When applied correctly, the backing compound poured behind the mantle and concave in cone and gyratory crushers carries the liner safely to its designed wear limit. Small mistakes in application, however, come back as loose liners, cracking and even permanent damage to the head and bowl surfaces. In this guide we bring together the most common backing-related problems seen in the field, their symptoms, root causes and solutions.
For correct application steps, see our crusher backing compound guide.
Troubleshooting Table
| Symptom | Possible Root Cause | Solution |
|---|---|---|
| Mantle or concave loosening, knocking noise | Porous or incomplete backing; loading before cure; head nut under-tightened | Remove the liner, clean the surfaces and re-pour; check the head nut torque |
| Early liner cracking | Unsupported areas (voids), liner not fully seated | Improve pouring technique and dams; check seating |
| Backing stays soft or tacky | Partial or off-ratio mixing, insufficient mixing, low temperature | Mix the whole kit; bring temperature into the data sheet range |
| Voids and porosity in the backing | Trapped air, pouring too fast, cold and thick material | Slow pour from a single point, warming |
| Layered backing (separated layers) | A break during the pour; too little material | Quantity calculation, spare kit, uninterrupted pour |
| Backing leakage, level too low | No dam or an inadequate dam | Seal lower edges and holes with suitable material |
| Backing not bonded to the surface | Oily, dirty, wet or icy surface | Surface cleaning and drying |
| Hammering marks on head or bowl seating surfaces | Liner has run loose for a long time | Surface repair; review backing and tightening procedure |
Loose Liner: Step-by-Step Diagnosis
- Confirm the symptom: Knocking noise, signs of movement between liner and body, an unexpected change in crusher setting, or shiny rubbing areas on the liner surface.
- Review the records: The product used at the last change, number of kits, temperature, cure time and return-to-service time.
- Inspect the backing on removal: Are there voids, layers, soft areas or lack of bond in the backing cross-section?
- Determine the root cause: Quantity, mixing, temperature or surface preparation problem, according to the troubleshooting table.
- Update the procedure: Add the lesson to the checklist for the next change.
Check Non-Backing Causes Too
Not every loose liner is caused by the backing. The following causes should also be considered:
- Head nut or locking system: Insufficient tightening or damage to the locking element (main shaft and head assembly).
- Liner worn past its limit: A very thin liner flexes and cracks (mantle and concave replacement).
- Uncrushable metal and tramp events: Frequent tramp events strain the liner and backing (magnetic separator and metal detector).
- Aftermarket liner fit: Liners with a different back-face geometry may need more backing.
- Lack of choke feeding: Irregular feed increases shock loads (cone crusher guide).
Preventive Checklist
- Are the right product and enough kits (plus a spare) ready?
- Are the material and parts at the data sheet temperature?
- Are the surfaces clean, oil-free and dry?
- Has the liner been fully seated and secured?
- Are the dams complete?
- Was the whole kit mixed in ratio and uniformly?
- Was the pour made from a single point without interruption, and is the level equal everywhere?
- Is the cure complete; is the sample hard?
- Have all values been recorded?
Cold conditions require additional measures; see our cold-weather backing application guide, and for quantity planning our backing quantity calculation guide.
Frequently Asked Questions
Will soft backing harden over time?
A cure slowed by low temperature can complete when the temperature is raised. Softness caused by off-ratio or partial mixing, however, is permanent; the backing must be removed and re-poured.
Can a crusher keep running with a loose liner?
Not recommended. A loose liner hammers the head and bowl surfaces, can crack and can lead to far more expensive damage.
Which backing product causes fewer problems?
A good-quality product suited to your crusher, applied with the correct procedure, is what matters. For every product, including CSP’s own Aurox backing compound, the data sheet conditions must be followed.
CSP Mühendislik Support
CSP Mühendislik provides on-site root-cause analysis, mantle–concave replacement and backing application support for loose liner and backing problems. See our Aurox backing compound guide and other crusher backing products, and our cone crusher spare parts page for mantles and concaves, or get support from our service, maintenance and repair team.
