Surface preparation can account for up to 40 percent of structural steel painting and repainting jobs and the life of anti‐corrosion coatings on a steel surface largely depend on how thoroughly the surface was prepared before painting.
At Rosler, we have extensive experience evaluating structural steel surfaces for coating before and after shot blasting. This knowledge of surface preparation standards and the widely used ISO and SSPC standards guide us in developing systems to expertly prepare and repair structural steel throughout its lifespan.
The Standards
Evaluating rust and mill scale pre- and post-shot blasting is a must. It is important to clearly specify the quality of the surface prior to preparation as well as the surface conditions after preparation. As a result, standards were developed to visually assess the initial surface conditions and the quality of the required surface preparation relative to the initial steel surface conditions.
The dominant and widely used standards for evaluating rust and mill scale are ISO 8501‐1:2007 (based on the Swedish Standard SIS 05 59 00) and the SSPC (Steel Structures Painting Council). While different in some minor details, these standards are practically identical.
Rosler Metal Finishing has decades of experience in the forge and foundry industries, especially when it comes to mass finishing for die-casted work pieces.
Our Forge & Foundry Blog Series continues with an overview of our top five mass finishing machines for precise cleaning of die castings.
Standard Rotary Vibrators
Media and parts are placed into a circular processing bowl in standard rotary vibrators. The energy from a vibratory motor causes the media and parts to freely tumble over each other. Some models are equipped with an internal separation device for separating the finished work pieces from the media.
Rotary vibrators can be used for batch and continuous feed processing.
The R620 Euro is one of Rosler’s standard rotary vibrator models
Rosler’s standard rotary vibrator models include the models EC, Euro, A, and R.
Ideal Work Pieces — Small to fist-sized die-castings such as shoe buckles, furniture fittings, gear shifter forks, electrical components
Finding a solution to our clients’ needs is nothing new for Rosler, nor is combining multiple solutions into a single finishing system. Take our work with Polish brake pad manufacturer Lumag Sp. z o.o. (Lumag), for example.
When they faced the challenge of de-oiling, deburring, and surface roughening brake pad carrier plates as part of their punch press process, they turned to us for a cleaning and mass finishing solution.
The Situation
Upon its founding in 1988 by Marek Zak, Lumag specialized in the production of brake linings. As the company implemented its own brake pad manufacturing technology, their products and offerings evolved. In addition to achieving enormous technological progress and applied engineering solutions, Lumag amassed a collection of machinery in need of constant upgrades and integration.
In order to meet the continuous rise of quality and safety standards for its brake pads for drum and disk brakes for commercial vehicles as well as brake pads for passenger cars and motorcycles under the trade name Breck, Lumag needed a partner with automotive expertise who could combine multiple solutions in a single system.
As an expert in the surface finishing industry, Rosler Metal Finishing knows that all the expertise in the world won’t do any good if the surface of the work piece is not properly prepared. When it comes to structural steel, we receive many frequently asked questions about preparation. This installment of our Structural Steel FAQ series will answer How is the presence of dust on shot blasted structural steel components evaluated?
The Dangers of Dust
Blast-cleaned structural steel surfaces must be completely free of dust to ensure proper coating and painting.
Residual dust will reduce the adhesion of subsequently applied coatings and, by absorbing moisture, may promote the corrosion of the blast‐cleaned steel surfaces. The potential accumulation of dust is especially critical on horizontal surfaces, the interior of pipes, and in structural cavities.
Special inspections must be carried out to ensure that such areas are adequately cleaned and free from dust before painting.
Structural steel components are used in many industries, including construction, shipbuilding, and the production of all kinds of heavy duty vehicles, trucks, railway vehicles, agricultural implements or construction equipment. From the construction of bridges, building of ships or production of equipment that must withstand heavy loads, steel is selected for its strength and durability.
To live up to its full potential and prevent premature failure, the steel must be guarded against corrosion with a protective coating. Shot blasting plays an indispensable role in preparing the steel surface for such coatings. Partnering with a shot blasting expert such as Rosler Metal Finishingcan help you determine the shot blasting equipment, blast media, and process required for your structural steel components.
In a series of blog posts, we’ll answer the most common questions about the surface preparation and coating of structural steel.
We begin with a basic question: Why do structural steel components need to be prepared for protective paint coating?
Shot blasting machines come in all shapes and sizes. Selecting a machine capable of cleaning and descaling complex fabricated components and welded constructions is not a task to pursue alone. Seeking the help of a company with proven expertise in the shot blasting field is always advised.
Designed specifically to clean wide head and base plates, ribs, re-enforcements, and the welds from fabrication, shot blast machines, such as roller conveyor machines, are designed around these types of work pieces.
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.
Centrifugal (high energy disc) finishing is a mass finishing technology that allows rapid finishing of smaller, robust parts. Whereas vibratory finishing utilises a moving bowl transferring energy into the contained media (chips) and parts in this case the bowl is static and movement is caused by a rotating disk, fixed on a shaft in the base of the bowl.
Barrel, vibratory and high energy disk centrifugal force machines are all precisely controlled methods of processing small and/or large batches of engineered components in order to; remove sharp edges, eliminate tool marks, remove flash, de-scale, radius edges, polishand/or burnish the surface.
Compared to traditional hand finishing methods the equipment brings a host of benefits including; reliability, consistency of finish produced, efficiency and effectiveness as well as reducing finishing cost per part. Added to that machines can be linked to dryers, washers, separators and transfer systems right the way through to being integrated into fully automatic ‘lights out’ production cells.
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Barrel, vibratory and high energy disk centrifugal force machines are all precisely controlled methods of processing small and/or large batches of engineered components in order to; remove sharp edges, eliminate tool marks, remove flash, de-scale, radius edges, polish and/or burnish the surface.