Rotating-Core Injection Molding Process Increases Burst Strength and Reduces the Detrimental Effects of Knit Lines; Solvay Advanced Polymers is Building a Development Tool to Evaluate Additional Benefits, Including Improvements in Dimensional Stability

Oct 07, 2004, 01:00 ET from Solvay Advanced Polymers L.L.C.

    ALPHARETTA, Ga., Oct. 7 /PRNewswire/ -- In conventional injection molding,
 cylindrical or conical sections within complex parts are formed by flowing
 thermoplastic material around a stationary core.  A molding process patented
 by Solvay S.A. has been shown to improve the strength of such parts by
 injecting the material onto a rotating core.
     Two-fold and greater strength increases have been demonstrated in parts
 molded of semi-crystalline polymers reinforced with glass or minerals or both.
 The improved burst strength is achieved, in part, by the ability of the
 process to produce a preferred orientation in the material itself.  On a
 macro-molecular level, the polymer chains become arranged around the
 circumference of a cylindrical or conical part -- like the reinforcing belts
 under the tread of a radial tire -- rather than simply along the flow path of
 the injected plastic.  The reinforcing fibers are also arranged in this
 direction, greatly increasing the part's ability to withstand internal
     Rotating the core during injection also reduces the detrimental effect of
 knit lines or weld lines -- areas formed when flow fronts meet, which results
 in incomplete material or fiber interaction across the front and introduces
 mechanical weakness.
     Improved dimensional stability
     Now Solvay Advanced Polymers L.L.C. is building a development tool to
 evaluate additional benefits of the process that have important implications
 in specific applications.  Jeff Peterson, one of the company's global market
 managers, is encouraged that the rotating-core process can produce cylindrical
 or conical sections that exhibit improved dimensional stability during
 operation over a wide range of temperature and humidity conditions.  "What's
 absolutely critical to an automotive throttle body, for example, is that it
 maintains both its dimensions and its roundness in operation," Peterson points
 out.  "The dimensional design tolerance between the air-regulating valve and
 the bore is quite tight and ideally would not change with fluctuations in
 environmental conditions.  So any process that improves the bore's dimensional
 stability over the full range of operating conditions in turn improves engine
 performance, including efficiency and emission characteristics."
     Rotating the core during injection could have other benefits, such as
 helping control the initial molded dimensions of the bore or improving the
 quality of the surface finish.
     New data will help optimize process for additional applications
     Speed and the duration of core rotation during injection are important
 parameters in maximizing the strength and stability of a finished part.  The
 new development tool will give Solvay Advanced Polymers data to help in
 optimizing the rotating-core process for a variety of materials and
 applications.  Parts molded in such advanced materials as IXEF(R)
 polyarylamide and AMODEL(R) polyphthalamide could benefit significantly from
 this process.
     Peterson anticipates that the patented process can produce improvements
 not only in automotive parts -. such as throttle bodies or brake power-piston
 cylinders -. but also in similar applications in other industries.  He cites
 such examples as plumbing fittings and thrust washers as applications that
 could realize significant improvements in strength and dimensional stability.
     About Solvay Advanced Polymers
     Solvay Advanced Polymers, L.L.C. is a subsidiary of Solvay America, Inc.,
 the U.S. holding company of Solvay S.A.  The company produces high-performance
 polymers that are used in a wide range of demanding applications in the
 automotive, aerospace, industrial, foodservice, medical, and electronics
 industries worldwide.  More information about this and other Solvay Advanced
 Polymers products and services can be found on the company's website at .
     Solvay is an international chemical and pharmaceutical group with
 headquarters in Brussels, Belgium.  It employs more than 30,000 people in 50
 countries.  In 2003, its consolidated sales amounted to EUR 7.6 billion
 generated by its three activity sectors: Chemicals, Plastics and
 Pharmaceuticals.  Solvay is listed on the Euronext 100 index of top European
 companies.  Details are available at .

SOURCE Solvay Advanced Polymers L.L.C.