Galvalume vs Galvanized Steel in PBR Forming

When producing PBR (Purlin Bearing Rib) panels, one of the most important material decisions is whether to use Galvanized steel or Galvalume steel.

Both are widely used in roofing and wall cladding systems, but they behave slightly differently in roll forming, surface durability, and long-term corrosion performance.

For PBR manufacturers, the choice impacts:

• Roll forming stability

• Tool wear

• Coating protection

• Panel lifespan

• Customer warranty expectations

• Machine load and setup

This guide explains the differences clearly from a production and machine engineering perspective, not just a marketing standpoint.

Visual Difference: Galvanized vs Galvalume

Galvanized Steel

• Zinc coating

• Slight matte grey finish

• Common coating weights: G60, G90

Galvalume Steel

• Aluminum-zinc alloy coating (typically 55% aluminum, 43–44% zinc, small silicon content)

• More metallic, reflective finish

• Common coating weights: AZ50, AZ55

What Is Galvanized Steel?

Galvanized steel is coated with zinc to protect against corrosion.

In PBR production, common grades include:

• Structural Grade 33

• Grade 37

• Grade 40

• Grade 50

Zinc protects steel by sacrificial corrosion — meaning it corrodes first to protect the base steel.

Advantages for PBR Production

• Good formability

• Stable roll forming behavior

• Lower coating hardness

• Reduced roll marking risk

• Widely available globally

What Is Galvalume Steel?

Galvalume uses an aluminum-zinc alloy coating.

The aluminum provides long-term corrosion resistance, especially in:

• Industrial environments

• Agricultural buildings

• Coastal regions

Advantages

• Better corrosion resistance than galvanized

• Improved heat reflectivity

• Longer life in many climates

However, the aluminum component changes forming characteristics slightly.

Key Differences in PBR Roll Forming

Coating Hardness & Tool Wear

Galvalume coatings are slightly harder than standard galvanized coatings.

Impact on production:

Factor	Galvanized	Galvalume
Coating hardness	Moderate	Slightly harder
Tool wear rate	Normal	Slightly increased
Roll marking risk	Lower	Slightly higher
Surface polish need	Moderate	Higher importance

If roll surfaces are not smooth and well finished, Galvalume can show marking faster.

Forming Stability

Mechanically, base steel grades are often similar between the two coatings.

However:

• Galvalume may feel slightly “stiffer” due to coating characteristics

• Surface friction can differ slightly

• Forming loads remain mostly similar if yield strength is identical

In most PBR lines, switching between G60 and AZ50 does not require major setup changes — provided base steel grade and thickness remain the same.

Springback Behavior

Springback is primarily controlled by:

• Yield strength

• Thickness

• Pass design

Coating type plays a minor role.

If both materials are Grade 33 or Grade 40 at same thickness, springback behavior will be similar.

High yield Galvalume (Grade 50) will behave like high yield galvanized in terms of springback.

Corrosion Performance in Field Applications

This is where Galvalume often wins.

Galvanized (Zinc Only)

• Good corrosion resistance

• Suitable for many commercial buildings

• Zinc sacrifices itself over time

Galvalume (Aluminum-Zinc Alloy)

• Better long-term corrosion resistance

• Performs well in coastal environments

• Higher resistance to red rust

For agricultural or industrial applications, Galvalume is often preferred.

Impact on Machine Settings

Roll Gap

No major adjustment required if:

• Same thickness

• Same yield strength

Always verify:

• Rib height

• Panel width

• Flatness

after switching material type.

Speed

Both materials can run at similar line speeds.

However:
If surface scratching appears on Galvalume, reducing speed slightly can reduce friction marks.

Tool Surface Finish

Galvalume requires:

• Highly polished roll surfaces

• Clean entry guides

• Proper strip alignment

Any roughness shows up faster.

Common Production Issues & Causes

Issue: Surface Scratching on Galvalume Panels

Likely Causes:

• Roll surface micro scratches

• Dirty entry guides

• Improper strip tracking

• Excessive roll pressure

Solution:

• Inspect roll finish

• Check guide alignment

• Verify roll gap not too tight

Issue: White Oxidation Spots (Storage Related)

Both materials are vulnerable to:

• Moisture trapped between panels

• Poor ventilation in packaging

Galvalume may show cosmetic staining if improperly stored.

Issue: Increased Tool Wear

If wear rate increases after switching to Galvalume:

Check:

• Coating weight

• Roll surface hardness

• Line speed

• Forming pressure

Coating Weights & Structural Standards

Common PBR coating weights:

Galvanized

• G60 (0.60 oz/ft² zinc)

• G90 (0.90 oz/ft² zinc)

Galvalume

• AZ50

• AZ55

Higher coating weight = better corrosion protection
But slightly increased forming friction.

Cost Comparison

Typically:

• Galvalume may cost slightly more than galvanized

• Price difference varies with global aluminum pricing

However, lifecycle cost often favors Galvalume in corrosive environments.

Which Is Better for PBR Production?

Choose Galvanized If:

• Budget-sensitive project

• Standard commercial building

• Inland environment

• Lower corrosion risk

Choose Galvalume If:

• Agricultural buildings

• Coastal projects

• Industrial chemical exposure

• Long warranty requirements

Machine Matcher Intelligence Insight

Production data across PBR lines shows:

• Switching coating types rarely causes instability if yield strength is constant.

• Surface marking complaints increase when roll finish quality is poor — not because of coating itself.

• Most quality issues blamed on Galvalume are actually roll alignment or guide setup issues.

Monitoring vibration and load helps ensure coating friction is not causing excessive mechanical stress.

FAQ

Does Galvalume require a stronger machine?

No. If yield strength and thickness are the same, mechanical load is similar.

Is Galvalume harder to form?

Slightly higher surface hardness may increase friction, but base forming behavior is similar.

Does Galvalume increase oil canning?

No. Oil canning is primarily yield and stress distribution related.

Which lasts longer?

In many environments, Galvalume provides better corrosion resistance.

Summary

Galvanized and Galvalume steels are both suitable for PBR panel production.

The key differences lie in:

• Coating composition

• Corrosion performance

• Surface hardness

• Tool wear sensitivity

From a roll forming perspective:

• Yield strength matters more than coating type

• Proper roll finish prevents marking

• Machine capacity should match thickness and grade

• Setup verification is essential when switching materials

For most PBR manufacturers, the decision comes down to environmental exposure and customer warranty requirements, not machine limitations.