Blast cleaning is uniquely capable and efficient at delivering the pre-coating surface preparation required for components that must be able to withstand severe ambient conditions including heavy equipment for construction and mining, agricultural machinery, transportation and material handling equipment, and railway equipment and rolling stock.
Based in Enschede, Netherlands, the company designs and produces numerous products including placement systems for container pads. Its customers largely work within the material handling, offshore, and transportation sectors.
Like mass finishing, shot blasting is an exceptionally versatile surface treatment technology. Its applications range from general cleaning after casting and forging to shot peening and, even, cosmetic blasting for placing a fine, matte finish on the work pieces.
For shot blasting orthopedic implants, Rosler recommends mainly air and occasionally wet blasting systems. In each process, blast media is accelerated by compressed air and thrown at the work pieces through a blast nozzle, creating an extremely precise blast pattern compared to turbine blasting. Another advantage of air blasting is that it can be used with metallic, mineral as well as organic blast media.
These attributes and many more make this surface finishing method particularly useful in the medical industry.
Examples of Shot Blasting
Shot blasting is an impact system in which small metal or mineral pellets are thrown onto the surface of a work piece at speeds of 200-800 feet/second. The impact on the work piece surface produces the desired cleaning, peening, or texturing effect.
For medical applications, mainly air and wet blast systems are used which generally make a surface rougher. The smoothest finishes achieved with shot blasting are about Ra = 16-32 microinches (= 0.4 to 0.8 μm).
Unlike dry blasting that only uses a solid abrasive media, wet blasting processes use a slurry of water with the shot blasting media. This greatly cushions the impact energy on the work pieces, providing gentler, yet effective results for delicate work pieces. The achieved surface finish and appearance will also differ between wet and dry processes, even when the same media type and size are used.
With more than 80 years of experience worldwide, Rosler can supply both the machines and media best suited for your wet blasting needs.
Common Media Types
As long as it is heavier than water and not water soluble, practically any media used for dry blasting can be used for wet blasting.
It is important to consider the usefulness of the media compared to its cost. While a cheaper or longer-lasting media may be available, it may also require additional processing time to accomplish the desired surface finishing. Selecting the most appropriate media for your process requires balancing initial costs with overall results.
True to our “finding a better way…” motto, Rosler partnered with thyssenkrupp AG to create a continuous flow shot blasting operation for the fastest crankshaft forge shop in the world.
World renowned for its drive trains, chassis, and automobile manufacturing equipment, the automotive division of thyssenkrupp AG significantly contributes to the technical progress and efficiency of motor vehicles. The thyssenkrupp Gerlach GmbH plant in Homburg, Germany, is a leading partner for the development of automobile engine components, offering a full-service package ranging from component design, prototype fabrication, and full-scale production.
Developing a Solution
To improve cost efficiency at its Homburg plant and to meet all customer requirements, thyssenkrupp AG installed its high-tech “production line 19” for forged crankshafts for engines with one to four cylinders in 2016. For this line, Rosler developed an innovative shot blast equipment concept known as the Rosler RKWS crankshaft shot blasting system.
While choosing the right implant material is of utmost importance, as discussed in our previous Orthopedic Implant Series post, the significance of optimum surface treatment throughout the entire implant manufacturing process cannot be overstated. This relates not only to the right surface finish, but also total compliance with the specified tight dimensional tolerances.
The functionality of an orthopedic implant is determined by the perfect match between the various implant components. This depends, to a large extent, on the surface treatment procedure(s).
Andersen Steel produces agricultural equipment including grubbers, front packers, and stubble tillers equipped with vibration tines for soil cultivation. Their equipment is exposed to extreme loads, causing decreased wear life of parts including the tines.
Made using specially arched rolled steel at the company’s Poland plant, Andersen Steel tasked engineers at Rosler with finding a better way to process the tines and improve their wear life. We delivered a solution in the form of two identical machines for blast cleaning and shot peening.
Delivering a Solution
Compared to flat steel, the rounded edges of the material Andersen uses prevent small cracks from forming during the shaping process. The work pieces pass through a blast machine to remove mill scale and other contaminants before shot peening to further improve their wear resistance.
For these dual shot blasting requirements, Rosler suggested two identical Rosler RHBD 13/18 K hanger machines. Successful blasting trials in a Rosler test center helped Andersen realize the advantages of purchasing these Rosler machines by demonstrating that shot peening the work pieces doubled the uptime of the tines.
As an expert in the surface finishing industry, Rosler 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 questions about preparation. Among the most common questions is, “How is the presence of dust on shot-blasted structural steel components evaluated?”
Understanding dust considerations and mitigation will help produce higher quality and longer-lasting structural steel components more cost-effectively and safely.
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 inside structural cavities. Special inspections must be carried out to ensure that such areas are adequately cleaned and free from dust before painting.
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.
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.
For millions of individuals, orthopedic implants provide the ability to regain mobility and reduce pain. Just as surgical skill is required to implant these artificial joints, so is skillful construction and finish of the joint components themselves.
Our Orthopedic Implant Series continues with an overview of the most common materials used for these endoprosthetic implants.
To date, the most common materials have been titanium, titanium alloys, and cobalt-chromium alloys. Both materials are very tough, resistant to corrosion, highly biocompatible, and absolutely reliable.
Because of its many technical advantages and versatility, wet blasting is the fastest-growing segment in the field of shot blasting.
As with dry blasting, the available scope of wet blasting machinery ranges from simple, low-cost blast cabinets to sophisticated, partially or fully automated systems. Customers can choose between a wide spectrum of standard wet blasting equipment, however, for certain applications, special custom-engineered systems may offer the most efficient and cost-effective solution.
The machine type is usually determined by the processing task, the size and shape of the work pieces, and the desired degree of automation. Frequently, multi-axis robots are used for work piece handling or guiding the blast gun movement.
Rosler has extensive experience in wet blasting technology and the development of customized solutions. We have even developed the Rosler PureFinish® system for cleaning stainless steel components for the chemical, food, and pharmaceutical industries through wet blasting. This system cleans the work piece surface while facilitating cleaning, sterilization, and prohibiting bacterial growth.
Learn more about common types of wet blasting systems and examples of machine use for a glimpse into the technical capabilities wet blasting offers.