If you work in mining, quarrying, or any aggregate processing operation, you have probably spent a great deal of time thinking about jaw plates. They are the obvious wear components in a jaw crusher, the parts doing the visible heavy lifting every time rock meets steel. But directly alongside those jaw plates, bolted to the inner sidewalls of the crushing chamber, sit two components that rarely get the attention they deserve. They are called cheek plates, and without them in good condition, even a perfectly tuned crusher will underperform, wear out faster, and create safety risks that nobody wants to deal with on a production site.
This article covers what crusher cheek plates actually are, where they sit in the machine, what they do during operation, and how to know when it is time to swap them out.
Jaw Crusher
Where Are Cheek Plates Located?
Cheek plates, also known as side liners or side plates, are robust wear-resistant plates bolted to the interior side walls of the main crusher frame. They are positioned parallel to the crushing chamber, running vertically along its length on both sides, directly adjacent to the moving and stationary jaw dies.
Most jaw crushers use two cheek plates per side, fitted as an upper and lower pair. Upper cheek plates are fixed to the top of the crusher frame, covering the feed zone where material first enters, and lower cheek plates extend toward the discharge opening. Together, they form a continuous protective lining across the full height of each sidewall.
This positioning matters because it is exactly where material makes lateral contact during the compression cycle. Every time the movable jaw swings inward and forces rock against the fixed jaw, that material is not just being crushed downward. It is also pressing sideways. Without cheek plates in place, that lateral force would be absorbed directly by the steel frame, causing accelerated and very expensive structural wear.
Jaw crusher parts diagram
What Do Cheek Plates Do?
The functions of cheek plates fall into three main areas: protection, material flow control, and safety.
Frame Protection
Cheek plates absorb the impact and sliding friction of feed material, acting as a sacrificial layer. They are designed to wear out long before the crusher frame does, making replacement faster and cheaper. This is a deliberate engineering decision. A cheek plate costs a fraction of what a crusher frame costs to repair or replace. By engineering the cheek plate to absorb the punishment, manufacturers ensure that scheduled maintenance stays affordable and predictable.
Material Flow and Crushing Efficiency
Cheek plates play a crucial role in shaping the crushing chamber and controlling material flow. They guide feed material downward toward the crushing zone to prevent jamming, reduce spillage by keeping particles contained within the chamber, and optimize crushing action by ensuring even compression between the jaws.
The inner surface profile of modern cheek plates is rarely perfectly flat. Often designed with strategically placed ridges or waves, they interact with material flow patterns, helping prevent smaller particles from packing tightly against smooth surfaces or becoming trapped inefficiently.
When cheek plates wear unevenly or are allowed to deteriorate too far, the geometry of the crushing chamber changes. Material starts to bypass the main crushing zone, throughput drops, and the machine consumes more power for less output.
Safety
During rare events like breaker bar failure or the introduction of uncrushable material such as tramp metal, cheek plates act as a secondary barrier, containing ejected fragments within the crusher and preventing dangerous projectile hazards. They also help absorb sudden shock loads, reducing stress on critical components such as bearings and hydraulic systems.
Materials: Why Manganese Steel?
Premium cheek plates are manufactured from manganese steel with 14 to 18 percent manganese content. This material must match the jaw dies in hardness, typically 180 to 220 HB, for balanced wear across the crushing chamber.
The reason manganese steel is the dominant material in crusher wear parts comes down to a property called work hardening. When manganese steel is subjected to repeated impact, its surface becomes harder over time. Over time, cheek plates become harder with prolonged use, improving their abrasion resistance. This means that in high-impact applications, a well-made manganese cheek plate actually improves in wear performance during its early service life, not just holds steady.
For very abrasive, low-impact applications, such as certain quartzite or silica-heavy feeds, standard manganese may not work-harden sufficiently. In those cases, chromium carbide overlay or tungsten carbide impregnated plates may be a better fit.
When to Replace Crusher Cheek Plates
Knowing when to pull cheek plates is one of the more practical skills in crusher maintenance. Replacing too early wastes money. Waiting too long risks damage to the frame, to the jaw plates, and to production schedules.
The following table summarizes the key replacement indicators:
| Indicator | What It Means | Recommended Action |
|---|---|---|
| Visible cracks on plate surface | Material fatigue, impact damage | Inspect immediately, replace if crack depth is significant |
| Wear depth exceeds 50% | Sacrificial layer nearly exhausted | Replace promptly |
| Uneven wear pattern | Misalignment or uneven feed distribution | Investigate feed setup and alignment, then replace |
| Increased vibration or unusual noise | Loose or failing cheek plates causing metal-on-metal contact | Stop crusher, inspect and re-torque or replace |
| Reduced throughput without process change | Altered chamber geometry from excessive wear | Measure wear depth, replace if geometry is compromised |
Visible cracks or deep grooves where wear depth has exceeded 50 percent mean replacement is urgent. Uneven wear patterns indicate misalignment or poor feed distribution. Increased vibration and noise suggest loose or failing cheek plates causing metal-on-metal contact. Quarry Wear Parts
Beyond these visual and performance signals, there are operational practices that accelerate wear and can be controlled. Avoid oversized feed larger than 80 percent of the inlet width, as it accelerates cheek plate wear at the upper edges. Maintaining correct closed side setting is also important, because improper adjustment causes sidewall scraping and premature wear. Accumulated fines on cheek plate backs create hot spots and uneven pressure distribution, so cleaning cheek plate backs regularly is recommended.
Cheek Plates vs. Jaw Plates: Understanding the Relationship
A common point of confusion for people newer to jaw crusher maintenance is the difference between cheek plates and jaw plates. They work together but serve different functions.
Jaw plates are the primary crushing surfaces. They are what the rock actually breaks against, the fixed jaw die and the movable swing jaw die. The fixed jaw plate is vertically installed on the front wall of the frame, while the moving jaw plate is inclined. Together, they form an efficient crushing chamber, and during operation, the moving jaw plate makes periodic reciprocating movements against the fixed jaw plate, breaking materials through compression, bending, and splitting.
Cheek plates are the side walls. They do not do primary crushing, but they define the chamber's lateral boundaries, contain the material in the crushing zone, and protect the frame from the sideways forces that jaw plate action generates. Both components wear at different rates and often need to be replaced on different schedules. Ignoring one while servicing the other is a common maintenance oversight that costs operations in unplanned downtime.
Sourcing Quality Replacement Parts
For operations running jaw crushers from major brands such as Metso, Sandvik, Terex, or Liming, getting the right fit matters as much as getting the right material grade. The crusher cheek plates produced by Duma Machinery are suitable for multiple well-known brands and models of crushers, including Metso, Sandvik, Terex, Shangbao, and Liming.
If your operation is also due for jaw plate replacement, it makes practical sense to handle both at the same scheduled maintenance window to avoid entering another downtime cycle shortly afterward. Duma's Jaw Crusher Upper and Lower Side Cheek Plates are manufactured in high manganese steel to fit standard and custom crusher configurations, and their Fixed Jaw Plates offer a range of manganese content options from 13 percent up to 23 percent depending on the application and wear requirements.
DUMA Jaw Crusher Upper And Lower Side Cheek Plates
A Practical Maintenance Summary
Crusher cheek plates rarely cause a dramatic failure on their own. They wear slowly, quietly, and out of sight unless you are actively inspecting them. That is exactly what makes them easy to neglect and exactly why neglecting them is so costly. A crusher running on worn or cracked cheek plates is losing efficiency, putting its frame at risk, and creating a safety hazard that a basic inspection would have caught.
Build cheek plate inspection into every regular maintenance cycle. Check for visible cracking, measure wear depth at the upper and lower zones separately since wear is rarely uniform, and look for changes in vibration or material spillage during operation. When the numbers tell you it is time, replace them. The cost of a pair of cheek plates is a small fraction of a frame repair, and the downtime for a planned replacement is far shorter than for an emergency breakdown.
