Incorrect Material Used During Testing — When Warranty Claims Fail Due to Wrong Steel Specification

One of the most overlooked causes of roll forming machine disputes is the use of incorrect material during testing or early production.

The buyer reports:

• Wavy panels

• Width variation

• Punch misalignment

• Cut length drift

• Surface cracking

• Motor overload

• Speed lower than promised

The supplier responds:

“You are not using the material the machine was designed for.”

This scenario is extremely common — especially during commissioning or first production runs.

This guide explains:

• Why material specification matters

• How incorrect steel affects machine performance

• When warranty is void

• When manufacturer responsibility still applies

• How to protect yourself during testing

Why Material Specification Is Critical in Roll Forming

Roll forming machines are engineered for:

• Specific thickness range

• Specific tensile strength range

• Specific yield strength

• Specific coating type

• Specific width tolerance

A machine designed for:

• 0.4–0.6 mm G300 steel

Will behave very differently if tested with:

• 0.7 mm

• G550 high tensile

• Thicker coating

• Inconsistent imported coil

Material affects:

• Forming pressure

• Springback

• Speed capability

• Punch force

• Hydraulic load

• Motor torque

Testing with incorrect material can create false “machine defects.”

Common Material Errors During Testing

1. Higher Tensile Strength Than Specified

If machine designed for:

• G300 or G350 steel

But tested with:

• G550 high tensile

You may see:

• Springback

• Open bend angles

• Incorrect profile dimensions

• Increased oil canning

• Punch deformation

• Reduced production speed

High tensile requires different roll design and pressure balance.

Using wrong tensile steel often voids performance-based claims.

2. Thicker Gauge Than Rated

Testing above rated thickness may cause:

• Motor overload

• Gearbox stress

• Hydraulic strain

• Frame deflection

• Excess vibration

If machine rated for 1.6 mm max and tested with 2.0 mm, warranty claims are weak.

3. Inconsistent Coil Thickness

If coil varies:

• Width changes

• Panel distortion appears

• Punch alignment drifts

Coil inconsistency can create symptoms blamed on machine.

Material certification must be verified.

4. Incorrect Coating Type

Pre-painted material behaves differently from:

• Bare galvanized

• Galvalume

• Heavy zinc coating

Coating thickness affects:

• Friction

• Surface marking

• Forming pressure

Incorrect coating can cause surface damage not related to tooling defect.

5. Using Scrap or Mixed-Grade Coil

Some operators test machines using:

• Leftover stock

• Mixed tensile coils

• Non-certified material

This leads to:

• Unpredictable results

• False performance conclusions

Testing must be done with certified material matching contract specification.

How Incorrect Material Creates False Faults

Incorrect material can cause:

• Wavy panels → due to springback

• Panel width variation → due to thickness variation

• Punch misalignment → due to stretch difference

• Cut length inaccuracy → due to feed slippage under high tensile

• Production speed limitation → due to torque increase

• Surface cracking → due to tight bend on high tensile

Without material verification, machine may be blamed incorrectly.

When Incorrect Material Voids Warranty

Warranty may be void if:

• Material outside rated thickness

• Tensile strength exceeds specification

• Coating type not compatible

• Material width outside tolerance

• Machine operated outside approved material range

Most manufacturers specify allowable material range clearly in contract or manual.

Operating outside this range shifts responsibility to buyer.

When Manufacturer Responsibility May Still Apply

Warranty may still apply if:

• Machine specification unclear

• Material range not defined in contract

• Machine incapable of handling stated range

• Roll design incorrect for approved material

• Supplier approved material in writing

If supplier confirmed material compatibility before sale, responsibility may remain with them.

Structured Material Verification Checklist

Before testing or claiming defect:

Step 1: Verify Thickness

Measure multiple points across coil width.

Confirm within specified range.

Step 2: Verify Tensile Strength

Obtain mill certificate.

Confirm yield and tensile strength.

Step 3: Confirm Coating Type

Check:

• Galvanized thickness

• Pre-painted system

• Surface lubrication

Step 4: Compare Against Machine Specification

Match material against:

• Contract

• Technical datasheet

• Quoted production range

Step 5: Perform Controlled Test Run

Test using certified material only.

Document results.

Real Case Example

A 32 m/min roofing machine struggled to reach 25 m/min.

Buyer claimed motor undersized.

Investigation revealed:

• Machine rated for 0.5 mm G350

• Buyer testing 0.6 mm G550

• Motor operating near overload

After switching to rated material, machine reached contracted speed.

Root cause: incorrect test material.

Warranty claim rejected.

Second case:

Structural machine rated for 2.5 mm S350 steel.

Tested with certified 2.5 mm S350.

Punch frame deflected and hole misalignment occurred.

Machine could not meet rated spec.

Root cause: underspecified punch design.

Warranty claim approved.

Signs Incorrect Material Is the Cause

• Machine performs well with thinner gauge

• Problems appear only with high tensile

• Motor load spikes under heavier material

• Springback excessive

• Punching becomes inconsistent only at higher grade

These strongly indicate material mismatch.

Protecting Yourself Before Testing

Before running machine:

1. Confirm material spec in contract

2. Obtain certified mill certificate

3. Verify tensile and thickness

4. Confirm machine rated range

5. Document first production run

Never test with unknown material.

Frequently Asked Questions

Can using high tensile steel void warranty?

Yes — if outside rated specification.

Should material spec be written in contract?

Absolutely. It protects both buyer and supplier.

Can thicker material cause motor overload?

Yes. Torque demand increases significantly.

Is surface cracking always tooling defect?

No. High tensile steel may crack under tight bends.

Who is responsible for providing correct material?

Typically the buyer — unless supplier provides sample coil.

What is the most common material mistake?

Testing with higher tensile steel than machine was designed for.

Final Conclusion

Incorrect material used during testing is one of the leading causes of false warranty claims in roll forming machines.

Material affects:

• Forming pressure

• Speed capability

• Punch force

• Springback

• Surface finish

• Structural load

If machine is tested outside its rated specification, performance disputes often fall to the buyer.

However, if machine cannot perform within its stated material range, manufacturer responsibility applies.

Always verify material before claiming defect.

Without material certification, disputes become difficult to resolve.

With proper documentation, liability becomes clear.