Shot Blasting for Surface Preparation

July 11, 2016 6:09 pm

An overview of the advantages of shot blasting for industrial surface preparation
  Shot blasting is a multi-purpose metal finishing process that can be used for a wide range of applications including surface preparation. Shot blasting has a distinct advantage over alternative surface preparation methods in the fact that shot blasting typically offers a higher quality finish, is a faster process and offers a more customised finish.
It offers a level of surface cleaning that is unmatched from other surface finishing methods. Virtually all other surface preparations rely on chemical reactions and processes in order to clean the surface of the part. They can be very effective at removing certain types of corrosion but fail to remove other types.Shot blasting has emerged as one of the most effective, as well as one of the cheapest techniques for surface preparation prior to operations such as galvanising, electroplating, welding, enamelling, glass coating and rubberising.
It is useful for many industries, including the aerospace, ship building, forging and steel industries because it provides a consistent and uniformly fine, rough or matt surface depending on the techniques and tools used and the type of surface required.
Advantages“Mechanical means of surface preparation, shot or grit blasting is not new to the steel, auto, general industry segment. In its evolution over the years, users have worked with manual and automatic equipment and dealt with its association to emissions and dust generation. Operating costs being very critical in this competitive industry, users are always looking at techniques to tune their process and increase productivity,” says Jagadish Kulkarni, Vice President Sales & Marketing (W&A), DISA India Ltd & Director (Growth Market Products), Wheelabrator Group.
For the steel, auto, general industry, DISA India, in partnership with Wheelabrator offers dry shot blast technologies which are one of the ideal replacements for major part of pickling process. Today, Indian industry is using shot blasting techniques to prevent corrosion of rolled products, surface preparation for the fabricated parts before painting and heat treated parts for the removal of the scales, etc.Shot blasting eliminates the usage of non-eco friendly and harsh chemicals. It provides higher production rates, wider abrasive selection and better blast pattern accuracy. The finished surface obtained is absolutely free from chemical deposits, scales and dust content. Shot blasting does not remove any virgin metal when removing scales. It facilitates the formation of a permanent bond between the protective coat (zinc, paint or epoxy) and the shot blasted surface. It also helps to detect surface faults or defects. Shot blasting increases longevity and durability of protective surface coats as it adheres better to the shot blast cleaned and scale free surface.
Some of the shots used for blasting are as follows:1. Steel shots: Small steel balls of diameter 1 to 6 mm are fired at high speed against the surface being prepared. The size of the balls determines the finishing achieved. Smaller steel shots are used for more polished surface, while larger ones lead to a rougher finish.
2. Chilled iron grit: These are angular, abrasive material used for general blast cleaning, i.e., for removing oxides and paints from ferrous castings and carbon steel. However, blasting with chilled iron grit is quite aggressive and therefore not suitable for softer metals like aluminium.
3. Steel grit: Blasting with steel grit is used for jobs where aggressive cleaning is required, such as for removing contaminants from steel or any other metal.
In India, DISA together with Wheelabrator, one of the world’s renowned manufactures of both, wheel and air shot blasting solutions have custom specific solutions for both surface preparation and the shot peening needs. The product program covers almost all key segments like automotive, aerospace, steel, foundry, forgings, ship building, construction industry, medical, military, railways, etc. The solutions address the demands based on the surface quality, consistent performance of jobs especially in the peened parts, adequate dust extraction system and safety norms to meet the environment and health needs.
Some of the product range of DISA & Wheelabrator includes:1. Auto and general segment – castings (de-sanding), forging, die cast parts:• Hanger type machine – model HB-I 10/12, HB-I 12/16, VH range• Spinner hanger type machine – shell concept SPH 2 5.5/12• Tubmlast machine – metallic belt m/c MB-I 500, rubber belt machine BB 170• Continuous or Batch type on line machines – DT, DS and DTC machines• Shot peening machine – DRT Range• Customised solutions – to meet the specific needs of the industry
2. Steel segment – descalling or surface preparation:• FL Machine – Wire and Bar De-scaling applications• Roller Conveyor – RB Range – for descalling of steel plates, sections, profiles, fabricated parts, slabs, etc.• Pass through solutions – customised – ex-fabricated parts used for construction industry• Blast rooms – bigger size parts• HB – strip descalling (stainless steel) – supplied from European operation
——————————————————————————————————-Over the years, users have worked with manual and automatic equipment and dealt with its association to emissions and dust generation.
Jagadish Kulkarni, Vice President Sales & Marketing (W&A), DISA India Ltd & Director (Growth Market Products), Wheelabrator Group