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.
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.
Many times, the brush unit is augmented by a
blow-off system with one or multiple radial fans to ensure there are no “dead
zones” where residue remains.
Monitoring the Work Piece
account for different work piece dimensions, a photo cell is often included in
the machine. This allows the machine to monitor the height of work pieces and
automatically move brush- and blow-off units to accommodate variations in size.
The Rosler Way
Whatever your structural steel media needs are, you can count on Rosler Metal Finishing to help you find a better way and the best machine. Contact us today to discuss your unique challenges.
Be sure to catch up on our
previous posts in the series including:
Rosler Metal Finishing understands that trauma implants and medical devices are subject to stringent quality standards. Any material defect or malfunction can have catastrophic consequences for a patient. That’s why we take our work in the trauma implant field very seriously.
Also known as osteosynthetic
implants, trauma implants include pins, screws, and plates used to surgically
fix a bone defect. Implant manufacturers must select the right material and attain
the required surface finish to ensure patient safety and best results.
In a series of blog posts, we’ll
answer the most common questions about trauma implant materials and finishes.
We begin with a basic question: What
materials are used in trauma implants?
The answer, in short, is usually stainless steel or titanium.
Does the material performance affect the selection?
In order to select the best material, trauma implant manufacturers must understand the specific performance attributes of the implant they are creating. Implants are subject to very strict performance and reliability standards. Selected materials must act as bone stabilizers and healing support while meeting the following guidelines.
Biocompatibility – The implants must prevent inflammation due to bacterial contamination. This includes corrosion resistance to prevent reaction with bodily fluids.
Low or No Osseointegration – It must be possible to remove the implant without complications once the bone has healed. Implant removal is especially important with implants for children. Excellent Gliding Characteristics – Tendons must easily glide over a bone plate without being damaged. High Tensile Strength and Load – Trauma and spinal implants are exposed to considerable tensile and bending loads and must be able to withstand the related forces. Relatively Low Modules of Elasticity – The implants must have a certain elasticity to reduce the amount of stress shielding. The implant should support the bone, but not absorb the complete load. High-stress shielding can lead to bone atrophy. High Ductility – Bone plates must be ductile, as their contours may have to be adapted to the bone contours before implantation. Non-Magnetic – Implants that are magnetic can pose a risk to patients.
Which materials offer the best performance?
Most trauma implants consist of
stainless steel (AISI 316L), pure titanium, or titanium alloys such as
Ti-6AI-4V or Ti-6AL-7Nb. All three materials fully meet the performance
requirements of trauma implants yet there are some slight technical
Ductility – All three are ductile, meaning they are able to undergo a certain amount of plastic deformation before rupturing.
Tensile Strength – Stainless steel has the highest while pure titanium has a somewhat lower tensile strength. The relatively “low” tensile strength of titanium makes this material more elastic which can reduce the negative effects of stress shielding.
Excellent Biocompatibility – Stainless steel is somewhat less biocompatible than titanium.
Corrosion Resistance – Titanium offers the highest corrosion resistance.
Strength-to-Weight Ratio: Titanium alloys offer the highest ratio.
Even though stainless steel and titanium are highly corrosion resistant by nature, they may be passivated – either chemically or thermally – to create an additional oxide layer on the metal surface for additional corrosion protection.
The Rosler Way
Whatever material you need to finish prior to medical use, Rosler Metal Finishing to help you find a better way and achieve precise finishing. Contact ushtoday to discuss your unique challenges.
Check back for additional blog
posts about trauma implants in the future.
Shot blasting machines are widely used for surface preparation and finishing structural steel components for a variety of industries. In addition to specifically designing machines able to accommodate large, heavy, and bulky structural steel workpieces, Rosler Metal Finishing also expertly designs the turbines within these machines for precise results.
turbines accelerate and throw the blast media against the workpieces. They are
for shot blast machines what the engines are for cars and trucks. Both
determine the performance of the respective machine or vehicle including the
speed of a sports car and the torque of a heavy-duty truck.
Like vehicle engines, the specifications of different turbines directly influence the performance of a shot blasting operation. This installment of our Structural Steel FAQ series will answer How do different blast turbines affect the quality of shot blasting results?
patterns are the size and shape of the area where blast media strikes a
workpiece as it progresses through the machine. The area of impact is also
referred to as a “hot spot.” Long blast patterns are required to accommodate the
large size of structural workpieces.
Concentrated blast patterns are often used in shot peening, but would not offer enough finishing coverage for structural steel applications. Similarly, the normal blast patterns used for casting and forgings are also not effective for structural steel.
of the large workpiece envelope, the travel distance of the blast media between
the turbine and workpieces can be very long. To generate the impact energy
required for blast cleaning of such large components, the acceleration or
throwing speed of the media by the turbine must be considerably higher than in
smaller shot blast machines.
with curved throwing blades generate a substantially higher media acceleration than
straight-bladed blast wheels and are the preferred blast turbines for large
structural steel components.
Gamma® G is an innovative turbine with curved throwing blades. Compared
to straight-bladed, conventional blast wheels, a Gamma® turbine of
the same size and running at the same speed, generate up to 25 percent higher
throwing speeds of the blast media. This improves the overall blast performance
by 15-20 percent.
offered by the Gamma® G turbine include:
of both blade sides, reducing maintenance costs and increasing equipment
lower energy consumption compared to conventional blast wheels.
blast pattern adjustment by changing the impeller position.
correct placement of the turbines around the blast chamber is another critical consideration
affecting the performance of blast machines for structural steel components.
placement must ensure that complete blast media coverage is achieved on the
workpieces without any “dead” spots where the media does not reach. Please note: In the case of large, complex
weldments, the prevention of dead spots may not be possible. In such cases,
manual touch-up is required. We will address this topic in Part 10 of this
turbines opposite from each other must be somewhat offset so that they are not
blasting into each other. This would not only produce poor blast cleaning
results but would also cause extensive, premature wear.
The turbine placement can be determined by computer simulation and allows for the evaluation of all faces of exposure.
The Rosler Way
Whatever your structural steel media needs are, you can count on Rosler Metal Finishing to help you find a better way and the best machine. Contact ustoday to discuss your unique challenges.
Be sure to catch up on our
previous posts in the series including:
Rosler Metal Finishing expertly designs shot blasting machines for these industriesand others to descale, clean, and prepare structural steel for surfaces for end-use. The particulars of each machine largely depend on the size and shape of the specific components in need of preparation.
This installment of our Structural Steel FAQ series will answer What are the most commonly used blast machines for structural steel surface preparation and how do they compare?
Machine Types by Workpiece
Whether surface preparation is needed for steel beams and plates, round bars, pipes and weldments, ship building, pipeline construction, or heavy equipment and machinery, there are machines tailored to produce consistent surface finishing results for each component.
The most common machine types by component include:
Roller Conveyor Machines for Plates and Beams
Round Bar and Pipe Machines
Roller Conveyor Machines for Large, Extra Heavy Components
Spinner Hanger and Monorail Hanger Machines for Large Components
As we established in Part 1 of this series, identifying and maintaining an optimal media mix is essential to realizing optimal mass finishing results. Rosler Metal Finishing understands that our equipment must work in tandem with media to provide you with the desired finishing results.
Understanding how your machine, the work pieces it is finishing, and the selected media will interact is key to delivering an optimal finish each cycle. Doing so requires understanding media consumption factors in order to maintain an optimal media mix.
What are the Factors of Media Consumption?
Media consumption and wear rates depend on ten key parameters. These rates change if even one of the parameters below change. Therefore, quoted wear rates and cut rates are relative values only.
Media usage can only be estimated, the actual consumption can only be determined by the end user under exact process conditions.
The surface profile created by shot blasting depends entirely on the blast media and the way it is handled. The right media selection and equipment operating parameters are critical for the surface quality of structural steel components being prepared for paint coating. While mineral abrasives play a role for certain air blast applications, the lion’s share of industrial surface preparation is done in highly mechanized turbine blast machines utilizing steel media.
Rosler Metal Finishinghas decades of experience in the turbine blasting field. Through the years, we’ve used and evaluated all kinds of media and resulting roughness or lack thereof. This installment of our Structural Steel FAQ series will answer:
What influence does metallic blast media have on the surface profile
of structural steel?
The best mass finishing equipment is useless without the proper media. That’s why the experienced engineers at Rosler Metal Finishing pair their quality equipment with the right type and amount of media to achieve consistent results.
Understanding how your machine, the work pieces it is finishing, and the selected media will interact is key to delivering an optimal finish each cycle. Doing so requires understanding why media levels are important, determining and tracking levels, and evaluating media consumption to avoid issues.
How do Media Levels Effect Processing?
Without a proper media level, a machine won’t work properly. Levels that are too high and too low can cause issues that result in poor processing results and unnecessary workpiece and machine damage.
Besides the degree of cleanliness – the removal of oil and grease, rust and mill scale, dust, and other contaminants – surface preparation specifications must also consider the surface profile and roughness relative to the coating to be applied. Rosler Metal Finishing builds shot blasting equipment to create the right surface profile on structural steel components as well as cleaning them in preparation for coating and painting.
This installment of our Structural Steel FAQ series will answer What is the optimum the surface profile for a structural steel component prior to painting and how is profile evaluated?
Optimizing for Painting
Shot blasting makes a surface rougher to increase the total contact area between paint and a work piece substrate and generally improves paint adhesion. A surface that is too smooth poses the risk of inadequate paint adhesion, while a surface that is too rough may not cover the peaks. The degree of surface profile required depends entirely on the coating to be applied.
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.