Surface preparation can account for up to 40 percent of structural steel painting and repainting jobs. As Rosler Metal Finishing’s Structural Steel FAQ series has already established, the life of anti‐corrosion coatings on a steel surface depends to a large extent
on how thoroughly this surface has been prepared for painting.
Properly evaluating the surface of structural steel surfaces for coating before and after shot blasting will help balance the cost of preparing, repairing, and monitoring structural steel throughout its impressive lifespan.
This installment of our Structural Steel FAQ series will answer How are rust and mill scale evaluated pre‐ and post‐blast?
Widely used 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.
The dominant standards for evaluating rust and mill scale are ISO 8501‐1:2007 (based on the Swedish standard SIS 05 59 00), SSPC Vis 1‐89, and NACE. While different in some minor details, these standards are practically identical.
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.
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.
Structural steel is a widely used material in a variety of industries due to its strength and durability. Our last post in the Structural Steel FAQ series established why this material must be prepared – namely to preserve its strength and longevity. This post will describe the type of surface preparation required before shot blasting structural steel.
In order to stand up to the harsh demands of the construction, shipbuilding, and heavy equipment industries, the most appropriate type of surface preparation must be undertaken to ensure the best shot blasting results possible.
Structural steel components are used in many industries, including construction, shipbuilding, and the production of all kinds of heavy duty vehicles, trucks, railway vehicles, agricultural implements or construction equipment. From the construction of bridges, building of ships or production of equipment that must withstand heavy loads, steel is selected for its strength and durability.
To live up to its full potential and prevent premature failure, the steel must be guarded against corrosion with a protective coating. Shot blasting plays an indispensable role in preparing the steel surface for such coatings. Partnering with a shot blasting expert such as Rosler Metal Finishingcan help you determine the shot blasting equipment, blast media, and process required for your structural steel components.
In a series of blog posts, we’ll answer the most common questions about the surface preparation and coating of structural steel.
We begin with a basic question: Why do structural steel components need to be prepared for protective paint coating?
Mass finishingmachines 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.
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.
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:
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
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.
It is not surprising that trauma implants, along with other medical devices, are subject to the most stringent quality standards. Any material defect or malfunction can have catastrophic consequences for a patient.
For implants, the two key issues for manufacturers to deal with are selecting the right material and attaining the required surface finish. The finishing requirements can range from simple cleaning or deburring to surface smoothing and high-gloss polishing. Components exposed to a lot of tensile and bending stress even undergo a shot peening process to improve their fatigue life.
Some implants must have a textured or “rough” finish to promote osseointegration, which is the attachment of surrounding bone tissue to the implant. Other trauma implants require a very smooth surface to prevent the bone from attaching itself to the implanted material.
We’ve created anotherexclusive surface finishing guidebookto cover this complex topic, in which we will discuss the surface finishing needs of trauma implants and the impact finishes have on their functionality and performance. Examples of mass finishing and shot blasting applications will also be presented followed by detailed machine reports of actual applications used in the industry today.
If you are interested in sending us your parts forFREE process development, contact us here.
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?