3D printing material: the main differences between PLA and PLA+

PLA is a polyester built from lactic acid. Standard grades print near 200–210 °C and give stiff, dimensionally stable parts with a glossy surface. The trade-off is brittleness: a thin wall or a snap-fit tab cracks rather than bends.

PLA+ is still PLA. Producers blend in impact modifiers, plasticizers or a small percentage of another polymer, then re-pelletize. The result keeps most of the stiffness but absorbs more energy before fracture. Print temperature usually moves up to roughly 210–230 °C, and bed temperature to 50–60 °C.

That reformulation is why a spool of PLA+ costs more. You are paying for the additive and the extra compounding step, not for a different plastic family.

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  PLAStiff, low odor, easy to print, cracks under impact
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  PLA+Same stiffness class, higher impact resistance, slightly wider print window
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  NeitherSuited to parts that sit in a hot car or take UV for years

Tensile strength numbers for PLA and PLA+ land in the same range, often 45–60 MPa. Tensile modulus is similar too. If your part only carries a static load, both grades behave almost the same way and the upgrade buys you little.

The gap shows up under impact and along layer lines. A notched Izod test on PLA typically returns a low value because the material has almost no yield before fracture. PLA+ blends raise that number noticeably, though exact figures vary by brand and by print orientation.

Layer adhesion improves as well, partly from the additives and partly from the higher nozzle temperature most PLA+ grades want. A part loaded perpendicular to the layer stack is where you feel it most.

Run PLA+ hotter than plain PLA. Start at 215 °C on the nozzle and 55 °C on the bed, then adjust in 5 °C steps. Cooling fan settings usually stay high, but dropping the fan a little on the first few layers helps bonding to the build plate.

Retraction and flow behave much like PLA, so existing profiles only need small edits. Stringing can appear if you push the temperature too far, and thicker layers reduce the toughness gain because there are fewer, coarser weld lines.

PLA+ also holds dimensional accuracy well, so it still works for fit-check fixtures, jigs and enclosure prototypes where a few tenths of a millimeter matter.

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  Nozzle215–230 °C for PLA+, 200–210 °C for standard PLA
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  Bed50–60 °C, with the fan reduced on early layers
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  Layers0.12–0.20 mm keeps weld lines dense

Choose PLA+ for brackets that get bumped, snap-fit covers, living hinges tested a few dozen cycles, and display models handled by people. The small price premium is cheaper than reprinting a cracked batch.

Stay with plain PLA for draft geometry, jigs that never see impact, and large cosmetic prints where surface finish matters more than toughness. The lower temperature also wastes less time on heat-up.

For anything that runs warm, takes sustained load or sees outdoor UV, neither grade is the right answer. PETG handles more impact and slightly higher heat. ABS or ASA handle heat and weather but need an enclosure. Nylon and polycarbonate cover structural parts. For load-bearing metal components, machining from 6061-T6 or 17-4PH removes the anisotropy problem entirely.

FDM parts are anisotropic. Strength along the extrusion direction can be several times the strength across layer boundaries, which makes design margins hard to predict. PLA+ narrows that gap but does not close it.

When a prototype moves toward a functional test rig or a production fixture, we usually machine the part instead. With 5-axis centers and tolerance held to ±0.005 mm, the result is isotropic and the surface finishes at Ra 0.8–1.6 μm straight off the machine.

A common workflow is to print the concept in PLA+, confirm the fit, then cut the working version from aluminum or stainless. Printers stay useful for handles, guards and cable routing where loads are low.