Factory Acceptance Test

A buyer may order a machine built to its specification, and before shipment both sides can test it at the factory, where finding problems may be easier than after installation. A fictional packaging company orders a new line, and its engineers visit the maker's factory and run agreed checks, so the machine is not shipped until defined critical issues are closed.

The FAT protocol should be agreed ahead of time, listing equipment identity, drawings, test steps, expected results, tolerances and who witnesses, because a demonstration is not enough without criteria. In a fictional case, a supplier starts a motor and says it works, so the buyer asks to see safety interlocks and throughput under the agreed test plan, and results are recorded.

The test environment may use simulated loads or temporary utilities and cannot always reproduce the customer's full site, so note these limits and reserve site tests for installation effects. A fictional conveyor passes at factory voltage and simulated product weight, yet after installation it still needs checks with the real upstream and downstream equipment.

Manufacturers may use a digital twin for virtual FAT, and Siemens describes such validation for machine builders. A virtual test can supplement, but not automatically replace, the physical acceptance required by the contract, so a fictional project that tests control logic virtually before the machine is complete still keeps the final physical checks on the agreed schedule.

The buyer or a third-party inspector may witness tests, so specify whether remote viewing is permitted and how evidence is captured, because attendance does not by itself mean acceptance and a fictional customer watching via video needs a test record containing instrument readings and signatures, not merely an attendee list. Calibration and measurement quality matter, since a pass based on an unverified instrument may be challenged, so record device IDs and certificates where required; in a fictional pressure test using a gauge with expired calibration, the parties repeat the measurement with a verified gauge before release.

Non-conformities should be classified by severity: a safety defect may block shipment, while a minor documentation issue may be closed later if the contract allows, and each exception needs an owner. A fictional panel passes performance tests but lacks a label, so the buyer conditionally releases it only if the agreed protocol permits that exception and specifies correction.

A FAT checklist can include readiness, witnessed results, corrective actions and a release or hold decision, and the supplier's test record should support the decision, since a generic certificate without results is weak evidence. A fictional machine passes eight of ten scenarios, so the team logs two failures and reruns them after repair, and the final report shows both original and retest outcomes.

A factory pass does not prove shipping caused no damage, so inspect on arrival and use site acceptance tests to verify installation, connections and integration; a fictional transformer passes at the manufacturer's works and, after transport, the site team inspects it and performs required commissioning checks. Payment milestones may be tied to FAT completion or shipment release, so read the contract before assuming the test signature transfers title, risk or final acceptance, as a fictional client learns when a witnessed test sheet is signed yet installation tests are still required before final payment.

The test should include failure modes and safety functions, not only normal operation, using practical scenarios based on risk and never unsafe conditions, and software and configuration versions should be captured, because a fictional firmware update after FAT may invalidate earlier results until the affected functions are retested. Documentation such as drawings, manuals, spare parts and training plans may be FAT prerequisites or handover requirements, so state the boundary and allow time for corrections and retests, since rushing a test just before collection can create expensive site fixes, and remember that the FAT is a pre-shipment evidence gate that strengthens confidence but does not replace site commissioning, warranties or continuing quality control.