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with Underwriters 9 Laboratories Recognition is required. TYPICAL PROPERTIES DRY AS MOLDED ASTM ENGLISH S.I.<br><br> PROPERTY TEST METHOD UNITS VALUE UNITS VALUE Melting Range D789 °F 482-509 °C 250-265 Specific Gravity D792 - 1.39 - 1.39 Water Absorption (24 hrs. immersion) D570 % 0.7 % 0.7 Rev. 6/03 Heat Deflection Temp.<br><br> at 264 lbs/in 2 (1.82MPa) D648 °F 482 °C 250 Mold Shrinkage* 1/8" section % 0.2-0.4 % 0.2-0.4 (Flow Direction) Tensile Strength at Break D638 lbs/in 2 28,500 MPa 197 Elongation at Break D638 % 2-4 % 2-4 Flexural Strength D790 lbs/in 2 42,000 MPa 290 Flexural Modulus D790 lbs/in 2 1,400,000 MPa 9,655 Izod Impact Strength D256 ft. lbs/in 2.5 J/m 133 (Notched, 1/8" specimen) of notch Rockwell Hardness D785 M scale M99 - - Flammability(all colors)** UL94 - - - HB 0.75mm min. thickness * Please review shrinkage projections for specific applications with an MDE Technical Representative.<br><br> **This laboratory rating of flammability characteristics is not intended either to predict behavior or to reflect hazards that may be presented by this or any other material under actual fire conditions. All data generated using test specimens injection molded from natural color material. Inclusion of color pigments or other add itives may change some or all of these test results.<br><br> Test specimens are stored in a moisture proof container immediately after molding and contain less than 0.2% moisture; tests are conducted at 23°C and 50% relative humidity unless otherwise stated. These mechanical property test data have been developed using injection molded specimens tested under standardized conditions; furthermore, many of the mechanical properties of thermoplastic materials can be influenced by changes in processing conditions, environmental fa ctors such as temperature and humidity, and rate of application of stress. Therefore, these test results, which characterize typical product ion material, should not be used either to establish specification limits or alone as the basis for engineering design.<br><br> Rev. 6/03 Nylon RN66G33HSL Processing Guidelines Drying Nylon compounds from MDE are shipped in moisture resistant packaging, dried to less than 0.25% moisture. Most processors will further dry nylon resins and compounds, especially after exposure of virgin resin to ambient air for more than an hour, or when a proportion of reground material is being used.<br><br> The use of dehumidifying dryers is strongly preferred. The dew point of the drying air stream should be no more than -20°F, and preferably lower. The drying air temperature must be high enough to achieve a pellet temperature of 175-180°F.<br><br> If using a hopper drier, depending on air hose length and insulation of hoses and hopper, the drying air temperature may need to reach 200-220°F to achieve the required material temperature. If the pellet temperature reaches 180°F, a residence time of 4 hours is generally adequate to ensure that the material is ready to be processed. Only if residence times are limited to 2 hours should a pellet temperature of 200°F be considered; at 200°F, there is a risk of material oxidation, with associated yellowing of natural color and loss of part performance.<br><br> Nylon compounds usually demonstrate visual evidence of unacceptably high moisture levels. This includes splay or silver streaking on the molded part surface, or an unstable melt or nozzle drool at the machine. Additional drying time is indicated i f these characteristics are observed.<br><br> If moisture analysis equipment is available, an acceptable moisture content range for normal processing is 0.1% to 0.25% maximum. Mold-in-color parts with critical cosmetic requirements may require drying to < 0.1%. Temperature Guidelines The following temperature guidelines are suggested for general use if a machine can be selected where shot size is 40- 70% of nominal machine capacity.<br><br> Typical Cylinder Tool Surface Melt Temperatures (°F) Temperatures(°F) Temperature (°F) Max. Preferred Min. Front Center Rear 160-180 590 550-575 540 540 550 560 " A "reverse" temperature profile helps ensure a homogeneous melt, improves screw recovery and helps to optimize cycle times.<br><br> " A mold surface temperature in the suggested range improves surface appearance, helps consistency of mold fill and therefore consistency of dimensions, minimizes the effect of weld lines and also helps realize best molded part performance. " A medium to fast injection speed maximizes weld line strength and minimizes molded-in stress. Good venting of cavities is essential to allow fast fill without burning.<br><br> Screw Forward Time Adequate screw forward time under follow-up pressure is important to ensure proper packing before gate freeze, during which time it is essential to maintain a "cushion" of 1/8"-1/4". Optimum screw forward time can be judged by a part weight vs. forward time plot.<br><br> Avoid overpacking, which can generate molded-in stresses. Screw Recovery It is recommended that back pressure be applied to the screw to help development of a homogenous melt, and to ensure consistent shot volume. For this reinforced grade, limiting back pressure to about 50 psi gauge will minimize the risk of mechanical damage to the glass fibers with consequent loss of part performance.<br><br> Screw rotation should also be as slow as possible consistent with cycle time goals, usually 40-80 r.p.m. Mold Shrinkage Standard ASTM test specimens are used to develop shrinkage guidelines. Test specimens are end-gated, 1/8 inch thickness, and molded at conditions recommended for this formulation.<br><br> Actual shrinkage in molded parts will depend on several variables, including processing conditions, part configuration and gate location, both of which influence material flow direction, and wall section thickness.

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