In tablet manufacturing, raw material milling and granulation prior to tableting are key steps in determining the quality and consistency of tablets.Mastering the use of these processes and their equipment can not only improve the efficiency of tablet pressing production, but also ensure the stability and safety of the final product.This article will explain in detail the important aspects of the milling and granulation processes and provide recommendations for related equipment.
Comminution and granulation are critical steps in the tablet manufacturing process, determining the quality of the final tablet and the efficiency of the tableting process.In pharmaceutical manufacturing, you need to process large particles or lumps of material into granules suitable for tableting.The right size and shape of granules can effectively improve the flow and compressibility of tablets, ensure a smooth tabletting process, and give the finished tablets consistent weight, hardness, and disintegration time.For example, granules that are too large may result in uneven hardness of the tablets during the compression process, while granules that are too small may affect the dissolution of the tablets. Therefore, optimizing the milling and granulation steps not only helps to improve productivity, but also ensures consistent product quality.
Pulverization is the process of processing large raw materials into fine particles or powders in preparation for subsequent granulation and tabletting. You need to consider the hardness, moisture content, and physical properties of the raw material when selecting pulverizing equipment to ensure uniformity and flow of the final granules. Here are a few common types of pulverizing equipment and their applications.
Classification and application scenarios of pulverizing equipment:
Device type |
Application Scenario |
Advantage |
Shortcoming |
Air mill |
Temperature-sensitive materials requiring low-temperature processing |
High speed, no pollution |
Poor effect on hard materials |
High efficiency mill |
High volume, high hardness raw materials |
Fast, efficient and adaptable |
Limited handling of heat-sensitive materials |
Hammer Mill |
Suitable for medium-hard and brittle materials such as herbs, dry plant materials |
Easy to operate, low cost |
Not suitable for ultra-fine pulverization, high noise level |
ball mill |
Suitable for ultra-fine powdering, such as cell breaking, nanomaterials |
Ultra-high fineness |
High energy consumption and long pulverizing time |
Hammer Mill: It is a common pulverizing equipment widely used for pulverizing medium hardness and brittle materials, such as herbs, ores, and dry plant materials.It impacts the material through high-speed rotating hammers for initial crushing and controls the size of the crushed material through a screen. The main advantages of hammer mill are simple structure, low cost, wide adaptability, especially widely used in small and medium-sized pharmaceutical plants and laboratories.However, you need to be aware that the hammer mill may perform poorly when handling particularly fine powders or materials that require high precision control.At the same time, it is noisy at work and requires proper noise control in the operating environment.
The wet granulation process is used to form granules by mixing powders and liquid binders to improve the flow and compressibility of the granules and to ensure the stability of the subsequent tabletting process.This process is widely used in the pharmaceutical industry and is particularly suitable for products that require a high degree of granule firmness and homogeneity.
Classification and application of wet granulation equipment:
Device type |
Application Scenario |
Advantage |
Fluidized bed granulator |
Suitable for the treatment of heat-sensitive raw materials |
Particle uniformity High particle uniformity, Suitable for mass production |
Mixing granulator |
Suitable for rapid granulation and mass production |
Easy to operate, suitable for small batch production |
Rotary granulator |
Suitable for strong viscous materials, uniform particles |
The granulation effect of viscous materials is good, and the particle size control is more accurate |
Fluidized bed granulator forms granules by suspending powder in an air stream while spraying a liquid binder. It is suitable for handling heat-sensitive materials and can ensure the homogeneity and consistency of the granules, and is commonly used in pharmaceutical, food and other industries that require high quality granules.
Advantages of wet stirring granulator:
The working principle of stirring granulator is to mix the powder and liquid binder by mechanical stirring, so as to make them uniformly into granules. Stirring granulator is easy to operate, especially suitable for small and medium-sized batch production.You can adjust the mixing speed and binder dosage according to the characteristics of different materials, so as to realize more accurate granule control. Compared to fluidized bed granulators, agitator granulators are less expensive and suitable for production environments with limited budgets.
Dry granulation forms particles by directly compressing the powder without the addition of a liquid binder. It is particularly suitable for materials that are not suitable for liquid contact, such as some active ingredients that are easily deliquescent, heat-sensitive or unstable. Compared to wet granulation, dry granulation eliminates the drying step and can significantly reduce energy consumption and time.
Roller Compression Dry Granulator: Powder is compressed into flakes by the pressure between two pressure rollers, which are subsequently crushed and sieved to form granules. The advantage is that no liquid binder is required, which makes it particularly suitable for raw materials that are not suitable for wet processing. In addition, dry granulation can significantly reduce energy consumption because the subsequent drying step is eliminated.
During dry granulation, you need to ensure that the raw material is sufficiently compressible, otherwise poor pellet formation or uneven pellet density may result. This method is usually suitable when dealing with moisture-sensitive active pharmaceutical ingredients or when rapid production is required.
Particle size and homogeneity are critical to the quality of the tablets to be pressed. Excessively large or small particles affect the flow and compressibility of the pressed tablets, which in turn affects the hardness and solubility of the finished product as well as the release of the drug effect. Controlling particle size in the crushing and granulation process is an important part of ensuring tablet consistency.
You can choose different pulverizing equipment and granulation processes for different drug products and production needs. For example, fine pulverization better ensures particle uniformity, while wet granulation improves particle compression. Regardless of the equipment used, it is critical to ensure that the pellets are the right size and meet production standards.
The choice of equipment depends on the size of the production, the characteristics of the raw material and the production requirements. If you are dealing with temperature-sensitive materials or need high-precision control, air flow pulverizers and fluidized bed granulators may be a better choice. Whereas for processing large quantities of medium-hard materials, hammer mills and agitator granulators are more cost-effective solutions.
Also, the GMP compliance of the equipment, the degree of automation, and the cost of maintenance are key factors to consider. When selecting equipment, it is critical to ensure that it meets your production needs as well as regulatory requirements.
Milling and granulation are critical steps in tablet production that cannot be ignored. By choosing the right equipment and process, you can increase productivity and ensure consistency and high quality standards for your product. Understanding and mastering the details of these processes will help you achieve greater success in tablet manufacturing.