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).
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).
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.
In our last trauma implant blog,Rosler Metal Finishing discussed the materials used in trauma implants. From hip replacements to cranial plates, there are numerous uses for trauma implants; each with its own unique surface finishing needs and requirements.
Trauma implant manufacturers must achieve
the necessary surface finish to ensure patient safety and best results. These finishing
requirements can range from simple cleaning or deburring to surface smoothing
and high-gloss polishing.
This blog will answer the question: What techniques are used to finish off trauma implants?
What types of finishes are used?
Trauma implants are subject to multiple finishing operations throughout the manufacturing process. After manufacturing steps including forging, blanking, machining, and thread cutting for screws, the workpieces usually undergo a surface cleaning (descaling, de-oiling), deburring, edge radiusing, or surface grinding operation, before they receive their final finish.
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.
In the area of medical technology surface finish of work pieces is an important factor. Component surfaces must be ground, smoothed and polished without risking their required shape and functionality. The reasons for these requirements are hygiene and sterilization.
Any time two metal parts come into contact with each other the resulting friction causes heat build up. These high temperatures cause wear and over time reduce efficiency and eventually create the need for replacement. By creating a smooth and shiny finish the process improves the life and efficiency of moving metal parts. Increased life translates into lower operating costs as well as better performance.