Category Archives: Mass Finishing

The Importance of Material Selection in Trauma Implants

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.

Spinal Rods & Screws

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.
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Titanium Cranial Plate

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 differences.

  • 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 us htoday to discuss your unique challenges.

Check back for additional blog posts about trauma implants in the future.

Optimal Media Mix, Part 2 – Understanding Media Consumption

As we established in Part 1 of this seriesidentifying 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.

Parameters affecting media consumption include:

Continue reading Optimal Media Mix, Part 2 – Understanding Media Consumption

Optimal Media Mix, Part 1 – Identifying and Maintaining Proper Levels

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.

Continue reading Optimal Media Mix, Part 1 – Identifying and Maintaining Proper Levels

Using Vibrascope to Measure Amplitude v. Frequency in Vibratory Bowls

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.

vibratory drive
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.

Continue reading Using Vibrascope to Measure Amplitude v. Frequency in Vibratory Bowls

Preventative Maintenance Enables Mass Finishing Equipment to Go the Extra Mile

Mass finishing machines 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.

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Specifying Polyurethane Qualities Produces Mass Finishing Success

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.

Read more about polyurethane materials

Part 2 – Aerospace Applications for Vibratory Finishing

Vibratory tub finishing is a great alternative to manual surface finishing for the aerospace industry.

From engine components and wings to landing gear, properly designed vibratory tubs can accommodate unwieldy work pieces, reduce production times and back logs, and produce a more consistent finish than manual finishing processes.

Our last blog post provided an overview of vibratory finishing’s role in the aerospace industry.

We now turn to specific applications and machine reports to demonstrate Rosler Metal Finishing’s vibratory finishing offerings and capabilities.

What We Offer

Vibratory tub finishing machines from Rosler can be customized to meet your unique aerospace finishing challenges.

Our most useful features include:machine2

  • Unload gates with external screening units.
  • Automatic media return.
  • Integrated rinse stations for finished work pieces.
  • Gantry systems for easy material handling of heavy, bulky parts.
  • Ergonomic equipment designs.

All Rosler tub vibrators are equipped with special vibration dampers to prevent the transfer of vibrations to the immediate environment. In order to keep the noise level below 80 dB(A), the machines are placed in special noise
protection cabins.

Continue reading Part 2 – Aerospace Applications for Vibratory Finishing

Part 1 – Vibratory Finishing Replaces Manual Finishing in Aerospace Industry

The aerospace industry  demands precision and high quality. The processes used to finish aerospace work pieces should adhere to the same rigorous demands.

Gone are the days when the surface of large structural aircraft components is frequently finished by hand. Thanks to the development of large, powerful vibratory tubs, costly manual deburring and grinding of large aircraft components can now be eliminated by highly controlled mass l finishing systems.

Finding A Better Way

Manual deburring and grinding are tedious and costly. Attempting these types of mass finishing by hand usually causes large quality fluctuations with relatively high scrap rates. Above all, manual processes demand highly skilled labor, which is especially hard to find in today’s economy and tight labor markets.

The lack of skilled labor and manual inefficiencies can lead to severe bottle necks in production and long lead times.

Continue reading Part 1 – Vibratory Finishing Replaces Manual Finishing in Aerospace Industry

Optimized Finishing Processes Can Reduce Operational Costs

You don’t throw your media out with the waste water, so why would you purchase new mass finishing equipment or muddle through with an inefficient process when optimization can extend the life and enhance the effectiveness of your processing equipment?

Whether a result of increased production needs or in response to poor performance, optimizing your mass finishing process is a great way to reduce operational costs and lower your equipment’s total cost of ownership.

A Proactive Approach

Revising a process to meet increased production demand is a cost-effective way to not only improve your processing times and results, but also increase and prolong your equipment’s usefulness.

Let’s say production has been steadily building over time. How do you know if it’s time to evaluate the process?

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Centrifuge technology offers eco-friendly advantages

The mass finishing process creates waste water. This substance known as effluent must be properly processed for reuse or disposal. Centrifuge technology offers solutions for cleaning and/or recycling effluent.

Rosler offers a variety of options to process waste water including flocculation systems and the elimination of vibratory finishing sludge. Each type of waste has unique factors and considerations.

Flocculants for Water Circulation Systems

floc graph

Continue reading Centrifuge technology offers eco-friendly advantages