Blade Technology: Straight vs. Curved Blades Explained
As an expert in the shot blasting industry,Rosler Metal Finishing knows about blade technology. All shot blasting machines require blades to propel media towards workpieces. While both straight and curved blades are used, each type offers advantages and disadvantages.
What’s the Difference?
Straight blades are, as the name suggests, blades that do not have curvature when viewed from the side and do not possess tangential curvature with respect to the turbine. Curved blades are blades that have some degree of curvature when viewed from the side.
As the newer design, curved blades are generally better than straight blades, but they also have some drawbacks related to longevity, maintenance, and cost of ownership.
Another major milestone for the Rösler Academy has been reached: starting in March 2019, the internationalization of the Academy is set to begin with the English-speaking seminar series. In twelve different training courses, participants will receive basic knowledge of vibratory finishing and blasting technology, in-depth knowledge of individual machine types, maintenance issues or processes such as shot peening. Interested persons can view all seminars with their contents, dates and prices on the new English Academy website; www.rosler-academy.com.
The trainers of the Rösler Academy, all experts in their field, are specially trained by a train-the-trainer course including TÜV certification to provide specialized knowledge in an effective and varied way. The aim is to procure a decisive competitive advantage through effective knowledge transfer. Therefore, in the future our international business partners and customers will be able to benefit from the wealth of experience of the certified specialist and use it profitably in their company.
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.
Shot blast machines are often a considerable investment for companies. When these highly specialized and high investment pieces of equipment start to show signs of wear and underperformance, expert surface finishing companies such as Rosler Metal Finishing can help prolong the life and effectiveness of your investment by repairing and rebuildinga machine instead of replacing it.
Cost is often the biggest factor considered when rebuilding a shot blasting machine. Generally, rebuilds offer shorter turnaround times than buying a new machine. Rebuilds also come with the added benefit of not needing to integrate a new process since the process already includes a proven shot blasting process.
Levels of Rebuilds
The extensiveness of the rebuild process depends on your specific machine, its condition, and your expectations for longevity versus quick repair.
Different levels of rebuilds fall into three categories:
Surface preparation can account for up to 40 percent of structural steel painting and repainting jobs. As Rosler Metal Finishing’s Structural Steel FAQ series has already established, the life of anti‐corrosion coatings on a steel surface depends to a large extent
Application of anti-corrosion paint in a preservation line blasting system.
on how thoroughly this surface has been prepared for painting.
Properly evaluating the surface of structural steel surfaces for coating before and after shot blasting will help balance the cost of preparing, repairing, and monitoring structural steel throughout its impressive lifespan.
This installment of our Structural Steel FAQ series will answer How are rust and mill scale evaluated pre‐ and post‐blast?
The Standards
Widely used 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 standards for evaluating rust and mill scale are ISO 8501‐1:2007 (based on the Swedish standard SIS 05 59 00), SSPC Vis 1‐89, and NACE. While different in some minor details, these standards are practically identical.
When it comes to mass finishing, amplitude and frequency require balance and careful consideration. Amplitude is a measure of movement and intensity while frequency refers to the rate of repetition.
The wrong amplitude, for example, if it’s too low, can create a lackluster finishing results and longer processing times. If too high it can cause unnecessary wear and tear on the machine.
Creating Vibratory Energy
Whether rotary or tub style, mass finishing vibrators always include these two key components; a work bowl containing the finishing media and the work pieces. Firmly attached to this work bowl is a vibratory drive system generating the energy to put the mass of media and work pieces in motion. The work bowl with attached vibratory drive system sits on a number of coil springs – in some cases on air cushions – which in turn sit on a machine base. The springs, respectively, air cushions allow the work bowl to “free float” up and down within a certain distance.
Example of vibratory drive
The force from the vibratory drive system puts the mass of finishing media and work pieces contained in the work bowl in motion. Depending on the type of finishing machine this force is generated by vibratory motors or electric motors driving a shaft with one or multiple imbalance units attached to it.
Imbalance units are made up of a rotating shaft with out-of-balance counterweights at each end of the shaft. Due to its imbalance, the rotating shaft causes an intensive wobbling effect.
Common drive systems in vibratory bowls and tubs include foot motors for small tub vibrators, flange motors for rotary vibrators, and multiple imbalance units with electric drives for large tub vibrators.
Structural steel is a widely used material in a variety of industries due to its strength and durability. Our last post in the Structural Steel FAQ series established why this material must be prepared – namely to preserve its strength and longevity. This post will describe the type of surface preparation required before shot blasting structural steel.
In order to stand up to the harsh demands of the construction, shipbuilding, and heavy equipment industries, the most appropriate type of surface preparation must be undertaken to ensure the best shot blasting results possible.
As always, consult a surface finishing expert such as Rosler Metal Finishing with to discuss your specific components, their condition, and the desired outcome for your structural steel applications.
We turn to another FAQ about structural steel: What type of surface preparation is required prior to shot blasting?
The answer depends on the condition of the component…
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?
Mass finishingmachines are workhorses of industrial finishing operations, combining engineering expertise and often a hefty price tag. When preformed according to manufacturer recommendations, preventative maintenance can make a big difference in the length of time between design and decommissioning.
Not convinced? Think of your mass finishing equipment like a vehicle. What would happen if you never checked the air pressure in your tires, changed the oil, or replaced the brake pads? Eventually your vehicle would leave you stranded on the side of the road through no fault of its own.
Mass finishing equipment manufactured by a proven expert such as Rosler is just the same as a vehicle that didn’t get the care it deserved. Without preventative maintenance, your high-dollar investment will break down. However, by performing preventative maintenance according to the manufacturer’s recommendations, your equipment will operate like a well-cared for vehicle, extending the life and return on your initial investment.
Diesel or unleaded fuel, anti-lock or drum brakes, manual transmission or automatic, preventative maintenance varies by vehicle type. Here are considerations for preventative maintenance based on your specific mass finishing equipment type.
Polyurethane (PU) is an elastomer mix (urethane) material that can be formed into in a wide variety of shapes, sizes, and hardnesses. Its uses range from insulation and cushioning to adhesives and car parts and more. PU’s unique ability to withstand tension and compression while maintaining its shape and flexibility makes it a great lining for mass finishing equipment.
The ability to specify the size, shape, and hardness of PU allows equipment manufacturers like Rosler Metal Finishing to build machinery with custom inserts and linings to protect components and enable precise surface finishing as well as relining existing equipment with upgraded lining.
Our expert engineers create a custom blend of shore hardness, PU type, and forming method to produce durable and resilient materials that can withstand the harsh demands and stresses found within mass finishing operations.
Measuring Material Hardness
The shore hardness of PU is measured by the material’s resistance to localized deformation. This hardness or durometer is identified with a durometer tester, which forces a conical shaped indicator into the surface of the material and then measures the depth of the indentation. The scale ranges from 0-100 durometer with many different properties in between.
