Two-Step Precision Hemming: Combines acute-angle pre-bending and final flattening into a specialized compound workflow, ideal for removing sharp burrs and reinforcing sheet metal edges.
Zero-Marring Surface Finish: Engineered with precision CNC ground contact faces to prevent surface scratching and galling on cosmetic stainless steel and aluminum panels.
Deep Hardened 42CrMo Alloy: Forged from premium 42CrMo steel with localized induction hardening (HRC 47±3) on high-friction crushing points to completely resist structural deformation.
Safety Flange Applications: Perfectly optimized for high-volume fabrication of metal lockers, cabinet doors, food equipment, and office furniture requiring smooth, safe, and flush sheet edges.
Achieve flawless, zero-gap dead folds and safety edges without changing tools between cycles. The ALAS Precision Spring-Loaded Hemming Tooling is a high-performance compound die engineered specifically for high-mix fabrication. By integrating an acute bending V-groove and an lower cushioning flattening anvil into a single spring-loaded mechanical assembly, this tool allows operators to pre-bend and flatten sheet metal edges in one smooth continuous stroke, cutting processing cycle times by up to 50%.
Dynamic Spring-Loaded Mechanism Explained
Unlike traditional rigid flattening blocks, the ALAS compound hemming tool utilizes heavy-duty internal die springs to manage structural movements seamlessly during the dual-stage bending cycle:
Stage 1 (Acute Pre-Bending): The upper punch presses the sheet metal into the top acute V-groove, achieving a crisp pre-bend angle (typically 30° to 45°). During this phase, the internal high-tension springs hold the lower block firmly in its extended position.
Stage 2 (Flush Flattening): The upper die carrier retracts smoothly into the lower housing block (which has a 65mm base profile), utilizing its 15mm dynamic stroke to allow the flat shoulders to crush the pre-bent flange flat against the horizontal anvil face.
Explicitly Optimized Application Scenes
This precision compound tooling is the ideal choice for high-end sheet metal lines where operator safety, edge rigidity, and pristine cosmetic finish are non-negotiable:
Safety Flanges & Enclosures: Perfect for fabricating commercial electrical cabinets, lockers, steel furniture, shelving, and laboratory equipment to completely eliminate sharp sheet edges.
Cosmetic Surface Protection: Specially optimized for stainless steel, architectural aluminum, and pre-painted panels where sliding friction scratching must be strictly controlled.
Door & Box Panel Reinforcements: Ideal for creating double-thickness structural hems along the perimeter of box plates to maximize overall sheet rigidity.
Forged 42CrMo Metallurgy with CNC Ground Finishes
To endure the severe crushing tonnages required for uniform hem flattening, every ALAS compound tool is manufactured to strict industrial standards:
Premium Material Core: Forged from genuine 42CrMo alloy steel (equivalent to AISI 4140) for supreme tensile strength and zero risk of cross-sectional cracking under off-center loads.
Precision Hardening: Fully quenched and tempered body, combined with high-frequency induction hardening on the critical V-shoulder and crushing faces to achieve a stable HRC 47±3.
Ultra-Smooth Contact: Precision ground surfaces finished down to ≤ Ra 0.8 μm, minimizing friction and material galling when processing mirror stainless steel.
Technical Specification & Dimensional Layout
Our standard configuration is fine-tuned to fit seamlessly into mainstream hydraulic press brake setups. Please refer to the dimensional breakdown below based on our factory blueprints:
Engineering Parameter
Standard CNC Specification Value
Total Assembly Height (a)
110 mm (Extended/Uncompressed position)
Retracted Height (b)
95 mm (Fully compressed flattening state)
Lower Base Housing Height
65 mm (Heavy-duty block stabilizing the spring core)
Upper Tool Head Width
45 mm (30mm offset centerline + 15mm clearance shoulder)
Top Dynamic Tool Height
30 mm (Precision milled acute V-groove carrier)
Optimal Sheet Range
0.8 mm – 2.0 mm (Mild Steel & Stainless Steel sheets)
Compatibility & Factory Customization Options
Every ALAS spring-loaded hemming die is available in flexible length configurations to match your exact part geometries on the shop floor:
Full-Length Integral Blocks: Stocked in standard 835mm and 1000mm single pieces for long, seamless straight-line edge folding.
Precision Segmented Kits: Assembled via multi-piece fraction blocks (e.g., 10, 15, 20, 40, 50, 100, 200, 300 mm) to form closed four-sided boxes without flange collision.
Bespoke Adaptations: Fully customizable base shanks and mounting pins to guarantee direct compatibility with Amada/Promecam, Trumpf, Wila, LVD, and Durma clamping systems.
Ordering Note:When submitting your request, please verify your press brake's minimum shut height to ensure the 110mm tool height fits within your operational daylight envelope. Complete spring tension certificates and rated load limits are provided with every factory shipment.
ALAS Spring Die · Technical Q&A
ALAS Spring-Loaded Flattening Die · Technical Q&A
Q1 What are the material width limits?
Overall die height is 110 mm. It's rated for mild steel from 0.8 mm to 2.0 mm, and stainless up to 1.5 mm. Going over 2.0 mm on mild steel will overcompress the internal springs — you risk jamming the die, and it's a pain to free up.
Q2 Why choose this over pneumatic or slide‑style hemming tables?
This block drops straight onto your press brake bed. No air lines, no hydraulic hoses, no extra controller — it's purely mechanical. As long as your brake uses standard Amada, Trumpf, or Wila tooling slots, it's a drop‑in fit. Simple, reliable, and costs a fraction of powered systems.
Q3 How do I estimate tonnage for the two‑step flattening cycle?
The first (acute bend) follows normal air‑bending formulas. The real load comes on the second step — the flattening crush. For 1.0 mm mild steel, expect roughly 50–60 tons per metre to get a fully flush, seamless hem. In practice, we recommend adding another 15‑20% margin on your machine's capacity — you'll thank yourself during setup.
Q4 Can the internal springs be replaced after heavy production runs?
Absolutely. The bottom housing is designed for service — a 65 mm base plate that unbolts on a standard workbench. The springs themselves are off‑the‑shelf items, easy to source and cheap to swap. After a few million cycles, if you notice a drop in return force, just change them out — no need to scrap the whole tool.
— internal reference · always validate with your own shop‑floor trials
Strict Tonnage Limit: Do not operate under off-center eccentric shock loads that exceed the rated capacity per millimeter, as it may cause asymmetric spring failure.
Debris Prevention: Laser-cutting slag, mill scale, and magnetic steel shavings must be continuously blown off the 15mm clearance shoulder to prevent the dynamic punch carrier from jamming inside the 65mm lower housing block.
Stroke Calibration: Always perform a low-speed manual stroke validation when configuring new CNC controllers to ensure the upper beam does not bottom out forcefully at less than the 95mm maximum compressed limit.
Precision Press Brake Compound Dies in Action: Advanced Hemming & Flattening Workflow
Watch our press brake compound dies run high-precision, two-stage edge folding on a CNC hydraulic press brake. Built to eliminate repeated tool setups and drastically cut down processing cycle times, this integrated tooling set combines an acute-angle bending profile with a dynamic heavy-duty flattening anvil to achieve uniform sheet crushing force across the entire part length.
Nanjing Alas International Co., Ltd. is a professional industrial tooling manufacturer focused on shear blades, bending dies, shredder blades, and custom wear parts. We offer full application engineering, material selection, setup guidance, and after-sales support to global customers. Tell us your requirements, and our engineering team will provide professional solutions for blade specification, tool life optimization, and cost-effective production.
