Industrial Chain Failures: A Visual Guide to Wear Patterns Part 1

Most industrial chain failures show warning signs before the chain breaks. Side wear, damaged rollers, hooked sprocket teeth and stiff links can all indicate a developing problem.

However, identifying visible damage is only the first step. The same symptom may result from poor lubrication, misalignment, incorrect tension, contamination or excessive load.

For example, wear on one side of a chain plate may indicate misaligned sprockets. It may also be caused by a displaced guide or axial movement in a shaft.

Replacing the chain alone will not solve a recurring failure. You must find and correct the root cause first.

This guide explains what common industrial chain wear patterns reveal, what you should inspect and which corrective action may be required.

Safety warning: stop and isolate the machine before inspecting a chain drive. Lock out all energy sources and prevent accidental start-up. Cracks, deformation and structural damage require an appropriate technical assessment.

Roller chain diagnosis table

Visible symptom	Likely causes	What to check	Recommended action
Side wear	Misaligned sprockets, non-parallel shafts, displaced guides	Alignment, bearings, guides and supporting structure	Realign the drive and replace damaged components
Hooked sprocket teeth	Elongated chain, poor lubrication, excessive tension	Tooth profile, chain elongation and engagement	Replace worn sprockets and assess the complete set
Broken rollers	Overload, impact, seized rollers, damaged guides	Actual load, guides, sprockets and roller movement	Stop the drive and replace the affected chain
Cracked plates	Fatigue, shock loading, jams or undersizing	Cracks, load history and torque limiter	Replace immediately and review the drive design
Rotated pins	Seized joints, poor lubrication or excessive tension	Rivets, chain tension and link movement	Replace the chain and remove the source of friction
Pitting corrosion	Moisture, chemicals or unsuitable material	Pit depth, operating environment and lubricant	Replace damaged chain and review material selection
Stiff links	Dirt, corrosion, poor lubrication or misalignment	Joint movement, alignment and contamination	Clean and lubricate or replace the chain
Uneven wear	Uneven load, eccentric sprocket or irregular lubrication	Elongation by section and load distribution	Correct the cause and replace affected components

1. Side wear on plates and rollers

How to identify it

Side wear normally appears as a polished, scratched or reduced area on one side of a chain plate.

You may also find contact marks on:

• Roller sides.
• One side of the sprocket.
• Chain guides.
• Nearby machine components.

When the damage remains on the same side, the chain is probably being forced away from its correct running line.

Common causes

Typical causes include:

• Misaligned sprockets.
• Shafts that are not parallel.
• Axial movement in a shaft or bearing.
• Incorrectly positioned guides.
• A twisted chain.
• A deformed supporting structure.

Misalignment creates side loads. These loads can reduce plate thickness and accelerate wear on the rollers and sprockets.

What to check

Check both parallel and angular sprocket alignment. Use a suitable straightedge, laser system or alignment instrument.

You should also inspect:

• Bearings.
• Sprocket mounting.
• Axial shaft movement.
• Guide position.
• Structural rigidity.

Corrective action

Realign the drive and correct the guide position.

Replace the chain if the plates have lost a visible amount of material. A worn plate may remain structurally weak after the alignment problem has been corrected.

2. Hooked sprocket teeth

How to identify them

A healthy sprocket has uniform and symmetrical teeth.

As wear develops, material disappears from one tooth face. The tip then becomes curved, sharp or hook-shaped.

In advanced cases, the chain no longer sits correctly in the tooth gap. It may climb up the tooth before engaging.

Common causes

Hooked teeth may result from:

• Chain elongation.
• Insufficient lubrication.
• Excessive tension.
• Misalignment.
• Unsuitable sprocket material.
• A new chain running on worn sprockets.

An elongated chain has a larger effective pitch. Therefore, it no longer engages evenly and transfers the load through fewer teeth.

What to check

Inspect:

• Every tooth around the sprocket.
• Chain elongation.
• Chain-to-sprocket engagement.
• Slack-side tension.
• Shaft alignment.
• Both the driving and driven sprockets.

Corrective action

Replace any sprocket with a clearly hooked profile.

Where wear is advanced, replace the chain and sprockets as a set. A worn sprocket can quickly damage a new chain.

3. Broken or deformed rollers

How to identify them

Rollers may show:

• Cracks.
• Flattening.
• Complete breakage.
• Impacted edges.
• Flat wear surfaces.
• Restricted rotation.

A seized roller does not roll into the sprocket. Instead, it slides and receives repeated impacts.

Common causes

Roller failures may be caused by:

• Overload.
• Product jams.
• Shock starts.
• Contamination.
• Corrosion.
• Damaged guides.
• Severely worn sprockets.
• Excessive operating speed.

What to check

After isolating the machine, check whether accessible rollers rotate freely.

Also inspect:

• Transfer points.
• Guide joints.
• Impact marks.
• Previous jams.
• Actual conveyed load.
• Torque-limiting devices.

Damage that repeatedly appears in the same position may indicate a guide defect or an obstruction.

Corrective action

Stop the machine when broken rollers are found.

Loose fragments can become trapped between the chain and sprocket. This may cause jumping, seizure or further damage.

After replacing the chain, inspect the sprockets, guides and overload protection system.

4. Cracked chain plates

How to identify them

Cracks often start:

• Around pin holes.
• At plate edges.
• Near the connecting link.
• In corroded areas.
• At impact points.

Oil and dirt may hide small cracks. Clean the surface appropriately before completing the inspection.

Common causes

Chain plates may crack because of:

• Sudden overloads.
• Fatigue.
• Repeated jams.
• Starting against a locked load.
• External impact.
• Corrosion.
• Severe misalignment.
• An undersized chain.

What to check