Two chains, a series of plates between them, a frame that carries the load. That is the whole idea of a chain plate conveyor, and most of the failures we are asked to diagnose come from treating the plates as a surface and the chains as a detail.
Start from the load per slat, not the total load
A 12 m conveyor carrying 800 kg sounds modest. Distributed over 60 slats, that is 13 kg per slat, which any 12B chain will carry. The same 800 kg concentrated on a single casting at the load station is a different problem: the slat bends, the chain pin sees a point load, and the wear strip underneath takes a dent that never recovers.
Calculate three numbers before selecting anything: the uniform load per metre, the maximum point load at any station, and the number of slats sharing that point load. The point load usually governs.
Slat pitch and the transfer gap
The gap between slats is set by the pitch and the slat width. Small parts need a small gap, but a small gap means more slats, more weight and more cost per metre.
For parts smaller than 80 mm, either reduce the pitch to 50 to 63 mm or run the parts in a tray. For parts above 300 mm, a 100 to 125 mm pitch is normal. The transfer point at each end is the other constraint: a gap wider than one third of the smallest part footprint will drop it.
Slat material
Carbon steel is the default for heavy castings, stampings and general industrial parts. It is strong, repairable and cheap. It rusts, which matters in washdown areas and on painted parts.
Stainless steel is used for food, pharmaceutical, wet or corrosive environments. It costs two to three times more and is softer than carbon steel in the common 304 grade, so it dents more readily under impact.
Engineering plastic (HDPE, PP, UHMW) protects finished surfaces and runs quietly. It is limited in temperature, typically 80 to 100 degrees Celsius, and it wears at the chain attachment holes.
Chain type
Standard roller chain is adequate for most horizontal runs under 15 m. For longer runs, high loads or curves, use a heavy series chain or a forged chain with a larger pin diameter. The chain's allowable working load should be no more than one fifth of its breaking load on a conveyor with frequent starts.
Curves are where chain selection becomes critical. A curve adds side load to every pin, and a standard chain in a curve wears the pin and bush oval within a year. Use a curve chain with enlarged clearances, or a chain with a built-in side roller.
Wear strips and return runs
The wear strip carries the chain between the slats and the frame. UHMW polyethylene is standard; it is quiet, low friction and cheap to replace. It also creeps under load at temperatures above 80 degrees Celsius, which is why high-temperature lines use a steel or bronze strip instead.
Design the strip as a consumable: bolt it from below, keep it in 2 m lengths and leave a 3 mm expansion gap between lengths. A strip that is trapped under the frame cannot be replaced without dismantling the conveyor.
Frame and support spacing
Support the frame every 1.5 to 2 m on a loaded run. A frame that deflects under load tilts the slats, and a tilted slat wears the chain on one side. The deflection limit we design to is 1/500 of the span under full load.
Selection checklist
- Maximum point load and the number of slats sharing it.
- Smallest part footprint, which sets the maximum gap.
- Temperature at the slat, not in the room.
- Presence of oil, coolant or washdown water.
- Number of curves and their radius.
- Start frequency and whether the conveyor runs loaded.
