In mechanical sand production industries, vertical shaft impactors are widely used as sand making equipment. The VSI crusher has two feeding methods: complete center feeding and center feeding accompanied by waterfall feeding. The way is also: “rock on rock” and “rock on steel”.
Today, we will introduce the difference between two crushing methods of VSI crusher, “rock on rock” and “rock on steel” from the aspects of working principle and application situation.
Application situation
Under normal circumstances, “rock on rock” is mainly used for shaping, and “rock on steel” is used for sand making.
The “rock on rock” crushing method is suitable for abrasive materials with medium hardness and above, such as basalt. During the crushing process, the material ejected from the throwing wheel impacts the material lining, and does not directly contact the metal components of the equipment. This can reduce iron consumption, thereby reducing maintenance time. The shape of the finished product is good under the working condition of “rock on rock”.
The “rock on steel” crushing method is suitable for materials with low abrasiveness below medium-hardness, such as limestone. The crushing efficiency is higher under the working condition of “rock on steel”.
| Model | VSI-7611 | VSI-8518 | |
| Capacity (t/h) | Cascade and center feeding | 120-180 | 200-260 |
| Center feeding | 60-90 | 100-130 | |
| Feeder Opening size (mm) | Soft material | ≤35 | ≤40 |
| Hard material | ≤30 | ≤35 | |
| Rotation speed (r/min) | 1700-1890 | 1520-1690 | |
| Power of double motors (kw) | 110-150 | 180-220 | |
| Overall dimension (mm) | 3700×2150×2100 | 4140×2280×2425 | |
Difference in working principle
The sand making machine has two feeding methods: “full center feeding” and “center feeding with waterfall feeding”. Under normal circumstances, the whole center feed is mainly “rock on steel”. Generally used for sand making, the output is relatively low. The central feed along with the waterfall feed is a combination of “rock on steel” and “rock on rock”. It is generally used for shaping, and the output is relatively high.
The working principle of “rock on rock” with complete center feeding
The material enters the central rotor of the crusher through the hopper. Then the high-speed rotor throws the material out, and the shot material bounces on the beating guard plate. When the material falls, it collides with the material ejected from the center rotor, and is broken by multiple collisions and frictions in the crushing cavity. The crushed materials leave the crushing cavity under the action of gravity and enter the lower casing discharge hopper for discharge.
The working principle of “rock on steel” with completely center feeding
The material enters the center rotor of the crusher through the feed hopper. The material is then ejected by high-speed rotors. The ejection material bounces off the impact guard. When falling with the central rotor after the ejection of material impact, in the crushing chamber for several times of impact, friction and broken. The crushed material leaves the crushing chamber under the action of gravity and enters the discharging hopper of the lower shell.
| Model | VSI-9526 | VSI-1140 | |
| Capacity (t/h) | Cascade and center feeding | 300-380 | 450-520 |
| Center feeding | 150-190 | 225-260 | |
| Feeder Opening size (mm) | Soft material | ≤45 | ≤50 |
| Hard material | ≤40 | ≤45 | |
| Rotation speed (r/min) | 1360-1510 | 1180-1310 | |
| Power of double motors (kw) | 264-320 | 400-440 | |
| Overall dimension (mm) | 4560×2447×2778 | 5000×2700×3300 | |
The working principle of “rock on rock” with central feeding accompanied by waterfall feeding
The material enters the crusher through the feed hopper. After the bulk tray falls onto the distribution tray and is divided into two parts. Part of it enters the spinning wheel that rotates at a high speed from the middle of the bulk tray. The material is rapidly accelerated in the throwing wheel, and then thrown out from the throwing wheel flow channel at high speed. These materials are first impacted and crushed with another part of the falling materials around the bulk material tray. Then it impacts on the material lining of the crushing cavity together, and after being bounced, it impacts diagonally upwards to the top of the crushing cavity, changing the direction and moving downwards. It forms a continuous material curtain with the material emitted from the spinner runner. In this way, a piece of material is crushed by multiple impacts, frictions and grinding in the crushing cavity.
The working principle of “rock on steel” with central feeding and falling feeding
The basic working principle is the same as that of “rock on rock” with central feed and waterfall feed. The difference is that the impact guard is installed in the crushing cavity when “rock on rock”. The material forms a lining around it, and the material impacts on the material lining and is broken. When “stone strikes iron”, the lower striking guard plate is replaced with a peripheral guard plate, and the material directly impacts on the peripheral guard plate and is broken.
The main wear parts are different
In the “rock on rock” crushing mode, the material forms a layer around the impact guard. The material impacts on the material layer and breaks, so the impact guard is the main wear-resistant part. In the “stone-strike-iron” crushing mode, the lower beating guard is replaced with a peripheral guard. The material directly impacts the peripheral guard plate and is broken, so the peripheral guard plate is the main wear-resistant part.
This is the difference between two crushing methods of VSI crusher. If you want to know more about sand making machine, please contact we Daswell!