Deblinding Balls vs. Sliders on a Round Vibratory Separator: Which Self-Cleaning System Belongs Under Your Screen

Ask a plant for their anti-blinding parts and you will almost always hear the same two words: deblinding balls. It is the name everybody knows, and it is the part everybody reorders.

It is also, for a large share of round-separator applications, the wrong part.

The engineer who wrote the definitive trade-press survey of screen-cleaning methods — a technical support representative at Sweco, writing in Powder & Bulk Solids — puts balls in second place, not first: "The most common self-cleaning device is the slider." Rubber balls, he writes, are "the second-most-utilized screen-cleaning method." And the same article lists four limits on balls that rarely make it into a parts catalog: they can be used only for dry screening, they are not recommended for fine mesh because they can damage it, they do not clear fibrous material, and they clean the rim of your screen better than the middle.

None of that makes balls a bad product. It makes them a specific product, with a job they do better than anything else — and a set of jobs they do poorly. This guide covers how each system actually works, where each one fails, what fits your machine, and what it costs to buy and to keep running.

Machine down right now?

Three things you can check with the machine still running, before you order anything:

1. Listen. A working ball tray rattles; a working clean ring hisses. Silence means the media is worn, packed out, or not getting enough amplitude — and none of those is fixed by buying more media.
2. Check your lower weights. Media is thrown at the screen by the machine's own vertical motion. Too little amplitude and it sits still — and that fix is free and immediate.
3. Back off the feed rate. An overloaded deck cannot stratify, and it blinds. Also free.

If you have to keep running — this one is our field experience rather than an OEM procedure: pulling the media and running the screen bare at a reduced feed rate will usually keep product moving, at lower throughput, until parts arrive. Do not keep running with a torn screen — a torn screen over a loaded tray puts media into your product.

Still stuck? Call 866-265-1575 or email support@screenerking.com with your machine make, diameter and what you are running, and a photo of the stack if you can. Standard ball tray kits ship within 24 hours — call for transit time to your plant and for rush options.

Jump to what you need

• Machine down right now?
• Before you buy anything: it may be your weights
• What is actually blinding your screen
• The part that defines the system: what sits under your screen
• Ball trays: high impact, dry service
• Sliders and clusters: low impact, shear action
• Top-side devices: the Power Wheel
• Side-by-side: which one for your application
• Where "FDA" stops meaning what you think it means
• Sizes, kit contents and prices
• Running the system: inspection, wear and refills
• When the answer is not hardware at all
• How to order
• FAQ

Before you buy anything: it may be your weights

This is the section most parts guides leave out, and it is the one that saves you the most money.

A self-cleaning device is passive. It has no motor. Balls and sliders are thrown into the underside of your screen by the machine's own vertical motion — so if the machine is not producing enough vertical amplitude, the media sits there and does nothing. Sweco's Greg Brock is explicit about the requirement: "Higher vertical separator motion is required to activate the balls' cleaning action because the balls must be thrown up against the bottom of the screen."

Sweco's 2025 troubleshooting guidance closes the loop on what to do about it: "If the separator is not producing enough vertical amplitude for the sliders/balls to impact the screen, an adjustment of the lower weights is needed."

Kason's long-running technical bulletin on blinding reaches for the same lever before it reaches for hardware: blinding from near-size particles "can usually be relieved by increasing the lower weight thus increasing the vertical force to dislodge the particles from the aperture."

So the order of operations is: confirm the cause, check your weight settings, consider the screen itself, and only then add media. A tray full of dead balls in an under-weighted machine is a setup problem wearing a hardware costume. If your screen is blinding and you are not sure where to start, our vibrating screen troubleshooting guide walks the diagnosis in order.

What is actually blinding your screen

"Blinding" gets used for several different failures, and the fix is different for each one. Worth knowing up front: the round-separator world and the aggregate world do not use these words the same way. Round-separator OEMs fold near-size wedging into "blinding." Aggregate and woven-wire suppliers often split it — reserving "blinding" for moisture-driven adhesion and calling the wedging "pegging." Neither is wrong; they are different dictionaries. This article uses the round-separator convention.

Kason's bulletin enumerates the mechanisms, and they are worth reading as a checklist against your own screen:

• Near-size wedging. Apertures "become clogged with near-size particles (particles from ½ to 1½ times the opening size)." This is the failure balls and sliders are built for.
• Fibrous wrap. "Long, flexible, usually fibrous material which tends to wrap around the wires."
• Sticky or electrostatic cling. "Very fine material tends to cling to the wire due to inherent stickiness or electrostatic attraction."
• Surface caking. "Resinous or fatty materials, or matted fibers which tend to cover the top surface of the screen and remain unaffected by the vibration."

That last one matters more than it looks. A ball or slider system attacks particles wedged in the aperture. It is not the tool for a resinous film caking over the top surface — Kason routes that failure to wipers and brushes instead — top-side devices that work the screen surface rather than the apertures, which is the family the Power Wheel belongs to. If you pull your screen and the openings are individually plugged, media is the right family of answer. If the top surface is glazed over, it is not.

Not sure which side of that line your cut sits on? Mesh count vs. micron rating covers how to read your opening size against your particle size distribution, and our guide to preventing screen blinding, pegging and plugging works through the diagnosis in more detail. If your problem is specifically a sticky or cohesive powder, screening difficult sticky powders takes that case on directly.

The part that defines the system: what sits under your screen

Here is the detail that trips up first-time buyers, and it is the reason a box of loose balls on its own accomplishes nothing.

Every under-screen cleaning system is really a sandwich: your working screen on top, a support surface underneath, and the cleaning media captive in the gap between them. The media has to be trapped in that gap to be thrown against the cloth. And critically, the two systems use two different support surfaces:

• A ball tray uses a coarse support screen. Sweco's aftermarket screens bulletin describes the arrangement: "A coarse screen is mounted two inches below the sizing screen. Elastomeric balls are placed on this coarse support screen and the separator's vibrating action bounces the balls against the underside of the screen cloth of the working mesh, dislodging any near-size particles." ScreenerKing's Ball Tray Assembly Kits ship with a stainless support frame and a 4-mesh support screen.
• A slider system uses a perforated plate. Same bulletin, describing self-cleaning kits: "a perforated plate mounted below the screen ring with sliders placed between the perforated plate and the working mesh." Our Clean Ring Assembly Kits ship with a stainless perforated plate and the sliders to fill it, and the perforated plate is available on its own if you are rebuilding an existing assembly.

Treat that as the usual arrangement, not a test. It holds most of the time, and it is enough to know what you are looking at — but it is not a reliable identification on its own, and the exception is a common machine rather than an obscure one. Sweco's own 72" low-profile separator runs its slider kit on a coarse support screen instead of a plate: the manual notes twice that "LX72 uses a screen slider support instead of a perforated plate," and the parts list bears it out — a 4-mesh slider support screen carrying 200 nylon sliders. Kason likewise says its rings are held "by using a perforated plate or by sandwich mounting them between the operating screen and a coarse retaining screen."

So confirm by the media in the gap, not by the surface underneath it. It is visible the moment the stack is open:

• Solid rubber spheres (ours are 1-3/8"; sizes vary by supplier) — ball tray.
• Open-centered rings — clean ring.
• Molded multi-cell blocks — honeycomb clusters, same family as the clean ring.
• No loose media at all, and a two-layer screen — a self-cleaning sandwich screen, where the media is sealed inside. There is no kit to reorder; you replace the screen.

You do not need to break the stack to find out. In rough order of effort:

1. Send us a photo. Email support@screenerking.com or call 866-265-1575. Useful shots: the machine nameplate, the stack from the side with the clamp visible, and the media itself if the stack is open. This is the same first step as our rescreening service — photos first, parts second.
2. Give us the machine make, diameter and serial number. The original parts list is keyed to it, and so is your last order with us.
3. Look at the frame band from outside. A ball tray assembly is visibly deeper than a clean ring, because the balls need roughly two inches of travel under the working mesh. You can often tell with the stack closed.
4. Confirm at your next screen change. When the stack is open anyway, look at the media itself — the four-way tell above.

Nobody should be breaking a stack on a food line purely to identify a part — that is a two-person job and a sanitation reset. Save the teardown for a change you were doing anyway.

If you want the broader picture of how these systems work before getting into the buying decision, our overview of how deblinding systems work covers the mechanisms; this article is the layer above it — which one to specify, and what it costs.

One more disambiguation worth making, because these get confused constantly: a backing screen is not a ball tray. A backing or support screen is passive — it carries load and protects a fine working mesh. A ball tray actively cleans. They can look similar in a parts bin and they do completely different jobs. Where each layer sits in the machine is covered in our guide to the separator frame stack.

Ball trays: high impact, dry service

Balls are the blunt instrument, in the best sense. Because of "their larger vertical motion and heavier balls," ball trays "cause a greater impact than either sliders or clusters." That impact is the whole point — and it is also the source of every limitation.

What balls are genuinely best at

Two things, and both are specific:

• Jagged, irregular near-size particles. "Balls are good at cleaning the near-size irregular or jagged-shape particles that wedge in mesh openings. These materials can trap sliders." That last sentence is the argument for balls: the very material that defeats a slider is what a ball handles.
• Shear-sensitive product. This one runs against a widespread assumption. "Balls are also good for shear-sensitive materials, which can cause smearing or balling agglomeration." Balls deliver impact; sliders deliver shear. So if your product smears or degrades when it is rubbed, the ball may well be the gentler option rather than the harsher one. The usable half of that: if your product smears or agglomerates when it is rubbed, the ball is the better bet. The reverse does not invert cleanly, though — a slider is documented as breaking friable material into smaller pieces, so it is not automatically the safe choice for something fragile either. A genuinely friable product is a conversation, not a rule.

The four limits

1. Dry service. Sweco's 2007 trade-press guidance is flat about it — rubber balls "can be used only for dry screening" — and its 2025 guidance is a shade softer, that "ball trays are typically used for dry applications with a courser [sic] cut requirement," while "self-cleaning kits and screens can be used in wet or dry applications." Either way the direction is the same: if you are running wet, do not start with a ball tray.
2. Not for fine mesh. Balls "are not recommended for fine screen meshes because they can damage the mesh." Kason names the specific failure: "with finer meshes, the balls' high impact momentum tends to stretch the wire." That is something you can recognize on a pulled screen — stretched, opened-out wire rather than a clean tear.
3. Not for fibrous material. "Balls are not recommended for cleaning fibrous materials because they do not perform the shearing action that is necessary for dislodging fibers from the mesh." (Worth flagging honestly: Sweco's installation manual carries near-identical sentences in its ball-tray and slider sections, and the ball-tray one does credit balls with scraping away fibrous material. The sources genuinely disagree here. Where fibers are the problem, the more specific guidance points at shear — and shear is the slider's job.)
4. Coverage is uneven. "The disadvantage of ball trays is that the balls spread radially to the periphery of the screen. This generates excellent cleaning action at the screen edge but leaves the center of the screen uncleaned." If you have ever pulled a screen and found a clean band around the outside with a blinded middle, that is this, and it is normal ball-tray behavior rather than a defect.

Sliders and clusters: low impact, shear action

Sliders are loose nylon rings — Kason describes them as "hollow cylinders" — that travel on the perforated plate beneath the screen. That open center matters: the rim edge is what does the shearing, which is why a slider clears fibrous material and a solid ball does not.

Sweco's manual describes the motion precisely: "the sliders bounce and rotate between the perforated plate and the separator screen." So they do two things at once — they travel radially around the plate and they are thrown vertically into the cloth. They are not purely a wiping device and not purely a tapping device.

That combination gives sliders four documented modes of action: vertical impact dislodges wedged near-size particles; the slider "shears or breaks protruding hard or friable materials into smaller pieces, which flow through the screen"; on soft pliable material they "help the material through the screen openings"; and on fibrous material "the sliders' horizontal scrubbing motion across the bottom of the screen dislodges trapped fibers."

Because their impact energy is far lower than a ball's, sliders are the ones that extend into finer mesh without beating up the cloth. They are also, per Sweco's rep, simply the most-used device of the three.

Where sliders struggle

The same source is unusually candid about the failure modes, and these are worth reading before you buy:

• Agglomerating material. "Sliders are not efficient for materials that tend to ball up or agglomerate inside the sliders." Product packs into the slider itself and it stops working.
• Temperature-sensitive product. Sliders "generate minor amounts of heat, which can fuse temperature-sensitive materials."
• Hard, irregular material. Sliders "may not perform well on extremely hard, irregular-shaped materials, which can partially protrude through the screen opening and stop the motion of the slider." This is the mirror image of the ball's strength.

Clusters — what ScreenerKing lists as Honeycomb Sliders

A slider cluster is several slider cells molded into one larger body. Trade literature describes the trade-off: "the slider cluster is four to eight times larger than the slider ring. Slider clusters are normally used for large-diameter machines for easier maintenance. While the impact force of the slider cluster is greater than that of the slider ring because of its larger weight and size, it has less impact on the screen because a small number of clusters are required."

So a cluster hits harder per piece but softer overall, and there are far fewer of them to handle at a screen change — which is why they show up on big machines. ScreenerKing sells these as Honeycomb Sliders. Worth quoting one more line from the same survey, because it is honest in a way vendor copy usually is not: "Opinions vary as to which self-cleaning method is more effective: individual sliders or larger slider clusters. In fact, their effectiveness depends entirely on the material being screened."

Standard De-Blinding Sliders come in two sizes, and the honeycomb version is the more aggressive option — with the caveat, per our own product data, that the added weight may be better suited to machines running stronger vibration amplitudes.

"Sticky" and "clumping" are two different problems

This distinction is worth pinning down, because the advice for each is opposite and the words get used interchangeably.

• Product that coats or clings to the mesh — a tacky film building on the wires. This is a scrubbing problem, and it is what the honeycomb geometry is aimed at: more contact points across more of the screen.
• Product that packs inside the slider itself — material agglomerating in the cavity until the slider stops moving. This is the failure mode Sweco's rep warns about, and no slider geometry fixes it, honeycomb included.

If your product coats the mesh, sliders are in play and the honeycomb is the aggressive end of that range. If your product packs into anything with a cavity, sliders are the wrong family — that is a ball tray case, or a top-side device working the bed above the screen. When in doubt, tell us what the material does rather than what to call it, and we will point you at the right one.

Top-side devices: the Power Wheel

Balls, sliders and sandwich screens are all bottom-side devices. There is a second family that works from above, and it is easy to mix them up in a parts conversation.

Sweco's parts literature describes the family and, usefully, distinguishes the three members: "TOP-SIDE SCREEN DEVICES include three available options. All devices have been designed for use in dry powder applications to break up material and assist the product through the screen. The Power Necklace breaks up the material that collects along the periphery of the screen. The Power Wiper provides a lightweight scrubbing action on the screen surface to keep material from sticking to the mesh. Power Wheels were designed with combined benefits of the Necklace and Wiper."

Two things to take from that. First, a top-side device does a different job — it is not clearing wedged particles from underneath, it is working the bed sitting on top of the screen. Second, this family is scoped to dry powder as well, so it is not the wet-service answer either.

ScreenerKing's Power Wheel is built with nylon honeycomb sliders and an FDA and EC compliant polyurethane belt, and is available for 24", 30", 48" and 60" screens (there is no stocked 40" — call us for that diameter). Per our own product specification, it creates an obstruction in the outer third of the screen to increase particle residence time and break up agglomerated material, and does so without requiring a change to your motor counterweight settings.

Worth being precise about that last point, because it is easy to over-read: on a round separator the primary control over how material travels and how long it stays on the deck is the lead angle between your upper and lower weights, which sets the spiral pattern the material follows across the screen. A top-side device supplements that; it does not replace it. If material is racing off your deck, look at the lead angle first.

Reach for a top-side device when your problem is clumping rather than plugging — when dry material is arriving agglomerated and needs to be broken down before it will present to the openings at all.

Side-by-side: which one for your application

On that last row: as the cut gets finer, mechanical media reaches a point of diminishing returns, and past it the honest answer is a different technology rather than a bigger box of balls. Where that crossover sits for your material is covered in ultrasonic vs. standard screening.

Published mesh brackets do exist, but they do not agree with each other and they are not interchangeable between machines. The most specific come from Kason, which puts balls at "screen media coarser than 30- or 40-mesh" and adds the mechanism for why not finer — "with finer meshes, the balls' high impact momentum tends to stretch the wire" — and rings or sliders at "screen media finer than 14-mesh," since "coarser mesh with heavier wire won't flex under the low-impact momentum." Sweco offers no number at all, scoping ball trays qualitatively to "dry applications with a courser [sic] cut requirement."

Note that those two brackets overlap between roughly 14 and 40 mesh, which is honest rather than sloppy — in that band either device can work and your material decides. Treat any published bracket as a starting point for a conversation rather than a specification, match your material's behavior first using the table above, and confirm against your own machine.

Where "FDA" stops meaning what you think it means

If you screen food, pharmaceutical or nutraceutical product, this section is the one to read twice, because "FDA" on a spec sheet is doing less work than most buyers assume.

Food-contact clearances are written per material, and they are scoped — by what kind of food touches them, and under what conditions. They do not certify a finished part.

Rubber balls: your food type decides the rule

Rubber articles for repeated food contact fall under 21 CFR 177.2600. The regulation splits three ways by food type, and the split is stark:

• Dry food, paragraph (d): "Rubber articles intended for use with dry food are so formulated and cured under conditions of good manufacturing practice as to be suitable for repeated use." That is a manufacturing-practice requirement — no extractives testing is imposed at all.
• Aqueous food, paragraph (e): extraction in distilled water at reflux, yielding "not to exceed 20 milligrams per square inch during the first 7 hours of extraction, nor to exceed 1 milligram per square inch during the succeeding 2 hours of extraction."
• Fatty food, paragraph (f): extraction in n-hexane at reflux, "not to exceed 175 milligrams per square inch during the first 7 hours … nor to exceed 4 milligrams per square inch during the succeeding 2 hours of extraction." Before you chase this one: our standard ball is natural rubber, which is the wrong material for fats regardless of clearance — see material compatibility below.

Notice what just happened: the same "is your product dry?" question that decides whether a ball tray will work mechanically also decides which regulatory tier your balls sit in. For dry screening — which is the only service balls belong in anyway — the requirement is GMP formulation and cure. Move to a wet or fatty product and you are in a tier with actual extraction limits, and you should be asking your supplier which tier their compound was qualified against.

Two more provisions worth knowing. Paragraph (g) is a genuinely actionable install step almost nobody follows: "finished rubber articles intended for repeated use in contact with food shall be thoroughly cleansed prior to their first use in contact with food." New balls get washed before they go into food service. And if nitrile appears on a specification you have been handed, note that paragraph (i) routes it to a separate rule: "Acrylonitrile copolymers identified in this section shall comply with the provisions of § 180.22 of this chapter," which clears them "on an interim basis." Our own compounds are natural rubber as standard, with neoprene and silicone available on request.

Nylon sliders: clearance is resin-specific

Nylon has its own listing at 21 CFR 177.1500, and it is not one blanket clearance. The regulation lists nylon 66, 610, 66/610, 6/66, 11, 6, 66T, 612, 12 and MXD-6 separately, among others, each with its own specifications — and some carry explicit conditions. Nylon 612, for instance, is listed "for use only in articles intended for repeated use in contact with food at temperatures not to exceed 212 °F." So "FDA nylon" narrows things considerably less than it sounds like it does.

Polyurethane: check the scope before you assume

The main food-contact listing for polyurethane resins, 21 CFR 177.1680, clears them "as the food-contact surface of articles intended for use in contact with bulk quantities of dry food" of a specific type. That is a narrow scope. It is not a TDI-specific restriction — the section covers eight different isocyanates — but it does mean "FDA polyurethane" on its own does not tell you the part is cleared for a wet or fatty product. If that matters for your process, ask us and we will confirm the clearance that applies before you order.

The part QA actually asks about: where does the worn material go?

This is the question that matters more than any CFR citation, and most parts pages skip it.

Cleaning media wears by design, and it wears into your product stream. A slider that has gone from 1.00" to 0.85" has lost that material somewhere, and it was sitting directly above your working mesh when it did. Sweco's own technical support rep says so in print, listing "the types of contamination associated with sliders, balls, or brush materials" as a reason to consider a non-contact method instead. That is an OEM conceding the point, not a competitor's marketing.

What follows from it, practically:

• Replace media as a complete set, not piecemeal. Mixed heights are what cause the piggybacking Sweco warns can "stretch or tear the screen," and a fresh ball among worn ones does not restore uniform action.
• Treat the tray as a product-contact surface. Sweco's dry-cleaning procedure names it explicitly: "Other parts of the sifter, including ball trays and balls, if used, also should be inspected for condition," alongside dismantling and cleaning all product-contact surfaces.
• A torn screen over a loaded tray is a foreign-body event, not just a screen failure. If the working mesh opens up, whole media can pass. That is the real reason the media-jamming checks further down matter — a circular imprint if you run rings, polished or dimpled spots if you run balls.
• Count the media in, and count it out. Your kit's ship count is in the table below — 30, 40, 80, 140, 200 or 300 balls by diameter; 25 to 250 sliders. Write the number down at install and reconcile it at every screen change. A short count with a torn screen is a hold, not a maintenance note.
• Standard media is not detectable. Natural rubber balls and nylon sliders contain no metal, so they will not trip a metal detector, and they are not reliably X-ray detectable either. If your foreign-material program treats downstream detection as the backstop, it is not covering this. Color contrast is the cheap version of a fix — white balls against a dark product, or black against a light one, for $5 more on a 25-pack or $15 on a 100-pack — and detectable compounds exist. Tell us before you order.
• If you do find a torn screen over a loaded tray: hold product back to your last verified screen check, reconcile the media count against the install count, and release on the count.

Material compatibility comes before the regulation

Our standard ball is natural rubber, and two things follow from that which the CFR tiers above do not tell you.

First, natural rubber is not the compound for fats and oils — it swells and degrades in them. So for a fatty product, the extraction limits in paragraph (f) are somewhat academic: the material is the wrong choice on compatibility grounds before compliance enters into it. Neoprene is the fat- and oil-resistant option, and is available on request.

Second, natural rubber is a latex material. Many food sites and most pharmaceutical sites exclude natural rubber from product-contact parts on allergen-control grounds, independently of anything FDA says. If that is your site's policy, say so when you order and we will quote an alternative compound rather than sending you something your own QA will reject.

Neoprene and silicone are also the answer for elevated temperature. We have not printed a temperature ceiling here because the right number depends on the specific compound — tell us your operating temperature and we will confirm what suits it.

What documentation we can and cannot provide

Material compliance is not the same as a certificate, and it is better to know which you are getting before you order.

Our stainless components — rings, trays and plates — can be supplied with material certification and alloy traceability on request. For the elastomer balls, the position is different: they are made from FDA-compliant material, but formal certification is not provided. That is stated on the product page, and we would rather you have it in front of you now than at the point where it matters.

If your process is food, pharmaceutical or nutraceutical and your screens need to match, our guidance on pre-tensioned screens and on 304 vs. 316 vs. duplex covers the sanitary side of the specification, including 316L for low-contamination service.

And rather than tell you to go and establish which clearance applies to your service — we are the supplier, so that is our job — tell us your food type, your temperature and your documentation requirements when you order, and we will confirm the compound and what paperwork comes with it before you commit.

Sizes, kit contents and prices

All of the below are stock configurations, purchasable online today.

Ball Tray Assembly Kits

Each kit includes a stainless steel support frame, a 4-mesh support screen, the balls, and hardware on the 48" and 60" kits. The screen tie-down assembly is not included, and center-hole configurations need additional support washers and hardware.

Two configuration choices affect the price: epoxy bonded or welded support mesh (welded runs $30–$40 more), and with or without a center hole ($10–$25 more). Prices above are the epoxy bonded, no-center-hole configuration.

Ball trays are the only item in this line with a published lead time: standard kits ship within 24 hours.

Clean Ring Assembly Kits

Each kit includes a stainless steel perforated plate, food-grade nylon sliders, and hardware on the 30" through 60" kits.

Media and components on their own

Two slider sizes are stocked and the right one depends on your kit rather than your machine badge, so confirm before reordering loose sliders — send us your machine diameter and we will tell you which size your assembly takes. Balls are stocked as a parcel item in both pack sizes. Neoprene and silicone compounds are available on request for elevated-temperature service — call for availability and pricing.

Note that the kits are stocked to 60". Larger machines — 72" units included — are handled as custom builds rather than off the shelf.

A note on how to read those two tables together. The kits are complete assemblies built to your machine diameter; the components below are what you buy when you are refilling or rebuilding an assembly you already own. They are not the same purchase, and the kit price is not the sum of the loose parts — if you are weighing one route against the other for your machine, call us and we will price both properly rather than have you infer it from the tables.

And on lead time: the 24-hour figure above is published for ball tray kits specifically. For clean ring kits, plates and the Power Wheel, call 866-265-1575 for current availability and a firm ship date — common sizes move fast, and rush options exist if you have a machine down.

Running a diameter that is not on these lists, or a machine that is not a standard round separator? We cut to any size, any machine, any material — any mesh, wire, weave or alloy. Custom sizes and configurations for these kits are quoted by phone.

Running the system: inspection, wear and refills

One scoping note before the numbers below: the published figures in this section are Sweco's, for Sweco parts on Sweco machines. They are the most detailed anyone publishes, which is why we use them — but if you run another make, or our media, treat them as the pattern to follow rather than the measurement to apply. Check the figures against the parts you actually run.

Inspect at every screen change. Replace on condition, not on a calendar.

Sweco's installation and maintenance manual puts media inspection on a weekly cycle, and says the same thing for both systems: "Inspect balls on a weekly basis for excessive wear and replace if necessary" and "Inspect sliders on a weekly basis for excessive wear and replace if necessary." It appears on the manual's preventive maintenance schedule as a standing line item.

In practice almost nobody breaks a stack weekly, and we are not going to pretend otherwise. The rhythm that actually holds is inspecting the media at every screen change — the stack is already open, the marginal cost is a couple of minutes, and it is the one moment you can see everything at once.

Between changes, there is a check that costs nothing and needs no teardown: listen to the machine. A working ball tray rattles and a working clean ring hisses, audibly, from several feet away. Media that has gone quiet has either worn down, packed out, or stopped getting enough amplitude to move — and all three are worth investigating before your throughput tells you the same thing a week later.

What the manual deliberately does not give you is a replacement interval — the instruction is to inspect on a schedule and replace on condition. You will see calendar intervals quoted in various places, and they can be reasonable rules of thumb, but they are not OEM specifications and your actual service life depends on your material, your amplitude and your duty cycle. Inspection frequency is the number worth committing to; replacement is a judgment about what the inspection finds.

Sliders have a published wear limit. Balls do not.

This asymmetry is genuinely useful and almost never mentioned. Sweco publishes a dimensional limit for sliders, and the reason is a specific failure mode: "Piggybacking of sliders can stretch or tear the screen. To prevent this problem, replace sliders when they have worn to a minimum height as shown below." The published figures are 0.59" new down to 0.44" worn on the 18" and 24" machines, and 1.00" new down to 0.85" worn on the 30" through 72" machines.

Important caveat on those numbers: they are Sweco's figures for Sweco's own sliders, and slider dimensions vary between suppliers and machine sizes — ours, for instance, are not the same heights. Do not measure a slider from another source against Sweco's limit and conclude it is worn out. What transfers is the allowance, not the percentage. Look at Sweco's two figures together and the pattern is absolute rather than proportional: both permit exactly 0.15" of height loss before replacement (0.59 to 0.44, and 1.00 to 0.85). That is a far more useful benchmark than a percentage, because it carries across slider sizes.

Applied to our sliders, whose new heights are 0.875" (2.5" OD) and 0.8125" (3.5" OD), that same 0.15" allowance puts replacement at roughly 0.73" and 0.66" respectively. Treat those as a working benchmark rather than a published spec — call us and we will confirm the figure for the compound you are running.

The shop-floor version: keep one new slider in the parts bin and compare against it. And replace the whole set at once — a mix of new and worn heights is exactly what produces the piggybacking the limit exists to prevent.

For balls, there is no equivalent published diameter threshold. Sweco's 2025 guidance defers it: check "the sliders or balls for the correct height or diameter … once they reach a certain height/diameter, these devices will no longer be effective and will need to be replaced. (Check with the manufacturer/provider for effective size ranges.)" That is a fair instruction — and it means the effective range for your balls is a question for whoever supplies them. Ask us and we will tell you what we know about the compound you are running.

Your cleaning media can break your screen

Anti-blinding hardware is not consequence-free, and a well-run plant watches for it. Kason documents the mechanism plainly: when Kleen-Screen rings jam, "the mesh face of the screen repeatedly vibrates over the ring until flexing leads to breakage." It also gives you the diagnostic tell — "be on the lookout for a circular imprint on the underside of the screen."

That imprint means media is sitting still where it should be moving. Replacing the screen without finding out why just buys you another screen. The usual causes, roughly in order of how often we see them:

• The tray has packed out with fines, so the media has nowhere to move.
• Mixed or worn media piggybacking, per the wear limit above.
• Not enough vertical amplitude — the weights problem from the top of this article.
• A dished or distorted support plate that has stopped presenting a flat running surface.

Which points at the maintenance step most plants skip: empty and wash the tray at every screen change. Trays accumulate fines, packed fines kill the cleaning action you paid for, and on a food line they are a sanitation finding waiting to happen. Sweco's cleaning procedure treats the tray and the balls as product-contact parts to be dismantled, cleaned and inspected — not as fittings you leave in place.

The circular imprint is one of several failure signatures worth learning to read; we cover the rest in why round separator screens fail early.

Refills are cheap. Plan them.

Replacing the media is a small fraction of replacing the assembly — between roughly 8% and 23% of the kit price depending on diameter:

Prices above are for black balls; white runs about 10-13% more. Note that on several sizes the cheapest combination overshoots the count you need — at 30" a single 100-pack is cheaper than four 25-packs, and it leaves you twenty spares on the shelf rather than costing you more.

The reorder rule is simply match the count your kit shipped with — the kit table in the previous section is your reference, and for a custom diameter, call us rather than estimating by area. The practical argument for the 100-pack is not the few percent it saves per ball; it is one purchase order instead of four, and spares on the shelf for the next change.

Prices shown are current as of September 2026 — confirm at time of order.

The operating pattern that works

The plants that never lose a shift to this treat the media as a stocked consumable rather than a repair item. Sweco's own spare-parts recommendation is a good starting list: if your unit includes a ball tray, stock "one center tie-down assembly (if applicable) for ball tray, one ball tray stud, and balls (specify material)."

Build that into the rhythm you already have: inspect the media at every screen change rather than scheduling a separate task, keep one refill pack on the shelf per machine size you run, and replace sliders on the published dimension rather than on how they look. Pair it with a spare screen on the shelf and a rescreening rotation, and a blinded screen becomes a scheduled swap instead of a production meeting. On a small machine with the spare staged that is genuinely quick; on a 48" or 60" with a tray to empty and wash, budget properly for it and plan a two-person lift.

One safety note that has nothing to do with lockout: the most common injury on this job is a hand on torn mesh or a screen edge. Gloves on, and treat a failed screen as sharp.

If you are retiring old screens as part of that rotation, ask about our ring credit program — we pay account credit for qualifying rings. Whether to remesh or replace is covered in rescreen or replace.

Opening the stack safely

Servicing a tray means opening the separator, and the reason to lock out is specific. Sweco's first warning in the manual reads: "Unit produces severe vibration and contains rotating parts. Accidental start-up of unit could result in death or serious injury. Turn off and lock-out system power before servicing." The screen-removal procedure begins "1. Shut off product flow. 2. Shut off and lock out power." Slider replacement begins straight in at "1. Shut off and lock out power."

Separately — and this is a different hazard with a different control — the manual warns that "higher amplitudes occur during shut down and start-up of unit. Stand clear of unit and keep accessory equipment away during these cycles."

When the answer is not hardware at all

Six situations where adding media is the wrong purchase:

Uniform build-up on the wires. Kason's worked example is the clearest illustration in the literature: a 200-mesh screen separating epoxy powder builds up until its 74-micron aperture behaves like 44 microns. The fix was not a cleaning device — it was moving to a 140-mesh screen, whose 105-micron openings reduce under build-up to about the 75 microns actually needed. The caution attached is important: "if the buildup on the wire is inconsistent, oversize particles will pass through the screen."

Moisture, and the calendar. If your blinding arrives in July and eases in October, you have a humidity problem, not a hardware problem. Damp fines adhere to the wires and cake over the surface, and no amount of media underneath fixes adhesion on top. The mirror image is just as diagnostic: static-driven blinding is typically worse in winter, because drier air leaves particles less conductive and better able to hold a charge. Before you buy anything, check whether your problem has a season.

Feed rate and bed depth. An overloaded screen cannot stratify, near-size particles never present cleanly to the aperture, and the deck blinds. Cutting the feed rate or adding screen area resolves more blinding complaints than any cleaning device ever sold, and both are free to try. Check this before you spend money.

Static. If fines are clinging or agglomerating from electrostatic charge, media is not addressing the cause — grounding is. Grounding straps, lugs and conductive gasket constructions all exist for exactly this, including in food-compliant form. Call us with your setup and we will tell you what applies to your machine.

The opening geometry is wrong for your particle shape. Sometimes the answer is a different weave or a different opening. Square vs. slotted openings covers when a rectangular opening reduces wedging.

Or the cleaning belongs in the screen, not under it. Self-cleaning sandwich screens seal the media between a working mesh and a support mesh, so the cleaning action is part of the screen you install. Sweco's own literature makes the case plainly: self-cleaning screens give better cleaning action than self-cleaning kits "at lower vertical machine amplitudes resulting in reduced stress on motors and increased screen life." That comparison is against self-cleaning kits rather than ball trays — but the same logic, media closer to the working mesh needing less amplitude, is why we point wet-service and even-coverage cases here.

They are also purchasable online right now — sandwich screens start at $375 for an 18" and run to $1,095 for a 60". Worth pricing against a $775 ball tray kit before you assume the tray is the cheaper route: at 18" the sandwich screen is roughly half the cost of the ball tray assembly, and it is one part instead of three.

And if your machine runs multiple decks, each deck may want a different answer; see ordering screens for multi-deck separators.

How to order

All of the kits, media and components above are available to order online today, and standard ball tray kits ship within 24 hours. Common sizes and configurations build fast — call 866-265-1575 for a firm ship date and rush options if you have a machine down.

To get it right the first time, have these ready:

• Your separator diameter and make. The kits above are sized to the standard round-separator diameters used by Sweco, Kason, Midwestern, Russell Finex, Great Western, Vibrascreener, Elcan, Eriez, Galaxy Sivtek, HK Technologies, Cleveland and similar circular machines. If you run a Rotex-style rectangular gyratory, the deck geometry is different and these round-separator kits do not transfer. We do make screens for those machines — it is the de-blinding kits that are machine-specific, so call us and we will quote the right thing.
• What media is in there now — solid rubber spheres (ball tray), open-centered rings or molded clusters (clean ring family), or no loose media at all with a two-layer screen (sandwich screen)
• Your working mesh, and whether the cut is coarse or fine
• Whether the process is dry or wet
• Your product's behavior: jagged, fibrous, sticky, agglomerating, shear-sensitive, temperature-sensitive
• Whether you need a center hole for a tie-down
• Any food, pharmaceutical or documentation requirements

Not sure how to measure? Our guide to measuring and ordering a replacement screen covers the dimensions we need. Everything we build is made to fit your machine — or we make it right.

Frequently asked questions

Can I just buy deblinding balls and drop them in?

No. Balls have to be captive between your working screen and a coarse support screen below it, so the machine's vertical motion can throw them against the cloth — about two inches of standoff on Sweco's published arrangement, though it varies by machine. Without a ball tray assembly they will not stay in position or do any cleaning. If you already have a tray, loose balls are the correct refill; if you do not, you need the assembly.

Can I use deblinding balls in a wet application?

A ball tray is a dry-service device. Sweco's older guidance says balls "can be used only for dry screening"; its 2025 guidance is that ball trays are "typically used for dry applications with a courser [sic] cut requirement," while self-cleaning kits and screens "can be used in wet or dry applications." For wet service, start with a self-cleaning sandwich screen. Sweco's technical rep is specific about why: sandwich-screen bottom meshes are "much better for wet screening because, unlike perforated plates, they do not allow liquids to build up." A slider-based clean ring is the next option. Talk to us about your specific cut.

Which is better, balls or sliders?

Neither, in the abstract. Balls deliver higher impact and are better on coarse, dry, jagged near-size material and on shear-sensitive product. Sliders deliver lower impact plus a shearing and scrubbing action, extend into finer mesh without damaging the cloth, run quieter, and are the most commonly used of the self-cleaning devices. Your cut size, your product behavior and whether you are wet or dry decide it — the table above walks through the cases.

How often should deblinding balls be replaced?

Inspect at every screen change — the stack is already open and it costs you two minutes. Between changes, listen: working media rattles or hisses, and media that has gone quiet is worn, packed out, or not getting enough amplitude. Sweco's manual specifies a weekly inspection, which almost nobody does literally, so the screen-change rhythm is the one that actually holds. Replace on condition: there is no published calendar interval, and no published minimum ball diameter — Sweco's guidance is to check with the supplier for effective size ranges. Sliders are different: Sweco publishes a wear limit for its own sliders — 0.59" down to 0.44" on 18" and 24" machines, 1.00" down to 0.85" on larger ones — because worn sliders can piggyback and tear the screen. Slider dimensions vary by supplier, so compare against a new one of whatever you actually run rather than against those figures; Sweco's two published limits both allow exactly 0.15" of height loss, which is the benchmark that carries across slider sizes. Replace the whole set at once.

Why is the middle of my screen still blinding when the edges are clean?

That is characteristic ball-tray behavior. Balls migrate radially toward the periphery, which gives excellent cleaning at the screen edge and leaves the center less worked. If uniform coverage matters for your cut, a slider-based clean ring or a self-cleaning sandwich screen will treat the whole screen more evenly.

My ball tray does not seem to be doing anything. Is the tray bad?

Check your motor weights before you replace anything. Balls and sliders are powered entirely by the machine's vertical motion, and if there is not enough vertical amplitude to throw them into the screen, they sit still. The usual fix is an adjustment of the lower weights. Then look at the underside of the screen. If you run sliders, a circular imprint means a ring has been jamming; with balls, look for polished or dimpled spots and localized wear where balls have been sitting rather than bouncing. Either pattern points at jammed media, not a faulty tray.

What food-contact documentation comes with your deblinding balls?

Our stainless components — rings, trays and plates — can be supplied with material certification and alloy traceability on request. For the elastomer balls themselves, the material is FDA-compliant but formal certification is not provided. Clearances are written per material and scoped by food type: for rubber in dry-food service the requirement is good manufacturing practice, while aqueous and fatty service carry extraction limits. Tell us your food type, temperature and documentation requirements before ordering and we will confirm the compound and the paperwork that comes with it.

Sources

Technical claims in this article are drawn from the following published documents. Where a figure or quotation appears above, it comes from one of these:

• Greg Brock (Sweco), "Vibratory Screen-Cleaning Methods Improve Efficiencies, Save Money," Powder & Bulk Solids, 8 October 2007 — the source for the comparative behavior of balls, sliders and clusters, including dry-service and fine-mesh limitations, ball migration, and slider failure modes.
• Jeff Dierig (Sweco), "Troubleshooting Round Separator Screens" (the page also carries the SEO headline "Troubleshooting Separator Screens in Processing"), Powder & Bulk Solids, 23 September 2025 — vertical amplitude and lower-weight adjustment; media wear and effective size ranges.
• Sweco, Installation, Operation and Maintenance Manual for Low Profile Separator, Models LX18–LX72 (August 2012, revised January 2015) — weekly inspection requirements, slider wear dimensions, spare-parts recommendations, self-cleaning kit construction, and the lockout and start-up warnings.
• Sweco, Aftermarket Separator Screens, Bulletin 457 (2021) — ball tray and self-cleaning kit construction; grounding options.
• Sweco, Aftermarket Separator Parts, Bulletin 488 (2022) — top-side screen devices: the distinction between the Power Necklace, Power Wiper and Power Wheel, and their scoping to dry powder applications.
• Kason Corporation, "How to Minimize Screen Blinding," Screen Tips Vol. 1 No. 1, September 1986 — causes of blinding, the near-size definition, and the screen-and-weights-before-hardware sequence.
• Kason Corporation, "A Review of Anti-Blinding Devices for Screening Equipment" — the published mesh brackets for balls and for rings/sliders, the wire-stretching mechanism on fine mesh, ring construction as hollow cylinders, and the two ways rings are retained.
• Kason Corporation, "Overcoming Static Problems in Your Vibratory Screen Separator," Screen Tips Vol. 2 No. 2, June 1987 — static mechanisms, humidity effects, and the mesh-count worked example.
• Kason Corporation, "5 of the Most Common Reasons Why Vibratory Screens Fail" — anti-blinding devices as a cause of screen fatigue and the circular-imprint diagnostic.
• US Food and Drug Administration, 21 CFR §§ 177.2600, 177.1500, 177.1680 and 180.22, as published in the Electronic Code of Federal Regulations — food-contact material scoping for rubber, nylon, polyurethane and acrylonitrile copolymers.
• ScreenerKing product specifications for the Self-Cleaning parts line — kit contents, dimensions, quantities, materials, lead times and pricing.

Get the right system under your screen

If you are not certain which system is in your machine, or whether your blinding problem is a media problem at all, call us before you buy. 866-265-1575 — tell us your machine, your mesh and what you are running, and we will tell you honestly whether the answer is a ball tray, a clean ring, a different screen, or a weight adjustment you can make yourself.

Browse the full Self-Cleaning parts line, or send us your old screens for rescreening. Everything is built to fit your machine, or we make it right — and material certification with alloy traceability is available on request for stainless components.