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DESIGN FOR MANUFACTURING (DFM) GUIDE

Understanding Material Strength

"Strong" can mean many things. This guide explains the key types of material strength to help you select a material that won't fail when it matters most.

The Language of Strength: Key Metrics

Engineers use specific, standardized tests to measure how a material behaves under different types of load. Understanding these terms is key to reading a material datasheet.

Tensile Strength

This is the most common measure of strength. It is the maximum stress a material can withstand while being stretched or pulled apart before it starts to permanently deform (yield strength) or breaks (ultimate tensile strength). A material with high tensile strength is strong and resists stretching.

Flexural Strength & Modulus

**Flexural Strength** is the ability of a material to resist bending or breaking under a flexural (bending) load. **Flexural Modulus** is a measure of the material's stiffness or rigidity in bending. A high flexural modulus means the material is very stiff and will not bend easily.

Impact Strength (Toughness)

This measures a material's ability to absorb a sudden shock or impact without fracturing. It is often measured with an Izod or Charpy impact test. A material with high impact strength is considered "tough." Note that very strong, stiff materials are often not very tough (they can be brittle).

Comparing Common Materials

Strong Plastics

For applications requiring high strength from a plastic material, consider these options:

  • PEEK: One of the strongest thermoplastics, with excellent strength retention at high temperatures.
  • Ultem™ (PEI): Offers very high stiffness and tensile strength, often used as a metal replacement.
  • Carbon-Fiber-Filled Nylon: Adding carbon fibers to Nylon dramatically increases its strength and stiffness, making it suitable for structural components.
  • Polycarbonate (PC): Known for its exceptional impact strength (toughness) rather than tensile strength.
The housing for a robotic gearbox, an application requiring high-strength plastics or metals

Strong Metals

For the highest strength applications, metals are the clear choice.

  • Steel (Alloy & Stainless): Offers very high tensile strength and durability. Grades like 4140 Alloy Steel or 17-4 PH Stainless Steel are exceptionally strong.
  • Titanium (Ti6Al4V): Provides the best strength-to-weight ratio, making it ideal for aerospace and medical implants where high strength and low weight are critical.
  • Aluminum (7075): A very high-strength aluminum alloy, significantly stronger than the more common 6061 grade. Often used for high-stress structural and aerospace components.
A high-performance aerospace arm machined from strong and lightweight titanium

Material Strength FAQ

Is a "strong" material also "tough"?

Not necessarily. These terms mean different things in engineering. A very strong and stiff material (like ceramic or glass) may have very low toughness, meaning it will shatter under a sudden impact. A tougher material (like polycarbonate or rubber) can absorb that impact energy by deforming without breaking. Often, there is a trade-off between strength and toughness.

How does temperature affect strength?

For most plastics, strength and stiffness decrease as temperature increases. For metals, this effect is much less pronounced until very high temperatures are reached. If your part will operate at elevated temperatures, it's critical to look at the material's properties at that specific temperature.

How do I know if a material is strong enough for my application?

The best way is to use Finite Element Analysis (FEA) simulation software. FEA allows you to apply virtual loads to your 3D CAD model and see how the part will stress and deform. This helps you identify high-stress areas and verify that your chosen material's yield strength will not be exceeded.