1. Prior confirmation and preparation
(1) confirm whether the material drying, mold temperature and heating cylinder temperature are set correctly and reach the machinable state.
(2) check the action and distance setting of opening and closing die and ejection.
(3) theinjection pressure (P1) is set at 60% of the maximum value.
(4) keep the pressure (PH) at 30% of the maximum value.
(5) the injection speed (V1) is set at 40% of the maximum value.
(6) the screw speed (VS) is set at about 60 rpm.
(7) the back pressure (PB) is set at about 10kg / cm2.
(8) the looseness is set at 3mm.
(9) the pressure maintaining switch position is set at 30% of the screw diameter. For example, for a screw with a diameter of 100 mm, 30 mm is set.
(10) the metering stroke is set slightly shorter than the calculated value.
(11) the total injection time is slightly shorter and the cooling time is slightly longer.
2. Manual operation parameter correction
(1) lock the mold (confirm the rise of high pressure), and the injection seat moves forward.
(2) manual injection until the screw completely stops, and pay attention to the stop position.
(3) screw back feeding.
(4) after cooling, open the mold and take out the products.
(5) repeat the steps from (1) to (4), the screw will stop at the position of 10% ~ 20% of the screw diameter, and there is no short shot, burr, whiteness, or cracking.
3. Correction of semi automatic operation parameters
1. The correction of metering stroke [measurement end point] increases the injection pressure to 99% and temporarily represses the pressure to 0, and transfers the end point S0 to short shoot, then moves back to the burr, with the middle point as the selection.
(2) the correction of exit speed returns pH to the original level, adjusts the exit speed up and down, finds out the individual speed of short shot and burr, and takes its middle point as the appropriate speed [this stage can also enter the parameter setting of multi-stage speed corresponding to appearance problems].
(3) correction of holding pressure adjust the holding pressure up and down, find out the individual pressure of surface depression and burr, and select the middle point as the holding pressure.
(4) when the pressure holding time [or injection time] is modified, the holding time is gradually extended until the weight of the molded product is obviously stable.
(5) the cooling time shall be adjusted gradually and the following conditions shall be confirmed:
a. The molding products will not whiten, crack or deform when they are ejected, clamped, trimmed or packed.
b. The mold temperature can be balanced and stable.
A simple algorithm for calculating the cooling time of products with meat thickness more than 4mm:
① Theoretical cooling time = s (1 + 2S) The mold temperature is below 60 ℃.
② Theoretical cooling time = 1.3s (1 + 2S) The mold is more than 60 degrees [S is the maximum meat thickness of the molding product].
(6) modification of plasticizing parameters
① Confirm whether the back pressure needs to be adjusted;
② Adjust the screw speed to make the metering time slightly shorter than the cooling time;
③ To confirm whether the metering time is stable, try to adjust the temperature gradient of the heating coil.
④ Confirm whether there is material dripping in the nozzle, whether there is pigtail or die sticking in the main channel, and whether there is gas mark in the finished product. Adjust the temperature of the nozzle or the loosening distance properly.
(7) flexible application of multi-stage pressure maintaining and multi-stage firing rate
① Generally speaking, under the condition of not affecting the appearance, the injection should be carried out at a high speed, but at a lower speed before switching between gates and holding pressure;
② The holding pressure should be decreased gradually to avoid the high residual stress and easy deformation.
