What is Power Charging? Is it some high tech paint technology? Or is it just a simple game of physics! This article intends to answer it all.  To understand  Powder Charging, we need to comprehend what the Powder Coating process is.

Powder Coating is a type of coating that is applied as a free-flowing, dry powder. Unlike conventional liquid paint delivered via an evaporating solvent, powder coating is typically applied electrostatically and then cured under heat or ultraviolet light. This powder is used for objects such as an electrostatic gun or corona gun. As we are acquainted with the basics of powder coating, let’s look into the fundamentals of Powder Charging.

Fundamental of Powder Charging

Powder Charging is the process of charging the power in the gun to coat the surfaces.

Let us start with the fundamental question: Why is a gun needed for powder coating? We need a Gun to charge the powder, and we need to charge the powder in order to deposit the powder on the object until it reaches the oven.

There are two ways of charging the powder.

1. External (Corona)
2. Internal (Tribo)

Let us see External Charging or Corona- When 100KV is released at the gun tip (corona discharge), it breaks the air between the gun tip and object.           The breaking of the air gap is known as Ionization, with millions of ions of both the polarity, i.e., positive and negative.

The positive ions will be attracted towards the gun tip as it has negative polarity (opposite charge attracts) and gets earthed. The powder releasing from the gun will collide with negative ions in the field and will acquire a negative charge due to the collision. The charged powder will move towards the object, which is earthed. This is how the powder is charged externally.

Internal Charging or Tribo- Tribo type gun powder is charged by friction. The powder moving in the gun gets rubbing action with the charge media and get charged. As the powder is charged in the gun itself, it is known as an internal charge. There are two types of guns in Internal changing are Automatic Turbo Gun and Manual Turbo Gun.

It is observed that the Corona type of charging is ubiquitous in use as it is an external type of charging; it can charge any powder. (I.e., epoxy, polyester, hybrid, metallic, etc.). Where Tribo charging is powder dependent, i.e., certain powders like pure epoxy andpure polyester will charge, while the hybrids will not. So it has limited application. Besides, powder-dependent Tribo guns require more maintenance and lower throughput of powder. But Tribo also has an advantage of better finishing over Corona.

Good powder gunning should give Higher coverage, Consistency in the coating, Convenience to operate and maintain.

Mitsuba Systems gun

With guaranteed 100 KV generation coupled with a range of nozzle and muzzle ensures higher coverage per KG of powder. Stringent quality control, high standard of components, and innovative design will consistently improve the coating process for the time to come. The coating job is very critical.

The Mitsuba machine has user-friendly features like Performance Monitor, Infinity corona resettable cascade, IP 54 International standard dustproof panel, CE certification.

Different types of nozzle and muzzle affect the transfer efficiency. The nozzle sprays the powder. If overspray is less, efficiency will be higher. An appropriate nozzle can give the highest FPTE and will reduce the overall coating cost.

There are different types of nozzle and muzzle effects, like Round spray muzzle and flat spray muzzles. Round Spray (i.e., four-electrode) muzzle dispenses the powder-like showers, ideal for the flat surface. Due to lower speed, the ability to penetrate the corner is limited.

The flat spay muzzle is the most popular due to its extraordinary ability to penetrate the corners. It offers the highest FPTE for even complicated jobs.

Powder recovery system

The overspray powder needs to be recovered for reuse purposes. Recovery needs to connect the powder booth to recollect the maximum. The different types of recovery are

Cyclone recovery: The cyclone recovery booth is the most popular among coaters. The blower sucks the powder from the booth, and powder will be introduced in the cyclone separator tangentially.The powder will settle in the collector bin. Cyclones are the cheapest recovery with a collection efficiency of about 85% to 90%. Due to tangentially, entry color change takes much time.

Rotary recovery: Instead of tangential entry, rotary cyclone offers axial entry to the powder-laded air. By offering axial entry, the duct has been totally eliminated, which results in fast color change. Axial entry cyclone is provided with rotary wings that give a necessary spin to air to create cyclonic motion, ensuring that the powder settles in the collection bin. The rotary cyclone offers 99% recovery with fast color change.

Cartridge filter: The cartridge filter is a special recovery. The filter is made of aluminum-coated polyester. The blower will suck the powder. The powder will get on the outside of the filter, and clean air will be exhausted out.

The filter cartridge is provided with the cleaning system. The air will be blasted inside the filter, which will dislodge the powder accumulated outside the filter. The powder will be collected in the powder collection bin. The cartridge recovery offers 100% powder recovery. It is not recommended for frequent color change as every color needs a dedicated cartridge bank, making it pricey.

Difficulties and Solutions

There are few difficulties faced in Powder Charging, such as

1. The charging of hazardous powders into reactors containing highly flammable solvent- Changes where charging of some wrong powder leads to dangerous situations. Ensuring that correct powder is being charged and having prior knowledge of the powders before use.
2. Using the wrong charging technique- Using improper technique may lead to the fruitlessness of the product or the surface.

Ensuring that the correct technique is used before going ahead with the coating.

3. Powder Getting Spread- When the powder is getting charged, its environment is polluted due to the power.

Ensuring that the coating is getting done only in a contained environment, like in one room or a particular containment zone, provided that powder disposition is done well.