PROCESS EXPLAINER
What is drop forging?
The classic term for closed-die forging — hot metal pressed inside shaped dies until it takes the part’s form, grain and all. Here is how it works, what it makes, and why the name stuck.
The process in five steps
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Billet cut & heatedAluminum bar sectioned and heated to its forgeable window — hot, never molten
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Die closed under forcePresses from 300 to 2500T drive the metal into the die cavity
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Flow & grain alignmentMetal flows around contours; grain refines and follows load paths
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Flash trimmed, heat treatedExcess trimmed; T6 solution + ageing sets final strength
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CNC finish & inspectCritical faces to Ra 0.8 per drawing; anodise; report + mill certificate
Why buyers specify it
Fatigue life
Continuous grain where loads run — the property machined and cast parts cannot copy.
Zero porosity
Solid metal consolidated under pressure; no gas or shrinkage cavities to find later.
Serial economics
Near-net shape saves material and machine hours at volume — see the cost guide.
One roof
Die shop, forging, CNC, anodising, inspection — all in our facility.
Terms you’ll meet
Closed-die / impression-die
Modern name of the family drop forging belongs to — metal fully enclosed in shaped dies.
Open-die
Flat or simple dies, giant custom shapes, no closed cavity — different product class.
Hot vs cold
Hot = flow + grain refinement (structural parts). Cold = room-temp precision for simple shapes.
FAQ
Common questions
What is drop forging?
A forging method where dies close on hot metal with impact or press force — historically a hammer ‘dropping’ onto the die. Modern production uses mechanical/hydraulic presses; our shop runs 300–2500T press lines.
Is drop forging the same as closed-die forging?
Practically, ‘drop forging’ is the traditional name for closed-die (impression-die) forging — metal compressed inside shaped dies. Open-die forging is the other family, for large custom shapes without closed cavities.
Why is it called drop forging?
From the old drop hammers whose ram fell under gravity onto the workpiece. The name survived even after presses replaced hammers in most aluminum forging shops.
What is hot forging vs cold forging?
Hot forging heats the billet so metal flows easily and grain refines; cold forging works at room temperature for simple, high-precision shapes with work-hardening. Aluminum structural parts are typically hot forged.
What can drop forging produce?
Safety-relevant cyclic-load parts: cranksets, motor mounts, steering components, brackets — for example our forged cranksets and adaptive-bike components.
Why does grain flow matter in drop forging?
The dies force metal to flow around the part’s contours, so grain follows the load paths — the core reason forged parts outlast machined or cast equivalents in fatigue. Diagram in this comparison.
What happens after the forging press?
Trimming of flash, heat treatment to T6, CNC finishing of critical faces to Ra 0.8 per drawing, anodising, then inspection — every shipment with a dimensional report, mill certificate per batch.
How long does drop-forging tooling take?
Dies are cut in-house; typical tooling plus first articles take a few weeks depending on complexity — and revisions never queue behind an outside die shop.
What quantity justifies drop forging?
Hundreds per year upward usually amortizes tooling; true prototypes are better machined from solid. The crossover for your part comes free in our 3-working-day drawing review.
Where next?
Comparisons: forging vs casting, forging vs CNC cost, or forged blanks vs billet.
MATERIAL GUIDES
6061 properties · 7075 properties · 6061 vs 7075 · What is billet aluminum · Forging vs casting · Forged blanks vs billet
Not sure which process fits your part?
Send one drawing — an engineer replies with an honest process recommendation and cost range within 3 working days.