注塑机性能测试

Closed Loop injection Machine Commissioning & TestingIntroductionThis document provides guidance for the commissioning and testing closed loop injection moulding hardware, injection system & control softwareCaution: Please ensure all instructions and guidelines regarding safety and normal operation of the machine referred to in the installation and normal operation provided by the manufacturer of the machine.Caution: It is the responsibility of the commissioning / testing technical team to ensure safe installation and initial operation of all systems of the injection moulding machine. Any person operating this equipment must be fully qualified and undergone comprehensive training. All documentation regarding the machines safe installation and operation provided by the machine manufacturer must be read and understood before the machine installation / operation of the machine.Caution: in order to prevent injuries from the machine and damage to the machine ensure enough caution and professional understanding is applied towards the setup of the machine.Additional Information:For further information, parts, service, or latest information related to the full installation and operating of this equipment etc, contact the Equipment Manufacturer.1.Pre-Commission / Testing Checks1.1.M achine1.1.1.C heck that the machine is installed per the manufacturers instructions and that properguarding and safety precautions have been observed.1.2.F acilities & Ancillary Equipment1.2.1.A ll facilities and equipment required to conduct moulding / machines trials should be availablee.g. Appropriate Power Supply, Compressed Air Supply, Mould Temperature Control; HotWater, Chilled Water, Normal Water with appropriate connections. Closed loop MaterialDryers & Dehumidifiers.1.2.2.A n appropriate mould should be selected, installed in the machine and allowed reach specifiedtemperature.1.2.3.R esin should be allowed sufficient time in the hopper / dryer to reach specified moisture levelsprior to beginning the machine set up and initial checks.1.2.4.O perators should be provided by all necessary equipment, safety and otherwise to safelyoperate the equipment.2.Machine Set-up & Testing2.1.Calibrate screw bottom reads zeroCheck that the screw bottom or zero point, switch the cycle to manual with low pressure and bring the screw full forward. Check the screw position reading: It should be zero. If not, recalibrate the position sensor.2.2.Check: Screw Drift, Shot-Size & Position Cut Off consistencyWith the machine cycling, check that the screw is not moving as the mould is opens, ejection / re-loading and then closing the screw should not move. Note the position of the screw at the end of screwrecovery, this should be identical on every shot. Check that the machine is switching from first to second stage as the screw hits the set cut off position (assuming cut off is via stroke position). Variation should be less than 0.05 mm. If the machine fails any of these tests, the shot size is fluctuating beyondacceptable levels.2.3.Load Compensation ChecksC hecks the machine’s ability to keep fill time constant by adapting to viscosity changes, such astemperature cycles, resin lot changes, colour changes, and other normal process variations.Start up the machine following your normal procedures, making sure you are operating with anappropriate Delta P and switching from first stage to second stage via stroke position. Make short shots by reducing Second-Stage Pressure as low as possible while leaving some time on the hold timer.Select three injection velocities, low, med and high. At each in turn, note the fill time and pressure at transfer to make this 90-99% full shot. The fill time is FT1 and the pressure at transfer is PK1. Now, either manually or in automatic cycle using screw decompression before screw rotation, pull the screw back (without screw rotation) to the exact same position used to make your 90-99% full part. That is, you have a shot of air, no plastic in front of the screw. Before you make this air shot, make sure you can easily dig out a very short shot. Now, on semi- or fully automatic cycle, shoot air into the mould and note the fill time and pressure at transfer. This is FT2 and PK2. The fill time should be the same, with asignificantly reduced pressure at transfer. The following equation calculates the machine’s loadsensitivity:(FT1 – FT2) ÷ FT1) ÷ (PK1 – PK2) ÷ 1000) × 100 = % error/1000 psi.The percent error should be near zero; slightly negative is ideal. If the error is greater than +5% error are not properly load compensated. Test at three different injection velocities—slow, medium, and fast. If your machine passes this severe load-variation test, it will keep fill time constant during production.2.4.Velocity LinearityCaution: Before beginning this test, make sure short shots can be ejected easily. If shorts cannot be easily ejected you will have to use second-stage pressure to finish filling the part.The purpose of this test is to compare a machine’s set velocity with what is actually achieved. To get good data, it’s recommended that the shot should be at least 60% of the barrel capacity. If you are using less than 40% of barrel capacity, do not use that mould for this velocity linearity test, as theresults may be useless.In normal production mode using normal procedures to begin production making full parts. Lower the second-stage, or pack and hold, pressure as far as the machine will allow. At whatever velocity is currently set on the machine’s controller, this should make a short shot. If not, adjust the position transfer to make a part that is short but at least 80% full.Make sure the machine is running under velocity control and you have an appropriate Delta P. Now increase the set injection velocity in reasonable (safe) increments until the machine is set to thefastest injection velocity allowable. As you increase the velocity, you may have to adjust the position transfer to ensure you are making short shots, and double check that you are still under velocitycontrol with an appropriate Delta P. Once at the fastest allowable velocity, adjust the positiontransfer to make a 99% full part.Once you are making 99% full parts under velocity control, you can start taking data. Note the actual “screw start position”—don’t go by the set shot size and decompression or suck back, if any. Then note the cut off or stroke transfer position and the fill time (to within 0.01 sec). Without changinganything but injection velocity, reduce the set velocity from as fast as the machine can go to nearly as slow as the machine can go. Make sure you are transferring on position and not time; that is,make sure the overall injection timer has enough time on it to allow you to reach the transferposition. The parts may change in size but do not readjust shot size or position transfer during the test.Set up the data table to look like Table 1 and if you want, graph the data as shown in Fig. 1. Tocalculate the actual velocity, subtract the cut off or transfer position from the actual screw startposition and divide by the fill time. Because this method includes the initial inertia to get the screw up to speed, expect the fastest actual velocities to be only 85% to 95% of the set velocities.Shot Set Velocitymm/sec.Fill Time sec.Actual Velocitymm/sec.% of Set Velocity1 2 3 4 5 6 7 8 9101112Note: At high velocities actual being a bit slower then set is to be expected because of inertia. If the data shows actual velocities hitting a maximum and levelling out this test has failed.2.5.Switchover Response from First to Second StageSwitchover response is the phase of the cycle is the critical stage where the first stage of filling the part to 90+% full ends and the second stage (pack and hold) begins.Try, check two methods, 100 parts each method:5.1.1. Rapid TransferRapid transfer from first to second stage, very little plastic has to be delivered to the cavity, the rapid drop of plastic pressure in the nozzle does not over pack or accentuate the rapid development of cavity pressure. If this method does produce consistent parts the performance of the screw’s check ring is suspect.5.1.2.Slow, Velocity Controlled PackRequires a three-stage moulding process, the filling or first stage gets the part 90+% full. Second Stage, packing is velocity controlled to slow the cavity-pressure development and ends when the cavity pressure reaches a level previously found to produce an acceptable part. Once this cavity pressure is achieved, the machine transfers to holding (third stage) to keep all the plastic in the cavity and hold the part to specified dimensions. This method will compensate for viscosityvariations and any leakage of the check ring.Data Recording:。