Why Tungsten Carbide Bushings Crack: Root Causes and Fixes

텅스텐 카바이드 부싱 are known for their high 경도 and long life. But they can still crack when the working conditions or installation steps are not correct.

Cracks reduce performance and may cause pump or machine failure. This guide explains the main reasons why these bushings crack and what you can do to avoid these problems.

Understanding Why Cracks Happen in Tungsten Carbide

Tungsten carbide is very hard, but also brittle. This means it can resist wear but cannot absorb strong impact or heavy stress.

When a bushing faces force it was not designed for, cracks can form, especially near edges or thin walls.

Key Characteristics That Influence Cracking

Material Property	Influence on Cracking
높은 경도	Strong wear resistance but low impact tolerance
취성	Cracks form under sudden loads or shock
Thermal Sensitivity	Rapid temperature change increases stress
바인더 유형	WC-Co and WC-Ni respond differently to corrosion and fatigue

Root Cause: Improper Press-Fit Conditions

Press-fitting is a common installation method, but too much interference or uneven force can create high hoop stress in the bushing. This stress builds up and leads to cracks after installation or during operation.

1). Signs of Press-Fit Cracking

Cracks forming around the outer surface
Bushing becomes tight or distorted
Chipping at the edges
Sudden failure after startup

2). Common Press-Fit Mistakes

Mistake	Effect
Too much interference fit	Excess stress on the bushing
Hammering instead of controlled pressing	Shock impact cracks
No lubrication during pressing	Uneven loading, scoring, cracking
Misalignment during press-fit	Bushing tilts and cracks at edges

Root Cause: Misalignment Between Shaft and Housing

If the shaft is not centered inside the bushing, the load becomes uneven. One side carries more pressure, leading to bending stress and surface cracks.

1). Symptoms of Misalignment Cracking

Wear marks on only one side
Out-of-round wear pattern
Early vibration
Vertical or angled cracks along the bore

2). Typical Misalignment Sources

Shaft machining errors
Housing bore not perpendicular
Machine frame distortion
Bearing seat damage

Root Cause: Thermal Shock and Temperature Stress

Tungsten carbide does not expand as much as steel or cast iron. If temperature changes quickly, the bushing can crack from thermal shock.

This often happens in pumps running hot fluid or experiencing sudden cooling.

1). Temperature-Related Crack Conditions

Rapid cool-down from cold water during flushing
Running dry, then sudden cooling from fluid
Heating due to friction from poor lubrication

2). Recommended Thermal Limits

상태	Recommendation
Temperature rise	Keep steady, avoid fast spikes
Cooling	No rapid cold-water exposure
Dry-running heat	Stop equipment before temperature rises too high

Root Cause: Corrosion and Binder Attack

Although tungsten carbide is stable, its binder metal (Co or Ni) is vulnerable in certain fluids.

If the binder corrodes, the structure weakens. Cracks then form under normal load because the material loses toughness.

1). Fluids That Increase Cracking Risk

High-chloride water
Acidic or low-pH fluids
Strong alkaline cleaners
Saltwater with high oxygen content

2). How Binder Attack Leads to Cracking

Corrosion begins at the binder.
Grain boundaries weaken.
Micro-cracks form.
Cracks grow under load.

Root Cause: Impact and Handling Damage

Tungsten carbide chips easily if dropped or hit. Many cracks start before the bushing is even installed due to poor handling during shipping, storage, or unpacking.

1). Common Handling Mistakes

Dropping the bushing on a hard surface
Allowing bushings to collide with each other
Using metal tools that strike the edges
Storing without padding

2). Early Crack Indicators

Small chips around the edge
Hairline cracks visible under magnification
Slight deformation at corners

How to Fix or Prevent Cracking in Tungsten Carbide Bushings

Preventing cracks begins with understanding how stress enters the bushing. Good installation, controlled operating conditions, and correct material selection solve most of the problems before they start.

Fixes and Preventive Actions

문제	해결책
Press-fit cracking	Use proper interference values and controlled pressing
Misalignment	Check shaft and housing geometry before assembly
Thermal shock	Control temperature changes and avoid dry running
Binder corrosion	Select WC-Ni or corrosion-resistant grades
Impact damage	Improve packaging and handling

결론

Cracking is preventable when the right installation, handling, and operating controls are followed.

By understanding how stress, temperature, alignment, and corrosion affect tungsten carbide bushings, companies can extend service life and avoid costly failure.

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