Most vibrating screen problems start small and get expensive when they are left alone. A slightly soft cut becomes a customer complaint; a blinded strip of deck becomes a lost shift; an ignored knock becomes a cracked side plate. The encouraging news is that screens are honest machines: nearly every fault announces itself early, in the product, the sound or the motion, and nearly every one traces to a short list of causes. This article works through the problems we are called about most, what each usually means and how to fix it.
Problem one: the product is going off-spec
Oversize in the fines means holes have grown or torn: inspect the media and measure the apertures, because worn wire quietly recuts the product weeks before it fails visibly. Undersize riding over into the coarse product points the other way, to blinding, pegging, an overloaded deck or a bed running too deep to stratify. Sample each product stream, look at which direction the misplaced material travels, and the screen tells you which fault you have.
Fixes follow the diagnosis: replace or re-tension media, clear and counter the blinding, or bring the feed rate back to what the deck area supports. What never works is nudging the stroke and hoping; settings were not the thing that changed.
Problem two: blinding
Damp fines and clay coat the mesh until the apertures close, throughput slumps and the undersize rides over. Short-term, cleaning restores the deck for a while. Long-term, the answer is to stop the build-up: electrically heated decks and mesh cleaning systems keep the wire too warm and too lively for damp fines to bond to, flexible media flexes deposits off, and on chronically wet feeds a change of deck geometry, towards finger sections or steeply inclined sizer decks with oversized apertures, removes the vulnerability altogether.
Problem three: pegging
Near-size particles wedge in the apertures and stay, closing the deck from within. Elongated stone in square holes is the classic case. Slotted apertures, self-cleaning wire profiles, polyurethane whose flex releases the wedged particle, or a small change in aperture size relative to the troublesome fraction all work. Pegging that appears suddenly on a deck that was fine usually means the feed’s shape or size distribution changed upstream, often at a crusher whose setting or liners have drifted.
Problem four: media failing early
Mesh that tears in weeks rather than months is trying to report something. Slack tensioning lets the wire flap and fatigue: check the crown bar profile and the tension bolts. Spot feeding hammers one strip: look at the feed arrangement, not the media. Impact at the feed end punches holes: consider liners or resilient panels in the landing zone. And genuinely abrasive feeds simply need media specified for abrasion, judged on cost per tonne rather than price per panel. Media is the machine’s consumable, but consumption at double the budgeted rate is a symptom, not a fact of life.
Problem five: springs, mounts and cracks
Suspension components are the machine’s fuses. A sagging or broken spring tilts the body, distorts the motion at one corner and shows up as uneven material travel or a new knock at speed. Springs are inspected easily and replaced cheaply, so they should never be the discovery made after a side plate has cracked.
Structural cracks themselves, in side plates, cross members or around the drive mounts, demand respect. They mean the machine has been running with a motion or a load it was not built for: failed suspension, out-of-sync drives, an added liner package that changed the mass, or plain overloading. Weld repairs done without asking why the crack formed are an invitation for the crack to return with friends. Find the cause, fix it, then repair the steel to the manufacturer’s detail.
Problem six: drives and bearings
Vibrator motors and exciter bearings live hard lives and reward routine: correct grease, correct intervals, correct quantities, and temperatures glanced at weekly. A bearing that runs hotter than its twin, a new whine at running speed or a motor drawing uneven current is asking for attention this month, not this year. On twin-drive machines, loss of synchronisation turns a clean linear stroke into an ellipse the machine was never designed for; it is audible, visible on a stroke card, and destructive if ignored.
Problem seven: the motion is wrong
Every screen left the factory with a designed stroke, angle and speed, and a surprising number run years later on none of the three. A stroke card at each corner, compared against the commissioning record, takes minutes and settles arguments. Short stroke means lost energy: look for failed springs, added mass or slipping weights. Distorted stroke means suspension or synchronisation. Right stroke but poor screening sends you back to feed, media and bed depth, because the machine itself is telling you it is healthy.
Problem eight: noise and transmitted vibration
New noise is diagnostic gold. Rattles are usually loose media, liners or bolts. Knocks at running speed are suspension or a cracked member. A building that has started to hum has been handed vibration the isolation should be absorbing: check the springs before checking the structure. Baseline noise on a healthy machine, mostly material on steel, responds to lined chutes and rubber deck coatings, which sites near neighbours fit as standard.
Problem nine: material travelling badly
Material that crawls, surges or drifts to one side of the deck is a motion or feed symptom. Crawling with a healthy stroke means the throw angle or deck angle no longer suits the material, often because moisture has risen. Surging is nearly always the feeder or hopper upstream, not the screen. Side drift means the machine is no longer level or one corner’s suspension has softened; a spirit level and a spring check settle it in ten minutes. Travel faults are worth chasing promptly because they overload one part of the deck, and the media bill quietly doubles.
Reading the machine rather than the folklore
Every plant carries folklore about its screens: the one that has always been fussy, the deck that never lasts. Nearly always the folklore is a fault that was never diagnosed. The machine only has a handful of variables, feed, media, motion, suspension, structure, and an hour of measurement across them beats a decade of accumulated opinion. Sample the products, card the stroke, gauge the apertures, walk the springs. The fault is in that list somewhere.
Frequently asked questions
What should we log to catch problems early?
Weekly product samples, monthly aperture checks, stroke cards each quarter and after any spring or drive work, bearing temperatures on a simple round, and every media change with its date and position. One page a month, and no fault gets six months of free development time.
When is it time to call the manufacturer?
When a fault survives the basic checks, when cracks appear, or when the same failure repeats despite the obvious fix. Recurring faults usually mean the duty and the machine have drifted apart, and that conversation is cheaper with the people who hold the design calculations. Our technical support team spends much of its time on exactly these calls.
Is it worth fitting condition monitoring?
On critical screens, yes: bearing and vibration sensors buy early warning on the failures that stop plants. On the wider fleet, the weekly human round with a temperature gun and a stroke card catches most trouble for a fraction of the cost, provided it actually happens.
Can an old, troublesome screen be made reliable?
Usually. Most chronic offenders are sound machines running the wrong settings, the wrong media or a duty that grew past them. A survey, a refurbishment and a proper recommissioning bring the majority back; the minority genuinely need replacing, and the survey proves that too. Aftersales support exists for precisely this judgement.
How long should a diagnosis take?
For the common faults, a shift or less once someone is actually looking. The checks in this article, samples, stroke cards, aperture gauge, springs, bearings, need no special equipment and no shutdown beyond a routine isolation. Faults that resist a day of honest measurement have earned a call to the manufacturer with the measurements attached, which shortens the visit that follows.
Which spares are worth holding on site?
Media for every deck, a full set of springs, drive belts where fitted, and the tensioning components that always shear on a Friday night. Vibrator motors are worth holding where the screen is critical to production, since motor lead times decide the length of your worst outage. The spares list should mirror the machine’s actual failure history, which is another use for the one-page log.
Faults are cheap while they are young
A screen problem caught at the weekly sample costs a media panel or a spring. The same problem caught at the customer’s lab costs a load rejection, and caught at the side plate it costs a machine. If a screen on your site is producing symptoms you cannot pin down, describe them to us; the diagnosis is often possible from the description, and the fix is almost always smaller than the fear.
