Maraging Tool Steel Filament

M300 Tool Steel Filamet™ — 1.75 mm, 0.5 kg

Print real maraging tool steel parts on the FDM printer you already own. After kiln firing and age-hardening, your print becomes 85–88% pure M300 — the steel used in injection mold tooling, die inserts and high-wear hardware.

85–88% M300 Maraging Tool Steel Age-Hardenable Mold & Die Grade Dimensional Stability
The Virtual Foundry M300 Tool Steel Filamet 1.75mm 0.5kg spool

Real M300 maraging tool steel, printed on a desktop FDM printer

M300 Tool Steel Filamet™ brings genuine maraging tool steel within reach of any FDM workshop. After sintering, finished parts are 85–88% pure M300 — the same low-carbon, nickel-rich steel used in injection mold cavities, die inserts and aerospace tooling. Unlike conventional carbon tool steels, M300 hardens through age-precipitation rather than carbon martensite, giving exceptional dimensional stability and very high hardness with minimal distortion.

For mold-makers this is a path to printable, fully-customised cavity inserts and core hardware. For hardware engineers it’s a way to make wear-critical parts without the lead time of traditional tool-steel machining. Once age-hardened, the part performs like the conventional billet stock you would expect to buy from a steel supplier.

Why maraging tool steel matters. Maraging steels were developed for tooling that needs both very high hardness and low distortion during heat treatment. The age-hardening cycle is gentle — geometries hold their shape — while the final hardness rivals or exceeds traditional tool steels. M300 is the modern workhorse for injection mold and die work.

How it works — the 4-step process

1

Print

Print on any FDM printer with a 0.6 mm hardened steel nozzle. A Filawarmer is required for tool-steel-loaded filament.

2

Pack

Nest the green part in refractory ballast inside an alumina crucible. M300 needs full ballast support during binder burnout.

3

Sinter

Fire to ~1250°C in the FireX kiln. The part densifies into a true tool-steel solid ready for solution treatment.

4

Age-harden

Solution treat then age-harden for maximum hardness. M300’s low-distortion cycle is one of its biggest advantages. Expect ~17–21% linear shrinkage from sinter.

Why M300 maraging tool steel

Exceptional dimensional stability

Maraging steels distort far less during heat treatment than conventional tool steels — critical for mold cavities and high-precision tooling.

Very high age-hardened hardness

After age-hardening M300 reaches hardnesses comparable to or exceeding traditional tool steels — without the brittleness.

Mold & die ready

M300 is the standard alloy for injection mold cavities, die inserts and forming tools where wear and dimensional accuracy matter.

Tough, not brittle

Maraging steels combine high hardness with high toughness — far less prone to chipping than carbon-hardened tool steels at equivalent hardness.

Print custom tooling on demand

Skip weeks of EDM and CNC tool-steel work. Print the cavity, sinter, age-harden, finish — production-ready insert in days.

USA-made, fully supported

Manufactured in South Central Wisconsin by The Virtual Foundry. Direct technical support from the team that makes the material.

Printing tips

  • Direct drive extruder strongly preferred
  • Filawarmer required for tool-steel filament
  • Solution-treat then age for maximum hardness
  • Scale models up 120–125% to compensate for sinter shrinkage

Common applications

  • Injection mold cavities and core inserts
  • Die inserts for forming and stamping
  • Wear-resistant tooling and bushings
  • High-end knife blanks (with subsequent grinding)
  • Aerospace tool components
  • Conformal-cooling channel mold inserts

Specifications

Specification Details
Final metal content (post-sinter) 85.0–88.0% M300 tool steel
Filament density 3.50–3.65 g/cc
Diameter 1.75 mm (±0.05 mm)
Spool weight 0.5 kg
Sintering temperature ~1250°C
Required nozzle 0.6 mm hardened steel
Linear shrinkage (post-sinter) ~17–21% in all dimensions
Heat treatable Yes — solution treat then age-harden for maximum hardness
Hygroscopicity Less hygroscopic than PLA — do NOT dry
Origin Made in South Central Wisconsin, USA

Inside the spool

Full M300 Tool Steel Filamet 1.75mm spool
M300 Tool Steel Filamet™ spool
M300 Tool Steel Filamet half spool
0.5 kg M300 spool — 1.75 mm

Frequently asked questions

What is maraging steel and how does it differ from carbon tool steel?

Maraging steels harden via age-precipitation of intermetallic compounds, not via carbon martensite. The result is very high hardness with much better toughness and far lower dimensional distortion during heat treatment than equivalent carbon tool steels — ideal for mold cavities and high-precision tooling.

How should I age-harden a sintered M300 part?

Solution treat at ~820°C, air cool, then age at ~490°C for 4–6 hours. Test on a coupon first as final hardness depends on your sintered density. The TVF technical team can advise on schedules tuned to your specific part geometry.

When should I pick M300 instead of 17-4 PH stainless?

17-4 is the right call for general high-strength stainless work. Choose M300 specifically for mold tooling, die inserts and parts that need both very high hardness and tight dimensional control after heat treatment.

Can I print conformal cooling channels in mold inserts?

Yes — this is one of the most compelling applications. Print the insert with internal cooling channels following the cavity geometry, sinter, age-harden. The result is a mold insert with cooling performance impossible to achieve with conventional drilled channels.

What kiln do I need?

M300 sinters at ~1250°C. The TVF FireX handles this temperature comfortably and includes the firing schedule for tool-steel Filamets.

What else you’ll need

TVF FireX Sintering Kiln

Required for M300 sintering at ~1250°C. Includes the firing schedule for tool-steel Filamets.

Filawarmer

Required for M300 Tool Steel Filamet™. Reduces snap risk and keeps dense filament feeding cleanly.

Made in South Central Wisconsin, USA. World-class technical support provided for all TVF products.

(TVF-FILAMET-M300-175)

SKU TVF-FILAMET-M300-175
Brand The Virtual Foundry
Shipping Width 0.220m
Shipping Height 0.080m
Shipping Length 0.220m

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