PETG vs PLA for Functional Parts

Most 3D printing discussions default to PLA. It's the cheapest, easiest material to print with, and it works beautifully for decorative objects, display models and anything that lives at room temperature in a dry environment. But for functional parts — things that have to do something, be somewhere specific, or survive conditions that aren't controlled — PLA has serious limitations that people don't always appreciate until it fails.

PETG is our answer to this. We print exclusively in PETG at 3D Guru, and this guide explains why.

Heat resistance: where PLA falls short

PLA begins to soften at around 60°C. This sounds like it should be high enough, but in practice it catches people out regularly:

• A car dashboard on a sunny summer day can exceed 80°C
• An electronics enclosure housing a Raspberry Pi or similar can run at 50–65°C
• A bracket near a heating vent may regularly hit 55–70°C
• A windowsill in direct sun in summer can reach 60–70°C

In any of these situations, PLA parts don't suddenly shatter — they slowly deform. Brackets sag. Clips stop holding. Enclosures warp so lids no longer close. The failure is gradual and sometimes only noticed when the equipment it was holding falls off the wall.

PETG maintains its shape up to approximately 80°C continuous use. This doesn't make it suitable for everything — engine bays and direct heater applications can exceed this — but it covers the vast majority of real-world functional applications where PLA is marginal.

Impact resistance and toughness

PLA is somewhat brittle. When subjected to sharp impact, it tends to crack or shatter rather than deform. PETG is tougher — it has better impact resistance and a tendency to flex slightly under load rather than snap. For anything subject to knocks, drops, vibration or mechanical shock, PETG's toughness is a meaningful advantage.

This is particularly relevant for:

• Workshop jigs and fixtures handled repeatedly
• Automotive clips subject to vibration
• Parts in machinery with moving components nearby
• Anything likely to be dropped or mishandled

Moisture resistance

PLA absorbs moisture over time, which causes it to become brittle and can cause dimensional changes. In outdoor or humid environments, PLA parts can degrade surprisingly quickly — becoming chalky in texture and losing mechanical properties. PETG is significantly more moisture-resistant and holds its dimensions in damp conditions far better.

For parts that will live outdoors, in bathrooms, kitchens, garages or any other humid environment, PETG is the clear choice.

Chemical resistance

PETG has reasonable resistance to oils, greases and many common chemicals. PLA is susceptible to degradation from oils and can be attacked by alcohols. For workshop or automotive applications where the part might come into contact with cutting fluids, lubricants or cleaning agents, PETG holds up significantly better.

Layer adhesion

PETG has better inter-layer adhesion than PLA when printed correctly. This means a PETG part is stronger along the Z axis (perpendicular to the build plate) than a PLA part of equivalent geometry. For parts loaded in unusual orientations relative to their print direction, this improved adhesion is meaningful.

When is PLA the right choice?

PLA is excellent for:

• Decorative objects and display models
• Prototype geometry checks where function doesn't matter
• Objects in stable, room-temperature, dry environments
• Applications where the lowest possible cost matters more than durability

Summary comparison

Property	PLA	PETG
Heat resistance	~60°C	~80°C
Impact resistance	Moderate	Better
Moisture resistance	Poor	Good
Chemical resistance	Poor	Moderate
Print difficulty	Easy	Moderate
Suitable for vehicles	No	Usually yes

We've made the choice simple: everything we print at 3D Guru is PETG. If you need a functional part, that's the right material.