DIN 22102

What the test does

A full-thickness strip is cut from a finished belt, clear of the edge and containing no ply joint, then clamped at both ends in a tensile machine. The crosshead pulls along the belt until the carcass ruptures, force and extension recorded throughout, so stretch at a working load and the breaking force come from one pull. Adhesion works differently: a strip is started at the interface and its two arms drawn apart in a peel jig, so separation travels along the bond instead of breaking it at once. Cover abrasion runs on a rotating drum, and troughability on a freely hanging length of belt.

What it measures, and why it matters

The requirements cover elongation under a reference load taken as a tenth of nominal breaking strength, tensile strength and elongation at break, abrasive wear of the covers, and resistance to separation between plies and between cover and carcass. Elongation under the reference load is used directly by the conveyor designer: it fixes how much take-up travel the installation needs and how far the belt creeps before it settles. Breaking strength sets the margin on the drive and the splice. Separation resistance decides whether the carcass survives years of flexing over pulleys: a belt that delaminates loses its load path long before the fabric is near failing. Cover abrasion predicts how long the rubber keeps bulk material off the carcass. The 2020 revision added an ageing step before the cover tensile determination, so covers are judged after heat exposure rather than fresh.

Specimen

Specimens are taken full thickness from the finished belt, away from the edge and clear of any joint, since a joint reports its own strength rather than the belt's. Peel specimens are started at the interface of interest so the split has somewhere to begin. The testing part is short and not publicly readable, so specimen counts and conditioning are best confirmed against the purchased text. The aligned methods it routes to expect nominally 23 °C and 50 % relative humidity, which is what most laboratories run, but that figure is derived, not quoted.

What the machine must be capable of

Nothing publicly accessible settles the machine parameters: capacity, force-accuracy class, extensometer class and test speed alike could not be confirmed, and all four should be taken from the purchased text. Capacity, at least, follows from arithmetic on the belt rather than from a clause: a full-thickness strip carries rated carcass strength times specimen width, so a 50 mm strip from a belt rated at 160 N/mm needs roughly 8 kN, the same strip from a 1000 N/mm belt about 50 kN, and textile classes here reach 3150 N/mm. Laboratories either cut narrow specimens to bring the load inside a general-purpose frame or run a dedicated belt frame. Adhesion peel sits at the other extreme, in the tens to low hundreds of newtons, which usually means a second, much smaller load cell.

One measurement must cover two strain regimes. Elongation under the reference load falls in the first few per cent — the permitted value depends on belt class and sits around one and a half to three per cent for common polyester–polyamide constructions — so resolution at small extension decides whether the figure means anything, while elongation at break is far larger and the device must survive to rupture. Grips must be serrated wedge or vice clamps able to hold a thick, resilient section without letting it draw out; peel needs a jig holding a controlled separation angle, and troughability a free-hanging rig rather than a frame.

What goes wrong in practice

Slippage is the standing problem. A rubber-covered strip under tens of kilonewtons creeps out of clamps that are not aggressive enough, and the record shows a falsely compliant curve before anyone sees the belt move. Over-clamping fails the other way: crushed covers start the fabric failing at the jaw line, so the figure reported belongs to a damaged belt. Internal delamination during a pull is a real result rather than a fault, but it changes what the break load means. A specimen that quietly includes a joint reports the joint. And a belt is thick and slow to equilibrate, so short conditioning shifts behaviour with no sign of it in the data.

Related and equivalent standards

DIN EN ISO 14890 is the nearest counterpart and the usual source of confusion, because the trade quotes cover abrasion figures from the two documents against each other as though they were interchangeable. They are not competing editions, and a belt specified to one is not automatically described by the other. Beneath both sit the aligned ISO methods for full-thickness tensile testing and for adhesion between belt elements, where the procedure detail lives. Underground coal belts go instead to a separate DIN series and to DIN EN ISO 22721.