics, polypropylene thermoplastic polymer and others.
Impact Strength – Absorb & Divert Impact Force?
The material’s impact strength combat shock and impact force before breaking.
Impact strength also called toughness. A high toughness material like nylon or polycarbonate, 7074 T6 aluminum can absorb energy and plastically deform before it cracks or fractures. So if you drop it, it will not break.
Tensile Strength – Break Under Tension?
Tensile strength is similar to elongation but it describes the maximum stress a material can withstand while being pulled apart.
High tensile strength materials include carbon, glass and steel.
When the material reaches its ultimate tensile strength, any brittle material will break sharply without any deformation or stretch marks.
Ductile material will stretch and deform a little before breaking.
Heat Deflection Temperature – Temperature Sensitive?
Heat deflection temperature describes the material’s deformation properties under a specific load. Yes temperature does affect everything else a particular material experiences.
Most deformation is measured in MPa in Celsius.
For parts that are designed to withstand heat such as hot gases or liquid, for example, a injection mold, a gas valve, gas nozzle and many other similar components.
Creep – Long-Term Stress Deformation?
Creep describes a material’s tendency to slowly deform over a long period of time under stress. Anything that hangs weight, anything that goes through constant stress, vehicle parts….
Creep is based on time, stress and temperature. So everything we have covered above will contribute to the creep physical property.
High creep material is more likely to deform than material with low creep. When choosing a durable part for prototyping, a low creep material is a choice so the tested part can withstand high stress, temperature and maintain its shape over time.
Real-World Examples
Aircraft wing
Aircraft wing flexes during flight to handle all types of forces acting on the surface of the wing.
It can withstand shear, bend, twist, expand and still fly safely.
Turbine blade
Fan blades go through high RPM usage, which exerts a multiaxial state of stress and strain. Fan blade fatigue off aircraft engine blades is a common reason for aircraft engines to be serviced for aviation safety.
Key Takeaways
A material can:
- Bend
- Stretch
- Crack
- Deform
A strong material designed within the expected operating perimeters can withstand all the accounted forces
