A test plan for slit coating equipment is the document both sides sign before the machine ships and again before the buyer accepts it. For a slot-die coater running perovskite solar cells, lithium-ion battery electrodes, quantum-dot LED and OPV work, the plan is not a checklist of mechanical parts. It is the list of coating results the equipment has to reproduce in your material, on your substrate, at your speed. Written before the purchase order is signed, most of the arguments about acceptance disappear on their own.
State your product target before you list any test
Four numbers set the rest of the plan, and all four come from you rather than from the machine: the coating thickness you need, the coating width, the line speed you intend to run, and the substrate you will actually feed. On the slit coating equipment page the recorded envelope is a coating thickness of 5 to 200 um, a coating width of 50 to 350 mm, an equipment speed that can be set from 1 to 10 meters per minute, and a slit coating method with electric heating. A plan that asks this class of machine to coat below 5 um, wider than that width, or faster than that range is asking the wrong question of the wrong machine.
Write those four numbers once and reuse them in every test below. A plan that tests a machine in the abstract passes easily and proves nothing. A plan that tests it against your product target is worth the paperwork it costs you.
Coating quality: the tests that decide acceptance
Define the film checks first, because coating uniformity and the width of the usable coating window are the reasons a lab moves from spin coating to a slot-die system. For each test, say who measures, with what instrument, on how many consecutive samples, and what result counts as a pass.
Across the width, measure left, centre and right of the coated stripe on every sample in the run and compare against your band. Along the web, measure the start, middle and end of one continuous run; that is where speed and drying behaviour show up. Then look for the defects that slot-die coating actually produces: streaks along the web, dry material falling from the die lip, edge beads, pinholes, and dewetting at the stripe edge on a substrate you have not treated.
Add a coating-window demonstration rather than a single nominal run. Require the result to hold at the slow and fast ends of your speed range and at both ends of your thickness band, not just at the comfortable middle setting. Finally, record how the web is held and whether the pass-through path marks or scratches the film, because upstream and downstream handling of a full perovskite production line equipment layout expects the incoming film to arrive untouched.
Throughput and pass rate: define how you will count, not what is printed
The specification table for this equipment family lists a machine appearance of 2540 mm by 800 mm by 1650 mm, an oven, an adjustable deviation correcting device, an inflatable shaft of 3 inches as the rewinding device, electric heating, an equipment pressure recorded as 6 kg/cm, a three-colour warning light for fault prompting, and a product pass rate of at least 99.5%. Read that last figure as a starting claim, not as your acceptance result.
In the plan, write how the pass rate is calculated in your own process: what makes a coil rejected, who judges a borderline film, and whether the scrapped metres at the start of a run count against the number. The same rule applied on both sides of the table is the only version of that figure that can settle a disagreement. For the drying section, ask for the profile you will actually run, how the length of the oven is set for your solvent, and what happens to film quality when you move across the speed range. The footprint and the oven length are also the numbers your lab layout depends on, so put them in the plan with a note asking the supplier to confirm the current figures against the configuration you are ordering; that page mixes units across rows, which is a reason to confirm rather than to assume.
Repeatability across days, batches and operators
One perfect coil proves very little. Require a repeat block: the same recipe run on three separate days, with a fresh batch of coating liquid, and the die cleaned between runs. Name who performs each run. If only the engineer who commissioned the machine can produce acceptable film, you have bought a demonstration rather than equipment.
Put the interruptions into the same block. A web break, a mid-run material changeover, a power interruption and the restart afterwards. These are where a coating system loses real production time, and they cost almost nothing to test while the machine is still in the supplier's plant and their engineer is standing next to it.
Changeover, cleaning and the research workflow
In a lab that changes material every week, changeover belongs in the plan as a measured activity rather than a hope. Time the slot-die change, the flush and clean, the loading of a new roll on the rewinding shaft, and the metres of substrate wasted before the first acceptable film. Those minutes decide how many experiments a researcher completes in a week, and they are the part of the ownership cost a specification table never shows.
If your formulations are atmosphere-sensitive, say so in the plan and test them there. Early screening for such work is often done on glove box spin coating equipment, so the plan should state which steps run inside the box, which run in air, and how the transfer between them is handled without ruining the film.
Documentation, fault handling and service terms as test items
The last part of the plan lists what you receive with the machine, because buyers forget to test it. Ask for the drawing and layout file, the parameter table for the exact configuration you bought, the recipe and setting list used during the demonstration run, and a spare-part and consumable list with part numbers. Confirm how the fault prompting works, including the three-colour warning light recorded on the page, and agree which faults stop the machine and which only warn the operator.
Write the service terms as tests too: response time, what support looks like when a defect appears on a film you cannot reproduce at your site, which consumables are stocked, and what a spare part costs and how long it takes to arrive. A supplier who has accepted your test plan in writing has already answered most of these questions before the negotiation starts.
A short acceptance checklist
Before you sign, check six lines. Your thickness band, width, speed and substrate are on page one and fall inside the recorded operating envelope. Every coating test names its instrument, sample count and pass condition. The extremes of speed and thickness are tested, not only the nominal setting. Repeatability is tested across days, batches and operators. Changeover, cleaning and wasted metres are timed. And the pass-rate rule, drawings, spares and service response are written down and agreed by both sides.
Send your material system, substrate size and target throughput with that checklist and ask which items the machine can demonstrate before shipment. A supplier who wants those details before recommending a configuration is answering the same question you are: whether this coater will hold your film on the days nobody from the supplier is watching.
