Why acceptance criteria matter more on custom lines
A standard machine can be bought against a catalogue. A non-standard line does not exist until it is designed for your product, your plant and your volume, so nothing can be compared against an off-the-shelf reference. Shenzhen PowerDe Automation Precision Equipment, which builds non-standard automation equipment alongside its cleaning and process equipment, works with buyers who have to describe an outcome rather than pick a model number. Without agreed criteria, each side measures success differently: the supplier points to the contract drawing, the buyer points to the line not running their product reliably.
Clear criteria also protect the supplier. A line accepted against a defined test set closes the project and releases the retention payment. A line accepted against a feeling stays open for months, with engineering support drawn back to the site.
Who writes them, and when
Acceptance criteria should be drafted by the people who will live with the line: the process or manufacturing engineer who owns the cycle time, the maintenance lead who services the equipment, the quality engineer who signs off the first articles, and the purchaser who holds the contract. A criteria list written only in the purchasing department tends to cover delivery dates and price, and to leave out changeover time, spare parts and operator training.
Timing matters as much as authorship. Criteria written after the machine is delivered are weak, because the design is already frozen and everything becomes a change order. The useful moment is the design review, before tooling is committed. At that meeting the supplier's engineering team and the buyer's team agree on the tests that will be run at the supplier's factory and the tests that will be run in the buyer's plant.
The four groups of criteria a team needs to define
1. Process and output
State the product the line is qualified on, including the variants and the material lot that will be used in the test. Define cycle time, and state how it is measured — over how many consecutive parts, and whether jams and operator interventions count against it. Define first-pass yield and the tolerance or defect list that decides a good part. For equipment where cleanliness or surface condition drives the result, define how the surface is inspected and what counts as residue, since this is exactly the kind of requirement that fails quietly when it is left unstated.
2. Availability, changeover and utilities
A rate achieved in one continuous run is not the same as a rate over a shift. Define the uptime window, the maximum acceptable stoppage, and who decides when the line is stopped. Add changeover: the time to move between the product variants listed above, measured from last good part to first good part. Then fix the utility expectations the line depends on — electrical supply, compressed air, water, and any process utility the equipment consumes — so both sides know what the plant must provide before the test starts.
3. Documentation, spares and support
List the deliverables by name: as-built drawings, electrical diagrams, the PLC or motion program and its backup, the parameter and recipe list, the risk assessment and declaration of conformity, the wear-part list with order codes, and the operator and maintenance manuals in the language the shop floor actually reads. A line that runs but cannot be maintained locally is a dependency, not an asset. State response time for support and what happens to the warranty if the buyer's own technicians carry out the repairs.
4. Training and safety
Define who must be trained, on what, and how competence is confirmed. Cover guarding, interlocks, emergency stop behaviour, noise and any emissions the process produces. Where a machine applies heat or pressure, the protection functions are part of acceptance, not a later safety review: on the fixed PowerDe HW02 steam cleaning machine, for example, the published parameter set includes 220 V operation with leakage, short-circuit, high-temperature, high-voltage, water-shortage and high-voltage-explosion protection, and its listed steam figures are 160° at 0.8 MPa. A buyer writing criteria for any heated or pressurised station should name those protection functions and the method for testing each one, instead of assuming the safety design is self-evident.
Make every criterion measurable
Write each item as a sentence with a number, a method and an owner. "The line shall run product A, variant set 1 to 3, at the agreed cycle time over a continuous production window, measured by the line counter, verified by the buyer's process engineer during the site run" is an acceptance criterion. "The line shall perform well" is an opinion. Where a requirement is genuinely qualitative, convert it into an inspection standard: a reference sample, a photographed defect list, or a checklist signed by the quality engineer.
Split the criteria into two stages, too. A factory acceptance test at the supplier's site proves the machine works before it ships, using representative product and the buyer's own witness. A site acceptance test in the plant proves the installed line works with your utilities, your operators and your material. Teams that skip the first stage carry every unresolved problem across the border on a crate; teams that skip the second stage accept a machine that only ever ran in someone else's factory.
Common gaps that turn acceptance into a dispute
The recurring gaps are predictable. Criteria that assume the buyer will supply perfect material, when incoming variation is what the line has to absorb. Test material that differs from production material. Cycle time defined without stating whether changeover, cleaning and change of consumables are inside or outside the measurement. Acceptance tied to a single machine rather than to the interface with upstream and downstream stations. And no defined treatment for findings: who logs them, who fixes them, what deadline applies, and what happens to payment while they are open. Writing these down at the design review costs an afternoon; discovering them during commissioning costs a production plan.
If your project starts from an outcome rather than a machine list — a process to automate, a cleaning or surface-preparation step to stabilise, a line to integrate — bring the draft criteria into the design review and ask the supplier to review it with you. PowerDe's engineering services cover product development, hardware testing and manufacturing automation, which is where a test plan agreed before build saves the most expensive rework. Send your process description, target output and the product variants you need qualified, and you will get back a proposal whose numbers your own team can verify at both the supplier's factory and your plant floor.
