Cheek plates (also called side liners) are the wear parts that line the two side walls of a jaw crusher’s crushing chamber. Although they are discussed less than jaw plates, the life of the crusher frame depends directly on them: once the cheek plates pass their wear limit, rock starts to wear the side walls of the frame directly, and repairing the frame costs many times more than replacing the cheek plates.
In this guide we cover in detail the function of cheek plates, the difference between upper and lower cheek plates, signs of wear, inspection and replacement steps, material selection and what to watch when buying spare parts. For general jaw crusher operation, see our jaw crusher guide.
Function of Cheek Plates
- Protect the frame: Prevent rock in the crushing chamber from rubbing and striking the side walls of the frame.
- Support the jaw plates from the sides: Some designs limit sideways movement of the fixed jaw plate.
- Complete the chamber geometry: Prevent material escaping from the sides of the chamber and define the crushing volume.
Cheek plates usually come in two parts, upper and lower. The lower cheek plates wear much faster because they receive more intense abrasion and pressure near the discharge opening. The lower plates are therefore replaced noticeably more often than the upper plates.
Material Options
| Material | Property | Suitable for |
|---|---|---|
| Austenitic manganese steel (Mn13–Mn18) | Surface work-hardens under impact; tough | Large feed, high impact, standard applications |
| Wear plate (400–500 HB) | High sliding abrasion resistance | Zones with little impact and heavy abrasion |
| Chromium alloy castings | Very high wear resistance, low toughness | Controlled feed, abrasive but low-impact conditions |
Manganese steel needs real impact load to work-harden. In areas with little impact, where material mainly slides past, hard wear plates can give longer life than manganese. The right choice depends on the abrasiveness of the rock, the feed size and the crusher type. For material selection you can also see our manganese steel grade guide.
Signs of Wear and Failure
- Marked thinning and grooves on the surface of the lower cheek plates,
- Breakage or cracks at plate edges,
- Gaps and movement between the plate and the frame,
- Loosening or breakage of mounting bolts,
- Shiny rubbing marks on the frame side walls (a sign that the plate no longer protects),
- Material jamming and knocking in the side areas of the crushing chamber.
Inspection and Measurement
| Check | Interval | Method |
|---|---|---|
| Visual wear check | Weekly | By eye after the crusher has been stopped and locked out |
| Thickness measurement | Monthly or during jaw work | Thickness gauge or template |
| Bolt tightness | Weekly | Torque wrench; check for loose bolts |
| Frame side wall | At plate replacement | Check for rubbing marks, thinning and cracks |
If thickness measurements are recorded and related to the tonnage processed, the next replacement can be predicted and parts prepared before the shutdown.
When Should They Be Replaced?
- When plate thickness falls to the minimum specified by the manufacturer,
- When the plate cracks, breaks or wears through,
- When the plate no longer sits properly on the frame and starts to move,
- When jaw plates are being replaced and the cheek plates are close to their limit (replacing them in the same shutdown avoids an extra stop).
Replacement Step by Step
- Preparation: New plates, mounting bolts and nuts, and lifting devices are prepared.
- Safe shutdown: The crusher and feeder are stopped, LOTO is applied and the crushing chamber is emptied.
- Access: If necessary, jaw plates or wedge elements are removed to give access to the cheek plates.
- Removal: Bolts are removed; seized plates are separated as recommended by the manufacturer. If plates are fixed by welding, cut carefully.
- Cleaning and inspection: The frame side surface is cleaned and checked for wear and cracks.
- Fitting: The new plates are seated fully against the frame and the bolts are tightened to the manufacturer’s torque.
- Check: The gap between the jaw plates and cheek plates is checked; confirm that the moving jaw does not rub on the cheek plates.
- Commissioning: Bolts are re-tightened after the first hours of operation.
Common Mistakes
- Tracking cheek plates only visually: Thinning in the lower area may not be visible from outside; measurement is essential.
- Running them until they wear through: Once the frame starts to wear, costs multiply.
- Unsuitable material selection: Using manganese in a zone without impact, or a brittle material in an impact zone.
- Not checking bolt tightness: A loose plate causes fast wear on both itself and the frame.
- Not checking aftermarket plate dimensions: Differences in hole positions and profile cause fitting problems and gaps.
Troubleshooting Table
| Symptom | Possible cause | Solution |
|---|---|---|
| Lower plates wear very quickly | Abrasive material, feeding fines, unsuitable material | Remove fines beforehand, review material selection |
| Plate cracks | Brittle material, loose fitting, impact | Choose a tougher material, check the bolts |
| Rubbing marks on the frame | Plate limit exceeded | Replace immediately and have the frame inspected |
| Bolts break | Wrong torque, fatigue, loose plate | Quality bolts, correct torque, regular checks |
| Jamming at the chamber sides | Unsuitable or worn plate profile | Check profile and dimensions |
An Example from the Field
At a granite quarry, jaw plates were replaced regularly while the cheek plates were only checked by looking from outside. During a major overhaul it turned out that the lower cheek plates were almost completely worn away and the frame side walls had worn by several millimetres. The crusher had to stop for a long time to repair the frame. Afterwards the plant started measuring cheek plate thickness monthly and assessing the cheek plates whenever jaw plates were replaced. This simple step completely prevented frame wear in the following years.
Choosing Cheek Plate Spare Parts
- Dimensions and hole match: Plate length, width, thickness and bolt hole positions must match the crusher model exactly.
- Material certificate: Request chemical analysis and hardness values.
- Casting quality: There must be no porosity, cracks or shape distortion.
- Replace as a set: Replacing left and right plates together gives a balanced crushing chamber.
CSP Mühendislik supplies upper and lower cheek plates, mounting bolts and other wear parts for jaw crushers of different makes and models as part of its jaw crusher spare parts range. We recommend assessing the jaw plates in the same shutdown.
Pre-Purchase Checklist
- Have the crusher model and serial number been identified?
- Have the upper and lower plate requirements been determined separately?
- Have the dimensions and hole positions of the existing plates been checked?
- Has the material (manganese, wear plate) been chosen for the application?
- Are mounting bolts and nuts included in the order?
Safety
- Replacing cheek plates may require entering the crushing chamber; the crusher and feeder must be locked out and the chamber completely emptied.
- The plates are heavy; use lifting devices and suitable slings.
- Take fire and fume precautions during welding or cutting.
Frequently Asked Questions
Should cheek plates be replaced together with the jaw plates?
It is not mandatory; but if the lower cheek plates are close to their limit, replacing them in the same shutdown avoids extra downtime and labour.
Can cheek plates be turned over?
In some designs, symmetrical plates can be swapped or turned and reused. This depends on the plate design.
Can the crusher run without cheek plates?
No. Without cheek plates the frame wears directly and is permanently damaged in a short time.
Which material lasts longer?
It depends on the application. If impact is high, manganese; if abrasion dominates, hard wear plates can give longer life.
What should be done if the frame is worn?
The frame surface can be built up with a suitable welding procedure and machined; major damage requires a manufacturer-approved repair. See jaw crusher main frame maintenance.
Spare Parts and Service for Cheek Plates
With many years of experience in manufacturing jaw crushers and supplying jaw crusher spare parts, CSP Mühendislik supplies cheek plates in a material suited to your application and provides service for on-site wear measurement, plate replacement and frame inspection. Send us your crusher model on WhatsApp for a quick quote.
