Manufacturing of Hybrid Overmoulded FRP Components: Impact of Process and Environmental Parameters on the Mechanical Properties

A manufacturing parametric study was carried out on a hybrid part, consisting of two organo sheets and injection moulded rib reinforcements, made out of a short fibre reinforced plastic. The effect of the temperature of all components, the pressure profile throughout the injection moulding process as well as the subsequent storage conditions on the mechanical properties was investigated. For this purpose a total of 96 parts was manufactured with different processing parameter combinations. Afterwards all parts were subjected to a cantilever beam test, analysing initial stiffness, deformation work and peak force. Furthermore a variety of potentially influencing factors such as temperature, humidity, order of testing, transfer durations and many more were tracked.

Parameter definition:

• part_ID: Unique part identifier.
• OS-degradation: Degradation of the organo-sheet(OS) because of thermal decomposition at temperatures above 260°C. Given as percentage of degraded mass.
• heating-duration: Time of heating the OS in seconds.
• heating_temperature-OS: Surface temperature of the OS at the end of the heating period in °C.
• heating_field-temp.: Temperature of the heating field immediately before the heating process begins in °C.
• stiffness: Bending stiffness of the structure in N/mm. Determined from the force-deflection-curve between 50 and 150 N.
• maximum_force: Highest force value measured during the cantilever beam test in kN.
• deflection: Value corresponding to the maximum force in mm.
• deformation_work: Absorbed work due to deformation in kN*mm. Determined by integrating the force-deflection-curve from 5 to 30 mm with a lower bound of 0.05 kN on the force.
• corrected-x: Value of x corrected by taking into account the water intake.
• rib_lengths-x: Length of the rib in mm (1à5^th, 2à7^th , 3à10^th).
• sprue_width: Diameter of the sprue in mm.
• part_length: Total part length in mm.
• mould_filled-x: Flag indicating whether the mould was filled (indicated by 1) at position x (1àbroad end, 2àmid, 3ànarrow end)
• rib_length: Mean of the measured rib lengths in mm.
• mould_filled: Mean of the flags for fill state.
• day_of_testing: Day on which the part was tested (1,2,3).
• no._of_test_per_day: Number of test on the respective day.
• no._of_test_total: Number of tests in total.
• delay_of_transfer: Duration between removal of the OS from the heating field and begin of the transfer in s.
• transfer_temp_beg.-x: Surface temperature in °C of the OS at the beginning of the transfer at position x.
• transfer_temp_end-x: Surface temperature in °C of the OS at the end of the transfer at position x.
• tool_surface_temp.-x: Surface temperature in °C of the tool at position x.
• fixing-x: Flag indicating whether the OS was fixed (indicated by 1) at position x (1àbroad end, 2àmid, 3ànarrow end).
• fixing: Mean of the flags for fixing.
• duration-rapid_traverse: Duration of the rapid motion phase of the press in s.
• duration-deformation: Duration of the motion phase of the press deforming the OS in s.
• press_profile: ID for translational velocity of the press (0àslow, 1àfast).
• duration-closing: Sum of duration-rapid_traverse and duration-deformation.
• duration-injection: Duration of the pure injection process in s.
• duration-holding_pressure: Time for which the holding pressure was kept up in s.
• temp.-cylinder-x: Mean of the temperature over one cycle at one heating band in °C.
• temp-hot_runner-x: Mean of the temperature over one cycle at one heating element in the hot runner in °C.
• temp.-defl._tool-x: Mean of the temperature over one cycle in the deflection tool at position x.
• delay-injection: Time between the press fully closing and the beginning of injection in s.
• holding_pressure-beg.-x: Holding pressure at the beginning of holding and position x in bar.
• holding_pressure-end-x: Holding pressure at the ned of holding and position x in bar.
• duration-form_stability-x: Time in s between maximum melt pressure and form stability, characterised by a pressure below 75 bar.
• max.-pressure-melt-x: Maximum pressure during the injection process at position x in bar.
• transmission-hold._press.-beg.: Ratio of pressure signal from the sensor at screw and in tool at beginning of holding.
• transmission-hold._press.-end: Ratio of pressure signal from the sensor at screw and in tool at end of holding.
• cooling_rate-hold._press.-x: Measured cooling rate at position x during the holding phase in °C/s.
• cooling_rate-cooling-x: Measured cooling rate at position x during the cooling phase in °C/s.
• tool-temp.-x: Measured tool temperature at position x in °C.
• max.-melt-temp-x: Highest measured melt temperature at position x in °C.
• demoulding-temp.-x: Measured tool temperature at position x at demoulding in °C.
• storage-standard_atmosphere: Storage duration at standard atmosphere in h.
• absoprtion_water-std.atm.: Water absorption during the storage at standard atmosphere in g.
• absoprtion_water-climate_chamber.: Water absorption during the storage in the climate chamber in g.
• storage-climate_chamber: Storage duration in climate chamber in h.
• vert._position-climate_chamber: Vertical position in the climate chamber in cm.
• air-temp.: Air temperature during manufacturing in °C.
• air-rel._humidity: Relative humidity during manufacturing in %.
• no.-production-day: Consecutive number indicating parts manufactured before the respective part.
• factor_level: Factor level in the DOE.
• prod.-date: Date of production.
• prod-time: Time of production in CEST.
• batch_number: ID in which batch the part was manufactured.