As previously discussed in our Automation Blog Series, building a robotically assisted process requires evaluating your surface finishing system along with its problems and goals and selecting the right machine and consumables. Automating a mass finishing or shot blasting process also requires selecting the automated hardware that will best achieve your overall goals and provides the most efficiency in terms of time and manual labor.
An experienced partner such as Rosler Metal Finishing can provide insight and advice on the numerous material handling tools specially designed or adapted to mass finishing and shot blasting process improvement.
Work Piece Loading Systems
Including skip loaders, lift and tip loaders, vibratory feed hoppers, and other tools, work piece loading systems are ideal for small- to mid-sized work pieces handled in bulk.
After
shot blasting, structural steel components often require some cleaning. The
degree of cleaning depends on the work piece’s condition prior to processing as
well as machine set-up.
This installment of our Structural Steel FAQ series will answer How are residual blast media and dust removed from shot blasted steel components?
Why Remove Residue
Ancillary machine attachments and processes may be
required to remove blast media and dust resting on structural steel components
to ensure surfaces are properly prepared for painting and coating.
The need for a clean and well-prepared surface after shot blasting mirrors that of the pieces surfacing in the first place as discussed in Part 1 of this series.
Methods of
Removal
Practically all plate and profile roller conveyor
shot blast machines are equipped with a media brush-off system at the machine
exit. By adding a rotary brush at the end of the process, residue is removed as
the work piece exits the machine.
These machines are capable of cleaning and descaling complex welded fabricated components and constructions. They are designed specifically to clean wide head and base plates, ribs, re-enforcements along with the welded seams after construction.
All round blasting is achieved after 3D simulation and actual placement of the blast wheels in the optimum locations of the blast chamber. The chamber can be designed with 2 blast zones, each zone designed to blast clean the surface of the infeed side and the second, the outfeed side and end. As the fabrication passes through the chamber, all gussets, re-enforcements, ribs, angles are descaled and cleaned to Sa Swedish standards and with the desired profile to optimise the adhesion of the coating to be applied.
The equipment requires to easily meet the most stringent customer specifications regarding surface cleanliness and cost, for steel traders, steel fabricators, equipment manufacturers, shipyards and manufacturers of wind power stations. In wind power applications roller conveyor systems are utilised for shot blasting of the steel sheets or plate required for the fabrication of the towers for off-shore and land based windmills.
Typical applications fall into these fabricating industries:
Steel traders/ distributors
Steel fabricators
Equipment manufacturers
Gas and oil
Aerospace
Power generation – including wind turbine columns
Transport – rail, bus, lorry, earthmoving, agricultural
Steel portal frame, tower block, stadium and steel construction
Bridge , crane, access, scaffolding and lifting gear
Partners for Steel
There are distinct benefits to be offered by the cooperation between the manufacturers of both shotblast equipment and multispindle drill/saw lines. The objective of cooperation (as partners for steel) is to support customers in resolving the interface problems between the various technologies, integrating shotblasting, measuring, marking, drilling and sawing or punching and shearing or coping and profiling thereby offering customers added value and profit from the processing of steel.
Steel trading companies and fabricators shot blast their steel plate, sections and pipes to achieve a degree of surface cleanliness that is required before protective coatings are applied or other surface preparation needs.
Automated roller conveyor shot blast systems offer solutions which guarantee a highly-efficient descaling, rust /oxidisation removal and general surface cleaning of all kinds of steel.
Shot blasting is a process for the surface treatment of plate, pipes, beams, tubes and bars.
Due to the design, roller conveyor shot blast systems are ideally suited for this application as it allows fast and highly-effective cleaning and surface preparation and at the same time, provides the surface with a profile to which a coating will adhere well, accommodating a wide- range of commercial to marine offshore standards.
The equipment descales the surface of the steel ready to accept a first-class coating, or further engineering processes.
Equipment design and efficiency are paramount and should include the following as basic design and inclusions;
Infeed and outfeed vestibules should be long enough to stop abrasive escapement
The blast chamber itself should be constructed from wear-resistant manganese steel
The blast chamber requires to be further periphery lined with replaceable tiles again manufactured manganese steel, for durability
The blast requires to be delivered by a number of highly-efficient blast wheels set at an ideal angle to optimise the blasting coverage of the profile or plate
The blast wheels require to be driven by highly energy efficient electric motors, that are energy saving to the latest design standards of power efficiency
The system requires to recycle the abrasive and to include an airwash separation screen that is also highly-efficient in its function of separating out dust, scale and fines out to waste bins
Only good cleaned abrasive should be recycled back for re use
Abrasive level control is a vital inclusion, as without information, the efficiency of cleaning, repeatability and uniformity of the steel surface is all but impossible
A rotational brush and blow off unit, after blasting will complete the process and provides a very clean component that can be either removed from the outfeed conveyor or be handled automatically for further processing
Dust and contaminated air requires to be always drawn through the shotblast system under negative atmosphere, and passed through a very efficient cartridge-type dust collector/filter unit with a discharge back into the hall as low as 1mg/cu mtr down to 0.5 micron particulates and has an efficiency of upto 99.09%
By placing the cleaned spent air back into the building, residual and any ambient heat can be retained in the winter months which can contribute to the reduction of heating costs of the internal working environment
Generally, standard equipment concepts allow the processing of components from 1000mm wide, upto 5200mm wide and 600mm high. Other configurations may be offered as bespoke equipment and to accommodate more complexly designed fabrications.
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