What are the reasons for poor demolding of plastic products, and how do plastic manufacturers eliminate them? 

(1) Defect characteristics: The main manifestation of poor demolding is that the plastic product cannot be easily removed from the mold after plastic manufacturing. 

(2) The causes and elimination methods of defects 

There are many reasons why Plastic Product cannot be easily separated from the mold, mainly related to the mold, plastic molding process. The specific analysis is as follows. 

1) Injection Mold 

(1) If the mold of the plastic factory has insufficient draft angle, it will often make demolding difficult. To this end, the draft angle should be increased without damaging the appearance during design. 

(2) If the accuracy of the movable and fixed mold plates is not high, the mold will be offset or misaligned during molding, resulting in difficult demolding. To this end, the injection supplier should pay attention to the accuracy requirements when processing and installing the movable and fixed mold plates. 

(3) If the surface of the mold is very rough, or damaged and worn, the plastic part will not be easy to separate from the mold, resulting in difficult demolding. To this end, the accuracy of the inner surface of the mold should be maximized, and surface treatment such as polishing and chrome plating can be performed. If the surface is damaged, it should be repaired immediately. 

(4) If the mold of injection molding manufacturer is worn, scratched, or the gap at the insert is too large, the overflow of the melt at this point will cause difficult demolding. To this end, the damaged parts should be repaired or the gap at the insert should be reduced. 

(5) If the mold material is soft and porous, it is also easy to form poor demolding. To this end, the surface should be chrome plated or the mold material should be replaced. 

(6) If the mold has poor exhaust or the core has no air inlet, it will also cause difficult demolding. To this end, the exhaust conditions of the mold should be improved, and an air inlet should be added to the core. 

(7) When using the core to demold, the Plastic Product is in close contact with the core, and the vacuum adsorption state is in effect. The effect of atmospheric pressure makes the core difficult to demold. To this end, it is best to set a bend pin and use the top plate to push the demolding. 

(8) If the new mold is easy to open when empty, but very difficult to open in actual use, it is often caused by insufficient mold rigidity. The mold has undergone deformation under the action of injection pressure, resulting in difficult demolding. To this end, the mold must have sufficient rigidity during design. If the mold rigidity is insufficient, reinforcement measures can be taken. 

(9) If the ejector is not uniform or the top plate does not work properly, it will cause the plastic part to be difficult to demold. To this end, the ejection speed should be controlled within an appropriate range, and it should not be too fast or too slow. 

(10) If the runner is too long or too small, and the strength of the main runner and branch runner connection is insufficient, it is easy to cause poor demolding. To this end, the runner length should be shortened and its cross-sectional area should be increased to increase the strength of the main and branch runner connection. 

(11) If the sliding parts of the ejector are obstructed when opening the mold, and cannot be opened freely, a large force must be applied to open the mold. The main reasons for the difficulty in opening the mold are mechanical processing errors, installation errors, and excessive wear. To this end, the processing, installation, and adjustment of each moving part must be in place, so that it can move freely, so as not to cause difficulty in demolding. 

(12) If the mold is subjected to excessive force and produces permanent deformation, making the mold difficult to open, the only way is to remove the deformed parts for correction. The technical level of this correction is very high, and must be operated by senior technicians. 

(13) If the diameter of the main runner and the diameter of the nozzle hole are not properly matched, it is also easy to cause poor demolding. Generally, the small end diameter of the main runner should be 0.5 to 1mm larger than the diameter of the nozzle hole. 

(14) If the gate balance is poor, the speed at which the melt enters the cavity is different, which will also cause difficulty in demolding. To this end, when determining the gate position, the filling speed of each cavity in the multi-cavity mold can be balanced by adding auxiliary gates and reducing the pressure in the cavity. 

(15) If there is a depression below the parting surface, the mold cavity edge line exceeds the parting line, the gate has no draw hook, etc., it will cause poor demolding to different degrees. To this end, the above problems should be dealt with accordingly. 

2) Injection molding process

(1) If the injection pressure is too high, the melt flow is good, and the melt is easy to enter the gap of the mold cavity, resulting in flash and poor demolding. To this end, the injection pressure should be appropriately reduced.

(2) If the fixed mold temperature is too high, the temperature of the two mold plates is inconsistent, and it is easy to have poor demolding. To this end, the fixed mold temperature should be reduced. 

(3) If the demolding is poor at the parting surface, the mold temperature can be appropriately increased and the cooling time shortened; if the demolding is difficult at the mold cavity, the mold temperature can be appropriately reduced or the cooling time increased. 

(4) If the injection and holding time is too long, it is easy to form excessive filling and poor demolding. To this end, the injection and holding time should be shortened. 

(5) If the melt temperature is too high, the fluidity increases, the melt is easy to enter the parting surface and overflow, resulting in poor demolding. To this end, the melt temperature should be appropriately reduced. 

(6) If the nozzle temperature is too low and the cooling time is too short, it is easy to cause poor demolding. To this end, the nozzle temperature should be appropriately increased and the cooling time extended, or the amount of cooling water should be increased.