Precision control is important for optimal cone crusher performance. Metso cone crushers enable such precision control through their fully adjustable eccentric throw, which is the distance the main shaft moves during one full rotation. Understanding eccentric throw — and how adjusting it impacts crushing — will help you optimize your operations.
What is Eccentric Throw?
Eccentric throw describes the cyclical movement of the main shaft in cone crushers that provides the crushing force. As the eccentric rotates, it moves the main shaft up and down in a specific range. This oscillating motion is what repeatedly squeezes and breaks the feed rock against the crusher liners.
The throw’s length determines the size reduction possible in one compression cycle. It also directly impacts the capacity and reduction ratio possible. The eccentric throw is a key factor to consider for overall crusher performance and efficiency.
Generally, a longer stroke yields higher throughput capacity, while a shorter throw allows tighter closed-side settings and higher reduction ratios per stroke.
How Eccentric Throw Impacts Crusher Performance
The eccentric throw length significantly influences several interdependent aspects of a cone crusher’s performance:
Capacity
Longer throw lengths allow you to feed more material into the crusher while providing more space in the crushing chamber for size reduction, resulting in higher throughput capacity. For example, a 45mm throw processes more tons per hour than a shorter 25mm throw, which allows less material intake per cycle.
Meanwhile, shorter throws limit the feed intake and workspace per compression cycle, thereby reducing total capacity. However, the increased crushing pressure and reduction ratio possible per stroke with shorter throws may balance overall production based on site-specific conditions.
Reduction Ratio
Conversely, shorter throws let cone crushers achieve a higher reduction ratio per stroke. The tighter settings made possible by less space between the mantle and concaves enable more effective particle size breakdown per compression.
For example, changing from a 40mm throw to a 25mm throw opens up the ability to install finer liners and operate at tighter closed-side settings. This change increases pressure intensity and results in greater size reduction in each crushing cycle.
Power Draw
Greater throw lengths require more power to crush material due to increased chamber volumes. Shorter throws save energy and allow tighter settings that increase crushing pressure intensity. Reducing throw may lower energy needs enough to drop motor sizes.
Product Shape/Size
Matching throw to feed material characteristics and desired product specs optimizes particle shape and size distribution. Too much space with longer throws can lead to flaky output shapes. Insufficient space with shorter throws may not fully break particles to target sizes. Dialing in through mitigates these issues.
Fully Adjustable Throw in Metso Cone Crushers
What sets Metso cone crushers apart is their fully adjustable eccentric throw via an internal bushing. Rather than requiring replacement parts to change throw length, Metso crushers allow easy adjustments even under load.
Rotating the eccentric bushing with a hydraulic cylinder or hex wrench shifts the position of the main shaft’s thick point in relation to the bushing’s thick point. Together, the interacting thicknesses of these two components create the total eccentric throw distance.
Simply rotating the bushing changes where these points align, increasing or decreasing how far the shaft moves on each rotation. This enables quick changes between multiple throw length options on the same base cone crusher to match the needs of your operation.
In addition, the ability to tweak the throw at any point gives you extremely precise control over your output. If your production needs to evolve or you want to adjust particle shape, no problem. Just turn the bushing to fine-tune the parameters for your specific feed materials and targets.
Optimizing Operations
This adaptability is invaluable when balancing production goals against the rock characteristics you need to crush. Being able to easily adjust throw-on-the-fly lets you respond to changing ore parameters or site requirements.
For example, you can tweak the throw to achieve choke-fed conditions for changing capacity targets, ensuring maximum crushing efficiency. Running crushers faster than they can swallow reduces performance. Lengthening throw prevents packing issues by matching intake rate to feed rate.
Conversely, sometimes you want to limit throughput to focus instead on reduction ratio or powder minimization. Reducing throw is an easy route to lower capacity requirements and energy consumption without needing to buy a different crusher.
The adjustable throw likewise maximizes liner lifetime. Being able to scale stroke to match rock hardness and feed conditions ensures optimal rock-on-rock compression angles and reduces needless liner wear from throwing material too far.
Leverage Metso’s Fully Adjustable Eccentric Throw with Mellott’s Expertise
Optimizing your cone crusher’s performance requires balancing capacity, reduction ratio, energy use, and product quality to match your operational goals — and throw length is key. Metso enables precision throw control without needing to purchase different parts.
Ultimately, the fully adjustable throw empowers you to choke feed for maximized throughput or tighten settings for increased reduction – whatever best suits your needs.
As an authorized Metso distributor, Mellott has the expertise to help you dial in perfect throw lengths. Contact us today at 888.621.8533 or online to leverage precision throw control in your Metso cone crushers for optimized efficiency.
