Due to their precision, efficiency, and economy, mass finishing and shot blasting are an indispensable part of the finishing process for a wide variety of orthopedic implants in different manufacturing stages.
These flexible machines can handle general cleaning; deburring; surface smoothing after casting, forging, stamping, machining, and heat treatment; surface preparation for polishing or coating; and the placement of the final finish on all kinds of implants and medical devices.
With an experienced partner such as Rosler, these processes are also capable of adapting to emerging trends with proper testing and processing trials.
Evolving Technology & Outlook
Orthopedic implant manufacturers are at the cutting edge of medical technology. New materials and manufacturing techniques and technologies are constantly evaluated to improve the performance and longevity of the implants and reduce the manufacturing cost. Two examples are the increased use of ceramics as base material or coating and additive manufacturing.
Specific mass finishing applications are developed through processing trials. Once defined, users should not deviate from the determined machine settings unless necessitated by work piece or process changes.
Rosler partners with clients to provide testing in our global Customer Experience Centers to demonstrate our capabilities on a specific work piece and to calibrate machine settings. Determining the exact machine settings requires considering and testing multiple factors.
The most common drive systems in mass finishing are vibratory. This refers to actual finishing machines such as rotary, tub, and linear continuous flow vibrators as well as auxiliary equipment like screening systems, vibratory conveyors, buffers, etc.
In all of these cases, the speed of the vibratory motor or the electric motor driving the imbalance unit(s) may have to be adjusted as well as the setting of the imbalance weights.
Mass finishing is a highly versatile finishing technology that can be used for a wide variety of different surface treatment operations including those in the medical industry. As a result, it is no surprise that mass finishing processes are utilized at practically every manufacturing stage for all kinds of orthopedic implants.
With decades of experience, Rosler leverages mass finishing technology and develops equipment to meet the tight tolerances required for orthopedic implants.
Common Finishing Processes
Mass finishing is a grinding system, utilizing the pressure between the media and work pieces, combined with the constant “rubbing” of the media against the work pieces. This generates a grinding and polishing effect, leaving a smooth surface finish that can be as low as Ra = 0.8 microinches (0.02 μm).
For the comfort of patients and effectiveness of the components, orthopedic implants must be finished to precise specifications.
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).
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.
Joint reconstruction implants are subject to the same zero-defect performance and reliability standards as any other implant. However, because two components are always interacting with each other, dimensional accuracy is of particular importance.
Within the medical industry, surface finishing experts such as Rosler assist implant manufacturers in achieving the exact finish needed for each surface of the joint.
In addition to increasing product popularity and demand for the manufacturer and providing medical professionals with safe and dependable joint replacements, ensuring that orthopedic implants have the exact finishing required enables the joint to function longer and more comfortably for the patient.
Fueled by more active lifestyles and increased life expectancy,the market for knee, hip, and other replacement body jointsis on the rise. With more than $19 billion in annual worldwidesales, implants for joint reconstruction make up nearly 40 percentof all orthopedic product sales.
Thanks to significant advancements in materials and new or improvedsurface finishing technologies, today’s artificial hips andknees can last more than 20 years, giving the recipient decadesof comfort and agility.
Parts that are finished using modern mass finishingand shot blastingmethods play a key role in extending the lifespan of orthopedic implants.
Rosler has extensive experience in these processes which often include cleaning, deburring/edge radiusing, surface smoothing, post-casting surface preparation, machining, CNC grinding, and, of course, final finishing. These finishing technologies make big differences in the quality and performance of such products.
Before the “dirty” process water coming from a mass finishing operation can be discharged to sewage, it must be cleaned to meet the legal discharge limits for hazardous materials. Likewise, for cycling the water back to the mass finishing process, the process water must also be cleaned. Uncleaned process water would cause a mass finishing process to collapse very quickly.
Rosler has more than 80 years of surface finishing expertise. In that time, we’ve developed countless efficiencies in both the design of our equipment and the processes they support. Centrifuge technology has long been an effective and cost-efficient tool, not only for cleaning the process water, but also for reusing it for the actual mass finishing operation.
Previous Cleaning Methods
To a large extent, this technology has replaced traditional waste water cleaning methods. Until recently, the most common cleaning systems for mass finishing applications were settlement tanks and flocculation (“floc & drop”) systems.