| Jaw dies (jaw plates) | Jaw crusher | Form the fixed and moving crushing surfaces; compress feed material as the jaw closes. | Manganese steel is common; alloy selection depends on feed and operating conditions. | Reduced tooth profile, uneven wear, lower throughput, or a product size that becomes harder to control. |
| Cheek plates | Jaw crusher | Protect the side walls of the crushing chamber from contact with moving rock. | Wear-resistant steel; manganese steel is used in some designs. | Visible thinning, cracking, or wear that exposes the crusher frame. |
| Mantle | Cone crusher | Covers the moving head and works with the concave to compress and reduce rock. | Manganese steel is commonly used; grade and profile vary with the application. | Worn or uneven crushing profile, reduced capacity, or changes in product gradation. |
| Concave (bowl liner) | Cone crusher | Lines the stationary bowl and provides the opposing surface to the mantle. | Manganese steel is common, with selection guided by feed characteristics and crusher design. | Uneven chamber wear, a changed closed-side setting, or declining crushing performance. |
| Blow bars | Horizontal-shaft impact crusher | Strike incoming material and accelerate it against the impact surfaces to break it. | Options include manganese steel, martensitic steel, and high-chrome iron; the best choice depends on material and impact conditions. | Rounded or heavily worn striking edges, cracking, or reduced impact-crushing efficiency. |
| Impact aprons and breaker plates | Impact crusher | Provide impact surfaces that receive and redirect material thrown by the rotor. | Wear-resistant cast steel or iron; material choice depends on the machine and the abrasive or impact conditions. | Deep wear grooves, damaged surfaces, or difficulty maintaining the intended product size. |
| VSI rotor tips | Vertical-shaft impact crusher | Guide and accelerate material from the rotor so it impacts other particles or the crushing chamber. | Wear-resistant metal tips, often with tungsten-carbide protection in high-wear areas. | Tip shortening, uneven wear, damage to protective inserts, or an imbalance between rotor positions. |
| VSI distributor plate | Vertical-shaft impact crusher | Distributes incoming feed into the rotor passages for more even loading. | Wear-resistant steel or cast material selected for the rotor design and feed abrasiveness. | Uneven erosion, damaged edges, or irregular feed distribution into the rotor. |