Selecting a chain conveyor for a factory in Thailand cannot be reduced to the quoted maximum load. The underside of the pallet, the location of its supports, the method of accumulation, chain and sprocket loading, and safe recovery after a jam can all change the required design and the price. This guide is for production engineering, maintenance and purchasing teams preparing a comparable request for quotation and an acceptance plan for pallet or workpiece-carrier transfer.
Define the type of chain conveyor first
The word “chain conveyor” covers several mechanisms: two chains directly supporting a pallet; a flat-top chain carrying a container; an accumulating roller chain supporting workpiece carriers; rollers driven by chain; and slat or bucket conveyors with attachments. Similar looking equipment can have different load paths and different friction during a stop. mk lists flat-top, accumulating roller chain and other chain conveyors separately. Its product-specific rated loads must not be copied as universal design limits. mk Chain Conveyors
This article concentrates on rigid pallets, fixtures and workpiece carriers conveyed on two rows of chains or chain-mounted supports. A belt or roller system may suit a bag or box that needs broad support. A chain system may suit a fixture that moves along a defined route and is indexed between workstations. Start with the actual load unit and stopping behavior, rather than a preferred equipment name. A chain-driven roller conveyor supports the load on rollers; a two-strand pallet chain conveyor supports it on the chain-side structure. Their transfer height, pinch points and maintenance parts differ. Our broader conveyor system design guide addresses line-wide design; this guide concentrates on chain selection.
Measure the load unit before selecting a chain
Record the dimensions, center of gravity, two possible support lines on the underside, bottom deflection, protrusions, permitted scratches, orientation, contamination and temperature of every load unit. Separate empty-pallet, normal, maximum and off-center loading. A short pallet carrying a heavy fixture at one end can temporarily load only one strand at the infeed. The total conveyor rating can be adequate while a roller, wear rail, frame, leg or transfer point is overloaded locally.
Do not treat an ideal drawing of the bottom as proof of contact. Put actual warped plastic pallets, repaired timber pallets and racks with unequal feet on a test section. Observe contact during stopping, restarting and any permitted reverse movement. If the bottom cannot rest reliably on both support lines, a carrier or additional rail may be necessary. Include the cost and replacement rules for that carrier in the comparison. Measure lateral misalignment on entry, contact with guides, post-emergency-stop position and alignment with forklifts or lifts. Forcing an imperfect pallet between side guides can create jams that appear to be speed problems.
The common RFQ package should therefore include photographs and dimensions of the worst permissible load unit, rather than only a nominal CAD drawing. State whether damaged pallets are excluded by an inspection rule or must still pass through the equipment. This is an operating decision with direct mechanical consequences.
Choose between two-strand, flat-top and accumulating designs
A two-strand design supports the left and right sides of a rigid pallet. It can leave an opening for a lift or workstation fixture, but the load is not necessarily shared evenly. Off-center loads, unequal rail heights, differential chain wear and a one-sided jam can tilt the carrier. Ask how the strands are synchronized, how their phase is checked, and how asymmetric conditions are detected. Do not simply divide total load by two: Tsubaki’s selection guidance explicitly calls for allowance for unequal loading with multiple strands. Tsubaki conveyor-chain catalogue
A flat-top chain offers a more continuous support surface for some products and containers. Evaluate bottom stability, curves, surface marking, oil or washdown exposure and wear-strip compatibility. A polymer flat-top chain and a large industrial metal pallet chain cannot be compared using one generic load chart. Check whether the existing load unit can remain unchanged. Changing pallets and handling rules can cost more than the conveyor difference.
An accumulating design allows carriers to wait while downstream equipment stops. “Accumulation capable” does not mean unlimited stationary loads. Specify dwell time, number of carriers, contact pressure, permitted product-to-product contact, restart gap, wear and heat. If contact is unacceptable, compare separated zones with sensors and stoppers. The required buffer length and merge/divert logic belong to the wider conveyor flow design. Here the task is to translate that buffer requirement into a chain design and an explicit contact policy.
Size for the arrival pattern, not only an hourly average
An hourly throughput figure hides the way loads arrive. An upstream machine may release one unit each cycle; a transfer cart may deliver several together; a product change may send a short burst. Measure the shortest, usual and peak arrival intervals and how long each peak persists. State separately the permitted time from infeed to discharge. These facts determine infeed sensing, acceleration, stopping positions and local buffer capacity.
As a first approximation, the continuous-flow capacity is chain speed divided by the occupied pitch of one load plus its required gap. This is only a comparison calculation. Stops, transfers and stopper movements reduce actual performance. A supplier should demonstrate the specified peak sequence with real load units during acceptance. Record infeed waiting, downstream waiting and recovery after a stop, not just motor speed.
Accurate stopping is a separate requirement from accurate positioning. If a pallet must enter pins at a machine, identify who supplies the stopper, lift, locating pins and clamp. A servo motor does not eliminate chain elongation or variations in pallet bottoms. When process position is tight, separate transport from final locating and test both operations.
Check allowable working conditions, not just breaking strength
Manufacturer tables use different quantities: minimum tensile strength, maximum allowable load, roller allowable load and attachment allowable load. They are not interchangeable. Surviving a tensile test does not guarantee acceptable wear, fatigue or attachment deformation in continuous operation. Tsubaki separates minimum strength from allowable load and applies operating-condition factors. Renold asks for route length, inclination, attachments, number of strands, speed, load and feed method as selection inputs. Renold Conveyor Chain Designer Guide
Give suppliers load cases rather than an unexplained single “safety factor”: empty run, full load, off-center load, start, emergency stop, downstream blockage, any short reverse movement and restart after cleaning. Request maximum chain tension, drive sizing, roller and attachment checks, and the manufacturer’s factor tables for each relevant case. Compare the margin against each maker’s allowable value under the same stated conditions. A ranking based only on breaking strength can select the wrong solution.
On an incline, distinguish the horizontal and inclined sections and consider back-driving after a power failure. Even on a horizontal line, include rail friction, chain and attachment weight, return-side resistance and sprocket losses. A calculation sheet should state where its friction coefficient came from, how many pallets can be present at once and what actual underside was assumed. More decimal places will not rescue an incorrect physical assumption.
Select pitch, sprocket and support rail as a set
Larger pitch can reduce the number of links but changes sprocket size, tooth count, transfer gap, polygonal motion and installed height. It is not automatically the strongest or best option. ISO 1977:2006 defines characteristics and interchangeability for specified conveyor chains, attachments and sprockets within its scope; it does not standardize every manufacturer’s allowable load or the complete conveyor structure. ISO 1977:2006
Demand drawings of sprocket tooth count and material, shaft arrangement, bearings, rails, wear strips, take-up method and removable covers. The transfer to the next machine is especially vulnerable where support briefly disappears. Test the shortest permitted pallet for nose drop, snagging and tail lift. Catalogue conveyor width does not prove a reliable handover.
Ask whether each strand requires independent tension adjustment or a common drive and shaft will maintain synchronization. Excess tension increases wear and bearing load; inadequate tension can disturb engagement and carrier orientation. The adjustment point must be safely accessible, and maintenance staff need a measurable after-adjustment reference. A tensioner hidden behind inaccessible guarding creates real maintenance time that does not appear in a catalogue.
Turn the local environment into specific design conditions
“Thailand is hot and humid, therefore stainless steel” is not a usable specification. Measure the conditions at the exact installation point: condensation, metal chips, dust, oil, detergent, chemicals, falling debris and wind-driven water. Dust entering pin and bush joints, a product that must not receive lubricant, and a line washed down daily need different solutions. Normal catalogue assumptions may not apply to a severe environment.
For food or clean production, define the product-contact boundary, chemical concentration, rinsing, drainage, lubricant control, debris collection and disassembly procedure. Stainless material alone does not settle corrosion or wear in the chain, shaft, sprocket, fasteners and support rail together. Confirm applicable plant and legal requirements with local specialists.
Where chips or powder are present, ask where contaminants accumulate and what cover staff remove to clean them. Check whether wear rails can be replaced, whether a chain can be split on site, and whether debris falls into the drive. Renold’s maintenance guide calls out lubrication, chain elongation, sprocket wear and alignment. Adapt its sample intervals to the real duty cycle and environment rather than copying a generic calendar. Renold Conveyor Chain Installation and Maintenance
Design safety from the jam-clearing task
Chains, sprockets, infeed and outfeed nip points, and lifts attract hands precisely when a load stops. Show fixed guards, access doors, interlocks, emergency stops, restart warning and means of energy isolation on both drawings and work procedures. OSHA’s conveyor guidance discusses guarding moving chains and sprockets, isolation for service, and emergency-stop access. It is a hazard-identification reference, not evidence of compliance with Thai law. OSHA conveyor safeguarding guidance
Ask: when a pallet skews, who approaches from which position, stops what, uses which tool, and authorizes restart? If a guard must be removed, the isolation and restart procedure must be explicit. A reverse button is not automatically a safe solution; reversing can move a load into another nip or toward a person downstream. Define the allowed reverse states and travel range, then reproduce jam recovery during FAT and SAT.
Locate emergency stops against the actual work positions, loading points, jam access and pedestrian crossings. Differentiate safety circuits from routine stop commands and define restart authority and upstream response to downstream stops. Do not accept an unqualified line item reading “safety devices included.” Ask for their location, function and test method, with the final safety design reviewed under local requirements.
Use sensors to prove that a transfer finished
“Load at infeed,” “load stopped at the stopper,” “downstream clear,” “load passed the exit,” and “receiver supports the load” are five different states. One photocell cannot always prove all five. Define each sensor’s position and target, contamination diagnostic, delay and fail state. If load identity matters, decide what happens when barcode or RFID reading fails: stop, manual verification or an exception path.
A transfer handshake can be described as: sender requests permission; both sides become ready; transfer moves; exit is detected; receiver confirms support; transfer completion is recorded. Specify the PLC I/O and ownership of each request and acknowledgement. Document recovery when a signal is delayed, power returns with the physical load between sensors, or the pallet stops mid-transfer. These are common sources of downtime even when the conveyor’s mechanical speed is ample.
Place sensor positions and the names of upstream and downstream machines in the chain-conveyor RFQ. This makes the control scope comparable between suppliers instead of leaving an undefined gap at the machine boundary.
Normalize quotations before comparing prices
Attach actual load-unit data, route drawing, infeed and outfeed heights, peak arrival sequence, permissible stop time, environmental conditions, safety requirements, power and PLC interfaces, and available installation windows. Request chain model and selection basis, tension calculations, motor rating, sprocket and support details, guard and sensor drawings, spare-part list, installation and training scope, and a FAT/SAT proposal in the same format from each supplier. “One chain conveyor set” is not a comparable offer.
Split capital cost into mechanics, drive, sensors and controls, guards, wiring, support works, modification of existing lines, shipment and installation, commissioning and spares. Split operating cost into chains, sprockets and wear strips, lubrication, cleaning, stoppage losses and replacement lead times. Local stock may shorten recovery, but stock is product- and date-dependent; obtain written part numbers and lead times at quotation time.
Identify scope differences behind price gaps. An accumulating system that lets pallets stop while the chain moves is not equivalent to a system that stops the whole line. A quote including transfer devices and fencing is not comparable to a bare conveyor. Normalize all offers to the same requirements, record exclusions separately, and invite alternatives in a separate column.
FAT and SAT must test stops and recovery
For FAT, prepare the lightest, heaviest, off-center and warped permitted pallets. Test normal and peak arrivals, downstream stop, jam, emergency stop and power restoration. Record chain tension, synchronization, noise, sensor detection, stopper operation and pallet orientation after restart. A vendor test bench may not reproduce the actual receiving machine; carry every unverified interface into SAT explicitly.
At SAT, test the existing handover, floor and height, actual pallet variation, forklift routes, guard access and maintenance reach. If acceptance uses a run duration and a maximum number of stoppages, record the product mix, speed and definition of a stoppage with the result. There is no universal figure suitable for every chain conveyor. Production, quality and maintenance should agree on signed criteria before purchase.
Do not merely adjust a jam away. Log its location, load-unit ID, cause, changed part or setting and repeat result. After a successful run, include initial retensioning and lubrication checks, spare handover, electrical drawings, PLC backup, operating instructions and recovery training in the acceptance package. Running once and being safely operable by the plant are distinct outcomes.
Carry evidence forward when replacing an existing conveyor
An existing machine may have worked for years while the product and duty changed around it. Record changes in weight, pallets, operating hours, cleaning agents and connected processes. Examine repairs to see which chains and sprockets were replaced and where jams occurred. If failures increased because the load changed, replacing the old machine with the same model will repeat the problem. A tight shutdown also demands a survey of the delivery route, removal, anchors, reusable cables, interface heights, PLC signals and any temporary transport. Check maintenance access and guard-door swing in the live plant, including pedestrian and forklift movement.
Measure the outcome of a replacement against a consistent baseline: failure downtime, spare lead time, cleaning and tension-adjustment labor, and product damage. Include any manual exception handling on the old line. Do not book a labor saving if that exception task will still be manual on the new one.
Control changes to the specification
Requests to increase speed, accept larger pallets or add accumulation can change tension, motor size, frame, sensor count, safety distances and transfer mechanisms together. Put the old and new load, peak arrival pattern, stopping requirement and layout on every change request. Ask the supplier to revise both the quote and acceptance tests. “Allow for future expansion” also needs a defined future load, footprint, process interface, I/O and available space. If these cannot be fixed yet, compare a modular connection point with an oversized machine and record the cost-versus-flexibility decision.
Chain conveyor selection checklist
Observe the shop floor consistently before asking for quotations
If observation can be done without stopping production, look separately at the start of a shift, steady production, immediately after a product changeover and near the end of a shift. This reveals demands that an average throughput figure conceals. Record the moment several pallets arrive at the infeed together, when downstream quality inspection pauses, and when empty pallets return. Use the same clock and record three events: when the upstream process was ready to release a load, when the conveyor accepted it, and when downstream equipment accepted it. This separates the boundary where waiting occurs instead of assuming that every delay is a conveyor fault.
Watch the adjustments operators make without being asked. Do they straighten a pallet by hand before feeding it, lift it slightly over a step, press a particular point to clear a jam, or insert a sheet to protect a product from scratches? If so, the actual transfer conditions may not appear in drawings or the production system. Decide whether to include that action in the new machine’s specification or to change the load unit so the action disappears. “We have always done it this way” cannot be an operating assumption once the process is automated.
Prioritize load variation and transfer points over measuring speed during the first site survey. It is not necessary to measure every pallet precisely, but retain separate examples of the heaviest, shortest, most warped and historically jam-prone units. If actual units cannot leave the site, photograph their undersides, sides and four corner heights next to a scale. Agree whether the test samples represent the variation on the real line. Put the result and any new assumption in the specification revision history so that a later change clearly identifies which design checks must be repeated.
Build the maintenance plan backward from replaceable part numbers
The dimensions chosen before installation cannot alone establish how long the chain will last. After commissioning, inspect elongation, lubrication, roller rotation, sprocket tooth form, wear rail condition and the height difference between the two strands. Use the selected manufacturer’s model-specific guidance to set the condition that triggers adjustment or replacement. “Inspect monthly” alone leaves too much room for different judgments by different technicians. Include photographs, measurement points, tools, record sheets and baseline values in the handover package.
The spare-parts list should include not just a complete chain but also connecting links, sprockets, wear strips, sensors, stopper wear parts and bearings needed to restore operation. A similar chain already in the plant is not proof of substitutability. Separate the dimensional interchangeability covered by an applicable ISO specification from a supplier’s own geometry, material and working-load limits. Define what guards or existing cables must be removed to replace each part, and which checks must be repeated after replacement.
For imported parts, confirm lead time, local stock status and emergency contacts at quotation time. A quoted lead time is not a promise about future inventory, so the plant must decide which outage-critical parts to hold. Maintenance staff should know how stored chains are protected against corrosion, packaged, identified and inspected after long storage. At handover, ask the manufacturer about possible early elongation and retensioning, then schedule the first inspection in the production plan.
This preparation also prevents a failure investigation from ending with an unsupported assertion that “the chain is bad” or “the motor is weak.” The team can instead examine changes in load weight, pallet underside, guide alignment, debris, lubrication and control signals in order. Connecting the original selection calculations to maintenance records makes the next replacement project more reliable.
| Question | Evidence from the plant | Required supplier submission |
|---|---|---|
| Load unit | Real minimum, maximum and off-center loads; underside photographs | Support position, accepted dimensions, local loading check |
| Capacity | Peak arrival sequence, model changes, stop duration | Capacity including transfer and accumulation, not only speed |
| Mechanics | Layout, height, existing equipment | Chain, sprocket, rail and drive drawings and calculations |
| Environment | Measured dust, oil, washdown and temperature | Materials, lubrication, drainage and inspection method |
| Safety | Work positions and jam-recovery route | Guards, stops, isolation and restart procedure |
| Controls | Upstream/downstream signal list | Sensor positions, I/O and abnormal-state sequence |
| Acceptance | Real samples and production conditions | FAT/SAT steps, pass criteria and open-item list |
Keep plant measurements separate from supplier assumptions. Label reference values and guaranteed values. Attach this conditions table, drawings and test conditions to the purchase order; a product catalogue alone will not explain a performance shortfall later.
Frequently asked questions
Chain conveyor or roller conveyor: which should we choose?
Choose from the underside, locating requirements, stopping and accumulation, dirt and safe recovery. On a roller conveyor the load rests on rollers; on a pallet chain conveyor the chain-side structure carries the load. Chain-driven rollers form a third category. “Chain versus roller” alone is not an equipment specification.
Can a chain strength table determine maximum conveyor capacity?
No. Check working tension, roller and attachment ratings, rails, sprockets, drive, frame, off-center loading and dynamic start/stop loads. Breaking strength differs from allowable continuous working load. Use the relevant maker’s method and physical tests.
Must a Thai factory choose stainless chain?
Humidity alone does not decide it. Specify cleaning chemicals, dust, oil, lubricant-contamination risk, cleaning method and spare supply. Ask the supplier to state material, lubrication and life assumptions against measured conditions.
What must be measured before asking for a quote?
At minimum: real minimum and maximum size and weight, underside and center of gravity, time series of peak arrivals, installation height and width, and upstream/downstream stop behavior. Photograph where an operator would stand during a jam. That is enough for a useful first comparison; detailed drive and chain calculations can then be completed with shortlisted suppliers.
Conclusion
Chain conveyor selection is the work of aligning the load underside and asymmetric loads, support and accumulation type, tension and wear, transfer control, safe jam recovery, spare parts and acceptance conditions. Measure real load units and peak arrivals first. Compare offers on the same boundary and prove stopping and restarting as well as movement in FAT and SAT.
If your Thai plant is considering pallet or workpiece-carrier transfer, you can contact TOMAS TECH while the layout is still open. Photographs of the load unit, its weight range and the current process layout are enough to begin deciding whether a chain system fits and what to measure next.
Sources
- mk Technology Group, Chain Conveyors.
- Tsubaki, Large Size Conveyor Chains & Sprockets.
- Renold, Conveyor Chain Designer Guide.
- Renold, Installation and Maintenance.
- ISO 1977:2006.
- OSHA, Safeguarding Equipment and Protecting Employees from Amputations. Used as a hazard reference, not as Thai legal guidance.
