Case Study: Eclipse Metallic Scrapers

Rod scrapers, wipers, and excluders are commonplace in the seal industry. Eclipse designs and manufactures these components on a regular basis. A wiper or scraper can be a critical part of keeping dust, dirt, and debris out of a hydraulic system. While a polymer scraper, such as a filled PTFE, can provide many years of low friction performance, some extreme applications need something much more robust and aggressive.

Eclipse was approached by a customer using a hydraulic cylinder in a metal foundry. The conditions presented a challenging environment for any seal component: intense heat and marring media. The cylinder was close enough to the molten metal to get slag deposits on the cylinder rod when fully extended.

Slag, a by-product of the smelting process, is often a mixture of metal and silicon oxides. The hard and abrasive properties of the slag were pushing conventional rod wipers and scrapers beyond their limits and allowing damaging contaminates into the hydraulic system. Frequent rebuilds and service delays where commonplace.

Eclipse was posed with a challenge to invent a scraping system that was up to the task.

Maximum Scraping Effectiveness

Polymer scrapers can be designed to withstand harsh environments. Dirt, rocks, and mud are usually effectively kept out of hydraulic systems by using polymer or plastic wipers. Eclipse’s EU000: UHMW-PE is an exceptionally tough polymer that can withstand tearing, impact, and abrasion in a wide variety of situations. But even UHMW would not be adequate for hardened slag. The abrasiveness combined with the intense, 500°F plus environment would effectively rule out the use of almost any polymer. Eclipse knew it had no choice but to fight fire with fire. A metallic scraper would be needed in this foundry application.

While metallic scraper rings are available in the market, the unique environment of the foundry also effectively excluded them from use. A typical metallic scraper uses a rubber or Nitrile element to both center the metallic scraping ring and allow for radial movement of the shaft. Using a metal scraper on a shaft without an element to allow for some “give” could result in high friction and damaging galling or marring of the cylinder shaft.

Often used in large industrial applications, shaft alignment and precision could be less than perfect. A hard-mounted metal scraper could easily damage the shaft if misalignment is present. A long axial scratch or gouge in the shaft would almost certainly cause leakage in the hydraulic system and be a costly repair.

But in an environment over 500°F, having a rubber element in the scraper would not be possible.

PTFE to the Rescue

With the extreme temperature ruling out the use of any rubber or elastomeric compound, Eclipse knew it would have to substitute a material for the centering and movement absorbing element used with the metal scraper ring. Eclipse chose its ET006: Carbon filled PTFE to fill this role. PTFE would be able to handle the intense heat but still be pliable enough to allow for misalignment and adequate centering. The addition of the Carbon filler further improves temperature capability and mechanical toughness. The slim jacket profile also works in minimal hardware space and allows for easy installation.

Eclipse’s chose to use a specific, unhardened grade of stainless steel for the metallic scraper. The unhardened stainless steel provides aggressive rod scraping while also reducing the risk of damaging the cylinder shaft.

Maximum Scraping

The combination of a stainless-steel scraping ring and a PTFE centering jacket proved to be an effective solution to the customer’s unique application. The high temperature capability of the PTFE meant a metallic scraping ring could be used without risk of severe damage to the cylinder shaft and thusly, maximum scraping effectiveness could be used.

The Eclipse Metallic Scraper ring efficiently removed any slag deposits from the shaft, ensuring the sensitive internal sealing components remained free of damaging contamination.

Eclipse Metallic Scrapers in Your Application

While a polymer scraper, wiper, or excluder might work for the vast majority of industry applications, extreme conditions might mean the next level of scraping aggressiveness could be necessary. A metallic scraping ring can withstand the harshest of media and could be essential in prolonging life of the sealing system.

While removing slag from a hydraulic cylinder shaft in a foundry is a perfect application for an Eclipse Metallic Scraper ring, a wide variety of situations could merit their use. Eclipse has specified metallic scrapers for use in applications of the other end of the temperature scale as well.

A particular customer was using a hydraulic cylinder on a bridge application where the cylinder location was prone to heavy icing conditions in the winter months. The metallic scraper effectively removed any ice from the shaft, while the PTFE jacket provided the benefits of having an indefinite shelf-life and no UV degradation. This meant extremely long service life and maintenance free operation for many years when compared to a scraper using rubber or Nitrile elements.

Another application well suited for an Eclipse Metallic Scraper was for a cylinder at a loading dock in a marina. The cylinder was to be actuated only a few times a year and was completely submerged in salt water. This meant the shaft was prone to barnacle and crustacean growth over the long periods of inactivity. A metallic scraper ensured the shaft was clean and free of contaminants when actuation was needed. The unique grade of stainless steel in combination with the degradation free properties of PTFE meant a long and effective service life of the scraper could be expected, even in salt water.

Contact Eclipse today to see if a Metallic Scraper Ring is right for your application >

< Older Post

Newer Post >

Learn how Eclipse solved manufacturing challenges for micro spring-energized seals

Case Study: The Manufacturing Challenges of Tiny Spring Energized Seals

By Doug Montgomery • March 21, 2025

Learn how Eclipse solved manufacturing challenges for micro spring-energized seals, optimizing sealing performance in epoxy dispensing equipment.

Case Study: Angled Spring Grooves for Custom Spring Energized Ball Seats

By Doug Montgomery • February 13, 2025

Learn how Eclipse Seal’s custom spring energized ball seats with angled grooves improve performance

Case Study: Dual Lip Crimped Case Seal in High Speed Rotary Vacuum Application

By Doug Montgomery • January 17, 2025

Eclipse deals regularly with challenging sealing applications from all industries. High pressures and speeds create unique sets of conditions where seal design and material properties are pushed to the limit. While reciprocating applications can certainly test seals to the edge of capability, often times rotary applications can present the greatest challenge to seal integrity and wear life. Unlike reciprocating configurations where the seal is acting on a different part of the shaft or bore throughout it’s operating range, rotary seals must operate on the same sealing area continuously. This makes things like heat rejection much more difficult, especially in unlubricated or dry running applications. Extreme localized heating can have negative affect on both seal and hardware life. Rotary applications also pose sealing difficulties due to the simple fact that surface speeds can be much higher than in reciprocating systems. A simple electric motor can operate at very high rpm, while long stroke, high speed reciprocating machinery is a major piece of equipment that is far less common (though Eclipse also has sealing solutions in a number of these situations). A customer approached Eclipse with an application that was beyond the scope and capability of any standard, off-the-shelf rotary seal. This sealing system would require a combination of both wear resistance in high-speed rotary, as well as excellent leakage control and sealability. Two factors that, more often than not, work in opposition to each other. The Customer Issue The customer was developing a test system that required an electric motor shaft passed through the wall of a large vacuum chamber. The testing apparatus needed a sizable motor to meet the speed and torque requirements. Adapting the motor to operate inside the chamber would not be practical due to contamination and motor cooling concerns. Therefore, the motor would have to be placed outside the chamber and a driveshaft would have to go through the chamber wall. Which, of course, would need a seal. Operating Conditions:  Rotary Shaft Seal  Shaft Diameter: 2.5”  RPM: 7,500 RPM - unlubricated  Pressure: Vacuum internal side / 1 ATM external side Temperature: 40° - 90°F The customer knew any kind of off-the-shelf rotary seal with a rubber element would not last any amount of time in the combination of speed and a dry running condition. They also knew a single lip PTFE seal would likely not meet their leakage requirements. Therefore, they turned Eclipse for a custom sealing solution.

Case Study: PEEK Spring Energized Seal in a High Temperature/High Radiation Application

By Doug Montgomery • November 25, 2024

Eclipse has engineered sealing solutions for applications all over the planet and in a plethora of environments. From the bottom of the ocean to orbiting the earth, Eclipse is challenged by the unique conditions in each application. Whether it be extreme temperature and pressure or severely caustic or abrasive media, Eclipse has a solution for most every sealing problem. One distinct environment presents a particularly challenging set of circumstances for seal design – high radiation. Eclipse’s primary seal material choice for many applications is PTFE and PTFE blends. With all the wonderful attributes PTFE possesses as a seal material, radiation resistance is not one. In high radiation environments PTFE’s properties can degrade to essentially rule it out as a suitable material. The options for effective sealing materials that are also radiation resistant becomes very limited. The seal designer is therefore confronted with creating a seal that is expected to perform in every way a typical PTFE seal operates, out of materials that are not as favorable to sealing. This is where Eclipse’s engineering experience and expertise in seal design come to the forefront. The Client's Issue Eclipse was approached by a customer that was looking for a seal solution for a sensor used in a nuclear application. It would be operating in an environment with both high temperature and high Gamma radiation. Operating Conditions:  Reciprocating Rod Seal  Rod Diameter: Ø1.000  Stroke: 1.5” Cycle Rate: 2-4 cycles per minute  Media: Air, Salt Water Mist  Pressure: 100 PSI  Temperature: 70° to 450°F  Gamma Radiation Exposure: 10^6 rads