Define the scope before defining the tests
A non-standard machine is built for one product, one line, and one set of operators, so its acceptance criteria start with what the machine is supposed to replace. Write down the parts or products it handles, the upstream and downstream equipment it connects to, the shift pattern it will run under, and the number of people assigned to it. If the machine is intended to run on a line that also processes other variants, the plan must state which variants are in scope and which are not, because "it works" on one variant is a different claim from "it works on the line".
For buyers sourcing non-standard automation equipment, this scope section is also the point where later change requests get priced. A test plan that only says "automatic feeding and discharge" leaves room for a dispute about tolerance ranges, part orientation, and reject handling. A plan that names the part geometry, feeding method, and reject route does not.
Functional and process tests
Walk through every station and every mode. The plan should list each function as a separate pass/fail line: manual and automatic modes, start, pause, resume, normal stop and emergency stop, recovery after a stop, alarm display and reset, and the behaviour of interlocks. Add the process functions that matter for quality: how the machine detects a missing part, a mis-oriented part, an out-of-tolerance result, and what it does with each. For any station that applies heat, pressure, vacuum, or force, the plan should require a recorded run of the actual process parameters, not just a check that the display shows a set value.
Where a machine has more than one recipe or product setup, require a changeover test with a timed sequence: unload the previous setup, load the new recipe, run first-piece verification, and record the elapsed time. Changeover work is where custom machines most often fail to meet expectations, and it is rarely tested because it is assumed to be simple.
Cycle time and continuous-running tests
A single fast cycle proves little. Split this into three items. First, a steady-state cycle-time measurement with the machine fully fed and discharging normally, recorded over enough consecutive pieces that one good cycle is not mistaken for an average. Second, a continuous running test over a realistic shift length, including interruptions, where the count of stops and their causes is logged. Third, a recovery measurement after a jam or an emergency stop, since a machine with a good nominal cycle and a poor restart loses more than a slower machine that recovers quickly.
For each item, state in the plan who starts the stopwatch, how many pieces or minutes are measured, and what counts as a stop. Those three details decide whether the two sides reach the same number.
Quality output and capability
The machine must produce parts that pass the buyer's own inspection, so the plan should name the inspection method, the gauge, and the acceptance limit for every characteristic the machine affects — alignment, position accuracy, bond or weld quality, absence of bubbles or burrs, and dimensional results. Specify that parts come from a run of real production material, not from a set of hand-picked samples, and that first-piece, in-process, and last-piece checks are all recorded. Where the process is sensitive to material lot variation, include a second run with a different material lot.
Integration, safety, and utilities
Non-standard machines rarely stand alone. The plan should test the signal exchange with adjacent equipment and the host system: ready, running, fault, and complete signals; the data fields the machine is expected to send or receive; and behaviour when the connection drops mid-cycle. On the safety side, list guarding, light curtains, interlocks, emergency-stop reachability from each operator position, and any pressure, temperature, or vacuum hazard specific to the process. Utilities are the least glamorous source of failure: verify the required power supply, compressed-air pressure and flow, water supply, and exhaust or drainage against the nameplate and drawing, and confirm the machine does not disturb the shared supply of other equipment on the same line.
Cleaning and maintenance access belongs here too. Specify how each wear part is reached, what the cleaning routine is, and how long a scheduled cleaning takes. A design that requires dismantling a guard to clear each shift's residue will be worked around by operators, and the resulting downtime shows up as a reliability complaint months after delivery.
Documentation, spares, and training
Make the document package part of acceptance rather than a follow-up delivery. At minimum: the electrical and pneumatic drawings as built, the parts list with the actual purchased components and their model numbers, the PLC and HMI program backup, the parameter and recipe list with factory-set values, the calibration records for any instrument used for measurement, and the instruction manual in the language the operators read. Add a spare-parts list with prices and lead times, and record consumable life so maintenance can be budgeted.
Training should have its own line in the plan: who is trained, on what, and what they must be able to do unaided afterwards — changeover, alarm clearing, consumable replacement, and the shutdown routine. An acceptance test that a supplier engineer performs alone proves nothing about the buyer's ability to run the machine the following week.
Factory and on-site phases
Divide the plan into a factory acceptance test and an on-site acceptance test, and be explicit about what is proven at each. Factory testing can cover function, cycle, and quality output using the buyer's material brought to the builder. On-site testing then covers installation, integration with the real line, and repeat performance under real shift conditions. The plan should list which items are repeated on site rather than assumed to carry over — integration and continuous running almost always are.
Close the plan with the decision rules: what counts as a pass, who signs each section, how a failed item is logged, and what the retest looks like. Keeping that record — one sheet per test item, with measured values rather than tick marks — is what makes the acceptance meeting short.
Working with an engineering partner
Because these criteria are written before the machine is designed, the supplier's engineering capability shapes how concrete the plan can be. Shenzhen PowerDe Automation Precision Equipment describes its work as covering equipment R&D and manufacturing, system integration, customized configurations, and technical support, with engineering services that include product development, hardware testing, and manufacturing automation. Buyers who supply the acceptance criteria at the specification stage — target cycle, inspection method, changeover time, and documentation package — typically get a machine whose test plan reads as a list of measurements instead of a list of intentions.
A practical way to start is to draft the test plan from the process complaint you are trying to solve, list every characteristic the machine must control, and put a measured value and a method next to each. If a line item cannot be measured with an instrument or a gauge you already own, it is not a test — rewrite it until it is.
