Foundry Sand Conveyor Belt: Heat, Sharp Scrap and Carryback
“Foundry sand” is a poor description of a conveyor load. Sand leaving shakeout may contain a gate still too hot to touch. After cooling and screening it is a relatively even granular stream. On the green-sand return, binder and water may leave a layer stuck to the belt at discharge. Those are three purchase specifications, even if the drawings give all three conveyors the same name.
A useful walkdown begins at the feed chute. Pick up what fell beside it, including the awkward oversized bits. Note the nearest screen, magnet and cooler, then follow the belt round the head pulley. That quick circuit often explains why a nominally suitable replacement failed at the same spot.
01. Map the sand loop before choosing a cover
The shakeout conveyor is the one to distrust first. A sample jar full of sand tells very little about the occasional gate, shot or flash. A torn screen or open bypass changes it again. Dry reclaimed grains wear a cover; wet bentonite sticks to one.
| Location | Likely material at the belt | Check first | Typical response |
|---|---|---|---|
| Shakeout transfer | Warm or hot sand, casting fragments, gates and flash | Temperature peaks, largest metal piece, drop height | Control stray metal and loading impact; select a verified heat and cut duty |
| After screening and cooling | Finer, more consistent sand | Actual discharge temperature and dust | Match cover and enclosure to the measured duty |
| Green sand return | Moist sand with binder | Adhesion at head pulley and return idlers | Provide accessible cleaning and a route for removed material |
| Reclaimed dry sand | Fine abrasive particles | Cover wear and transfer dust | Contain dust and inspect cover loss across the load path |
The distinctions also explain why related applications are only partial guides. Glass cullet helps illustrate sharp-particle damage, while sand washing has a much heavier water circuit. Neither duplicates a shakeout conveyor with intermittent hot metal. The industry overview covers the adjoining equipment.
02. Follow the hot piece to the belt
A furnace reading tells the belt buyer almost nothing. Take readings at belt entry for both a routine pour and the hottest casting run. Also record what sits on the belt during a stop. One gate left in place can leave a square scorched imprint; a gate moving through may leave none. Write down the duration as well as the peak.
Look at a retired cover near the feed. Fine transverse checking, a stiff patch or a lifted splice tells a more useful story than its colour. Sand works into the cracks, and cleaning becomes harder. The quote should name the compound and construction used for the stated continuous and short peak temperatures; “heat resistant” by itself is not an acceptance criterion.
Where the measured exposure exceeds that rating, the cooling or transfer arrangement needs work. Extra top cover is wear allowance, not a temperature certificate. The heat-resistant belt guide gives the grade terminology to check against the quote.
03. Sharp scrap needs control upstream of the belt
Do not call every damaged top cover “abrasion.” A broad, shallow loss under the sand path suggests abrasion. A puncture at the loading zone asks for a search in the chute. A long narrow slash that begins beside the skirt asks whether metal jammed there. Preserve the fragment and photograph both it and the start of the cut before the area is cleared.
A heavy belt is still vulnerable at a bad chute. Inspect the screen bypass and magnet during production. Where does the largest piece land? Support under the impact zone matters when a fragment hits between idlers. The skirt must leave no pinch point for scrap. The loading-zone discussion covers the support side of that decision.
Two fields belong on the order sheet: hot-material history and worst metal fragment. Request evidence for each proposed property. Where fabric is visible at a cut, assess the carcass before restart under the plant repair procedure; the next bend around a pulley may open damage hidden by sand.
04. Damp sand comes back on the return run
A green-sand conveyor sometimes discharges only the easy portion of its load. Under the frame, that sand leaves a succession of little piles below the idlers. One roller with a lopsided clay coat can become a tracking fault. Late-shift drift often coincides with that coat building up.
Inspect what the blade produces: crumbs, a smear or almost nothing. Sand wedged in cover cuts needs attention separately. A collection tray makes the quantity visible and stops the cleaner creating another pile. Check its contact against the belt and splice limits. Carryback control and return-side cleaning require access for inspection as well as a blade.
Water at the dry reclaim belt may defeat the purpose of drying the sand. The newly made slurry has to go somewhere, and a joint exposed to it needs checking. Show its drain on the drawing. Keep two samples, one from the feed and one from under the return. Label the time and location before they dry out.
05. Carcass, edge and splice choices
EP and NN are choices about carcass behaviour, not shortcuts for a sand duty. Send the pulley schedule and available take-up travel with the load data. A belt that cannot bend over the smallest pulley or be spliced within the available space is a poor choice whatever its cover. The EP and NN comparison is a starting point, not a substitute for that calculation.
On a wet return, open fabric at the edge is worth noting early. A frayed edge can then snag on a skirt. The packing record should name the edge finish and splice method. Check them on the actual belt. The splicing checklist lists details to record before installation.
06. An RFQ the supplier can actually price
A ruler in the photograph gives a cut dimension the buyer can send with the chute drawing. Write “not measured” in the peak-temperature box until someone takes that reading.
| Request from the plant | Why it changes the selection |
|---|---|
| Normal and peak material temperature at loading, with duration | Defines the heat exposure the cover and splice must tolerate |
| Feed rate, belt width, speed and loading pattern | Sets carrying capacity and identifies concentrated impact |
| Largest metal fragment, frequency and drop height | Separates cut and impact risk from sand abrasion |
| Moisture, binder, cleaning method and carryback observations | Shapes surface, scraper and return-run design |
| Smallest pulley, take-up, troughing and current splice | Constrains carcass and joint construction |
| Failed belt photographs and measured cover loss | Provides evidence for the replacement specification |
At goods-in, compare the marking and documents with the order. Keep a small record of top-cover thickness at marked locations, particularly beneath the load point and along the cleaner line. A year later, those numbers are much more useful than a note saying “worn belt.”
SINOCONVE supplies heat-resistant conveyor belts and rubber conveyor belts. Components such as rollers and impact idlers can be discussed as part of the line arrangement; confirm their source and specification separately. Send the measured duty through the contact page for a belt proposal.
07. Read the pattern of the next failure
Take baseline photos on the first shift. The feed and first return roller are the most revealing views. A changed screen or casting mix deserves another look, since the material can change while the conveyor itself appears untouched.
| Observation | Likely investigation | Immediate check |
|---|---|---|
| Cracked or hardened patch near the loading zone | Intermittent heat, possibly during stops | Temperature and dwell time of hot pieces |
| Local slit or puncture | Metal scrap, trapped fragment or inadequate support | Screen, separator, chute and carcass depth |
| Uniform loss along the load path | Sand abrasion | Cover measurements at fixed locations |
| Return roller coated with damp sand | Carryback and ineffective discharge cleaning | Blade condition, material chute and drainage |
| One edge frayed with sideways drift | Loading bias, build-up or skirt contact | Remove deposits and inspect alignment before retensioning |
08. Questions from the belt specification review
Will a heat cover survive a gate?
Not automatically. Heat ageing and cutting are different tests. Specify the material temperature history and the size and frequency of fragments separately, then review the proposed cover and the transfer design together.
Should we order a thicker top cover?
It can give sand more rubber to wear through. If the old belt has one narrow tear, however, find the gate or pinch point before adding thickness. A broad, fairly even worn path is a better reason to consider extra cover.
What changes before the belt drifts?
A crescent of packed sand on the return idler is a clue. Check the feed position too. A fresh tension setting will not remove the lump that has changed a roller’s shape.
Can the same belt run on shakeout and sand return?
Only if one construction is verified for both sets of conditions. Shakeout may need heat and fragment protection; return may be dominated by damp carryback and cleaning. Compare both duties on the same RFQ rather than assuming a shared sand label makes them equivalent.
What evidence should accompany a belt quotation?
Ask for construction, cover grade, thicknesses, splice method, applicable heat limits and test basis, plus the assumptions used for material temperature and fragments. If a proposed grade assumes a working cooler or metal separator, put that assumption on the drawing.
