28° V20 Spring-Loaded Hemming Die for 2.5 mm Sheet Metal
A custom spring-loaded press brake hemming die designed for acute pre-bending and final flattening of approximately 2.5 mm sheet metal. The tooling shown features a 28° V20 opening, an overall height of approximately 150 mm, a 60 mm wide base, and a maximum rated load capacity of 100 ton/m. The internal spring-supported moving structure enables the second-stage flattening process and automatically returns the movable section after the press brake ram retracts. This provides a compact mechanical hemming solution without requiring a pneumatic system. For many sheet metal hemming applications, material thickness is typically not much greater than approximately 2.5 mm, because thicker material generally requires substantially higher forming force and may be less suitable for conventional edge-flattening applications. Actual tooling selection should always be based on material grade, tensile strength, bend length and required hem geometry.
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Description
28° V20 Spring-Loaded Hemming Die for 2.5 mm Sheet Metal
This spring-loaded hemming die is designed for sheet metal components that require an acute pre-bend followed by final flattening or hemming.
The illustrated tooling combines a 28° V20 acute bending opening with a spring-supported movable tooling structure.
During the first operation, the sheet metal edge is bent to an acute angle using the V20 opening.
For the second operation, the pre-bent workpiece is repositioned into the flattening section. As the press brake ram moves downward, the movable tooling section compresses against the internal spring system while the machine supplies the main forming force required to flatten the folded edge.
After the ram retracts, the internal springs return the movable section to its original position.
This mechanical two-stage design integrates acute bending, flattening and automatic return in one compact press brake hemming tool assembly.
Two-Stage Hemming Process
First Operation – 28° Acute Pre-Bending
The first press brake stroke forms the sheet using the 28° V20 opening.
This creates the acute preliminary bend required before the final flattening stage.
Second Operation – Spring-Assisted Flattening
The pre-bent flange is then repositioned into the flattening area.
During the second stroke, the press brake applies the required forming force while the movable section travels against the spring system.
The folded edge is progressively compressed until the required flattened or hemmed geometry is achieved.
Automatic Spring Return
When the press brake ram retracts, the stored spring force restores the movable section to its initial position.
The tooling is then ready for the next production cycle.
Key Features
28° Acute Bending Geometry
The first forming stage uses a 28° acute angle.
V20 Opening
The illustrated version features a 20 mm V-opening, matched to the specified 2.5 mm sheet metal application.
Designed for 2.5 mm Sheet Metal
This configuration is typically used for approximately 2.5 mm sheet thickness, subject to material strength, ductility, bend length and final hem geometry.
Spring-Loaded Moving Structure
Internal springs support the movable tooling section and provide automatic return after the flattening cycle.
Integrated Acute Bending and Flattening
The same tooling assembly provides both the initial acute bend and the final flattening function.
No Pneumatic System Required
The tooling operates mechanically and does not require compressed air or pneumatic cylinders.
60 mm Wide Base
The illustrated lower die uses a 60 mm wide base, making this configuration suitable for press brakes with relatively large lower tables or die support surfaces.
Maximum Rated Load: 100 ton/m
The tooling has a maximum rated load capacity of 100 ton/m, subject to actual working length, material properties and application conditions.
Technical Specifications
| Parameter | Specification |
|---|---|
| Tool Type | Spring-Loaded Hemming Die |
| Tooling Function | Acute Pre-Bending + Flattening |
| Pre-Bending Angle | 28° |
| V Opening | V20 |
| Overall Tooling Height | 150 mm |
| Upper Tool Width | 60 mm |
| Lower Die Base Width | 60 mm |
| Designed Sheet Thickness | Approx. 2.5 mm |
| Maximum Rated Load | 100 ton/m |
| Flattening Structure | Spring-Loaded Moving Section |
| Tool Return | Automatic Spring Return |
| Pneumatic System | Not Required |
| Custom Angles | Available |
| Custom V Openings | Available |
| Custom Heights | Available |
| Custom Base Widths | Available |
| Custom Mounting Interfaces | Available |
Working Principle
The spring-loaded hemming die completes the hemming process in two press brake operations.
First, the sheet metal is bent to an acute angle using the 28° V20 opening.
The pre-bent edge is then repositioned for flattening.
During the second operation, the press brake ram supplies the main forming force while the movable tooling section compresses against the internal spring system.
The folded edge is flattened to the required final geometry.
When the press brake ram retracts, the springs automatically return the movable tooling section to its original position.
This design provides a practical mechanical solution for repeated hemming operations without relying on a pneumatic system.
Advantages of the Spring-Loaded Hemming Structure
Integrated Two-Stage Forming
Acute pre-bending and final flattening are combined within one tooling assembly.
Automatic Mechanical Reset
The spring system automatically returns the movable section after each production cycle.
No External Air Supply Required
No pneumatic cylinder, air hose or compressed-air control system is required.
Suitable for Repetitive Hemming Operations
Automatic return improves convenience during repeated production.
Compact Tooling Arrangement
The acute bending and flattening functions are integrated into one spring-loaded structure.
Flexible Customization
The V-opening, angle, tooling height, base width, spring structure and mounting interface can be adapted to the application.
Typical Applications
This spring-loaded press brake hemming die can be used for sheet metal components requiring folded, closed or flattened edges, including:
- Electrical enclosures
- Control cabinets
- Cabinet doors
- Sheet metal housings
- Equipment covers
- Stainless steel panels
- Machine covers
- Appliance panels
- Sheet metal boxes
- Industrial equipment panels
- Fabricated steel components
- Custom enclosure products
Suitable Materials
Depending on material properties, sheet thickness and final hem geometry, custom spring-loaded hemming tooling can be designed for:
- Mild steel
- Stainless steel
- Galvanized steel
- Aluminum sheet
- Pre-painted sheet metal
- Other sheet metal materials
Actual V-opening, hemming clearance, spring configuration and required press brake tonnage should be confirmed according to the specific material and application.
About the 2.5 mm Hemming Range
For many conventional sheet metal hemming applications, material thickness is commonly concentrated in the light- to medium-gauge range.
As sheet thickness increases, the force required for acute bending and final flattening rises significantly, while thicker material also has greater structural stiffness.
For this reason, approximately 2.5 mm is often near the upper practical range for many conventional spring-loaded hemming applications, although the actual limit depends strongly on:
- Material grade
- Tensile strength
- Bend length
- Hem length
- Final hem geometry
- Available press brake tonnage
- Tooling load capacity
- Required production quality
This tooling shown is designed specifically for approximately 2.5 mm sheet metal.
60 mm Base for Large-Table Press Brakes
The lower die shown uses a 60 mm wide base.
This wide-base configuration is particularly suitable for press brakes with larger lower working tables or die support surfaces.
However, this is only one available structure.
For press brakes using different die holders, narrower support surfaces, single-V bases, European-style interfaces or other lower tooling systems, the base and mounting profile can be redesigned accordingly.
Custom Spring-Loaded Hemming Tooling
The Tool Shown Is Only One Example
The tooling displayed on this page represents one specific 28° V20 spring-loaded hemming solution for approximately 2.5 mm sheet metal.
It does not represent the full range of hemming tools that we can manufacture.
We can customize:
- Acute bending angle
- V-opening
- Sheet thickness range
- Hemming clearance
- Spring configuration
- Spring force
- Overall tooling height
- Upper tool width
- Base width
- Lower die mounting interface
- Tooling length
- Segmentation
- Load capacity
- Tooling material
- Heat treatment
- Surface treatment
The tooling can be designed according to the customer's finished part drawing, material and actual press brake configuration.
Compatible Press Brake Tooling Systems
The mounting structure can be customized for different press brake and tooling systems.
Available configurations include:
AMADA Type
TRUMPF Type
WILA Type
LVD Type
Bystronic Type
and other press brake tooling systems.
Custom mounting profiles can also be manufactured according to machine specifications, existing tooling samples or customer drawings.
Custom Tooling Design Service
Special hemming applications often require tooling designed around the finished part rather than only around a standard catalogue size.
Customers can provide:
- Finished part drawings
- Sheet thickness
- Material grade
- Required hem dimensions
- Bend length
- Press brake model
- Lower table configuration
- Existing tooling interface
- Available machine tonnage
Our engineering team can evaluate the complete forming process and recommend a suitable custom press brake hemming tooling solution.
Important design factors include:
- Acute pre-bending angle
- V-opening
- Sheet thickness
- Material tensile strength
- Material stiffness
- Springback
- Hemming clearance
- Spring configuration
- Final hem geometry
- Tooling load capacity
- Press brake tonnage
- Workpiece interference
- Lower die mounting structure
Spring-Loaded Hemming Die Selection by Sheet Thickness
| Typical Sheet Thickness | Example V Opening | Tooling Type |
|---|---|---|
| Approx. 1.0 mm | V8 | Spring-Loaded Hemming Die |
| Approx. 1.5 mm | V12 | Spring-Loaded Hemming Die |
| Approx. 1.8 mm | V14 | Spring-Loaded Hemming Die |
| Approx. 2.0 mm | V16 | Spring-Loaded Hemming Die |
| Approx. 2.5 mm | V20 | Spring-Loaded Hemming Die |
The table above represents example tooling configurations rather than universal selection rules. The correct V-opening should be confirmed according to the material, hem geometry and machine conditions.
Spring-Loaded vs. Other Hemming Tooling
| Hemming Tool Type | Initial Forming | Flattening Method | Main Structural Characteristic |
|---|---|---|---|
| Spring-Loaded Hemming Die | Acute V-bending | Movable section compresses during flattening | Internal spring return |
| U-Groove Hemming Die | Acute bending | Flattening in the same fixed groove | Fixed groove structure |
| Pneumatic Hemming Tool | Acute bending | Pneumatically assisted flattening | Air-powered mechanism |
| Separate Flattening Die | Separate acute bend | Independent flattening operation | Separate tooling process |
Related Press Brake Hemming Solutions
Depending on sheet thickness, mounting structure and production requirements, we can provide:
- Spring-Loaded Hemming Dies
- U-Groove Hemming Dies
- Pneumatic Hemming Tools
- Two-Stage Hemming Dies
- Press Brake Flattening Dies
- Acute Angle Punches
- Custom Hemming Punches
- Special Press Brake Forming Tools
