Scope: Mold shrinkage is the shrinkage of the polymer as it cools after the molding process. It is typically used to properly machine injection molds so that final. Purchase your copy of ASTM D – 08() as a PDF download or hard copy directly from the official BSI Shop. All BSI British Standards. Buy ASTM D R TEST METHOD OF MEASURING SHRINKAGE FROM MOLD DIMENSIONS OF THERMOPLASTICS from SAI.
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Injection Molds Digital micrometers Digital calipers Weighted digital drop gauge. Your Alert Profile lists the documents that will be 9d55-08. This standard and ISO are equivalent in the design of specimen D2. If you need to be able to add standards to the monitoring service, you must register as a user with your own username and password. Test specimens are molded under specified conditions.
Calculation and Report The values given in parentheses are given for information only. Signicance and Use 5. It is typically used to properly machine injection molds so that final part dimensions are d9550-8 desired. The principles of For example, thermoplastics, which absorb moisture must be dried before molding. Last previous edition approved v955-08 as D – The mold shall have at one end a gate 6.
Thus the mass of material injected into the cavity is not clearly dened and the orientation of the material astj the gate will be perturbed. Factors, such as the amount of material in charge, cooling time, and pressure application are known to affect shrinkage significantly. NOTE 3—If the injection machines of appropriate capacity are not available, the requirements of 7. Factors such as mold and melt temperature, ll times, and s955-08 conditions are known to affect shrinkage signicantly.
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Webprint Printed and bound. At point R, the value of the cav ity pressure at hold is recorded. NOTE 2—Although scribe marks are not required, if they are used for injection or compression molded specimens for the measurement of shrinkage, the scribe marks shall be 1. The length or diameter of the cavity is measured depending on shape of mold. Historical Version s – view previous versions of standard.
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Current edition approved Nov. Standards Subsctiption may be the perfect solution. The preparation given to the material prior to molding shall be recorded and reported.
astj As the voice of the U. The benefits of a subscription: The method also accommodates shrinkage at 24 and 48 h, which may be critical for some materials. Begin with a short shot to ensure the ow front is straight and not radial and that the ow is laminar and does not exhibit melt fracture jetting.
Pressure transducers for monitoring the pressure in at least one cavity are mandatory for Type D2. Three percent warp is dened as 3 mm depth deection, positive or negative, per mm in length. Orientation effects due to ow direction do not generally pertain to compression molding. Each laboratory obtained one test result for each material.
ASTM D955 – 08(2014)
Mold shrinkage is calculated as inches per inch or percent or mm per mm for the specified dimensions and conditions. The parts cool and after 48 hours, the ast parts are measured and the shrinkage is calculated.
Intermediate values may also be used, however. Pressure transducers are recommended, but not mandatory for specimens Type A and Type B. The values given in parentheses are given for information only.
ASTM D – 08 Standard Test Method of Measuring Shrinkage from Mold Dimensions of Thermoplastics
Values would not be expected to be in agreement with those obtained using the specimens described in 8. The molding is done by an approved outside source. It is recommended to cool specimens in a horizontal position at room temperature by placing them on a material of low thermal conductivity to minimize warpage.
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