Impact Crusher Input 170mm and Output 35mm: A Reliable Solution for Medium-Hard Material Reduction
An impact crusher with a feed opening capable of accepting 170 mm material and producing a final product of 35 mm or smaller represents a highly efficient, single-stage crushing solution for medium-hard, non-abrasive rocks such as limestone, gypsum, coal, and dolomite. This specific configuration delivers a reduction ratio of approximately 5:1, which is typical for horizontal shaft impactors (HSI) operating in secondary or tertiary roles. The ability to reduce 170 mm feed directly to a 35 mm product without intermediate screening or additional crushing stages makes this machine particularly attractive for quarries and recycling operations where space, energy efficiency, and capital cost are critical constraints.
The working principle of an impact crusher relies on high-speed rotor rotation—typically between 600 and 1200 rpm depending on rotor diameter—and the kinetic energy imparted to the material. When a rock of up to 170 mm enters the crushing chamber through the feed opening, it strikes the rotor’s blow bars (or hammers) which accelerate it toward stationary breaker plates mounted on the top and sides of the chamber. The repeated impacts between the rock and these plates, as well as collisions among particles themselves, cause fragmentation along natural fracture planes. The discharge opening is controlled by adjusting the gap between the rotor tip and the breaker plates; for a target output of 35 mm, this gap is set accordingly. Modern impact crushers also incorporate hydraulic adjustment mechanisms that allow operators to change the setting in minutes without stopping production.
One key advantage of using an impact crusher for this size reduction task is its ability to produce a cubical product shape. Unlike compression-type crushers (e.g., jaw or cone crushers), which tend to generate elongated or flaky particles when reducing material from around 150–200 mm down to sub-40 mm sizes, an impactor’s high-energy collisions break rocks more uniformly along all axes. This results in a higher percentage of cubic grains in the final product—an essential quality for concrete aggregates and road base materials. Field data from limestone quarries show that an HSI set at a closed side setting (CSS) equivalent to about 30–40 mm can yield over 85% cubical particles in the –35 mm fraction.
Energy consumption is another important consideration. For reducing limestone from 170 mm to –35 mm, specific energy typically ranges from about 2.5 to 4 kWh per ton depending on moisture content and hardness. This compares favorably with two-stage crushing circuits (e.g., jaw + cone) which often require combined energies above 5 kWh/t due to additional motors and conveyor losses. Moreover, an impact crusher’s wear parts—blow bars and breaker plates—are made from high-chrome iron or manganese steel alloys designed to withstand abrasion while maintaining consistent performance over thousands of tons processed.
Application-wise, this machine fits naturally into medium-hard rock processing lines where primary crushing has already reduced run-of-mine material down to around <200 mm (often via a jaw crusher). The impactor then takes over as either a secondary or tertiary unit delivering final aggregate sizes suitable for asphalt mix designs (typically requiring –38 mm base layer stone) or cement raw meal preparation where particle size must be below about 30–50 mm before entering ball mills. In recycling applications—such as processing demolished concrete containing rebar—the same machine can accept mixed rubble up to ~150–180 mm side length while rejecting metal contaminants via magnetic separators downstream..jpg)
Operators should note that while this configuration excels with materials having compressive strengths below about 150 MPa (typical for limestone), harder rocks like granite or basalt will cause accelerated wear rates on blow bars unless special alloy inserts are used; even then throughput may drop significantly due to reduced breakage efficiency per pass. Therefore careful material characterization before selection is essential.
In summary, an impact crusher designed for input up to 170 mm with output at 35 mm offers proven performance across many industrial sectors: it reduces capital expenditure by eliminating intermediate screens; lowers operating costs through lower specific energy; produces superior particle shape; simplifies maintenance via hydraulic adjustment systems; and adapts easily both as standalone unit or integrated into existing plants handling medium-hard feedstocks up to about half its maximum rated capacity per hour depending on rotor width (typically ranging from single-rotor units handling ~100 t/h up to large dual-rotor machines exceeding 500 t/h). For any operation targeting consistent sub‑40‑millimeter aggregates from moderately abrasive stone sources at minimal cost per ton delivered stockpile-side —this specification remains one of industry’s most straightforward choices since its introduction decades ago.**