All in the (Polymer) Family: Meldin® Line Combines Thermoplastic & Thermoset Materials to Solve High-Demand Applications 

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Finding the right material solution for specialized applications is always challenging as they may be exposed to extreme environments or chemicals or may need to be nonconductive or lighter in weight. Often low temperature thermoplastics and metal parts may not be the best fit in these instances, which is where high-performance polymers provide a more precise fit and a better option as they are recognized for greater temperature and chemical stability, mechanical properties, strength, and rigidity. 

In the healthcare and life sciences industry, high-performance polymers are valuable as they withstand chemicals and stringent operating conditions as well as address needs for longer life and reduced maintenance in applications such as portable oxygen concentrators, in vitro analytical equipment and dental drills. In automotive, they can increase part lifetime while reducing emissions and fuel consumption with lighter weight materials in air conditioning compressors and braking system components. 

Saint-Gobain Seals’ Meldin® polymer material offers a complete range of polyimide and engineered thermoplastic materials for specific high-demand applications. These parts can be used in specialized applications where high thermal resistance and good mechanical properties at high temperatures are required. They retain critical properties at continuous operation at temperature ranges from cryogenic through +600°F (+315°C), and can be used intermittently at even higher temperatures [up to +900°F (+482°C)]. They withstand harsh chemicals, tremendous pressure, extreme speeds, friction and wear and are also lighter in weight. 

A Family of Formulas Grow

First developed in the 1970s by Ted Rulon Miller as an alternative to melamine, the Meldin® 2000 product line was used as a filler for the Rulon® product  – a polymer material developed in the late 1950s by another Miller in the family, Robert Rulon Miller, as part of a new plastic saddle design for longer wear life.. Since that time, numerous series and grades of Meldin® have been developed for use in seals, bearings, bushings, piston rings, thrust washers, vanes, gears, and other engineered critical parts in a variety of industries. 

Meldin® grades are available in thermoplastics, which can be melted down and reused, and thermoset polyimides, which becomes irreversibly hardened upon being cured but can still offer even higher temperature resistance. The Meldin® product line includes: 

The Family of Thermoplastic Materials

Launched in 1980, this family of high temperature Meldin® polymers began with the 1000 and 5000 series that are used often in life sciences and automotive applications. 

  • Meldin® 1000: This material is a proprietary polyphenylene sulfide (PPS) thermoplastic that can withstand harsh chemicals and temperatures. It is good up to 205°C continuous use and offers good wear properties up to 150°C. It offers a low coefficient of thermal expansion and good steam and chemical resistance. 
  • Meldin® 4000: This series was launched in 2014 after the acquisition of LS Kunststofftechnologie GmbH, a German manufacturer of high-performance thermoplastics. This series leverages polyamide-imide (PAI) to provide superior mechanical properties at very high temperatures (up to 275°C). It is frequently used to replace metal components. 
  • Meldin® 5000: This grade is based on PAEK and PEEK to provide superior thermal resistance, strong mechanical properties, and chemical resistance. It has high tensile, compressive, and flexural strength and is injection molded into tight-tolerance finished components. Advantages include lighter weight and corrosion resistance, offering good steam and chemical compatibility, low coefficient of friction, and good wear properties. It can withstand up to 260°C continuous use.
The Family of Thermoset Polyimide Materials

These thermoset materials were developed before thermoplastics and evolved to the commercial production of Meldin® 7000 in 1991, becoming Saint-Gobain Seals’ flagship series for high-performance solutions especially for aerospace and space industries. 

  • Meldin® 2000, 6000, 8000, and 9000: These series are legacy thermoset polyimide grades that provide up to 316°C continuous use. 
  • Meldin® 7000: This grade offers very good temperature resistance, able to withstand up to 316°C continuous and 482°C intermittent use, good mechanical properties and chemical resistance. It recently passed UL94 tests (from Underwriters Laboratories, Inc., a global independent safety science company) for flammability, confirming its suitability in challenging applications and helping end users to save time and cost of additional testing. Meldin® 7000 includes five grades:
    • Meldin® 7001: This unfilled pure, base grade polyimide offers maximum mechanical properties (good tensile strength at high temperature), good thermal and electrical insulation. It provides long use and can often be used multiple times. This material was recently used in a jet engine electric harness.
    • Meldin® 7021: This grade is 15% graphite filled, offering low wear properties and low friction and used in launch vehicle bearings.
    • Meldin® 7022: This grade is 40% graphite filled and offers the lowest coefficient of thermal expansion and very good dimensional stability at high temperatures. For this reason, it is often used in aerospace engine applications.
    • Meldin® 7211: This grade is 15% graphite and 10% PTFE filled. The latter gives it the lowest coefficient of friction.
    • Meldin® 7003: This grade is 15% molybdenum disulfide filled. With good lubrication in dry and vacuum environments, it is often used in space and defense applications where parts cannot be easily accessed to apply oils. 
Finding the Right Meldin® Family Member   

Selecting the right Meldin® material solution often depends on a number of factors surrounding the application such as:

  • Temperature (including typical and maximum temperatures)
  • Chemical exposure (steam, acids and bases)
  • Level of friction, lubrication, wear
  • Dry environments
  • Need to reduce weight
  • Mechanical integrity 
The Family of Applications

With the potential to provide longer use, higher temperature resistance, and lighter weight, Meldin® products have been used extensively in diverse markets. Specific applications include: 

  • Vanes for air operated surgical tools: Meldin® 1000 and 5000 series are a good fit for these dry environments, where using oils or coolants are not an option, and standing high temperatures are common, often helping to extend tool life. 
  • Automotive start/stop systems: With its light weight, the polymer material is frequently relied upon to reduce fuel usage and in this application, Meldin® 1000 sealing parts enable a quick start after stopping to save gas after the vehicle comes to a stop. 
  • Automotive brake wear sensors: Meldin® 7001 material is often used in wire holders in braking systems for trucks and high-performance vehicles, holding the sensor in place to indicate if the brake part is wearing. Even with the complex geometry of these parts, the material can be molded without additional machining, withstand high temperature braking conditions, is nonconductive and will not interfere with brake wear sensor electrical signals. 
  • Automotive transmission thrust washers and oil pump gerotors: Meldin® 5000 material is used in racing and motorsport applications because it withstands high pressure and speed conditions and is self-lubricated and resistant to aggressive fluids. 
  • Electronic plasma etch: Meldin® 7001 material is used in retaining rings in plasma processing machinery used to fabricate integrated circuits. The material is used for its ability to withstand harsh environments, provide good mechanical properties and temperature resistance. 
The Family History of Expertise

With over 50 years of global manufacturing experience at the Bristol, Wertheim and Neuhaus, sites and close collaboration with customers, Saint-Gobain Seals delivers the precise fit thermoplastic or thermoset solution. 

Every Meldin® batch manufactured is tested before materials are molded. State-of-the-art tribology labs test wear rate, coefficient of friction, and surface temperatures in real time to determine the most suitable materials for the application.  Finite Element Analysis (FEA), 3-D modeling, CAD drawings, CAE simulation of processes and mold flow are also often used.  Leveraging the most modern manufacturing techniques such as WCM, 5S, Kaizen, and Six Sigma also ensures the highest quality products. Saint-Gobain Seals’ worldwide facilities are all ISO 9001 certified and one of the few to be AS9100 certified for aerospace and IATF 16949 certified for automotive. 

Which Meldin® material might be right for your application? Contact us today to learn more.