In 3D printing, why do a PLA toy and an ABS automotive part have drastically different lifespans? The answer lies in the hardness of material for 3D printing—a key property that determines a part’s ability to resist scratches, deformation, and wear. Choosing a material with the wrong hardness can lead to premature part failure, whether it’s a brittle PLA prototype or an over-hardened metal component that cracks under stress. This article breaks down the hardness characteristics of common 3D printing materials, how to measure hardness, real-world applications, and selection tips, helping you match material hardness to your project’s needs.
What Is Hardness in 3D Printing Materials?
Hardness of material for 3D printing refers to a material’s ability to resist permanent deformation (like dents or scratches) when exposed to external pressure or force. It directly impacts three critical part performance factors:
- Wear Resistance: Harder materials (e.g., stainless steel) resist wear from friction, making them ideal for moving parts like gears.
- Impact Resistance: Balanced hardness (not too hard, not too soft) helps parts absorb impacts—for example, ABS’s moderate hardness prevents it from shattering like brittle PLA.
- Service Life: Materials with appropriate hardness last longer in their intended use—stainless steel medical implants (high hardness) outlast PLA prototypes by years.
Think of hardness as a “protective shield”: a harder shield (e.g., titanium alloy) defends against scratches and pressure, while a softer shield (e.g., PLA) is more flexible but less durable.
How to Measure the Hardness of 3D Printing Materials
Hardness isn’t a one-size-fits-all metric—different materials use different testing methods. Below are the three most common measurement standards, along with how they apply to 3D printing materials:
| Measurement Method | How It Works | Ideal for Materials | Example Values for Common 3D Materials |
| Shore Hardness (A/D) | Uses a durometer to measure indentation depth under a fixed load; Shore A for soft materials, Shore D for hard plastics. | Plastics (PLA, ABS, PETG) | – PLA: Shore D 50–60 – ABS: Shore D 70–80 – PETG: Shore D 65–75 |
| Rockwell Hardness (HRC) | Measures the depth of indentation from a diamond or steel ball under two loads; focuses on metal hardness. | Metals (stainless steel, titanium alloy) | – Stainless Steel: HRC 25–30 – Titanium Alloy: HRC 30–35 |
| Vickers Hardness (HV) | Uses a diamond pyramid indenter to create a square indentation; calculates hardness from indentation size. | Composite materials (carbon fiber reinforced nylon) and metals | – Carbon Fiber Reinforced Nylon: HV 120–150 – Titanium Alloy: HV 300–350 |
Hardness Characteristics of Common 3D Printing Materials
Not all 3D printing materials have the same hardness—each is engineered for specific uses. The table below details the hardness, key properties, and ideal applications of 6 popular materials:
| Material Type | Hardness (Common Measurement) | Key Properties Related to Hardness | Ideal Applications |
| PLA (Polylactic Acid) | Shore D 50–60 | – Lowest hardness among common plastics – Brittle (breaks under high impact) – Biodegradable, odorless | – Prototypes (e.g., toy models, display props) – Indoor decorative parts (e.g., plant pots) – Non-functional parts (e.g., 3D printed art) |
| ABS (Acrylonitrile-Butadiene-Styrene) | Shore D 70–80 | – Moderate hardness – High toughness (resists impact without breaking) – Good dimensional stability | – Automotive parts (e.g., interior trim, dashboard brackets) – Home appliance shells (e.g., small fan casings) – Functional prototypes (e.g., tool handles) |
| PETG (Polyethylene Terephthalate Copolymer) | Shore D 65–75 | – Balanced hardness (between PLA and ABS) – High impact resistance – Chemical-resistant (resists oils/solvents) | – Food-contact parts (e.g., clear containers) – Outdoor small parts (e.g., garden light covers) – Structural components (e.g., drone frames) |
| Stainless Steel | HRC 25–30 / HV 200–250 | – High hardness – Excellent corrosion resistance – High strength (supports heavy loads) | – Aerospace components (e.g., small engine parts) – Medical devices (e.g., surgical instrument tips) – Industrial tools (e.g., wear-resistant nozzles) |
| Titanium Alloy | HRC 30–35 / HV 300–350 | – Ultra-high hardness – Lightweight (1/2 the weight of steel) – Biocompatible (safe for human implantation) | – Medical implants (e.g., artificial hip joints, dental crowns) – Aerospace parts (e.g., aircraft wing brackets) – High-performance sports equipment (e.g., bike frames) |
| Carbon Fiber Reinforced Nylon | HV 120–150 / Shore D 80–85 | – High hardness (harder than most plastics) – High strength-to-weight ratio – Resists warping | – Automotive structural parts (e.g., suspension components) – Sports gear (e.g., tennis racket frames) – Industrial machinery parts (e.g., gear wheels) |
Real-World Cases: Matching Hardness to Application
Choosing the right hardness avoids costly mistakes. Here are 3 practical cases showing how hardness impacts part performance:
1. Case 1: PLA for Indoor Prototypes
- Problem: A designer needs a 3D printed prototype of a new phone case to test fit. Using a hard material like ABS would be overkill and more expensive.
- Solution: PLA (Shore D 50–60) is soft enough to print quickly and cheaply, yet rigid enough to show the phone case’s shape. The prototype works for fit testing and costs 50% less than an ABS version.
- Result: The designer iterates 3 times on the PLA prototype before finalizing the design, saving time and material costs.
2. Case 2: Stainless Steel for Medical Tools
- Problem: A medical device firm needs 3D printed surgical instrument tips that resist wear from repeated use and sterilization. Soft plastics like PETG would scratch and degrade quickly.
- Solution: Stainless steel (HRC 25–30) has high hardness and corrosion resistance. The instrument tips withstand 100+ autoclave sterilization cycles and show no visible wear after 6 months of use.
- Impact: The firm reduces tool replacement costs by 70% compared to plastic instruments.
3. Case 3: Carbon Fiber Reinforced Nylon for Drone Frames
- Problem: A drone maker uses ABS for frames, but the frames crack under hard landings—ABS’s moderate hardness isn’t enough for the impact.
- Solution: Switch to carbon fiber reinforced nylon (HV 120–150). Its higher hardness and toughness absorb impact energy, and the frames survive 10+ hard landings (vs. 2–3 for ABS).
- Outcome: The drone’s failure rate drops from 15% to 2%, improving customer satisfaction.
How to Choose the Right Hardness for Your 3D Printing Project
Follow this 4-step process to match material hardness to your needs:
- Define Your Part’s Purpose:
- Ask: Will the part be functional (e.g., a gear) or decorative (e.g., a figurine)? Functional parts need higher hardness; decorative parts can use softer materials.
- Identify Environmental Stressors:
- List forces the part will face: friction (needs high hardness), impact (needs balanced hardness), or corrosion (needs hard, corrosion-resistant materials like stainless steel).
- Check Hardness Data:
- Use the table in the previous section to narrow down materials. For example:
- Indoor prototype → PLA (Shore D 50–60).
- Medical implant → Titanium alloy (HRC 30–35).
- Test with Small Samples:
- Print a small test piece (e.g., a 2cm×2cm cube) of your chosen material. Test its hardness with a durometer (for plastics) or hardness tester (for metals) to confirm it meets your needs.
Yigu Technology’s Perspective
At Yigu Technology, we see the hardness of material for 3D printing as a critical yet often overlooked factor in part performance. Our 3D printers are optimized to enhance material hardness: our FDM printers (YG-FDM 800) use precise temperature control to boost ABS’s Shore D hardness by 5–10%, while our metal 3D printers (YG-Metal 500) ensure stainless steel parts reach HRC 30 for maximum wear resistance. We also provide free hardness testing for clients, helping them confirm material suitability before full production. As new materials emerge (e.g., ultra-hard ceramic composites), we’ll keep updating our systems to unlock their full hardness potential.
FAQ
- Q: Can I increase the hardness of a 3D printed part after printing?
A: Yes! For plastics: Post-cure resin parts with UV light (boosts Shore D hardness by 5–10%); coat PLA/ABS parts with epoxy (adds a hard, scratch-resistant layer). For metals: Heat-treat stainless steel parts (annealing at 800°C increases HRC by 3–5).
- Q: Is a harder material always better for 3D printing?
A: No. Overly hard materials (e.g., titanium alloy for a simple prototype) are more expensive and harder to print. Soft materials (e.g., PLA for decorative parts) are cheaper and more flexible—choose based on your part’s use, not just hardness.
- Q: How do I measure the hardness of my 3D printed part at home?
A: For plastics: Use a handheld Shore D durometer (costs \(50–\)100) — press it against the part’s flat surface and read the value. For metals: You’ll need a professional Rockwell tester (often available at local engineering labs for a small fee).