Hot Forging (鍛造)
Manufacturing processes
Follow a process claim from step to finished-tool scope
General metallurgy and a named factory claim are different evidence layers; preserve the material, step, actor, and exact product. Apply to Hot Forging (鍛造)
- 01 Define Use the process term precisely and distinguish adjacent methods.
- 02 Place the step Record input material, sequence position, controls, and stated purpose.
- 03 Verify the actor Separate general process context from named factory documentation.
- 04 Bound the claim Attach any property or origin statement to the exact finished product.
Do not inferA forge, spark, hammer, heat, workshop, or process name cannot prove a scissor factory, alloy, temperature, grain flow, quality, or result.
Description
Hot forging shapes scissor blades from heated steel billets. How the process works, what it does to the grain, and what to ask a maker.
Hot Forging (鍛造 / tanzō)
Quick look
- Process: Steel heated to ~1,100 °C and shaped under drop hammer dies or hydraulic presses.
- Key benefit: Refines the grain and aligns it with the blade shape.
- Cost position: Premium — slower cycle times, higher energy use, skilled operators required.
- Where used: Japanese artisan workshops (Seki, Sakai, Tsubame-Sanjo), premium German manufacturers (Solingen).
Why it matters
Hot forging is the method closest to traditional bladesmithing. When steel is heated past its recrystallisation temperature and struck repeatedly, the internal grain structure compresses and realigns along the shape of the blank. The grain follows the shape of the blank instead of being cut across by a die.
Forging aligns the grain with the blade shape; how long the edge lasts still depends on the steel, heat treatment and grind.
Connection to Japanese sword forging (日本刀鍛造)
The scissor forging tradition in Seki City and Sakai descends directly from centuries of Japanese sword making (日本刀鍛造 / nihontō tanzō). The same principles apply: repeated heating and hammering expel impurities, close internal voids, and create a layered grain that resists fracture. Modern scissor forges have traded charcoal hearths for induction furnaces and hand hammers for precision drop hammers, but the metallurgical logic is unchanged.
How it works in practice
- Billet preparation: A rod or bar of scissor steel (VG-10, ATS-314, SUS440C, cobalt alloy, etc.) is cut to the approximate weight of the finished blank.
- Heating: The billet enters an induction or gas furnace and reaches forging temperature — typically 1,050-1,150 °C, where the steel glows bright orange-red.
- Die forging: The hot billet is placed between matched dies and struck by a drop hammer or squeezed by a hydraulic press. Multiple strikes progressively shape the rough scissor profile.
- Trimming: Flash (excess metal squeezed out at die edges) is trimmed while the blank is still warm.
- Normalizing: The blank is allowed to air-cool slowly to relieve internal stresses before moving on to heat treatment.
Trade-offs
- Pros: Grain that follows the blade shape, honored craft lineage.
- Cons: Slow production, expensive tooling, requires experienced operators, limited to relatively simple shapes (complex handle designs may need secondary machining).
What to ask a manufacturer
If a brand claims “hand-forged” or “forged blades,” ask whether the entire blank is forged or only the blade portion. Some manufacturers forge only the cutting blade and weld it to a stamped or cast handle — which is a legitimate technique (two-piece welding) but different from a fully forged shear.
See Also
Sources
1 source- 🇯🇵 S2 Hasami (エスツー) (manufacturer official)
Frequently Asked Questions
3 answers you can open one at a timeAt what temperature is steel forged for professional scissors?
Typically 1,050 to 1,150 °C, where the steel glows bright orange-red and sits above its recrystallisation temperature. The billet is heated in an induction or gas furnace, placed between matched dies, and shaped by a drop hammer or hydraulic press. Flash is trimmed while the blank is still warm, then the blank is allowed to air-cool slowly to relieve internal stresses before it moves on to heat treatment.
What does forging change in a scissor blade?
Heating steel past its recrystallisation temperature and shaping it under pressure refines the grain and lets it follow the blade shape. How long the edge lasts, how the blade flexes and how it takes sharpening still depend on the steel, heat treatment and grind, so a well-treated stamped blade can outperform a poorly treated forged one.
Is every 'hand-forged' scissor fully forged?
Not necessarily. Some manufacturers forge only the cutting blade and weld it to a stamped or cast handle — a legitimate technique called two-piece welding, but different from a fully forged shear. If a brand advertises ‘hand-forged’ or ‘forged blades,’ ask whether the entire blank is forged or just the blade portion, where the weld joint sits if present, and what alloy each section uses.
Comments & questions
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