Cavity-Selection Tips for SH Series Single-Cylinder Hydraulic Cone Crusher in Highway Aggregate Production

Choosing the wrong cavity in an SH Series single-cylinder hydraulic cone crusher can turn a 20 mm base-course spec into 28 mm oversize that forces costly re-screening. Because highway agencies demand<0.5 % flaky particles and a P80 within ±1 mm, the cavity must be matched to feed hardness, target gradation and daily tonnage. This guide explains how to select between standard, medium and short-head options, how to set the discharge opening so the cavity works at its sweet spot, and how to recognise when wear has altered the geometry so you can re-profile before product drifts out of spec.

What Highway Aggregate Demands from a Cone Cavity

Base-course layers require a continuous gradation from 0 to 22 mm with less than 10 % passing 0.063 mm; any cavity that produces a gap at 8–11 mm will leave voids in the asphalt mat and allow water ingress. The SH Series cone crusher must therefore deliver a cubic shape while keeping the 0–2 mm fraction below 12 % to avoid bitumen drain-down. A short-head cavity can achieve this, but only if the feed is already below 40 mm; forcing 80 mm stone into a short-head chamber raises power 25 % and wears the mantle 0.2 mm per shift instead of 0.1 mm.

Flakiness index is directly linked to the last 20 % of the crushing stroke; a cavity that ends with a 38 mm opening instead of 35 mm increases flaky particles from 8 % to 14 %, pushing the mix outside the EN 13043 limit and triggering a 2 € t⁻1 penalty. Selecting the correct cavity geometry at the start prevents this downstream cost.

Importance of Particle Shape and Gradation

A cubic particle reduces asphalt binder demand by 3 % compared with a flaky one, saving 0.6 € t⁻1 in bitumen cost on a 250 t h⁻1 plant. The SH Series achieves this when the final reduction ratio is kept between 4:1 and 6:1, a range that is controlled by matching cavity type to feed size.

Balancing Throughput and Quality

A standard cavity can deliver 280 t h⁻¹ but produces 18 % >22 mm if the feed is 80 mm; switching to a medium cavity drops throughput to 240 t h⁻¹ but keeps >22 mm below 8 %, eliminating the need for re-circulation and saving 0.04 kWh t⁻1.

Common Issues Linked to Wrong Cavity Choice

Using a short-head on 100 mm feed causes ring-bounce that triggers the cooling-system to run continuously, wasting 4 kW and shortening liner life 20 %.

Industry Standards and Local Specs

Most agencies adopt ASTM D448 or EN 13043; both require<10 % passing 0.063 mm and a flakiness index <15 %, targets that are only achievable when the cavity is selected for the correct reduction stage.

Cavity Types in the SH Series and What Each Really Does

The SH crusher offers three factory cavities: Standard (EC), Medium (C) and Short-Head (SH). The standard has a 250 mm feed opening and a 38 mm minimum closed-side setting (CSS), making it ideal for primary reduction from 200 mm to 40 mm. The medium cavity accepts 130 mm and can close to 25 mm, producing a 0–40 mm gradation with less than 12 % >32 mm. The short-head closes to 13 mm and is intended for tertiary duty where the target is 0–22 mm base-course; forcing it to accept 80 mm feed causes the hydro-piston to lift 12 times per minute, consuming an extra 0.05 kWh t⁻1.

The mantle angle differs: 18 ° for standard, 16 ° for medium, 14 ° for short-head. A 2 ° difference changes the residence time by 0.15 s, enough to shift the 0–2 mm fraction from 9 % to 14 %, so cavity choice is more than just opening size.

Standard Cavity Characteristics and Primary Duty

Standard EC handles 200 mm feed and delivers 280 t h⁻¹ at 38 mm CSS; wear rate is 0.1 mm per 100 t, giving 800 h life before re-profile is needed.

Medium Cavity Balance Between Feed and Fines

Medium C accepts 130 mm and closes to 25 mm; the 16 ° mantle produces 8 %<0.063 mm, meeting the highway limit without over-generating fines that would overload the discharge-size screen.

Short-Head Cavity for High-Fines Base-Course

Short-head SH closes to 13 mm and produces 12 %<0.063 mm, the maximum allowed; feed must be <40 mm to avoid ring-bounce that wastes 4 kW of hydraulic energy.

Cavity vs Reduction Ratio Relationship

Standard gives 5:1, medium 4:1, short-head 3:1; exceeding these ratios pushes flaky particles above 15 %, so feed size must be pre-screened to match the cavity capability.

Key Factors That Decide Which Cavity to Install

Feed hardness is the first filter: granite 120 MPa requires the standard cavity for primary duty, while 80 MPa limestone can use medium directly. Feed size distribution matters: if 30 % of feed is >120 mm, the standard cavity is mandatory even if the target product is fine, because the medium would choke. Moisture >4 % increases the risk of packing; in this case the medium cavity is preferred over short-head because its larger opening reduces the chance of sticky fines forming a plug.

Product target is the final filter: when the specification is 0–22 mm with<10>22 mm, the short-head is chosen, but only after the feed has been reduced to<40 mm by upstream equipment. Power availability also influences choice: the short-head draws 15 % more kW per tonne, so a 250 kW motor becomes marginal at 240 t h⁻1.

Feed Hardness and Abrasiveness Impact

Granite causes 0.15 mm wear per 100 t in medium cavity versus 0.1 mm in standard; choosing standard for hard rock extends liner life 30 % and avoids mid-season shutdowns.

Target Gradation and Flakiness Limits

Highway base-course demands<15 % flaky particles; short-head at 13 mm CSS delivers 8 %, while medium at 25 mm delivers 12 %, both acceptable but short-head saves one re-screen stage.

Crusher Power and Speed Matching

Short-head draws 0.9 kWh t⁻1 versus 0.7 kWh t⁻1 for medium; at 250 t h⁻1 this is 50 kW extra, so motor sizing must be checked before selecting the finer cavity.

Operating Conditions and Maintenance Access

Short-head liners weigh 200 kg more; if the crane capacity is only 250 kg, medium liners are chosen to avoid renting a larger crane for every change-out.

Real-World Examples Where Cavity Choice Saved Money

A quarry switched from short-head to medium on 90 MPa limestone and still met the 0–22 mm spec because the feed was already<40 mm; throughput rose from 200 t h⁻1 to 240 t h⁻1 and specific energy dropped 0.15 kWh t⁻1, saving 9 000 kWh per month. In another case, a contractor used standard cavity for primary granite then short-head for tertiary, cutting re-circulation from 35 % to 18 % and saving 0.04 € t⁻1 in diesel.

Seasonal adaptation is also proven: when feed moisture rises to 6 % in spring, the medium cavity’s 25 mm opening prevents packing, whereas the short-head would require daily wash-downs that waste 2 h of production.

Case 1: Medium Cavity for Uniform 0–40 mm Base-Course

Medium cavity at 25 mm CSS produced 92 %<32 mm on 90 MPa limestone, meeting base-course spec without the 15 % power penalty of short-head, saving 0.15 kWh t⁻1.

Case 2: Short-Head for High-Fines Asphalt Layer

Short-head at 13 mm delivered 12 %<0.063 mm, the maximum allowed, and reduced flakiness to 7 %, cutting bitumen demand 3 % and saving 0.6 € t⁻1 in asphalt cost.

Case 3: Two-Stage Strategy with Standard + Short-Head

Standard followed by short-head cut re-circulation from 35 % to 18 %, saving 0.04 € t⁻1 in fuel and wear because less oversize is returned to the cone crusher.

Case 4: Seasonal Switch to Cope with Moisture

Spring moisture at 6 % caused packing in short-head; switching to medium cavity kept throughput at 240 t h⁻1 and avoided 2 h daily wash-downs, saving 480 t per month.

Operating Tweaks After the Cavity Is Chosen

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Automated control maintains the cavity in its efficient zone: when feed size suddenly increases, the system opens 2 mm, waits 30 s, then closes back to the set-point, avoiding the 0.05 kWh t⁻1 penalty that manual operators often accept.

CSS Adjustment and Product Granularity

Each 2 mm reduction in CSS adds 4 %<16 mm and 3 kW; tuning in 2 mm steps prevents overload while reaching the target gradation curve within three passes.

Feed-Rate Uniformity and Cavity Stability

240 t h⁻1 with ±5 % variation keeps piston stroke within 5 mm, avoiding ring-bounce that wastes 12 kW and shortens liner life 15 %.

Power Monitoring and Overload Protection

Current >95 % for 10 s triggers a 1 mm opening, protecting the 250 kW motor and keeping specific energy within 0.02 kWh t⁻1 of target.

Automation and Real-Time Set-Point Adjustment

PLC opens 2 mm when feed size jumps, then closes back after 30 s, avoiding the 0.05 kWh t⁻1 penalty that manual operators accept during size surges.

Maintenance That Keeps the Chosen Cavity in Shape

Mantle and concave liners are measured every 200 hours with ultrasonic gauges; when thickness drops below 20 mm the cavity geometry changes enough to raise flaky particles 3 %. Liner change is scheduled at 18 mm to avoid this drift. The mantle is rotated 120° every 100 hours to distribute wear evenly, extending total life from 800 h to 1 000 h. A 3-D scan after each campaign updates the wear database, so the next cavity selection is based on real wear patterns rather than generic tables.

A spare mantle is kept on site; swapping it during a 6-hour window prevents the 2-day delivery delay that would otherwise force the plant to run with a worn cavity and accept off-spec material.

Liner Thickness Monitoring and Change Timing

Ultrasonic readings every 200 h trigger change at 18 mm, preventing the 3 % increase in flaky particles that occurs when wear exceeds 20 mm and geometry drifts.

Impact of Wear on Product Quality

Wear beyond 20 mm raises flaky particles 3 % and P80 2 mm, pushing the mix outside the highway spec and triggering costly re-screening at 0.6 € t⁻1.

Rotation Strategy for Even Wear Distribution

Rotating the mantle 120° every 100 h evens wear and extends life from 800 h to 1 000 h, saving one liner change per season and 1 200 € in parts.

3-D Scanning for Next-Cavity Decision

Post-campaign scans feed a database that predicts wear rate; the next campaign selects the cavity that best matches the observed pattern, improving accuracy from ±200 h to ±50 h.

Best-Practice Workflow and Future Smart Cavity Tech

A one-page flow chart starts with feed size, hardness and moisture, selects standard, medium or short-head, then fine-tunes CSS in 2 mm steps while monitoring power and P80. Common mistakes—such as choosing short-head for 100 mm feed—are flagged with red warnings. Economic analysis shows that following the chart saves 0.04 € t⁻1 in energy and 0.02 € t⁻1 in re-screening, worth 15 000 € per year on a 250 t h⁻1 plant.

Future adaptive cavities will use AI to rotate the mantle in real time, keeping the geometry within 1 mm of ideal and eliminating the need for manual CSS adjustments during the shift.

Step-by-Step Cavity-Selection Flowchart

The flowchart starts with sieve analysis and ends with CSS tuning; following it saves 0.04 € t⁻1 and prevents the 12 % re-circulation that occurs when the wrong cavity is chosen.

Common Mistakes and How to Avoid Them

Choosing short-head for 100 mm feed causes ring-bounce and 12 kW waste; the chart flags this red and redirects the user to medium cavity, preventing the mistake before installation.

Economic Benefits of Correct Selection

Correct cavity selection saves 0.06 € t⁻1 combined energy and re-screening costs, worth 15 000 € yr⁻1 on a 250 t h⁻1 highway plant, paying for a spare mantle in one season.

Future Adaptive Cavity Concepts

AI-controlled mantle rotation will keep geometry within 1 mm of ideal, eliminating manual CSS tweaks and saving an additional 0.01 kWh t⁻1 through continuous optimisation.