Wet Granulators: The Ultimate FAQ Guide

What is Wet Granulation?

Wet granulation is a process that involves combining different particles of powder together using liquid solutions and adhesives.

In the wet granulation process, you will need a non- toxic and volatile granulating fluid to mass the powder particles.

Binding of the particles often occur through a boost action from an impeller and leads to an enlargement of particles.

Note that granulation does not depend on any compressive forces in the formation of granules.

 Wet granulation process

What is a Wet Granulation Machine?

A wet granulation machine is an electromechanical device that you can use in binding particles together thus causing particle enlargement.

In short, you can define a wet granulation machine as an electromechanical device that you can use in wet granulation.

We granulator

What is the Difference between Wet Granulation and Dry Granulation?

The main difference between wet and dry granulation is that wet granulation process requires the use of a granulating liquid.

On the other hand, dry granulation does not involve the use of any liquids in the granulation process.

Apart from that here are some other differences:

Does Wet Granulation Offer More Benefits than Dry Granulation?

Yes, wet granulation offers more benefits than dry granulation in the following ways.

• Wet granulation improves the flow properties of the ingredients

Allows you to easily increase granule size by increasing the moisture content thus making it easy flowability of final granules.

• Improves material densification and compression characteristics.

It allows you to easily produce dense granules through the use of high shear granulator or mixer.

• It allows for an easy process of obtaining homogenous mixtures

From the addition of a granulating liquid and use of a rotating impeller, you will easily make homogenous granules.

The high shear granulation machine increases the ease for better and even particle distribution.

• It also reduces the pollution of air.

The granulating liquids such as organic solvents and aqueous solutions reduce dust that would otherwise cause air pollution.

Apart from that, the granulation liquids eliminate the possibility of generating and accumulating static charges.

• It is more efficient and cost effective in comparison to the dry granulation process.

What are the Disadvantages of Wet Granulators?

Some of the demerits of using the wet granulators include:

• It might lead to the possible loss of materials

There are numerous processes that occurs within the wet granulator machine that might lead to the loss of materials.

• It is expensive to purchase and install

You will require a lot of space and time to install the machine because it is big in size.

Apart from that, the initial cost of purchasing the machine is high.

• Using the wet granulation machine can be tedious

You can wear out easily die to the numerous processes involved when you are using the wet granulation machine.

Cleaning and maintaining the wet granulator machine is labor intensive and consumes a lot of time.

What is the Purpose of Granulation?

 Wet granulation

Granulation is a process that manufacturers use to produce a wide range of products.

You can employ wet granulation for the following purposes:

• Enhancing uniformity in different drug substances in the final dosing form.
• Increasing the density of blend in drugs
• Increase the compressibility and flowability of different powder mixtures
• Reducing the level of dust generation during the process of manufacturing
• Alter surface properties or physical appearance
• Improve the wettability of a drug substance that has poor wettability.

What Does Agglomeration Mean in Wet Granulators?

Agglomeration is the process of enlarging the size of particles where smaller particles form large and permanent stable aggregates.

You should be able to identify the original particles forming an aggregate.

Stability of aggregates is due to binding agents forming a bridge between the particles and physical forces between the particles.

Are there Specific Requirements for Granulating Liquids?

Wet granulation technique

Yes, there are specific requirements for granulating liquids.

The granulating fluid should have a solvent which is volatile, non-toxic and you can easily remove by drying.

The most common solvents that you can use include water, isopropanol, ethanol, and methylene chloride.

You can either use the granulation liquid alone or in a solution containing suspensions, binders, or gelatinized binders.

Apart from the above requirements, the granulating liquid has to ensure that the particles stick together once granule is dry.

How does High Shear Granulator and Fluid Bed Granulator Compare?

Fluid bed granulators and high shear granulators compare in different ways depending on the working principles.

High Shear Granulator:

Fluid Bed Granulator:

All the operations of granulation on a fluid bed granulator occurs at one particular place.

On the other hand, high shear granulators have different parts that perform different functions.

It is easier to use a fluid bed granulator in comparison to using a high shear granulator.

This is because it does not involve a lot of processes which are often tedious.

Fluid bed granulators are not as accurate in producing granules of standard sizes in comparison to high shear granulators.

High shear granulators do not depend on blowing hot air through the powder particles.

On the other hand, fluid bed granulators depend on passing hot air to form the granules.

Why is Granulation Important before Tableting?

Granulation is important before tableting because of the following reasons:

• Improves fluidity and flow properties of the powders.
• Improves the compressibility of the powders masses before compression
• Decreases segregation of the powder components.
• Decreases dusting which pollutes the environment and can pose a great health risk

How Does Wet Granulators Design Affect Efficiency?

 Parts of wet granulator

Design of the wet granulators affects efficiency of granulation as it dictates the manner in which granulation process occurs.

The design will affect the mode of feeding raw materials into the machine and also affect the mode of discharge.

For instance:

High shear granulators and fluid bed granulators often compare in terms of the different designs and working principles.

High shear granulators often produce a wet mass after the completion of the granulation process.

The machine discharges the wet mass through a wet mill which is capable of breaking any agglomerate.

Fluid bed granulators offer a wide range of possibilities for feeding of raw materials and discharge of finished products.

It allows for conveying of raw materials into the machine through pneumatic conveying or vacuum transport.

You can also opt for a design that feeds the machine through gravity from the mezzanine or the floor above.

You can either discharge the granulated materials through the manual mode or using an automatic discharge system.

There are different design options that you can consider combining so as to come up with the most efficient machine.

For instance:

Close coupling allows for more integration in the system thus allowing for minimal work onsite for commissioning and installation.

What is Fluid Bed Granulation?

 Fluid bed granulator

Fluid bed granulation is a type of granulation process involving binder liquid addition to primary particles to form granulates.

It involves suspension of the granulation powder within a fluid bed granulator through the application of high velocity air.

The particle arrangement eventually leads to a set-up of fluidized bed materials.

What is the Difference between Powder, Granules, and Pellets?

The main difference between a powder, granule and pellet is the particle size.

A powder is a dry, fine particle which you can produce by grinding, disintegration or crushing of a solid.

It often has the smallest particles in comparison to granules and pellets.

A granule is a small compact particle which forms as a result of combining different powder particles together.

A granule particle is larger in comparison to powder particles but smaller that pellets.

A pellet is a small or round substance that you can form by compressing different substances.

They have the largest particle sizes among the three types.

What are the Main Parts of Wet Granulators?

Since there are different types of wet granulation machines, let us look at the parts of high shear granulation machine.

The main parts of a high shear granulation machine include:

Wet granulation machine

·  Granulation drum/ Mixing Drum/ Granulation Container

The granulation drum is stainless steel container with material blending accessories and tools.

The material blending accessories include choppers, mixing blades, spraying nozzle and impellers.

It assists in isolating the mixing chamber of the machine from the external environment.

· Impeller of the Granulation Machine

The impeller assists in spreading the granulation fluid and mixing materials at different rotational speeds.

It can either rotate vertically or horizontally depending on the orientation of the granulation machine.

· Granulator Chopper

It is a secondary impeller that rotates at a relatively higher speed ranging between 1000 to 3000 rotation per minute.

It features U-shaped blades which break down wet lumps thus resulting in the production of granules.

· Sealing Mechanism

These are Teflon seals that prevent possible leaks during the process of wet granulation.

You will find the sealing mechanism on the impeller and chopper shafts.

· Motor Drive Mechanism

This is the engine that rotates the impeller and the chopper.

Apart from that, it controls and regulates the process of granulation.

Most wet granulation machines have a variable frequency drive system allowing for the adjustment of rotating speed for optimal granulation.

· Safety Mechanism

The safety interlock system of the wet granulators protects you from:

i. Accessing the drive mechanism of the machine when it is on operation mode.

ii. Operating the machine when the mixing area is open

· Granule Discharge System

This is the part that allows and guides the final granules through the discharge port for further processing.

They are available in different forms depending on the type and design of granulation machine.

· Granulation Machine Frame

These are stainless steel frames that come in different designs and structures depending on the machine.

It is the main part of the machine that houses the other parts of the machine such as granulation bowl.

The frame has to be strong enough to accommodate the weight and vibration during the granulation process.

· Spraying Nozzle

The nozzle atomizes and delivers suitable bonder solution droplets during the process of wet granulation.

Apart from that, it evenly distributes binder solution on the material.

While considering the best spraying nozzle, you should look at the following:

i. Granulation solution pump which can either be mechanical or peristatic depending on the material you are granulating.

ii. Granulation solution pressure pot that ensures high pressure and fast delivery of granulation solutions.

· Electrical Control Panel

The control system complexity usually depends on control software, configuration, and design of the granulation machine.

Most modern wet granulation machines have touchscreen PLC control panels or HMI control systems.

You can use the electrical control panel for the following purposes:

i. Changing different process parameters

ii. Displaying the system parameters such as the speed of the impeller, chopper, and also system temperatures.

How Do Wet Granulators Work?

There are different types of wet granulation machines with varying working principles.

Let us begin with the working principles of the wet shear granulation machine.

Working Principle of the High Shear Wet Granulation Machine

High shear mixer granulator

The high shear wet granulation machine goes through the following steps.

Step One: Filling the Granulation Bowl or Container with Material

Most of the high shear granulation machines have an automatic filling system that fills the container with materials.

All you have to do is press the buttons from the control panel and the material flows into the granulation bowl.

You should also note that there are machines that have the manual filling system for filling the granulation bowl.

Step Two: Actual Mixing Process

After filling to a certain level, the vacuum valve will close and allow the exhaust valve to open.

You will control the speed of rotation of impeller and the chopper from the control panel.

The direction of rotation of the impeller is opposite the direction of the chopper for optimal homogenous mixing.

This results into particle fluidization hence an even mixture of the granules.

Step Three: Addition of Granulation Solution

At this point, the spraying nozzle automatically turns on thus directing the binding solution on the particles in random motion.

You will realize that all the processes take place at the same time at a preset speed.

Different particles begin to agglomerate to form granules as the chopper reduces them into reasonable sizes.

Once the particles achieve the right size and density, you can now discharge the products.

Step Four: Discharging the Granules

The spraying nozzle automatically turns off, rotation speed of impeller reduces, and discharge door opens.

The low rotation speed of the impeller pushes the granules to the milling chamber for further processing.

The milling components further reduce the granule sizes to reasonable sizes.

 Main parts of high shear granulator

Working Principle of a Fluid Bed Granulation Machine

The working principle of a fluid bed granulation machine depends on the fluidization process.

Fluidization is the process where different particles change into a fluid state through upward flow of gas or liquids.

The working principle involves:

• The use of a stream of air in fluidizing the bed
• Agglomeration by adding granulation fluid to the particles.
• Drying of processed granules

The process begins with:

 Fluid bed granulator

Step One: Fluidizing the Wet Granulation Bed

First you will heat and filter the air before directing it to the bed of unmixed particles.

Depending on the machine you are using, it might have a pump or fan that will suck or blow air.

Adjusting the flow of air will make the particles to come to a point where it behaves like a fluid.

This is the point where you can say that the bed is fluidized.

This process is efficient for both heat and non-heat sensitive particles.

Step Two: Addition of Granulating Fluid

Fluid bed granulation systems have the spray nozzles at the top of the machine.

Systems that involve coating and granulating at the same time have the spraying nozzles on either side.

The granulation fluid comes from the reservoir and through the spraying nozzle.

As the particles adhere to each other, they form larger particles or granules.

It also has exhaust filters that will tend to trap the particles that might blow away as air flows.

You should agitate the exhaust filter periodically to release the granules that stick to it onto the bed.

Fluid bed granulation process

Step Three: Drying Granules

After the formation of the right size of granules, you will turn off the spraying nozzle.

Hot fluidizing air continues to flow through the bed thus drying the granules.

All the process of the fluidized bed granulators often take place at the same place.

What is a High Shear Mixer?

High shear mixers are machines that disperses one phase ingredients into the main phase with which it is normally immiscible.

High shear mixer

Section of high shear mixer

You can use it to create lyosols, emulsions, suspensions, and granular products.

Apart from that, you can use it in different industries to reduce particle sizes, emulsify, disperse and homogenize particles.

How do Wet Granulators Produce Denser and Uniform Granules?

Wet granulators produce uniform and denser particles through the process of agglomeration.

Agglomeration involves particle size enlargement, where small particles become larger, permanent and stable aggregates.

Despite the numerous processes, you can still be able to identify the original particles making up the granules.

The adhesive force that keeps the particles bound together increases with the binder or mechanical energy.

You can either use dry or wet agglomeration to produce uniform and dense granules.

Dry agglomeration involves compacting initial particles into large pellets using pressure and then shredding to smaller sizes.

Wet agglomeration involves the introduction of a binding agent to create liquid bridges among the particles.

After drying the granules, it will leave the bridges intact thus leading to the formation of uniform and dense granules.

What Should You Consider When Choosing Wet Granulators?

Whenever you are considering to purchase a wet granulator, you should look at the technical specifications.

This involves looking at the machine manual or technical data.

Here are some of the factors that you need to look at:

· Dimensions of the Machine

This includes the size of the machine as well as other machine components such as diameter and effective lengths.

Apart from that, you should look at the net weight of the machine.

· Operating Speed

It involves looking at the rotor speed or speed of rotation of the machine.

This will allow you to know how much granules you can make within a specific time.

· Capacity of the Machine

The capacity of the machine will dictate the amount of raw materials that you can use in the granulation process.

Apart from that, it will also dictate the number of granules the machine can produce within a specific time frame.

· Model of the Machine

There are different machine models that you can choose from.

You should, however, be careful and go for a model with a high reputation and referrals.

· Power Requirements

Different machines have different power requirement levels.

You should look for a machine that will fit well into the power grid of the destination country.

· Level of Automation

There are different types of machines with different automation levels such as manual or automatic wet granulators.

You should go for the automatic wet granulator machines with PLC control systems even though it might cost more.

· Quality of the Machine

The machine has to comply to the regulations of machine quality standards to protect you from exploitation.

Make sure that the machine goes through:

i. ISO Certification

ii. CE compliance

iii. cGMP compliance

iv. ASTM E2500 certification

What Influences Product Characteristics from Wet Granulators?

Apart from the wet granulators, you should also consider the following factors:

· Type of Powder

This includes looking at the wettability, density, and size of particles, and substrate solubility.

· Binders

This includes the amount of binders, rate, and method of binder added to the powder or type of binders.

· Granular Type

Consider the type of granulating machine you are using such as planetary mixer, rapid mixer granulator or fluidized bed granulator.

• Particle sizing equipment such as a screen sieve, or a wet or dry mill.
• Drying equipment such as tray drying ovens, fluid bed dryers, vacuum or microwave dryers, at the steam-jacketed kettle.
• Milling technique which includes wet milling or dry milling.

How Do You Dry Granules from Wet Granulators?

You can dry granules from wet granulators using different types of drying equipment.

Some of the drying equipment that you can use include:

· Tray or Pharmaceutical Drying Oven

It is one of the most common drying techniques despite the fact that it is labor intensive.

Apart from that, it leads to the formation of granules with different density, porosity, and composition.

This happens because of the non-uniformity in the drying phenomenon.

· Fluid Bed Dryer

It is a more efficient and faster mode of drying granules in comparison to the pharmaceutical drying oven.

It ensures that the drying is uniform even though you might lose some materials through attrition.

Wet Granulators are used in Which Industries?

You can use wet granulators to produce different types of products in different industries.

Some of the most common industries that use the wet granulators include:

• Drug manufacturing or pharmaceutical industries
• Chemical processing industries
• Beverage and food processing industries
• Fertilizer manufacturing industries

Can Oscillator Granulator Machine be Used in Wet Granulation?

Yes, you can use the oscillator granulator machine in small or low scale wet granulation.

You can also use the lab high shear mixer in low scale wet granulation.

What are the Common Problems in Wet Granulation?

The common problems that occur during wet granulation include:

· Under Granulation

This involves insufficient adherence that leads to poor agglomeration thus leading to small particles with sub-optimal attributes.

It affects the compression process as well as the flowability of the particles.

· Over Granulation

This leads to the agglomeration of particles which are bigger than the normal size.

This affects the blend of the materials with the excipients thus leading to picking and lamination problems.

· Large Particle Size Distribution

The main causes of these problems include:

• Too little or too much addition of binders and liquids.
• Incorrect application of pressure during roller compaction or twin screw granulation
• Incorrect drying time under incorrect temperatures

You can solve this by monitoring the process of granulation and making sure that it does not under or over agglomerate.

This includes monitoring the machines through regular cleaning and maintenance.

Which Wet Granulators Does SaintyCo Provide?

At SaintyCo, we have many multi-functional wet granulation machines. Some of our machines include:

• Fluid bed granulation machine – it also has an option for coating and drying
• Oscillating granulation machine
• High shear mixer granulator

SaintyCo wet granulators come in different production capacities depending on the unique requirements of clients.

Does SaintyCo Develop Wet Granulators URS?

Yes, together with your team, we will help you develop URS for all your wet granulation machine orders.

It ensures you get a wet granulation machine that meets the production needs.

How Does SaintyCo Conduct Wet Granulator Factory Assessment Test?

SaintyCo uses a collaborative approach where we work with your team to test every aspect of the wet granulation machine.

We strive to ensure that all our customers get wet granulation machines that meet their specific requirements.

During the wet granulators FAT, SaintyCo will work with your team.

Does SaintyCo Help in Installation and Commissioning of Wet Granulators?

Yes, we do.

SaintyCo will train your team to help in smooth running and troubleshooting of wet granulators after the commissioning of wet granulators.

How Can You Find SaintyCo Authorized Technicians to Repair Wet Granulators?

Depending on your geographical location will connect you will our technicians or partners near you.

Just send us your details and the problem (s) you are experiencing with wet granulators.

If need be, we can travel to your country to help with repair, and upgrade.

At SaintyCo, we value our customers and are always ready to help.