3D Printing InfoFilament comparison
Magnetic vs TPU-CF
Compare printing settings, strength, heat resistance, dated prices and sources.
2 selected · all documented properties
| Property | Magnetic filamentSPECIALTY | Carbon-fibre TPUFLEX |
|---|---|---|
| Market snapshot | ||
| Listing priceUSD/kg; dated snapshots | $64.99/kg median; $64.99–$64.99/kg across 1 dated product listings | $107.05/kg median; $107.05–$107.05/kg across 1 dated product listings |
| Identity & Market | ||
| Base polymer / chemistry | PLA loaded with ferromagnetic iron powder, so printed parts respond to magnets[1] | Carbon-fibre reinforced thermoplastic polyurethane at the hard end of the range[2] |
| Densityg/cm³ | About 1.85 (Proto-pasta manufacturer figure) — 1.5× standard PLA[1] | 1.22 (Extrudr FLEX HARD CF, ISO 2781)[2] |
| Typical priceUSD/kg | 1 kg spools cluster near 65[3] | 107 for the only retail listing found (Extrudr 0.5 kg coil, incl. VAT)[4] |
| Price range across brandsUSD/kg | 64–70 across formats; 1 kg spool 65, 500 g 70, 2 kg 70[3] | One listing only: EUR 49.56 incl. VAT per 0.5 kg coil, direct from Extrudr; no reseller or second brand found[4] |
| Market availability1–5 | Niche, a handful of specialist brands[3] | Niche, a handful of specialist brands — Extrudr's FLEX HARD CF is the only carbon-filled flexible with a published datasheet found here[2] |
| Spool sizes & diameters | 1.75 and 2.85 mm; 0.1, 0.5, 1 and 2 kg spools[3] | 1.75 mm; 0.5 and 2 kg coils[4] |
| Typical applications | Sensor targets, magnetic fixtures, and props that need to stick to a magnet or rust deliberately[1] | Stiffened flexible parts — damping mounts and semi-rigid brackets[2] |
| Printing Parameters | ||
| Nozzle temperature°C | 192 (Proto-pasta)[1] | 230–260 (Extrudr FLEX HARD CF)[2] |
| Bed temperature°C | 60 (Proto-pasta)[1] | 50–90 (Extrudr FLEX HARD CF)[2] |
| Enclosure / chamber requirement1–5 | Open frame is fine[1] | Open frame is fine[2] |
| Bed surface & adhesion aid | Not documented | PEI sheet or painter's tape; Polymaker warns TPU can over-stick and advises a glue stick as a release agent[5][6] |
| Maximum volumetric flow (mm³/s; see test conditions)mm³/s | 1.6–2.4 at Proto-pasta's 20–30 mm/s on a 0.4 mm nozzle at 0.2 mm layer[1] | 1.6–8 at the 20–100 mm/s Extrudr specifies on a 0.4 mm nozzle at 0.2 mm layer[2] |
| Overall printing difficulty1–5 | Intermediate — dry filament and a tuned profile; slow, and brittle in filament form[1] | Advanced — enclosure, hardware upgrades, tuning; hardened nozzle needed[2] |
| Extruder requirement | Proto-pasta advises an extrusion width 0.05 mm larger than the nozzle and warns feeding is inconsistent below 0.4 mm and on Bowden machines[1] | Not documented |
| Hardware Wear & Reliability | ||
| Nozzle hardness required1–4 | Brass acceptable; hardened steel for volume work[1] | Hardened steel required — Extrudr marks FLEX HARD CF as needing a hardened nozzle where its unfilled FLEX grades do not[2] |
| Abrasiveness1–5 | Moderately abrasive — metal fill[1] | Highly abrasive — standard CF composite[2] |
| Nozzle clog risk1–5 | Moderate — needs dry filament and a clean nozzle; Prusa lists metal-filled composites as a higher clogging risk and recommends a 0.6 mm nozzle minimum[7] | High — jams from moisture, heat creep or particles; a flexible base plus chopped carbon fibre, which Prusa lists as a higher nozzle-clogging risk, and Extrudr requires a hardened nozzle[8][2][5] |
| Hotend requirement | Proto-pasta recommends a wear-resistant or larger nozzle for longer service intervals[1] | No special hot-end required, but a direct-drive extruder is (Simplify3D)[5] |
| Moisture Behaviour | ||
| Moisture absorption (hygroscopicity)1–5 | Not documented | Moderate[9] |
| Drying temperature & time | Not documented | 60 °C for 6 h (Extrudr FLEX HARD CF)[2] |
| Symptoms when wet | Not documented | Bubbling and popping at the nozzle, stringing and a rough surface[9] |
| Effect of moisture on strength | Polymaker rates PLA low-sensitivity and publishes no dry-versus-conditioned figures; absorbed water flashes to steam and shows as bubbling and poor layer adhesion[9] | Polymaker groups TPU with the highly hygroscopic materials; no dry-versus-conditioned figures are published[9] |
| Storage requirement | Not documented | Sealed with desiccant; often kept in a dryer during the print[9] |
| Mechanical Properties | ||
| Young's modulusMPa | Not documented | 35 (Extrudr FLEX HARD CF, ISO 527-2/5A/500)[2] |
| Elongation at break% | Not documented | 380 ultimate elongation (Extrudr FLEX HARD CF, ISO 527-2/5A/500), against 490 for the unfilled FLEX HARD[2] |
| Brittleness1–5 | Brittle — Proto-pasta describes the filament as more brittle than standard PLA and needing extra care in handling[1] | Very ductile — bends far before failing[2] |
| Hardness (scale-specific)Shore A / Shore D / Rockwell | Not documented | 70 Shore D (Extrudr FLEX HARD CF, ISO 868), against 58 Shore D for the unfilled FLEX HARD[2] |
| Creep resistance / sustained load1–5 | Not documented | Below average — no CF-grade creep test; the grade is 70 Shore D where a 95A TPU bar crept from 74.5 to 82.7 mm over 5 days at 1.25 kg[2][10] |
| Fatigue / repeated-flex resistance1–5 | Not documented | Good — 380 % ultimate elongation and a damping application set (Extrudr cites longboard wheels), below the unfilled grades[2] |
| Elasticity / flexibility1–5 | Rigid[1] | Semi-flexible[2] |
| Wear resistance & friction | Not documented | Abrasion 26 mm³ (Extrudr FLEX HARD CF, ISO 4649-A) — the same as the unfilled FLEX HARD[2] |
| Thermal Properties | ||
| Glass transition (Tg)°C | Not documented | -24 (Extrudr FLEX HARD CF)[2] |
| Melting point / Vicat°C | Not documented | Vicat A 140 (Extrudr FLEX HARD CF, ISO 306)[2] |
| Environment & Chemical | ||
| UV resistance1–5 | Not documented | Good — years with some colour shift; Polymaker lists UV exposure among the conditions TPU withstands[6] |
| Outdoor durability | Deliberately rustable — Proto-pasta markets the iron content as oxidising when exposed to moisture[1] | Not documented |
| Chemical resistance | Not documented | Withstands industrial solvents and UV exposure (Polymaker)[6] |
| Food contact | Not documented | Not food safe without specific certification (Polymaker)[6] |
| Biodegradability / compostability | Not documented | Not biodegradable[6] |
| Recyclability | Not documented | Not accepted in household plastic collection[6] |
| Electrical & ESD properties | Ferromagnetic: Proto-pasta states it responds to magnets and behaves similarly to pure iron[1] | Not documented |
| Health & Safety | ||
| Fume toxicity1–5 | Low hazard — minimal VOC and particle emission; none of these materials was in the chamber study[11] | Low hazard — minimal VOC and particle emission; TPU was not among the nine filaments in the chamber study[11] |
| Ventilation / filtration requirement1–5 | Open a window / occasional ventilation[11] | Open a window / occasional ventilation[11] |
| Dust & fibre handling hazard | Not documented | Carbon fibre is bound in the matrix; sanding dust should not be inhaled[2] |
| Post-Processing | ||
| Sanding & machining | Polishing and deliberate rusting are the intended finishes[1] | Difficult to sand or smooth; Polymaker limits post-processing to trimming or tumbling[6] |
| Gluing & solvent welding | Not documented | Cyanoacrylate bonds TPU; no common solvent welds it[6] |
| Vapour / chemical smoothing | Not documented | No practical vapour smoothing[6] |
| Support material pairing | Not documented | Polymaker warns TPU supports are often very difficult to remove[6] |
| Dimensional accuracy & detail | Not documented | Tear strength 165 kN/m (Extrudr FLEX HARD CF, ISO 34-1B)[2] |
| Solvents & Solubility | ||
| Soluble in | Chloroform dissolves the PLA matrix and leaves the iron powder behind; laboratory reagent, not workshop stock.[12][1] | DMF, DMSO, NMP and THF dissolve the TPU matrix and leave the fibre; ketones are partial solvents. Laboratory reagents.[13] |
| Softened or crazed by | Acetone and ethyl acetate plasticise the matrix rather than dissolving it; water attacks the exposed iron.[12][1] | Toluene and benzene swell it up to +50 % by weight at 23 °C; esters swell it severely; ethanol and IPA soften it.[13] |
| Solvent welding & smoothing agent | None — PLA has no workshop-safe solvent, and the iron loading blocks the surface flow smoothing needs.[12] | None practical — the true solvents (DMF, THF, NMP) are laboratory reagents and leave the joint swollen and weak.[13] |
Material entries describe families or representative grades, not an interchangeable specification for every spool. Test methods, orientations and conditions may differ. Unknown values are marked “Not documented”. Prices and source dates remain historical snapshots; check the linked guide for product details. Differences highlight text, not a universal winner.
Sources for this comparison
- Magnetic Iron PLA — product page and technical data Proto-pasta · 2026-08 · tds
- Extrudr Product Catalogue (DURAPRO PA12 data block) Extrudr · 2025-03 · tds
- Proto-pasta product catalogue Proto-pasta · 2026-08 · vendor
- Extrudr TPU FLEX Hard CF — product page (1.75 mm, 0.5 and 2 kg coils, price) Extrudr (FD3D GmbH) · 2026-08 · vendor
- Flexible (TPE/TPU) — Ultimate 3D Printing Materials Guide Simplify3D · 2026-08 · doc
- TPU — material basics Polymaker Wiki · 2026-08 · doc
- Composite materials with metal or wood particles Prusa Knowledge Base · 2026-08 · doc
- Composite materials filled with carbon, kevlar or glass Prusa Knowledge Base · 2026-08 · doc
- Wet Filament — signs, causes and drying Polymaker Wiki · 2026-08 · doc
- BambuLab TPU 95A HF vs Qidi TPU 95A HF — results spreadsheet My Tech Fun (Igor Gaspar) · 2024-02 · test
- Emissions of Ultrafine Particles and Volatile Organic Compounds from Commercially Available Desktop Three-Dimensional Printers with Multiple Filaments (Azimi et al.) Environmental Science & Technology 50(3) 1260-1268 · 2016-01 · paper
- Solubility Study of Ingeo Biopolymer Grades in Common Organic Solvents (NWPD003) NatureWorks · 2019-10 · tds
- Elastollan — Chemical properties: swelling and chemical resistance BASF · 2026-08 · tds