Commissioning a Grain Cleaning Line: The Sequence From Empty to Stable Run

Commissioning goes wrong when the steps are taken out of order. Balance the air before the fans turn the right way and the settings mean nothing. Tune the machine while the feed is still changing and nothing you adjust will hold. Ramp the feed before the empty run has shown you what is rubbing, and you will be diagnosing a noise with material inside the machine.

The sequence below gives each step a fixed place. Before starting a step, agree what finished means for it, and write down what you set.

Mechanical completion, checked against the drawings

Walk the whole line against the drawings before any motor runs. This is the point where corrections are still cheap.

• Frames set, levelled and anchored, with shims bearing properly rather than loose under the feet.
• Every fastener present and tight, especially on the vibrating bodies and on the drives, which is where loose fasteners appear early.
• Nothing left inside: no tools, no blocking timber, no shipping braces, no welding slag in a spout.
• Screen decks tensioned and clamped correctly, cleaning balls present and counted, and the count written down.
• Spouts and chutes aligned and free, with no gap at a joint and no section where material can sit and build up.
• Flexible sleeves fitted between vibrating bodies and fixed ductwork, not twisted, not stretched, and clamped at both ends.
• Fans and ducts assembled, flanges meeting squarely, damper handles reachable and their positions marked.
• Guards in place, inspection doors sealing, magnet faces clean, and dust hoods over the discharge points.
• Drive alignment checked: pulley and sprocket faces in line, belts and chains at the correct tension, and nothing rubbing where it cannot be seen.

Rotation direction and safety devices, before any material goes in

Electrical work, including the checks in this step, is work for a licensed electrician, with the supply isolated, locked out and the voltage verified before any terminal is opened.

• Compare the motor nameplates with the supply you agreed, and record what you find.
• Check the earthing and bonding of frames, motors and cabinet, including the bonding across a vibrating body, made so that vibration does not loosen it.
• Confirm the direction of every motor against the arrow on the machine or the drawing, using a momentary start with the machine empty or the drive uncoupled. A fan running backwards sounds close to normal and moves very little air. This is the check that gets skipped more often than any other, and it explains a whole class of puzzling air problems.
• Check conveyor and elevator direction, and the direction of any screw conveyor, which is easy to reverse at the gearbox.
• Test every safety device for real. Each emergency stop must stop the line rather than light a lamp; each blocked chute switch must stop the feed; each level probe must act at the level intended.
• Test the start and stop sequence. Start downstream and work upstream so the material has somewhere to go; stop the feed, let the line run empty, then stop downstream.
• Test the fault response. When one machine stops, the upstream feed must stop, and the downstream should run on long enough to clear.

The empty run and the air balance

Run the line empty and record a baseline for everything measurable. That baseline is what makes later diagnosis possible.

• Listen at each machine and note periodic noise, knocking or rubbing, and where it comes from.
• Record motor current on each drive with the machine empty, along with bearing temperatures and the cabinet temperature.
• Watch belt tracking, chain movement, screen box motion and duct vibration. Note anything that moves which should be still.
• Check that the time delays and the sequence behave as intended with no material in the line.

Do not tune anything yet. The purpose is to know what normal sounds like, so that an abnormal sound later has something to be compared with.

Then balance the air, with the line still empty, because material changes everything you are measuring.

• Confirm fan rotation and drive tension once more, then set each damper to the position that gives the flow needed at its hood. Mark every damper position on the duct and write the number into the record.
• Check the pickup at each hood with a light dust source and look for escape at the hood rather than at the collector. Dust escaping before it reaches the hood is a hood problem, not a fan problem.
• Read the differential pressure across the dust collector and record it as the clean baseline for that filter set. A collector already restricted at commissioning will get worse, and without a baseline nobody can tell when it started.
• Check the air at the aspirators and at the destoner deck for even distribution across the width. Air that leans to one side gives a machine that cleans well on one half and poorly on the other.

Feed ramp-up, then sampling

Bring the feed up gradually and let the line settle at each step before increasing again. A line taken straight to production rate hides its limits and its faults together.

• Start at a low rate and watch the material across the full width of each screen. Uneven flow across a deck is a feed problem, and it is far easier to correct at low rate than at production rate.
• At each step, hold the rate long enough for the whole line to reach steady conditions, then look at bed depth, elevator current, the load on each machine, and whether any spout is running full.
• Change one thing at a time. If the feed and an air damper are moving together, you will not know which one fixed the problem.
• Note the rate at which quality begins to fall away and the rate at which the line begins to choke. Your working range sits between them, and both numbers belong in the record.

Once the line runs steadily, sample properly and agree the acceptance line with the buyer or the quality manager present. That agreement is what ends commissioning.

• Sample at each outlet at the same time, including the reject outlets, and keep every sample labelled.
• Look at the rejects, not just at the product. Whole sound grain in the light reject points to too much air or too thin a bed; sound grain in the heavy reject points to the density separation being misadjusted; whole small grain in the screen underflow points to mesh that is too open on that deck.
• Weigh the sound grain you pick out of a reject sample. Even a rough figure turns a feeling that some grain is being lost into something you can manage across a season.
• Agree how samples will be taken and tested during normal production, so the acceptance line is measured the same way every time.

What to record and hand over

• Every setting: damper positions, feed gate position, deck angle marks, screen deck identification, drive and fan configuration. Photograph each adjuster with its mark visible.
• A commissioning record with baseline currents, temperatures, damper positions and feed rates, signed by both sides.
• A short session with the operators: how to start and stop the line, what the safety devices do, how to check magnet faces and cleaning ball counts, and who to call when a noise changes.
• A written list of anything still outstanding, with an owner and a date, instead of a verbal agreement.
• The baseline sheet kept with the machine documents, so that next season starts from a known condition rather than from guesswork.

Commissioning is finished when the line holds its quality at a steady feed rate and the record explains how to get back to that point.