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High Precision Lapping Equipment Ensures Premium Seal Face Quality

ceramic mechanical seals

Morgan Advanced Materials is a global leader in the production of engineered advanced materials, including ceramics, specialty brazing alloys, composites and carbon

Key end-use markets for Morgan’s products include petrochemical, electronics, energy, healthcare, industrial, transportation and defence.

The manufacturing facility, in Coudersport, Pennsylvania, manufactures carbon-based materials as well as a variety of silicon carbide parts, many in high volume.  Products include mechanical seal faces and sliding axial and radial bearings with sizes ranging from less than 0.9mm to over 500mm in diameter.

Components used for mechanical seals require extreme precision in terms of flatness, parallelism and finish.  A seal failure in a high pressure or corrosive application can lead to expensive repairs or result in substantial environmental, health and safety consequences. The focus on continuous improvement in seal face quality at Morgan has led to a 30-year relationship with Engis® Corporation which supplies Coudersport with high precision lapping equipment, application technology and engineered consumables.

“Seals require precision lapping due not only to their material properties, but to their form, fit and function” explained Tom Grossman, Morgan’s Manufacturing Engineering Manager.

lapping machines

Lapping machines and precision lap plates are used to lap/polish ceramic parts and other stain-sensitive materials

“When lapping ceramic seals, selection of the lapping plate is critical,” commented Mike Pisauro, Engis Applications Manager. “It is very important that the appropriate lap plate material be selected for the material being lapped so that the diamond charging into the plate performs effectively. Engis provides composite plates in Copper, Iron, Tin and ceramic that can be chosen to suit the material to be lapped”

Another important consideration for plate selection is whether or not metals can be tolerated, as copper or iron based composite plates are typically the workhorses for many lapping processes.  “In some cases customers are concerned about staining or metallic contamination when lapping ceramics” explains Pisauro “so, oftentimes Engis recommends the Hyprez® HY Ceramic lapping plate.  Grooving the lapping plate further increases the cut rate of the diamond slurry and creates a channel for the evacuation of abraded material.”

Selecting the right diamond slurry depends on the material removal requirements and final surface finish of the parts.  It is important to consider not only the size of the diamond, but also properties such as friability, aspect ratio, and uniformity and consistency of the particle size distribution.  Engis engineers are able to select the appropriate slurry based on requirements along with decades of application experience, and to tailor these properties to fit specific needs.

When it comes to lapping process development, plate preparation is a key consideration.  When lapping ceramics it is important to remember to keep the plate slightly damp, but not flood it with lubricant, to avoid the parts hydroplaning.  The plate conditioning process must also be chosen carefully.  Pisauro suggests that, when using ceramic based lapping plates, they should be conditioned dry, so they produce a powder during the process. Conditioning a wet ceramic lap plate can produce a “muddy” swarf which is difficult to clean and which will eventually load the diamond conditioning ring and prevent it from cutting.

For Morgan, the quality and fit of its ceramic seals is critical.  As a general rule, Pisauro recommends slowing the lap plate rotational speed toward the end of the process in order to improve the flatness of the seals.  These types of multi-stage processes can be best accomplished with machines that offer programmable process recipes, such as Engis FastLap® series of lapping machines.

Coudersport

The Morgan facility in Coudersport, Pa., produces high-precision ceramic mechanical seals as well as seal noses engineered from silicon carbide

“We don’t need Engis every day” explained Grossman, “but the support has been there when we do. We spend a lot of weekends here in Coudersport to keep the ball moving on cost and quality, so we need to partner with technically competent vendors.”

Joe Boylan, Manager of Sales & Marketing for Morgan’s Seals & Bearings business in North America, confirmed that; “The performance bar has continued to rise over the past few years as the application requirements for mechanical seals continues to increase, sometimes to staggering levels.  These critical face components are being designed to handle higher pressures, speeds, and temperatures.  Maintaining the integrity of the interface between the seal faces is key.  The unique material technologies of Morgan, coupled with the extensive machining expertise of Engis, create the ability to tailor the topography of the seal face to precise levels, making these designs a reality.”

Engis Product Manage, Alicia Walters explained the Engis approach to supporting its customers, “No two applications are exactly alike, therefore it is critical to approach process development from many angles.  Engis is unique in our ability to control the machine design, slurries, plate materials, and accessories combined with our Process Development Labs to develop and deliver a process to the end user.  The ability to select from a wide range of available and proven options allows us to quickly achieve the desired results in the majority of cases, and to develop unique solutions when necessary.”

Contact:

John Wellings
Engis (UK) Ltd.
9 Centenary Business Park, Station Road, Henley-on-Thames, Oxon RG9 1DS
Tel.01491.411117,
[email protected]
www.engis.com

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