Are you eager to explore more about cone milling machines?
Cone or conical mills are the most valuable equipment for reducing material. Accordingly, this guide details the most vital information regarding cone mills. Let’s dig in for more information.
What is Cone Mill?
Cone mills are equipment that help in sizing material particles, breaking up large material lumps, and screening granules and powder.
They can also be used to mill wet and dry materials. Additionally, they are significantly adaptable. For example, you only need to change the granulating screen to meet your process or material specifics.
Benefits of Conical Mill for Size Reduction
- The most outstanding cone mill advantages include noise, dust, heat reduction, and higher outputs.
- Likewise, cone mills come in flexible designs, and you can quickly replace worn-out and unsuitable sieves and impellers.
- Conical mills produce more uniform and finer particle sizes since they allow gentle milling.
- Cone mills are also easy to clean.
- Cone mills require less human oversight, reducing production labor costs.
More resources:
- Conical Screen Mill – Source: SaintyTec
- Conical Mill – Source: SaintyCo
Types of Cone Mill Machines
Conical mills are primarily used to reduce material or particle sizes uniformly in various industries.
Come mills come in various sizes, screens, and impellers for each specific use.
Thus, you can buy portable lab machines or high-capacity ones to process larger volumes of materials.
The conical mill machines you will frequently come across include:
1. Tabletop Laboratory Cone Mills
This moveable milling machine is made from high-grade stainless steel. It comes with a stand, meaning you can place it on a stable surface. Besides, it can perform core functions, such as size reduction and granulation.
The tabletop laboratory cone mills are easy to operate and clean.
2. Under-Driven Cone Mills
Under-driven cone mills have an enhanced throughput and capacity than other conical mill machines. They sieve and mill materials through the impeller’s centrifugal force.
Besides, under-driven conical mills are known for their high flexibility.
3. Sifter Cum Multi Mills
This innovative milling system redefines the conventional powder-sifting process.
Sifter cum multi mills can uniformly size dry granules. Likewise, they allow economic processing by minimizing product loss.
4. Comminuting Cone Mills
You can use comminuting cone mills for wet and dry materials granulation. Their primary parts include a heavy-duty motor, beater assembly, and sieve. Other comminuting cone mill parts are the processing chamber, hopper, and throat hopper.
5. Oscillating Granulator Mills
They are primarily used to granulate dry pharmaceutical materials. As their name implies, oscillating granulators mill materials through an oscillating motion.
6. Multi Cone Mills
They are suitable for granulating dry and wet materials. You can use multi cone mills for speedy granulation, size-reduction, grinding, and mixing of materials.
Multi-cone mills reduce material sizes by bombarding them with fast-rotating blades inside a hopper.
Multi-cone mills also have removable components, enabling easy cleaning. As a result, multi-cone mills reduce downtime and enhance productivity.
Parts of Pharmaceutical Conical Mill
In this section, the guide delves into the major cone mill components.
· A Feeding Hopper
You will place all material you wish to process in cone mill here. The hopper have different configurations:
- Manual feeding system
- Vacuum feeding system
- Automated in-feed system
· An Impeller
The impeller’s main role is to help maximize the milling throughput. It has two or three blades and comes in two types – square bar and round impellers. Generally, the impeller’s centrifugal acceleration thrusts the material through the screen.
· A Mesh Screen
It sieves the granulated material while retaining the ungranulated matter for reuse in other processes. The particular size and shape of your screen holes will depend on your process requirements.
· Drive system
A gearbox or belt system can drive a cone mill. Similarly, the drive system can be located distantly, below, or on top of the cone mill.
· A Receptacle
Its main function is to receive the processed granules sieved by the screen. Some cone mills also automatically convey the finished products to other processes. In this case, you will notice that the cone mil has a vacuum transfer equipment attached to its receptacle.
· Base Plus Frame Support
This is the part you will use to fix your cone mill to a stable surface. Your exact requirements will determine whether you select a movable or fixed base frame.
Steps in Cone Mill Working Principle
The cone mill’s operating principle is straightforward. Its primary function is reducing the size of material particles.
The following chronological steps explain the technical steps behind this principle:
Step 1: Feeding
This first step involves transmitting materials into the milling chamber through the feeding chute. The material is fed through gravity, hand, or vacuum. In vacuum feeding, the material is automatically fed from the hopper, while gravity feeding relies on the gravitational force.
One important clarification is that the cone mill’s technical specifications determine the feeding mode. For example, some cone mills have IBC bins that are inverted and interlocked onto the mill’s surface. Hence, you can easily feed materials into these cone mills using gravity.
Step 2: Disintegration of Particles
The second step entails grounding the powder particles. Here, the rotating impeller shears and shreds the powder materials. Consequently, the impellers’ centrifugal force pushes the material onto the perforated screen surface.
Step 3: Granulation
In the third step, the grains with desired sizes permeate the perforated screen into the receptacle component. Increasing the impeller’s rotation speed will increase the fineness of the granules. High impeller speed flattens the grains’ approach angle to the screen surface.
More resources:
- Fritz Cone Mill – Source: SaintyCo
- Pharmaceutical Conical Milling Machine – Source: Wikipedia
Factors Determining Conical Mills’ Size Reduction Efficiency
1. Lubrication
Moving parts like granulators and blades reduces a cone mill’s speed if insufficiently oiled or greased. Furthermore, improper oiling and greasing can result in rusting of parts. Lubricating granulators and blades also lessens friction, ensuring high milling efficiency.
2. Mesh perforations
It determines product quality
For instance, the screen hole size impacts the crystal sizes and the mill’s efficiency. Most importantly, a cone mill machine with switchable sieves is the best option.
3. Operating Temperature
The milling process often yields considerable amounts of heat. However, operating a conical mill under high temperatures alters the product quality. Therefore, you should minimize the resulting heat yield during the milling process to increase efficiency.
How Over-driven Conical Mills Compare to Under Driven
You must first understand your material and process specifics.
Table 1 compares over-driven and under-driven cone mills:
| Attribute | Overdriven Cone Mill | Underdriven Cone Mill |
| Structure | They have belt-driven gearboxes. | Their impellers are directly driven by sealed gearboxes. Additionally, they allow faster system integration because they have a shorter stack-up height.
|
| Operation | The material from the infeed chute drops onto the screen cup, where the impeller shreds them. The resulting centrifugal acceleration forces the material onto the perforated screen. Accordingly, the screen produces desired particle size reductions, which it discharges to the chamber’s bottom. | Same operation principle as over-driven cone mills. However, the under-driven cone mill’s head is detachable. So, they are easier to dust and scrub and more hygienic. |
| Suitability for materials that are heat sensitive | Their belt-driven gearboxes that yield less heat. Hence, run cooler and are ideal for heat-sensitive materials. | Direct gear drives for impellers produces considerable heat. They are unsuitable for milling heat-sensitive materials. |
| Spacers between impeller and the screen | The gap between their impellers and mesh screens contain spacers. This implies that you can adjust the gap between the impeller and screen to suit your material type. | Under-driven cone mills are spacer-less. Instead, manufacturers set the optimized milling gap during their assembly. The merit of this spacer-less design is that it eliminates time spent on setting the right milling gap. |
| Noise Reductions | They produce minimal noise during milling. | Gear system produce low noise. |
| Appropriateness for rugged applications | Over-driven cone mills’ robust belt-driven gearboxes make them suitable for significantly rugged applications. For example, they can best used for tough and plant-like materials. | Their mills’ inlet lies on the same line with the outlet. Hence, they are more suited for in-line processing than rugged applications. |
How to Choose the Best Cone Mill for Material Processing
Different factors will determine your cone mill choice.
First is the type of the material to be milled.
The second factor is your desired particle size and particle size distribution (PSD).
Last is your target production capacity.
Conical milling generally can achieve particle sizes of as low as 250 microns.
So, remember to select an excellent screen type and a mill with the correct screen hole shape and size. Similarly, strive to choose a cone mill should that can attain the required impeller speed.
Overall, if you select the right model, you can achieve higher milling volumes for small footprints.
Parameters for Material Size Reduction in Conical Mill
Raw Material Hardness
It determines efficiency of size reduction.
Materials with high toughness require special heat conditions to attain optimal size reduction.
For example, reducing the sizes of these materials under lower temperatures lessens their decomposition. Additionally, it renders them less explosive and oxidating.
Material Stickness
The stickiness of materials is another important parameter. Sticky materials often stick on the mill surface. However, the good news is that you can reduce materials’ stickiness by mixing them with inert materials or completely drying them.
Slippery materials lubricate the mill’s parts during milling. Thus, it is safe to say that they increase a cone mill’s efficiency.
Moisture Level in Material
A material with high moisture levels is likely to be stickier, but less hard or tough. Therefore, you should consider this parameter before beginning your milling operations.
Other essential parameters include the material’s melting point, size, and quantity. Further, you should evaluate the ratio of the material’s feed to product size.
How to Maintain Conical Milling Machine
Maintaining a cone mill is relatively easy since it has a detachable head, which you can clean effortlessly. The everyday maintenance procedures for cone mills include:
- Monitoring the temperatures regularly to ensure the mill’s smooth functioning.
- Cleaning the mesh screen properly and frequently to clear the material stuck on the screen perforations.
- Regular and adequate lubrication. As previously mentioned, improper lubrication of moving parts like blades decreases the mill’s overall speed. If you lubricate your cone mill’s moving parts regularly, you will also record improvements in its efficiency.
Cone Mill Uses in Pharmaceutical Industry
- Reducing dry materials’ particle sizes: Size-reduction is probably the most vital cone milling role. Size reduction helps increase materials’ surface area and increases their solubility.
- Sizing wet materials: You can use cone milling to increase the size of wet materials. This process increases the materials’ surface area, aiding faster drying.
- Deagglomeration: A cone mill also performs the important role of disintegrating loose lumps of granules.
- Dispersion: Dispersing a material entail milling it to powder to enable it scatter onto other materials. To this end, using a cone mill to mill materials is a sure way of enhancing their dispersibility.
- Granulation: In this application, you will use your conical mill machine to granulate solid or powdered materials. Granulation processes that use liquids are called wet granulation.
- Retrieving powder from substandard or poor-quality granules or tablets for reuse in processing.
- Shredding oversized products to the appropriate size.
Conclusion
Regardless of size and type, all cone mills help individuals and companies reduce particle sizes uniformly.
Cone mills are advantageous because they are less noisy and rarely heat up. Furthermore, they come in several designs to suit your specific needs.
Overall, cone mills are efficient, flexible, reliable, and convenient size-reduction equipment.
