You printed the bracket in PLA, it snapped, so you bought a spool of PLA+ and printed it again. It failed in the same place, in the same way, in about the same time. That is not a bad spool and it is not a settings problem — PLA+ is not a stronger plastic than PLA, it is a tougher one, and those two words describe different properties that fail for different reasons.
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First, Which Kind of Strength Failed?
"Strong" bundles four separate material properties, and a spool that improves one can leave the other three where they were. Find your failure here before you buy anything.
| What the part did |
The property that failed |
Does PLA+ help? |
| Shattered when it was dropped or knocked |
Impact toughness |
Yes — this is the one |
| Bent, sagged or drooped over days or weeks |
Creep under sustained load |
No |
| Went soft, warped or lost its shape in heat |
Heat deflection / glass transition |
No |
| Split cleanly along the printed layers |
Interlayer adhesion and part orientation |
Slightly |
| Flexed too much under load |
Stiffness (modulus) |
No — often marginally worse |
Only the first row is what the plus was formulated to fix. If your symptom is in any other row, a second spool of PLA+ is the most expensive way to reproduce the original failure.
What the Plus Actually Is
There is no standard behind the name. "PLA+", "PLA Pro", "Tough PLA" and "PLA Max" are brand names, not specifications, and no body defines what a manufacturer has to do before using one. In practice the plus is an impact modifier — a small fraction of a tougher polymer or elastomer blended into the PLA — and sometimes a different additive package for flow and colour.
What that blend does to the numbers is consistent across brands, even though the formulations are not:
- Elongation at break goes up, often several times over. This is the headline change. Plain PLA snaps after stretching a few percent; a PLA+ grade bends noticeably further first.
- Izod or Charpy impact resistance goes up. The part absorbs more energy before it fractures.
- Tensile strength stays about the same, and in some grades drops a little.
- Stiffness usually drops slightly. Toughening a brittle polymer means trading some rigidity for give. That is the deal, not a defect.
- Glass transition and heat deflection do not move. Both sit where PLA has always sat.
So the honest one-line version: PLA+ makes a part harder to break suddenly, and does not make it harder to deform slowly. The parts that benefit are the ones described in why 3D printed parts shatter on impact.
Heat Is the Failure PLA+ Cannot Touch
This is the most common disappointed purchase, and it is worth being blunt about the numbers.
PLA's glass transition is around 55–60°C. Above that the material does not melt — it softens, and a loaded part starts to move. The additives in PLA+ do not change the polymer backbone, so that number is the same on both spools. A parked car in summer, a loft, a south-facing windowsill, the inside of a printer enclosure and the housing of anything with a motor in it all reach that range without trying, which is the whole of why 3D prints deform in a hot car.
Watch for the specification sleight of hand here. Spool listings often quote a melting or printing temperature near 180–220°C, which is true and irrelevant: it is the temperature the material flows at, not the temperature it stops holding its shape at. The number that predicts your failure is heat deflection temperature or Vicat softening point, and it barely differs between PLA and PLA+.
The fix is a different material, not a different grade. PETG is the smallest step and still prints on an open machine, with roughly 15–20°C more headroom and much better behaviour under load — the trade-offs are in why PETG prints worse than PLA. Above that, ASA holds near 100°C and survives UV, and polycarbonate goes higher again while staying tough. Both want a chamber that holds its heat — a printer enclosure is usually the cheaper half of that purchase, and whether your machine can run those materials at all is covered in why your printer can't print ABS or nylon.
Sustained Load Doesn't Read the Label Either
The second failure PLA+ does not fix is slower and easier to misread as a design problem.
Hold any PLA under a constant load at room temperature and it creeps: the part keeps deforming over days and weeks under a stress it survived instantly on day one. A shelf bracket that was flat in January and visibly bowed by March did not get weaker — it was always going to do that. Impact modifiers do not help, and because they slightly reduce stiffness, a PLA+ version of the same part can sag a little sooner. The mechanism and the design fixes are in why 3D printed brackets sag.
Creep is the property that most reliably sends a part out of PLA entirely. If something has to hold a static load for months, pick the material for that, not the grade.
Your Part Is Still Weakest Across the Layers
An FDM part is not one solid piece of plastic. It is a stack of welded beads, and the weld between layers is weaker than the bead itself — commonly well under its strength in the printing plane, depending on material, temperature and cooling.
PLA+ narrows that gap a little, because the toughened blends generally flow and re-melt slightly better, so each layer keys into the one below it a bit more. It does not close it. A part loaded across its layer lines fails along those lines whatever is on the spool, which is the subject of why 3D prints snap along layer lines.
The response that works costs nothing: rotate the part so the load runs along the layers rather than across them. On a hook, a lever or a bracket, that single change usually beats every material swap available at this price.
Where PLA+ Genuinely Earns Its Price
None of the above makes it a bad buy. It makes it a good default that is being asked to do a job it was never formulated for.
Buy PLA+ for the things that get handled: enclosures and cases, clips and snap fits, printer parts, tool holders, cosplay and prop pieces, toys, anything with a thin arm that will eventually be dropped. The failure mode it prevents — a clean brittle fracture from a knock — is the single most common way a hobby print dies, and the premium over basic PLA is small enough that keeping plain PLA on hand for anything but display prints is false economy. eSUN PLA+ is the long-standing default here, and it prints on the same profile as the plain grade. The rest of the field is compared in our PLA filament guide.
What it will not do is substitute for a material decision. Our filament comparison guide lines the common materials up by heat, toughness and difficulty, which is the comparison to make before buying a fifth spool of the same polymer.
The Changes That Actually Make a Printed Part Stronger
In rough order of return, and the first four are free:
- Orientation. Put the layers across the part rather than across the load path. Largest single effect available to you.
- Walls over infill. Perimeters carry bending load; infill mostly stops the walls buckling. Four or five walls beats a jump from 20% to 60% infill, costs less time, and uses less plastic — the arithmetic is in why more infill doesn't make 3D prints stronger.
- Fillets on internal corners. A sharp internal corner is a stress riser, and most snapped prints break exactly there. A 2–3mm radius is often worth more than any material change.
- Hotter, slower, less part cooling — on the layers that matter. Interlayer welds improve with nozzle temperature and suffer from aggressive fans. Give up a little surface finish on a functional part.
- Then the material. PETG, ASA, nylon or polycarbonate, chosen against the actual service condition.
Note what is not on the list: a filled filament. Carbon fibre grades are stiffer and look like an upgrade, while being measurably more brittle — the trap is laid out in why carbon fiber filament makes brittle parts. Annealing is not on the list either, for the reasons in why annealing warps 3D printed parts.
How to Read a Spool Instead of Its Name
Since the plus means nothing by itself, judge the grade on published numbers. Ask the manufacturer's technical datasheet for four:
- Tensile strength (MPa) — how much pull before it fails.
- Tensile modulus (MPa or GPa) — stiffness. Higher means it bends less and absorbs less.
- Elongation at break (%) or Izod impact (kJ/m²) — toughness. This is the number that should be clearly higher on a PLA+ than on the maker's plain PLA. If it is not, you are paying for the name.
- Heat deflection temperature or Vicat (°C) — the real service ceiling.
Two cautions. Published figures are usually measured on injection-moulded test bars, so your printed part will come in below them — treat the numbers as a comparison between materials, never as a prediction for your bracket. And if a seller publishes no datasheet at all and only adjectives, there is no claim there to check; a brand that puts its elongation at break on the product page has told you more than one that says "1.5× stronger" with no axis named.
When the Answer Is a Different Process, Not a Different Spool
Some parts are out of reach of any filament. If the thing has to survive 120°C, carry a real load for years, hold a tight tolerance across a long dimension, or be made in fifty identical copies, the bench printer is the wrong machine rather than the wrong material.
That is the point to get a quote instead of another spool. Shops running SLS nylon, industrial FDM in polycarbonate and ULTEM, or a quick aluminium machining pass are listed by location and process in our provider directory, and what 3D printing actually costs breaks down where a one-off sits against an evening of reprints. If the part needs a material a desktop machine cannot run — and if the honest answer is that your printer tops out below 250°C with no enclosure — comparing the upgrade against Anycubic's current printer range is a fairer comparison than another retrofit.
Otherwise: keep the PLA+ for everything that gets dropped, and pick the material for everything that gets hot or loaded. The plus was never the part of the name doing the work.
Hero photograph by Snapmaker 3D Printer on Unsplash.
