ASTM D1238:13 pdf free download – Standard Test Method for Melt Flow Rates of Thermoplastics by Extrusion Plastometer.
5.5.2 Thc preferred method for calibrating the temperature is to use a temperature sensor assembly having a sensor with at least an accuracy of 60.08°C at 200°C and a 20 6 0.5-mm long brass tip press fit on the end of the sensor. Thc diameter of the brass tip shall closely match the diameter of the die and the length of the active measuring length of the temperature sensor (sec Appendix X3).
5.5.3 Temperatures shall be verified with the bottom of the temperature sensor at 10 and 75 6 I mm above the upper face of the die and at cach test temperature, without touching the die. Allow at least four minutes for equilibrium of temperature to be reached for each position. Temperature variation shall be determined over a minimum of 15 minutes. When using the “half’ die, the temperature indicating device shall be calibrated as stated in Table I except temperatures are measured at 79 6 1 mm and 14 6 I mm above the upper surface of the die.
5.5.4 An alternative method is to insert the temperature sensor without a brass tip into the melt from the top of the cylinder so that it is 10 and 75 6 I mm above the upper face of the die.
5.5.5 The temperature sensor and readout equipment used for calibration of the extrusion plastometer shall be traceable to a national standard (for example. N 1ST).
5.6 Timing Derice/Svxvem—For Procedure A. a timing device with an accuracy of 0.1 s shall be uscd. For Procedures B. C. and D. an automatic timing system shall measure and time piston movement within the specified travel range. The requirements of the automatic timing system shall bc as follows:
5.6.1 Sense and indicate the piston travel time within 60.01S.
5.6.2 Measure piston travel within 60.4 % of the nominal selected value (sec 10,7) for use in the flow rate calculations.
5.6.3 Operate within a fixed portion of the cylinder. This is defined as the portion of the cylinder between 48 mm and 18.35 mm above the top of the die.
5.6.4 Any effects on the applied load caused by the Timing Device/System must be included in the allowable tolerance given in 5.4.3.
5.6.5 The equipment used to calibrate the Timing Device/ System shall be traceable to a national standard (for example. NIST).
9. Procedure A—Manual Operation
9.1 Select conditions of tcrnpcrature and load from X4. I or in accordance with material specifications. Where multiple test conditions exist. test conditions shall be agreed upon by the cooperating laboratories. If test conditions arc not known. select conditions that result in flow rates between 0.15 to 50 g/lO mm.
9.2 Inspect the extrusion plastometer for cleanliness (see Note 10). All surfaces of the cylinder bore, die and piston shall be free of any residue from previous tests.