Aluminium is a metal that is seen as easy to bend.

It may be able to use less forming force than many steel applications, but less forming force does not necessarily mean an easier production process. But, the actual issues in the aluminum fabrication are usually manifested as springback, cracking around the bend, visible tooling marks, flange dimension variations, or angle variations between batches.

This will alter the selection and usage of the CNC press brake machine for aluminum bending.

It is not just to ensure that the machine is powerful enough to move the sheet. It is to establish a bending process with the collaboration of material information, tooling, CNC correction and the accuracy of the machine.

The first point of interest to a manufacturer, therefore, in considering the various configurations should be the parts being manufactured, and not tonnage of machines. APEX’s Press Brake lineup also features CNC controlled systems for repeatable bending of sheet metal, such as aluminum.

Aluminium is NOT One Generic Material that may be entered into the CNC.

“Aluminum” is an incomplete bending specification.

Changes in alloy, temper, actual thickness and required bend radius can alter the response of the material to the forming operation. Hydro also points out that the proper alloy, temper and bend radius are the keys to successful aluminium forming.

It is important for the operator to know, in advance, before production programming:

• material, material specification and temper;
• actual sheet thickness;
• Inside bend radius required:
• bend length;
• flange dimensions;
• finished-surface requirements;
• Acceptable tolerances of dimension and angle.

The term ‘aluminum’ should not be the only reason for using the same bend program for 2 different aluminum jobs with the same sheet size.

The CNC program should be for the actual material and tool combination and not just the part’s nominal geometry.

Tooling control of the radius and the surface simultaneously

Press brake tooling is particularly critical when there is a finished surface of the aluminum parts that are visible.

The V-die opening affects at the same time the following variables: forming force, inside radius to be achieved, minimum possible V-die flange geometry and contact conditions between the sheet and the V-die. The tonnage guidance for APEX itself, therefore, considers V-die selection as one of the main inputs in bending-force calculations.

When considering which tooling to use to produce aluminum, the tooling should address two questions:

Does this punch and die set give the necessary shape?

and

Is it able to do that geometry without an unacceptable surface damage?

For decorative panels, cabinets, appliance parts, and architectural aluminum components, it is important to clean tooling surfaces, use appropriate punch radii and have good contact with the lower die.

If appearance is included in the specification, a successful bend with heavy marking is a rejected part.

Springback should be a Stored Process variable.

Springback shouldn’t be viewed as an operator game of trial and error.

The first bend is controlled and is the start of a practical process. This angle is then measured and the necessary correction determined and kept with the material, thickness and tooling information.

This is much easier with modern CNCs as programs, bend sequences and correction values can be saved and recalled for repeat production. Graphical programming and sensor bending/correction interfaces are also available on the appropriate configurations with the APEX controllers.

This is where a CNC press brake machine for sheet metal bending proves to be more useful than a machine just operating as a programmable hydraulic press.

The object is to change:

Bend – Measure – Guess – BEND AGAIN

into:

Measuring a validated setup → storing a correction → redo production.

Crowning and Ram Control are still required for Long Aluminum Panels.

A machine’s accuracy is not forgone by having a lower forming force.

The operator still has to work on ram parallelism, tooling alignment and deflection along the working length when bending long panels. If not, it is possible for one end of a part to be right and the rest to twist toward an alternate direction.

APEX hydraulic CNC configuration takes advantage of synchronized cylinders and programmable backgauges and V-axis crowning options. These functions will be used to maintain uniform bending conditions on complex and longer workpieces.

Thus, it should be considered a function of the production control rather than an option available solely to heavy steel bending and is ideal for manufacturers producing long aluminum cabinets, architectural panels, equipment covers or enclosure components.

Production Symptom	First Variable to Check	Next Action
Bend angle opens after forming	Stored angle correction	Perform controlled test bend and update correction
Cracking near bend	Material condition / bend radius	Confirm material specification and required radius
Visible die lines	Tool contact condition	Inspect die surface and protection method
Angle varies across long part	Alignment / crowning	Check tooling alignment and crowning setup
Flange dimension drifts	Backgauge position	Verify gauge reference and programmed position
Batch-to-batch variation	Material and setup records	Compare material batch and saved job parameters

If the aluminum job is done in smaller amounts, tonnage should be scaled down.

An oversized machine capacity will not cure an improper bending set-up.

The force for a press brake to operate depends on many factors such as the tensile strength, actual material thickness, bending length, punch radius and V-die opening. APEX’s press brake tonnage calculation guide states that it is better to use real bending circumstances to calculate tonnage, and by no means only material name.

In an aluminum shop this means that the work envelope should be used as the starting point for machine selection:

• The thinnest and thickest aluminium processed;
• MABS: Maximum Actual Bend Length;
• smallest required flange;
• target inside radii;
• largest part dimensions;
• expected production volume.

The machine is then dimensioned for actual work rather than buying the biggest tonnage machine.

Repeatability begins With the 1st production part.

If the bending job is repeatable a defined aluminum bending setup should be used versus the experienced operator’s memory.

Document Material, Thickness (Measured), Punch/Die No., Backgauge and CNC Correction and First Piece Inspection Results. Once this same job comes back, the operators should be able to re-create the validated process.

Manual adjustment may be minimized with servo-controlled backgauges, programmable axes and CNC crowning as the part geometry becomes more complex. These types of CNC and multi-axis functions are included in the configuration of APEX’s Hydraulic Press Brake Machine.

The higher the number of times that the aluminum SKUs repeat, the more valuable is this stored process knowledge.

Job Data	Information to Record	Why It Matters
Material	Alloy / Temper / Batch	Keeps repeat jobs tied to the correct material
Sheet	Actual Thickness	Prevents nominal thickness from becoming the only reference
Tooling	Punch ID / Die ID	Makes the setup reproducible
Geometry	Bend Length / Flange / Radius	Defines actual forming conditions
CNC Setup	Program / Offset / Correction	Preserves validated machine settings
Surface	Finish / Protective Requirement	Adds cosmetic acceptance to dimensional QC
First-Part QC	Angle / Flange / Surface Result	Establishes the approved production reference

Select CNC Press Brake Around the Aluminum Part Mix

No single specification is ideal for all the aluminum bending factories.

The requirements of a short bracket manufacturing workshop are different than those of a long enclosure panel bending manufacturer. A factory that’s working on two bend simple parts might not need the same type of backgauge that a factory that is working on multi-bend cabinets does.

Real drawings and production information should be provided to the supplier before making the selection, and a machine suitable for “aluminum” should not be ordered.

The important question is:

Which press brake set up generates our aluminum parts with the desired angle, size and surface finish with minimum set up corrections?

That question results in a much more helpful machine spec.

Final Production Check

Ensure correct material, actual thickness, tooling selected, bend radius, CNC correction, flange size, finished surface prior to releasing an aluminum part to batch production.

Then check something other than the angle.

The key to a good aluminum bending CNC press brake machine is to enable the factory to make the whole product, rather than just one acceptable bend.

FAQ

Q1. Is Aluminium bendable with CNC press brake machine?

Yes. Using a CNC press brake to form Aluminium Sheet and Plate is possible, as long as the tooling, Bend Radius and Process Parameters are appropriate to the alloy and temper.

Q2. Would it take less tonnage to bend aluminum compared with steel on my press brake?

It can be used in many applications however, the tonnage shall never be determined by name of material alone. Strength, thickness, length of the bend and the type of tooling and type of bending for the actual situation must be taken into account.

Q3. How to control Springback of Aluminum during Bending?

Test with controlled test bends, measure and use verified CNC correction. Keep the correction with the material and tooling set-up to use for repeat jobs.

Q4. What are some ways to minimize tooling marks on aluminum?

Use clean, appropriate tooling; consider size of V-die contact area, punch radius and surface-protection needs. Cosmetic Aluminium parts are to be checked for surface as well as Dimension accuracy.

Q5. What information should I provide when I go to purchase an aluminum CNC press brake?

Give the Aluminium specifications, thickness range, maximum bend length, the radius and flanges needed, the tolerance and part drawings and the required quantity of production. With these inputs it is possible to align the machine capacity, tooling and CNC configuration to the actual production.