I thought about calling it Hephaestus but that seemed too on-the-nose.

Hammerland

Daevata, Morworf, Kroth, Mabar, Nodama, Kett, Sinyesta, Trost. Idk depends on your theme I suppose.

Drogbora

GrimArsenal

I think I like Aresenal the most of that bunch.

Here are a bunch of Zulu words for build, hammer, etc. Its a really cool African language that might add some flavour to your world?
Yenza
Akha
Isando
Ithuluzi [pronounced eeh-too-loo-zee]

Damn I butchered the spelling of arsenal.

Ares anal. Hmm god of war out here being kinky

Oh dang I read it wrong.
Headcanon

Arse anal* XD

Ratchet and Clank: Up your Arsenal

Could call it's Skitarii contingent the Sons & Daughters of Ares. Also I'm pretty surprised Bethorien hasn't popped up here yet. She loves her Adeptus Mechanicus.

Where is she?

list of actual forge world names that are canon planets,
agripinaa (this one has table top 40k wargame rules)
graia (has rules on the tabletop)
lucius (has rules)
mars (has rules, is the capitol of the mechanicus)
metalica (has rules)
ryza (rules)
stygies VIII (has rules)
accatran
alarmedian
antax
anuaris
anvillus (this one makes titans)
artemia majoris
belacane
beshic V
cerix magnus
constanix II
cyclopea
cypra mundi
cyraxus II
diamat
dominica II
estaban III, VII, and VIII
fecundia
gantz
gorgonum
helios
hellgrace
hexium minora
hypnoth
ironhelm
orestes
palatine III
proximus
skorgulian
straxos
telemachus
taslan's forge
vanaheim
voss and voss prime
zosma (closest forge world to the eye of terror)

Given that this planet's major exports are guns, vehicles, and Titans (and some Psi-Titans back in the day), I think Arsenal is a bit too on the nose.

I've created worlds of ragin cajun/redneck space marines. And I love them.

I've also named the Skitarii and the Titan legions the Scythes of the Omnissiah and the Legio Combinicus respectively.