How To Determine The Size of A Jaw Crusher?

Introduction: Why Jaw Crusher Size Matters

Choosing the right Jaw Crusher size can make or break a project. It affects how fast material gets crushed, what size it ends up, and how much energy it uses. In mining, recycling, and construction, using the correct size boosts productivity and reduces costs. If the Jaw Crusher is too small, it breaks down more. Too big, and it wastes power and floor space.

So what is a Jaw Crusher? It’s a heavy-duty machine used to crush large rocks into smaller pieces. These machines use two plates — one fixed, one moving — to crush the material. Getting the right size depends on three key factors: feed size, product size, and tonnage goals.

Jaw Crusher Sizing Basics

What Does “Sizing a Jaw Crusher” Mean?

"Sizing" means choosing a Jaw Crusher model based on the max input size, desired output, and the tons per hour (TPH) requirement. You need to match the size of your input rock to the feed opening of the crusher.

Key terms:

• Feed size: Size of the largest input rock

• Output size: Desired size of crushed product

• CSS: Closed Side Setting, controls output size

• Throughput: Material volume processed per hour

How Jaw Crushers Work

Jaw Crushers use compressive force. The moving jaw moves in a V-shaped alignment against a fixed jaw. As rock enters, it gets squeezed, breaking apart. This continues until particles are small enough to fall through the gap at the bottom. It's simple, efficient, and works well with hard material.

Three Golden Rules to Determine Jaw Crusher Size

Rule #1: Identify Maximum Feed Size

Measure the feed size by checking the width and thickness of the largest rock. For safety and performance, your Jaw Crusher opening should be 1.3 to 1.5 times the size of this rock.

Example: If your max rock size is 400mm, pick a crusher with at least a 520mm feed opening.

Don't forget:

• Check the shape of your rock. Flat, slabby rocks feed differently than round ones.

• Feed angle affects how rocks flow into the crusher.

Rule #2: Define Desired Product Size

Output size depends on your project. For road base, 50mm may be enough. For concrete, you might need 20mm or finer.

Use the Closed Side Setting (CSS) to control final size. Most Jaw Crushers reduce material by a ratio of 6:1 to 8:1.

So, if you feed a 400mm rock and need 50mm output: 400 ÷ 8 = 50mm. That matches an 8:1 reduction ratio.

Rule #3: Establish Tonnage Goals

Calculate how many tons you want to crush per hour. Look at:

• TPH requirements

• Rock hardness

• Rock shape

• Moisture content

A harder rock needs more force. Moisture slows crushing. Irregular rocks reduce efficiency. Estimate conservatively.

Types and Sizes of Jaw Crushers

Primary vs. Secondary Jaw Crushers

Primary Jaw Crushers handle big, raw rock directly from blasting or digging. They're larger, stronger, and have wide openings. Use them when you need serious capacity.

Secondary Jaw Crushers come after the primary stage. They finish the job, reducing the material to a size ready for screening or further crushing.

Common Jaw Crusher Size Chart

This chart helps you compare models side-by-side. Choose based on your feed and throughput goals.

Design Factors That Affect Jaw Crusher Size

Feed Opening Dimensions

Bigger feed openings take in bigger rocks. But oversizing wastes money. Match feed size carefully. If your rock is 300mm, a 500mm opening is usually enough.

Stroke, Angle of Nip, and Motion

These design details change how rock moves through the crusher:

• Stroke: Long strokes mean more crushing per cycle

• Angle of nip: The angle between jaws; too wide, rocks don't grip

• Motion type: Straight vs elliptical motion affects flow and breakage

CSS (Closed Side Setting)

Smaller CSS = smaller product. Changing the CSS fine-tunes output. Check specs for min and max CSS for your crusher model.

External Factors That Influence Sizing

Material Properties

Harder rocks (on the Mohs scale) need more crushing force. That means:

• Higher wear on parts

• Lower throughput

Abrasiveness wears down liners. Brittleness causes easy fracture, which helps crushing.

Feed Method

Uniform feed improves crusher life. Irregular feeding causes:

• Uneven wear

• Material build-up

Use grizzly feeders or scalping screens to remove fines and deliver steady flow.

Moisture Content and Contaminants

Wet, sticky materials clog the chamber. Dirt and clay reduce throughput. Keep feed dry or use pre-screening.

Selecting the Right Jaw Crusher Model

Matching Crusher Size to Job Site Needs

• Mobile crushers: For field work or small jobs

• Fixed crushers: For big plants, higher capacity

Choose size based on:

• Daily tonnage

• Rock type

• Budget

Matching Size with Downstream Equipment

If your crusher feeds a conveyor or screen, it must deliver the right size and rate. Undersizing your Jaw Crusher slows the whole line. Oversizing wastes energy.

Sample Use Cases

• Construction demolition: Mobile crushers with 400-600mm openings

• Mining: Large fixed crushers, up to 1200mm feed

• Recycling: Mid-range crushers, adjustable CSS for mixed material

How to Measure and Confirm Crusher Sizing

Tools Used to Measure Feed and Product Size

• Calipers for rock size

• Laser measurement for chamber width

• Jaw templates from manufacturers

Checking Manufacturer Specifications

Look for:

• Feed opening

• CSS range

• Max feed size

• Capacity chart

Monitor liner wear too. As jaws wear, opening size changes.

Common Mistakes in Jaw Crusher Sizing

Oversizing the Crusher

• High cost

• More energy use

• Maintenance harder

Right-sizing keeps operations lean.

Undersizing the Crusher

• Frequent shutdowns

• Excessive wear

• Slow output

Test your material and run capacity simulations.

Ignoring Rock Properties

Different rocks crush differently. Always test samples. Don't assume limestone and granite crush the same.

Upgrading or Adjusting Your Jaw Crusher

When to Upgrade to a Larger Size

Watch for:

• Missed tonnage targets

• Frequent blockages

• Rapid wear of parts

If these happen, consider going up one model size.

Alternatives to Jaw Crushers

Consider cone crushers, impact crushers, or gyratory crushers for:

• Finer product

• Higher capacity

• Specific material needs

Each crusher type fits different goals.

Tools and Resources for Sizing a Jaw Crusher

Online Calculators and Software

Some major brands like Metso and Sandvik offer:

• Sizing calculators

• Flow simulation tools

• Application guidelines

Use these to simulate your operation.

Consulting with a Supplier

Bring your data:

• Feed size

• Desired output

• TPH

• Rock type

Experts help you choose the right model and setup.

FAQ: Jaw Crusher Sizing and Selection

How do I know if my jaw crusher is too small?

Signs include blockages, low throughput, high liner wear.

Can jaw crushers handle all types of rock?

Most hard and medium-hard rocks, yes. Not ideal for soft or clay-rich material.

What if my feed size varies?

Choose a model based on the largest rock size you expect. Use a grizzly feeder.

How does CSS affect output size?

Smaller CSS = smaller output. Adjust CSS to fine-tune product.

Is there a difference between feed opening and actual input size?

Yes. Feed opening is chamber size. Actual input should be smaller by 20-30%.

Where can I find Jaw Crusher Parts for sale?

Many OEMs and resellers offer Jaw Crusher Parts for sale online. Look for liner kits, toggle plates, and bearings from trusted brands.

Conclusion: Right-Sizing Starts with Understanding

To size a Jaw Crusher properly, understand your material, output size, and capacity needs. Don’t just buy the biggest machine. Use data. Check specs. Test materials. A well-sized Jaw Crusher boosts efficiency, saves money, and extends equipment life.

Whether you need a compact mobile unit or a massive industrial machine, start with the basics. Feed size, product size, and tonnage. Get those right, and everything else falls into place.