As an alternative to conventional wet paint solvents, powder coating provides an environmentally and friendly method of applying paint.

When applying conventional 'wet' paints solvents are added to the paint to make it a liquid which in turn allows it to become sticky which in turn allows it to stick to the surface of the required article or object.

Powder coatings work in a completely different way as only the 'solids' are sprayed or applied to the article in the form of an atomised powder spray. An electrostatic charge is applied to the powder during spraying and this allows the powder to be drawn to the product.ral 9005 powder coating

Once the article is sufficiently covered, the article along with the powder coating is heated in an oven to around 200 degrees centigrade. This causes the layer of powder to fuse and melt onto the article and forms a resilient smooth tough coating.

The application of powder coating has many benefits and just some of these are:

o High quality

o The process is suitable for automation

o Recoverability

The high quality of a powder coated product is instantly recognisable. It is smooth in appearance and protects the article by forming a sealed skin of paint around it which greatly reduces the effects of corrosion and provides good scratch resistance properties.

Labour requirements are reduced due to the ease with which the process can be proficiently automated.

The use of powder allows any over spraying to be easily collected and re-used in automated systems. Conventional 'wet' paint spraying can waste as much as 50% when being applied and is not recoverable. Powder coating can help make huge savings because the excess powder can easily be collected and then re-applied to another product.

To apply powder coatings successfully there are two main pieces of equipment that must be employed:

o Spray booth

o Curing oven

A spray booth allows over spray to be safely transported or ventilated away from the operators, and reclaims the powder for re-use.

A curing oven is needed to place the coated articles in which are then heated to fuse the powder onto the product.

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Knowing the definite characteristics, behavior and Powder flow properties are of the utmost importance in various industries such as the pharmaceutical industry. This information is vital because it helps us to know the exact result, we will obtain in doing certain operations. For example, the complete and definite knowledge of powder flow properties helps us in different operations such as compression, transportation etc.

These powder flow properties can further be measured using various metrics. Some of the most popular and most useful properties which are used to predict the behavior of flow of powders are powder cohesion, the dynamic angle of repose, powder compressibility, Carr's index and Hausner ratio. Various instruments are used to measure and predict these properties accurately such as Powder Rheometer, Bulk density testers, powder flow testers and much more. Let us dive deep and get an overview of each of these properties.ral 9005 powder coating

Powder Cohesion
Cohesion is defined as sticking together of particles of the same substance. The particles tend to collect together or attract each other. They exert attractive forces towards each other called the Wander Waal’s forces. This is an important factor that determines the powder flow. Another type of attractive force that the particles can exert is an electrostatic force. This property signifies how the powder will flow through hoppers. Too much attractive forces inhibit the flow.

The Dynamic Angle of Repose
There are two kinds of angles of repose that affect powder flow properties, static and dynamic angle of repose. Here we will consider the dynamic angle of repose.

Dynamic angle of repose is the angle observed when the powder particles are moving continuously downwards on an inclined slope. Different angles of repose exert different effects on the powder flow properties. Different angles are associated with the size of the particles present in the powder.

Powder Compressibility
This is yet again an important factor which determines the powder flow. The powder compressibility is the ability of particles present in the sample of powder to shrink or compress in volume when pressure is applied. In other words, a material’s compressibility is its bulk density/pressure relationship.

Wall friction
The flowability of powder is also largely dependant on external factors such as the friction between the walls of the container they are flowing through and the particles of the powder. Wall friction affects the angle of the hopper and it is required to be designed keeping the wall friction in mind. Taking account of this property, the shape of the hopper is decided whether it will be shaped as a cone or a wedge because wall friction dictates the mass flow.

Powder Rheometers
These instruments are capable of measuring the shear, bulk and various above mentioned dynamic properties of a powder. The powder samples are analyzed for various different conditions like consolidated, conditioned or even in the fluidic state leading to a full exploration of various properties.

With the advent of sensitive instruments like Powder Rheometer, measuring the powder flow properties has become accurate. The knowledge of powder flow properties is very vital if we want our system to run at maximum efficiency

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