FAT vs SAT for Automated Assembly Equipment: Acceptance Checklist

When we review an automated assembly project at KH Group, we start acceptance planning with a practical question: What evidence will show that the equipment meets the buyer's requirements? A machine running smoothly for a few minutes is useful to see. It does not, by itself, prove output, quality, safe recovery, or reliable integration with the buyer's plant.

Factory Acceptance Testing (FAT) verifies the equipment under agreed conditions at the supplier's facility. Site Acceptance Testing (SAT) verifies the installed system in its actual production setting. We recommend one acceptance matrix that connects both stages, with clear test conditions, pass criteria, evidence, and owners. The goal is to prove good-part output, controlled recovery, and complete handover, not just machine motion.

This guide explains how we would structure that review for automated assembly equipment. Use it to prepare a project-specific test protocol with your supplier. The signed technical specification, approved requirements, applicable safety obligations, and agreed acceptance procedure remain the basis for decisions.

What Is the Difference Between FAT and SAT for Automated Assembly Equipment?

FAT establishes evidence before shipment; SAT adds evidence that depends on installation and real plant conditions. Both address the same agreed requirements, but their methods and test boundaries can differ. Keeping that distinction clear helps buyers avoid accepting an unresolved interface simply because the machine completed a factory run.

One acceptance plan connects the factory tests, shipment decision, site verification, and final handover.

When Should FAT and SAT Acceptance Criteria Be Defined?

Acceptance criteria should be defined before equipment build. Start with the RFQ and technical specification, then agree the test method before detailed design choices become difficult to change. Our Automated Assembly Line RFQ Checklist: What Buyers Should Specify explains the upstream information buyers should prepare.

Connect each requirement to a test

Give each requirement an ID and state how it will be checked. Record the product variant, test conditions, sample quantity, measurement method, pass threshold, and responsible person. A statement such as "verify cycle time" is incomplete until both parties agree what starts the clock, what stops it, and how losses are handled.

Identify the site-only scope

Mark functions that cannot be fully demonstrated at the supplier's facility. These may include live MES transactions, conveyor handshakes, actual utility behavior, or operator tasks under the final layout. Assign them to SAT with defined prerequisites and owners so they do not disappear between shipment and installation.

What Should Be Completed Before the FAT Begins?

A FAT readiness review prevents the acceptance visit from turning into an unfinished build review. Confirm that the agreed scope is ready and that the right samples and measuring tools are available. Separate planned limitations from unexpected failures.

• Approved drawings and specifications: Confirm the current mechanical, electrical, pneumatic, layout, and requirement revisions.
• Machine completion: Check that the hardware needed for the planned tests is installed and ready.
• Software and recipes: Identify the PLC, HMI, robot, vision, and recipe versions under test.
• Test materials: Prepare the agreed variants and sample range, including representative difficult parts where relevant.
• Measuring equipment: Use instruments with suitable range, resolution, and calibration status for the acceptance measurements.
• Approved protocol: Agree test order, attendance, recording format, and handling of deviations.
• Open issues: Identify any issue that prevents a meaningful or safe test before the run begins.

What Should Be Checked During the Factory Acceptance Test?

Mechanical construction and access

Review fixtures, guarding, fasteners, alignment, component identification, and access for routine service. Check the real tasks involved in replenishing feeders, changing tooling, and removing rejected parts. Maintenance access should be considered within the approved safety design, not improvised during the test.

Electrical and pneumatic systems

Compare the installed system with the approved drawings. Check component identification, cable and tube routing, air preparation, and agreed operating conditions. Record the actual supplies used during FAT because a stable temporary supply may differ from the buyer's plant.

Controls and assembly functions

Exercise automatic and manual modes, recipe selection, alarms, and sequence transitions under the approved procedure. Follow parts through feeding, positioning, assembly, inspection, and disposition. Confirm what happens to each part, including failed and interrupted parts, rather than checking only whether each actuator moves.

Safety functions

Qualified personnel should verify the required protective functions against the approved safety specification and test protocol. The scope may include emergency stops, guard interlocks, protective devices, and reset behavior. Keep the results and required timing measurements where applicable; a general checklist does not replace the machine's safety validation.

AI-generated illustration: An automated assembly equipment FAT run-off setting. This is not a photograph of an actual KH Group project.

How Should Cycle Time and Production Capacity Be Verified During FAT?

In our engineering review, an output target needs a complete measurement definition. "Eight seconds per part" could describe one station, the line's output interval, or an average that includes stops. For the underlying terms, see How to Calculate Takt Time, Cycle Time, and Line Capacity for an Automated Assembly Line.

Define the measurement boundary

Specify the event that starts and ends each measurement. For example, consecutive completed units at the same output point can establish output intervals. A fixed-duration run can establish total and good-part throughput, but elapsed run time divided by output is not proof that every individual cycle meets a maximum limit.

Fix the test conditions before the run

• Products: Identify the SKU, variant mix, material condition, and batch or cavity counting method.
• Time: Define the run duration, warm-up treatment, and any permitted exclusions.
• People and losses: Record staffing, operator intervention, micro-stops, replenishment, and longer downtime.
• Line boundaries: Define upstream supply, downstream discharge, buffer levels, and changeover treatment.
• Acceptance measures: Agree cycle-time statistics, good-part output, quality thresholds, and stability requirements.

Buffer conditions matter. A short test can look strong if it starts with full upstream buffers or stores unfinished work downstream. Record start and end conditions so inventory movement does not disguise a bottleneck or incomplete processing.

These figures are examples only, not KH Group equipment specifications or recommended universal acceptance limits.

Agree the timing method and compare output, losses, and quality against the same test conditions.

How Should Product Quality Be Verified During FAT?

A fast machine has not proved its target if the required good-part rate is missed. Define the critical-to-quality features, measurement methods, and acceptance limits alongside throughput. Depending on the process, checks may concern assembly position, fastening, electrical results, or other specified product characteristics.

Use samples that represent the agreed production range

Prepare normal samples, relevant boundary samples, and known defects as appropriate to the project. Testing only easy-to-feed, ideal parts leaves uncertainty about the agreed material range. Record sample identities and expected results so a challenge test can be repeated and reviewed.

Verify detection, rejection, and data together

Check that the system detects the selected defect, assigns the correct result, and routes or contains the part as specified. Confirm that rejected parts cannot silently rejoin accepted output. Keep measurement records linked to part IDs where required, and distinguish first-pass good parts from parts accepted only after rework.

What Fault and Recovery Scenarios Should Be Tested?

Normal running shows only part of the equipment's behavior. We recommend a planned fault-recovery review to examine what the machine reports, how it responds, and what happens to work in progress. A cleared alarm is not enough to prove a correct recovery.

Choose controlled fault challenges

Depending on the equipment, scenarios may include missing or misoriented parts, feeder jams, inspection failures, robot or servo faults, and loss of a supply. Emergency stops and guard openings also require verification within the safety test plan. Use qualified personnel and approved methods; do not bypass safeguards or create uncontrolled hazards to force a fault.

Follow the part through the recovery

1. Detect: Verify the correct alarm, location, and operator guidance.
2. Respond: Check the specified protective or process response and containment of affected work.
3. Identify: Determine which parts are complete, incomplete, suspect, or awaiting inspection.
4. Recover: Correct the cause and restore the required conditions using the approved procedure.
5. Restart: Confirm the intended sequence without unexpected movement, duplicate processing, or skipped operations.
6. Verify: Inspect the recovered output and check routing, quality results, and traceability.

For example, interrupting a fastening operation may leave a part with uncertain process status. The expected recovery could require rejection, a controlled rework path, or a verified resume sequence, depending on the design. Define that disposition before testing, then check the physical part and its record together.

Recovery testing connects machine behavior with product disposition, controlled restart, and traceability.

What Changeover Tests Should Be Included in FAT?

For a multi-variant system, test the agreed tooling and recipe changes as real operating tasks. Specify whether changeover timing begins with the last good part of the previous variant or another defined event. State whether it ends at mechanical readiness or the first accepted part of the next variant.

Check tooling identification, recipe selection, parameter limits, and any specified wrong-recipe prevention. Include the normal staffing and tools. Confirm the first part after changeover, and record adjustments or manual steps that were needed to obtain it.

What Documentation Should Be Approved Before Shipment?

Successful machine tests should be accompanied by an agreed document handover status. Define which files must be complete before shipment and which approved items, if any, will follow later. A document list needs revisions, owners, and delivery dates to be useful.

• Drawings: Mechanical drawings, electrical schematics, pneumatic diagrams, and installation information.
• Program and parameter files: PLC, HMI, robot, vision, and recipe backups within the agreed delivery and licensing scope.
• Safety records: Required risk assessment and safety verification documentation for the project.
• Operating support: Operation and maintenance manuals, spare parts, wear parts, and service instructions.
• Acceptance evidence: FAT report, raw test records, deviations, retest results, and release decisions.

Which FAT Findings Should Block Shipment?

Agree issue severity and release authority before the test. The labels below are a practical structure, not automatic contractual rules. Severity should reflect the consequence of the issue, not simply the component or document involved.

Shipment authorization, payment milestones, and final acceptance may be separate decisions. Their consequences follow the contract and applicable requirements. Do not treat an engineering punch-list label as a substitute for those decisions.

What Should Be Checked When the Equipment Arrives on Site?

Start with a documented delivery and installation check. Inspect transport damage, verify machine identity and delivered components, and check reassembly, leveling, alignment, and connections. Compare the installed configuration with the approved FAT baseline and record any difference before relying on earlier results.

Verify that actual power, compressed air, network connections, and other required services meet the design conditions. Confirm the physical space for operation, replenishment, maintenance, and safe access. A machine that passed FAT still needs this installation evidence.

What Should Be Verified During the Site Acceptance Test?

Real utilities and connected equipment

Test the machine in the agreed installed arrangement with actual upstream and downstream interfaces. Check handshakes, blocked and starved conditions, and recovery after interruptions. Where MES or traceability is in scope, verify live records, acknowledgments, and the specified handling of unavailable connections.

Production materials and site operators

Use the agreed production materials and involve the operators who will run the equipment. Observe replenishment, response to guidance, changeover, and restart tasks. Supplier engineers completing every intervention would not demonstrate that the intended operating method is ready for handover.

Installed production performance

Confirm output, quality, and stability under the agreed site test conditions. If these differ from FAT, record the differences rather than comparing headline numbers alone. For example, real bulk feeding and fluctuating plant air can expose behavior that was not represented by staged parts and a temporary supply.

Which FAT Tests Should Be Repeated During SAT?

Repeat tests because the risk or conditions changed, not because SAT is simply a second FAT. Reverify required safety functions after installation and examine functions affected by transport, reassembly, software changes, or interface integration. Include critical process functions, cycle-time confirmation, quality checks, and traceability as defined by the site protocol.

A changed robot program or vision recipe may require targeted regression beyond the edited function. Use the change record and acceptance matrix to identify the affected requirements. Preserve the original FAT result while adding the new configuration, reason for retest, and SAT evidence.

How Should Deviations and Punch-List Items Be Managed?

Each deviation should show the requirement, expected result, actual result, test conditions, and supporting evidence. Assign an owner and record the cause when established, without presenting an early assumption as fact. Define corrective action, due date, and the scope of retesting.

Close the item only after the agreed evidence is reviewed by the authorized person. A note saying "program updated" does not show that the failure was corrected without creating another problem. Link the retest record and revised configuration to the original issue.

What Should Be Included in a FAT-to-SAT Acceptance Matrix?

The matrix below brings the two stages together. Add requirement IDs, test conditions, owners, and result fields to your working project record. Set the numerical thresholds before testing; X, Y, and Z below are placeholders, not universal limits.

What Should Buyers Sign Before Final Equipment Acceptance?

Final handover should connect the acceptance decision to the tested configuration and supporting records. Review the FAT report, SAT report, closed punch list or expressly approved residual items, document handover, software backup delivery, and training records. Confirm that the people signing have the agreed authority.

Keep shipment release, completion of installation, and final equipment acceptance distinct. The final record should state what has been accepted and identify any approved exception with its resolution plan. That gives the buyer and supplier a clear reference after the equipment enters normal production.

Which Assembly Line Projects Can Use This Acceptance Structure?

The same requirement-to-evidence approach can be adapted to different assembly projects. The actual test content should follow the product, process, and agreed equipment scope. Explore these KH Group assembly line pages when preparing your project discussion.

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