Impact Plates and Apron Liners for Impact Crushers
Impact plates—also referred to as apron liners, curtain liners, or impact aprons—are the secondary wear components inside impact crushers that receive material rebounding from the rotor. Together with blow bars or crusher hammers, they define the crushing action and determine product size and shape. Their wear life and dimensional condition directly affect product gradation consistency and crusher throughput.
Mine Components manufactures impact plates in manganese steel and high-chromium alloy iron for horizontal shaft impact (HSI) crushers, vertical shaft impact (VSI) machines, and hammer mills across the mining, aggregate, cement, and recycling industries.
Applications
Impact plates are installed in the following equipment types:
Horizontal shaft impact (HSI) crushers — primary and secondary applications in aggregate quarrying, mining, and recycling. The primary and secondary aprons absorb material from the rotor at high velocity and redirect it for further reduction. Wear on apron liners controls the gap setting and thus the product size; as liners wear, the CSS opens and product coarsens unless the apron position is adjusted or the liners replaced.
Hammer mill impact chambers — the breaker plate or impact wall opposite the rotor receives material driven by the hammers and dissipates kinetic energy through a combination of impact and abrasion. Liner wear rate in this zone is high and replacement frequency is correspondingly greater than for other positions.
Vertical shaft impact (VSI) crushers — anvil rings and chamber liners in rock-on-anvil configurations. Material thrown by the rotor strikes the anvil or liner at high velocity; liner material must sustain high-frequency impact without chipping while providing sufficient hardness to resist progressive abrasive wear.
Material Grades and Selection
The optimal material for an impact plate depends on the same variables that govern crusher hammer selection: impact energy, feed material hardness and silica content, and whether the loading mechanism allows sufficient dwell time for work hardening.
Manganese Steel (Mn14, Mn18)
Manganese steel impact plates are appropriate for primary HSI applications with hard or mixed feed, where impact energy is high and tramp metal risk makes toughness a priority. Manganese plates work-harden progressively in service, developing a hard surface layer while maintaining ductile back material that resists fracture. Mn18 is preferred for the primary apron position in large primary impact crushers; Mn14 is standard for secondary apron positions and for smaller machines.
High-Chromium Iron (GX260Cr27 and similar)
High-chromium iron provides the highest abrasion resistance of the available materials and is the appropriate choice for the breaker plate position in hammer mills and for VSI anvil liners processing high-silica feed. The trade-off is reduced toughness: high-Cr iron plates will fracture under direct impact from tramp metal or from operating the crusher at feed sizes significantly above design. Where tramp metal exclusion is reliable, high-Cr iron liners typically outlast manganese by a significant margin in abrasive applications.
Composite Construction
In some impact plate designs, the backing structure is manganese or alloy steel for toughness and the wear face is built up with high-chromium iron inserts, weld overlay, or ceramic composite materials. We can produce composite impact plates to client specifications for applications where neither standard manganese nor standard high-Cr iron provides adequate performance.
Geometry and Dimensional Options
Impact plates must conform precisely to the crusher’s apron mounting geometry to ensure correct gap setting and effective sealing of the crushing chamber. We produce impact plates in the following configurations:
Single-piece apron liners — for standard HSI models where the apron is replaced as a single unit. Mounting hole pattern and radius are matched to the crusher model.
Segmented liner sets — for large aprons where single-piece handling weight is impractical, or where differential wear across the liner width makes sectional replacement more economical. Segment joints are designed to maintain a continuous wear surface without gaps that would allow material bypass.
Profiled and stepped liners — some impact crusher models use a stepped or corrugated apron profile to improve the secondary fracture mechanism. We produce these profiles in both manganese and high-Cr iron.
Custom modifications include: plate thickness adjustments for retrofitting non-OEM crushers, modified bolt patterns, wear-indicator steps at defined depth intervals, and alternative materials for specific feed conditions.
Fit and Crusher Compatibility
Impact plates are safety-critical components—a plate that does not fit correctly in the apron frame creates a gap that allows uncontrolled material bypass and introduces an impact risk to the apron structure. We work from client-supplied drawings or confirmed crusher model data to ensure dimensional accuracy before committing tooling for custom plates.
For crusher models where the OEM no longer supplies liners, or where the OEM lead time is unacceptable, we can produce compatible plates from worn originals or field measurements. This process requires a clear dimensional reference; we will advise on the minimum measurements needed to produce a reliable replacement.
Manufacturing and Quality Assurance
Impact plates are produced by sand or resin-sand casting with post-cast heat treatment appropriate to the material grade. Critical dimensions—mounting surfaces, radius of curvature, bolt hole positions—are verified after machining against the drawing tolerance. Hardness is tested at multiple locations across the wear face to confirm uniformity.
Each delivery includes: chemical composition certificate, hardness test report, dimensional inspection record, and heat treatment documentation. NDT is available on request. For a complete overview of our quality standards, see the Quality Assurance page.
Ordering and Lead Times
Standard-geometry impact plates for common HSI crusher models are available with lead times of 3–5 weeks. Custom profiles, composite construction, or large plates may require 5–8 weeks. Provide the crusher model and current liner drawing or part number to receive a precise lead time and quotation.
Request a Quote for Impact Plates →
Related Products
Impact plates are typically replaced in conjunction with Crusher Hammers or blow bars. We can supply complete wear part sets—liners and hammers—for a crusher in a single order. Clients in jaw crushing applications may also require Jaw Plates.