Acceptance Test Disagreements — When Roll Forming Machine FAT & SAT Results Don’t Match Expectations

Acceptance testing is supposed to prevent disputes.

Yet in the roll forming industry, Acceptance Test Disagreements are one of the most common causes of commercial conflict between buyer and supplier.

Typical scenarios:

Machine passed factory test — but fails onsite
Performance at FAT was higher than at SAT
Speed achieved in factory cannot be repeated
Profile dimensions differ from approved samples
Punch alignment shifts after installation
Buyer refuses final payment due to performance concerns

At the center of these disputes are two critical terms:

FAT — Factory Acceptance Test
SAT — Site Acceptance Test

When expectations are not clearly defined in contract, disagreements become inevitable.

This guide explains:

What FAT and SAT really mean
Why results differ
When warranty applies
When responsibility shifts to site conditions
How to protect your position

What Is a Factory Acceptance Test (FAT)?

A FAT is performed at the manufacturer’s facility before shipment.

It typically verifies:

Machine runs mechanically
Profile matches drawing
Punch locations correct
Cut length within tolerance
Electrical system functional
Safety circuits operational
Production speed demonstrated

FAT conditions are usually:

Controlled material
Stable power supply
Factory-trained operators
Ideal setup conditions

FAT proves the machine functions — but not necessarily under every site condition.

What Is a Site Acceptance Test (SAT)?

SAT occurs after installation at buyer’s facility.

It verifies:

Machine installed correctly
Electrical supply compatible
Foundation stable
Local material compatible
Production meets contractual performance

SAT is where most disputes arise.

Why?

Because site variables introduce new factors.

Why FAT and SAT Results Often Differ

1. Different Material Used

At FAT:

Certified material within spec

At SAT:

Local coil
Higher tensile
Thickness variation
Width inconsistency

Material differences dramatically affect performance.

2. Electrical Supply Variation

Factory power is stable and balanced.

Site power may have:

Voltage drop
Phase imbalance
Frequency fluctuation

This affects:

Servo stability
Motor torque
Hydraulic performance

3. Installation & Leveling Differences

Factory setup is:

Precision leveled
Properly shimmed
Optimally aligned

Site installation may introduce:

Frame twist
Uneven anchoring
Floor flex

This impacts product quality and vibration.

4. Operator Experience

Factory operators:

Know optimal settings
Understand roll progression

Site operators may:

Adjust incorrectly
Overtighten stands
Alter parameters

Training gaps create perceived “performance loss.”

5. Environmental Differences

Temperature, humidity, dust, and vibration affect:

Electrical components
Hydraulic systems
Material behavior

Factory conditions are controlled — site conditions may not be.

Common Acceptance Test Dispute Scenarios

Scenario 1: Speed Achieved at FAT but Not at SAT

Buyer claims machine cannot reach contracted speed.

Investigation reveals:

Higher tensile material
Conservative servo tuning
Hydraulic pressure reduced

Responsibility depends on contract-defined speed conditions.

Scenario 2: Profile Dimensions Different Onsite

Factory sample approved.

Onsite panels slightly out of tolerance.

Cause may include:

Material variation
Installation twist
Setup differences

Mechanical defect must be proven before warranty applies.

Scenario 3: Punch Alignment Correct at FAT, Misaligned at SAT

Potential causes:

Strip width variation
Encoder recalibration
Frame flex
Installation misalignment

Responsibility depends on root cause.

When Acceptance Test Disputes Become Warranty Claims

Warranty may apply if:

Machine cannot meet agreed tolerance under defined conditions
Performance guaranteed in contract
Material and installation match specification
Mechanical defect identified

Warranty may not apply if:

Conditions at SAT differ from FAT
Material differs from approved specification
Installation not compliant
Parameters modified without authorization

Contract clarity is critical.

The Importance of Written Performance Specification

To avoid disputes, contract must define:

Material thickness range
Tensile strength range
Strip width tolerance
Production speed definition
Dimensional tolerance
Whether punching included in speed rating
Acceptance criteria

Without written criteria, disagreements become subjective.

Structured FAT & SAT Protection Checklist

Before FAT

Define performance criteria in writing
Confirm material specification
Confirm speed definition
Agree measurement method
Record full FAT video
Sign FAT approval document

Before SAT

Confirm electrical supply matches specification
Confirm foundation compliance
Use certified material
Reconfirm PLC baseline parameters
Ensure trained operator present
Document SAT results clearly

Real Case Example

A 30 m/min structural machine achieved 30 m/min at FAT.

At SAT, maximum stable speed was 24 m/min.

Buyer withheld payment.

Investigation revealed:

Site material tensile 18% higher than FAT material
Motor operating at near full torque
Frame vibration increased

Under contracted material spec, machine met performance.

Dispute resolved in supplier’s favor.

Second case:

Roofing line approved at FAT with 1000 mm cover width ±1 mm.

At SAT, width tolerance ±4 mm.

Material confirmed correct.

Inspection revealed:

Frame base twisted during installation
No proper shimming

After re-leveling, tolerance returned to ±1 mm.

Root cause: installation error.

Warranty claim rejected.

Third case:

Punching line passed FAT.

At SAT, hole alignment consistently off by 2 mm.

Material and installation verified correct.

Inspection revealed punch frame deflection under load.

Design reinforcement required.

Warranty claim approved.

Signs Acceptance Dispute Is Site-Related

Performance varies by coil
Vibration increases at higher speed
Electrical alarms inconsistent
Issues improve after re-leveling

Likely SAT condition difference.

Signs It May Be Manufacturing Defect

Same issue reproducible at factory
Mechanical measurement shows tolerance error
Machine cannot meet stated spec under agreed conditions
Defect independent of material or installation

Likely warranty responsibility.

Frequently Asked Questions

What is the difference between FAT and SAT?

FAT is factory testing before shipment. SAT verifies performance after installation onsite.

Can performance differ between FAT and SAT?

Yes. Material, electrical supply, and installation differences affect results.

Should acceptance criteria be written in contract?

Absolutely. Without written criteria, disputes are difficult to resolve.

Can buyer refuse final payment due to SAT performance?

Yes — if machine fails to meet contract-defined criteria.

Is supplier responsible for site conditions?

Typically no — unless installation and commissioning included in contract.

What is the biggest cause of acceptance disputes?

Unclear performance definitions in contract.

Final Conclusion

Acceptance test disagreements are rarely about bad faith — they are about unclear expectations.

Most disputes arise because:

Material not defined clearly
Speed not defined precisely
Tolerances not written
Installation conditions not verified
FAT and SAT criteria not aligned

A roll forming machine may perform perfectly at factory — yet fail at site due to environmental or setup differences.

Clear contract terms, documented testing, and structured verification prevent costly disputes.

Without written acceptance criteria, disagreements become subjective.

With structured FAT and SAT documentation, liability becomes clear.