Scope drift starts as a small drawing change
Most non-standard automation projects do not fail in one dramatic moment. They fail in increments: one extra sensor bracket, one re-arranged workstation, one actuator moved to a different side of the frame. Each change looks reasonable on its own. Stacked together across three revision rounds, they change what the machine has to prove, and the verification plan that was agreed at the start no longer matches what is being delivered.
If your team is buying custom automation, the first place to look is the boundary of the delivery. Decide where the machine stops and where the line, the utilities, the fixtures and the operators begin. Write that boundary down and attach it to every change request. When a modification crosses the line you drew, treat it as a new scope item with its own cost and its own schedule, not as a favour between engineers.
Confirm the takt before you confirm the machine
Cycle time is usually quoted as a clean, ideal number. Real production has changeover, jam recovery, material that arrives slightly out of position, and operators who pause to check a result. Ask how the required cycle time was measured, and whether it includes the loading and unloading steps that sit outside the machine frame.
Two numbers are worth separating in the contract language. The first is the steady-state cycle time the machine should hold once running. The second is the availability the line needs across a shift, including stops. A machine can meet the first number and still miss the production target. Agreeing on both avoids an argument at the factory acceptance stage, when nobody wants to reopen the layout.
Put change control in writing early
A written change-control process is not paperwork for its own sake. It is the mechanism that turns a design idea into a priced decision. For each change, require the same four items: what the change is, why it is needed, what it costs, and what it delays. Without the fourth item, schedule impact stays invisible until the installation window collapses.
Also fix the version of the drawings and the control logic used during acceptance. A machine accepted against an out-of-date drawing creates disputes later about what spare parts belong to the delivery. Confirm that the released drawing set, the PLC and HMI program and the bill of materials all carry the same revision reference before handover begins.
Design for the people who will maintain it
A machine that works well in a supplier's workshop can still be unusable on your floor if routine maintenance is difficult. Before sign-off, walk the machine with the maintenance technician who will own it. Check that guards open far enough for a hand and a tool, that consumables can be reached without dismantling a station, and that worn parts can be ordered by an exact name and quantity.
Ask for the spare-parts list to separate two groups: parts expected to wear within a defined interval, and parts held only for breakdown cover. That distinction changes both the purchase order and the stocking plan. Ask the same question about the consumables that the machine needs — filters, seals, nozzles — because these are frequently the items that stop a line while everyone waits on a shipment.
Make integration tests part of acceptance
Functional testing usually proves that each station does its job. Integration testing answers a different question: what happens when the machine talks to the equipment next to it. Signal timing, handshaking, alarm behaviour and restart sequence are where projects lose weeks. A single disagreement about which side clears a fault, or how the line resumes after an e-stop, can turn a short commissioning visit into several.
Write the integration cases into the acceptance document as a list you will actually run. Include a power-loss recovery, an intentional fault injection at a handoff point, and one run with parts that are at the tolerance limit rather than perfect samples. Those three cases reveal far more than a smooth run with ideal parts.
Cleaning and housekeeping are part of the machine
Custom automation collects residue: cutting fluid, oil mist, dust, grease, food residue. What matters is how the machine is cleaned and how often, and whether the cleaning method was considered during design or discovered afterwards. Check that surfaces likely to hold residue are accessible, that electrical enclosures are protected from the cleaning method you plan to use, and that drains and drip trays are part of the frame rather than an improvised addition.
If your site already cleans machinery with heat, the cleaning method needs to be stated in the machine specification before build. Our industrial steam cleaning equipment is specified for exactly this kind of maintenance work on production machinery, where removing oil and residue without dismantling stations is the whole point. For a line being built from scratch, the same decision has to be made earlier: which surfaces will be cleaned, how, and what the machine design must provide so that cleaning does not become a teardown exercise.
Check the supplier's engineering capacity, not just their quote
A competitive price means little if the same two engineers carry the design, the panel build, the programming and the commissioning. Ask who will be assigned to your project, at what stage, and what else they are carrying. Ask who covers their absence. These answers predict schedule risk more accurately than the Gantt chart.
Shenzhen PowerDe Automation Precision Equipment works on custom automation and process equipment alongside its cleaning-equipment line, and offers non-standard automation equipment built around the customer's process rather than a fixed catalogue machine. If you need an engineering partner from concept through build, the integrated engineering team services cover development, testing and manufacturing support under one delivery responsibility.
A short list to review before you sign
Before contract signature, be able to point to a document for each of these: the delivery boundary; the measured cycle time and the availability target; the change-control rule including schedule impact; the released drawing and program revision used for acceptance; the spare-parts and consumables lists with wear intervals; the integration cases including power-loss recovery; and the cleaning method with its access requirements. Anything you cannot point to is a risk you have accepted without pricing it.
Send those seven items to your supplier as questions rather than statements. The quality of the answers — and how quickly specific documents come back — tells you more about the delivery to come than any promise in the proposal.
