1.Prior confirmation and preliminary settings
⑴ Confirm whether the material drying, mold temperature and heating tube temperature are correctly set and reach the processable state.
⑵ Check the action and distance setting of opening and closing mold and ejection.
⑶ The injection pressure (P1) is set at 60% of the maximum value.
⑷ Keep the pressure (PH) set at 30% of the maximum value.
⑸ The injection speed (V1) is set at 40% of the maximum value.
⑹The screw speed (VS) is set at about 60RPM.
⑺Back pressure (PB) is set at about 10kg/cm2.
⑻The loosening distance is set at 3mm.
⑼The holding pressure switch position is set at 30% of the screw diameter. For example, for a φ100mm screw, set it to 30mm.
⑽The metering stroke is set slightly shorter than the calculated value.
⑾The total injection time is slightly shorter and the cooling time is slightly longer.
2.Manual operation parameter modification
⑴ Close the mold (confirm the rise of high pressure) and move the injection seat forward.
⑵Inject manually until the screw stops completely and pay attention to the stop position.
⑶ The screw rotates back to feed the material.
(4) After cooling, open the mold and take out the molded product.
⑸ Repeat steps ⑴~⑷, and the screw will eventually stop at a position of 10%~20% of the screw diameter, and the molded product will have no short shots, burrs, whitening, or cracking.
3.Modification of semi-automatic operation parameters
⑴ Correction of metering stroke [metering end point] Increase the injection pressure to 99%, and temporarily adjust the holding pressure to 0, adjust the metering end point S0 forward until a short shot occurs, and then adjust it backward until burrs occur, with the middle point as the selected position.
(2) Correction of injection speed: Restore the PH to the original level, adjust the injection speed up and down, find out the individual speeds where short shots and burrs occur, and take the middle point as the appropriate speed [at this stage, you can also enter the parameter setting of multi-speed corresponding to appearance problems].
⑶ Correction of holding pressure: Adjust the holding pressure up and down, find out the individual pressure where surface depression and burrs occur, and select the midpoint for holding pressure.
(4) Correction of holding time [or injection time]: Gradually extend the holding time until the weight of the molded product is obviously stable.
⑸Correction of cooling time Gradually reduce the cooling time and confirm that the following conditions can be met:
a. The molded products will not turn white, bulge or deform when being ejected, clamped, trimmed or packaged.
b. The mold temperature can be balanced and stable.
Simple calculation method for cooling time of products with a thickness of more than 4 mm:
① Theoretical cooling time = S (1 + 2S) …. mold temperature below 60 degrees.
②Theoretical cooling time = 1.3S (1+2S)…….Mold is above 60 degrees [S represents the maximum thickness of the molded product].
⑹Correction of plasticizing parameters
① Confirm whether the back pressure needs to be adjusted;
② Adjust the screw speed so that the metering time is slightly shorter than the cooling time;
③ To confirm whether the metering time is stable, try adjusting the temperature gradient of the heating coil.
④ Check whether there is material dripping from the nozzle, whether there is pig tail or sticking in the main channel, whether there are air marks on the finished product, etc., and adjust the nozzle temperature or retraction distance appropriately.
⑺Use of stage holding pressure and multi-stage firing rate
① Generally speaking, injection should be carried out at high speed without affecting the appearance, but it should be carried out at a lower speed before passing through the gate and switching to pressure holding;
② The holding pressure should be gradually reduced to avoid excessive residual stress in the molded product, which may cause the molded product to deform easily.
