FDM Part II PLA Family

FDM Polymers — A Technical Reference ›

Part II — PLA Family

The PLA fam­i­ly - the most-print­ed ma­te­ri­al in FDM and the nat­u­ral start­ing point. Easy to print, biodegrad­able in prin­ci­ple, and the ref­er­ence against which every other poly­mer's print­abil­i­ty is judged.

6. PLA family

PLA (poly­lac­tic acid) is the most-pro­duced biopoly­mer and the most-con­sumed FDM fil­a­ment by vol­ume. Sourced from corn-de­rived lac­tic acid, it pro­cess­es at the low­est tem­per­a­ture and pres­sure of the main­stream struc­tur­al fil­a­ments (only niche materials like PCL print cooler; PVB prints in a PLA-like 190–225 °C window), prints re­li­ably with­out an en­clo­sure, and gen­er­al­ly sits among the low­est-emit­ting main­stream FDM ma­te­ri­als under typ­i­cal desk­top print­ing con­di­tions. The con­ven­tion­al “not strong” crit­i­cism of PLA mis­reads the ma­te­ri­al: PLA ex­ceeds PETG on ten­sile strength and mod­u­lus and match­es ABS on most non-im­pact met­rics. The ac­tu­al weak­ness­es are ther­mal (T_g 55–65 °C) and notch sen­si­tiv­i­ty, not bulk ten­sile.

6.1 PLA variants in the commercial market

Stan­dard PLA is the base poly­mer; ten­sile strength 50–70 MPa, elon­ga­tion 3–8%, brit­tle in notch load­ing. PLA+ / Tough PLA / Poly­Max PLA blends im­pact mod­i­fiers (typ­i­cal­ly a flex­i­ble poly­mer phase or rub­ber) to raise notched im­pact at the cost of 10–20% ten­sile strength. HTPLA (high-tem­per­a­ture PLA) in­cludes nu­cle­at­ing agents to ac­cel­er­ate crys­tal­liza­tion; the as-print­ed part is weak but an­neal­ing rais­es crys­tallini­ty from <5% to 30%+, shift­ing HDT from ~55 °C to ~120 °C. LW-PLA (lightweight PLA) contains chemical foaming agents that activate at elevated nozzle temperatures, producing a part with 30–65% density reduction (colorFabb documents up to 65% weight reduction, ~0.43 g/cm³, at full foaming — the regime RC-aircraft work relies on); standard in RC aircraft. PLA/PHA blends (col­or­Fabb, Fil­la­men­tum) com­bine PLA with poly­hy­drox­yalka­noate for biodegrad­abil­i­ty and im­proved layer ad­he­sion. Filled PLAs (wood, metal, glow, car­bon, glass) are PLA ma­trix with cos­met­ic or mod­est func­tion­al ad­di­tives.

6.2 Property envelope

Property	Standard PLA	PLA+ / Tough	HTPLA (annealed)	LW-PLA (foamed)
Density (g/cm3)	1.24	1.20–1.24	1.24	0.43–0.9 (foaming-dependent)
Tm(°C)	150–170	150–170	150–170	150–170
Tg(°C)	55–65	55–65	55–65 (post-anneal effective HDT ~120 °C)	55–65
Tensile strength (MPa)	50–70	40–60	60–70	20–35
Tensile modulus (GPa)	3–4	2–3	3–4	1–2
Elongation @ break (%)	3–8	10–25	3–6	5–10
Notched Izod (kJ/m2)	2–4	6–12	2–4	low
Nozzle (°C)	200–220	210–230	210–230	220–260*
Bed (°C)	50–60	50–60	50–60	50–60

_{Table 6.1 — PLA fam­i­ly prop­er­ty en­ve­lope. *LW-PLA noz­zle tem­per­a­ture is the foam­ing-con­trol vari­able: 220 °C gives near-solid ex­tru­sion; 250 °C+ ac­ti­vates full foam­ing. Per-spool cal­i­bra­tion of foam­ing tem­per­a­ture is manda­to­ry.}

6.3 Process and calibration

PLA prints on es­sen­tial­ly any FDM hard­ware with min­i­mal tun­ing. Noz­zle 200–220 °C, bed 50–60 °C, fan 100% after layer 2 or 3, brass noz­zle ad­e­quate for un­filled grades. Glue stick or hair­spray on glass for ad­he­sion; smooth PEI grips with­out ad­he­sives. Wood-filled, metal-filled, and glow-in-the-dark PLA re­quire hard­ened noz­zles; LW-PLA is unfilled and no more abrasive than standard PLA, so brass nozzles are fine.

Cal­i­bra­tion order match­es the gener­ic FDM work­flow: tem­per­a­ture tower 190–220 °C in 5 °C steps, max vol­u­met­ric flow (typ­i­cal­ly 12–18 mm³/s on stan­dard ho­tends, up to 30 mm³/s on high-flow set­ups like CHT or Bambu HF), ex­tru­sion mul­ti­pli­er via sin­gle-wall cube, pres­sure ad­vance brack­et (0.020–0.040 typ­i­cal), XY shrink­age com­pen­sa­tion (0.3% stan­dard). PLA is the cal­i­bra­tion base­line for most print­ers.

6.4 Application fit

PLA earns its dom­i­nant mar­ket share by being the right choice for pro­to­typ­ing, dis­play mod­els, RC air­craft (LW-PLA), ed­u­ca­tion­al and con­sumer 3D print­ing, and cos­met­ic parts that do not see ser­vice above 50 °C. It is not the right choice for parts that see sum­mer car in­te­ri­ors (above 70 °C in­side; PLA creeps), re­peat­ed im­pact load­ing (brit­tle), long-term unprotected outdoor service (UV and hu­mid­i­ty both de­grade unan­nealed PLA), or parts under sus­tained me­chan­i­cal load. An­nealed HTPLA broad­ens the tem­per­a­ture win­dow but does not fix the im­pact prob­lem.

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