SHOT BLASTING

SHOT BLASTING

No metal industry owner can function without is shot Blasting. It is used in almost every industry such as aerospace, construction, automotive, foundry, rail, ship-building and many more. It is used to clean, induce strength also known as shot peening or to polish the metal surfaces.

The process of blasting has become an extremely important aspect of the metal building and the steel structure industry. This blasting technique provides some major benefits for the protection and maintenance of steel and metal products.

The basic blasting technique are:-

·    Sand Blasting

·    Shot Blasting

·    Grit blasting

·    Abrasive Blasting

·    Media Blasting

·    Bead Blasting

Types of Blasting Machine

There is basically two types of shot blasting technique used in Industries.

1. Wheel Blasting (Air Less Shot Blasting) Technique

2. Air Blasting ( Pneumatic Shot Blasting / Air Operated Shot Blasting)

Wheel Blasting:-

In Wheel blasting, the abrasive media is propelled on the workpiece to be blast clean, using directly converts electric motor energy into kinetic energy by rotating a turbine wheel. It is categorized as an airless blasting operation because there is no use of air, liquid or gas to propel the abrasive media.

Air Blasting:-

sandblasting machines are designed to inject shots such as glass beads through a nozzle by means of compressed air supplied by a compressor. Air blasting machines are further classified into gravity suction, direct pressure, and blower types.

There are basically two types of Air Blasting System are available

•   Pneumatic shot Blasting

•   Suction Shot Blasting

•   Wet Shot Blasting

Pneumatic shot Blasting:-

The machine works on the pressure blasting principle, consist of a blast generator. The abrasives are filled at the top of the machine when the machine is not working and the blast generator is not pressurized. At the top, a vibrating sieve is provided to sieve the abrasive filled. The oversize abrasive are retained on the screen, thus prevent the choking of blast line. When the mushroom valve is opened the abrasive particle will moves toward blast generator for blasting. The mushroom valve gets closed when compressed air enters the abrasive storage tank which increases pressure inside the storage tank, for free fall of abrasive into the mixing tube. From the mixing tube, the abrasive is carried away by compressed air to the nozzle for blasting.

Suction Shot Blasting:-

A siphon blast system (suction blast system) uses the compressed air to create a vacuum in a chamber (known as the blast gun). the suction pulls the abrasive into the blast gun where the compressed air directs the abrasive through a blast nozzle.

Wet Shot Blasting:-

It is a self-contain System that uses a slurry of Abrasive Media & water to clean, descale and degrease surfaces in a single operation. The slurry is directed through a special high volume pump to blast a gun where regulated air pressure adjusts the aggressiveness of the process. The process is free of dust and tiny particles spread in the blasting environment. Waterworks as a buffer between metal & media to cushion the shock on delicate components. This wet shot blasting machine is recommended for degreasing & Blast Finishing of delicate machined equipment

In this method, cabinet hopper contains the slurry and abrasive media. The slurry is continuously agitated to ensure thorough mixing of the abrasive and the liquid. The slurry is drawn up by a pump through a flexible pipe to the nozzle of the blast gun. Where it is propelled by compressed air to increase the velocity. The stream of abrasive, suspended in a liquid is projected at high velocity through a gun. The fired slurry from nozzle gets collected into the hopper like the bottom of the blast cabinet. From where it is passed to the slurry pump for recycling. The quantity of slurry in the blast nozzle can be controlled through the valve provided inside the blasting chamber. An arrangement with the help of a washing gun will be provided for cleaning of the job after micro wet blasting.

Advantage of Shot Blasting

Removal of Corrosion: This is the most preferred technique for removing all forms of rust and corrosive materials for metal and steel surfaces without reducing the strength of the product and leaving its base unaffected. Typical builds of corrosive that develop on the surfaces are:

•        Rust

•        Chemical Stains

•        Mill Scale

•        Faded or Chipped Paint

•        Heat Treatment Scale

Preparation of Surface: This method blasting is by far the most effective and most efficient process for preparing a metal surface before the painting or coating process is

done. It provides high blast pattern accuracy, with an extremely powerful bond between the blasted surface and the protective coating. The technique helps in revealing any type of defects and errors. It also increases the lifespan and the endurance of any future coating.

Environmental Reasons: This blasting the technique is one of the only few options that provide environment-friendly options for the removal of corrosion and the preparation of surface:

The process involves the use of the only abrasion to clean the surface of the metal products

No chemicals are used during the entire process.

Acids too are not used at any time in the entire process.

The only required cleanup is of the physical pellets.

All the blasted steel or dust of media is blown away by a powerful vacuum and dust collecting system.

The process also provides the freedom and the convenience of recycling the materials used in the process.