not filled
1. Characteristics of defects in injection molded parts
The injection molding process is incomplete because the cavity is not filled with plastic or some details are missing from the injection molding process.
2. Possible causes of problems
(1).Insufficient injection speed.
(2).Plastic shortage.
(3). The screw does not leave any screw gasket at the end of the stroke.
(4).Running time changes.
(5). The temperature of the injection cylinder is too low.
(6).Insufficient injection pressure.
(7). The nozzle part is sealed.
(8). The heater outside the nozzle or the injection cylinder cannot operate.
(9). Injection time is too short.
(10). The plastic is pasted on the throat wall of the hopper.
(11). The capacity of the injection molding machine is too small (ie injection weight or plasticizing capacity).
(12). The mold temperature is too low. (13). The anti-rust oil of the mold has not been cleaned.
(14). The stop ring is damaged, and the molten material has backflow.
3. Remedy
(1). Increase the injection speed.
(2). Check the amount of plastic in the hopper.
(3). Check whether the injection stroke is set correctly, and change it if necessary.
(4). Check whether the check valve is worn or cracked.
(5). Check whether the operation is stable.
(6). Increase the melt temperature.
(7). Increase back pressure.
(8). Increase the injection speed.
(9). Check whether there is any foreign matter or unplasticized plastic in the nozzle hole.
(10). Check all heater outer layers to verify correct energy output with an ammeter.
(11). Increase the screw forward time.
(12). Increase the cooling capacity of the throat area of the hopper, or reduce the temperature of the rear area of the injection cylinder.
(13). Use a larger injection molding machine.
(14). Properly raise the mold temperature.
(15). Clean up the anti-rust agent in the mold.
(16). Check or replace the stop ring.
Size difference of injection molded parts
1. Characteristics of defects in injection molded parts
The change in weight and size during the injection molding process exceeds the production capacity of the mold, injection molding machine, and plastic combination.
2. Possible causes of problems
(1). The plastic input into the injection cylinder is uneven.
(2). The temperature or fluctuation range of the injection cylinder is too large.
(3). The capacity of the injection molding machine is too small.
(4). The injection pressure is not stable.
(5). The screw reset is unstable.
(6). Changes in operating time and inconsistencies in solution viscosity.
(7). The injection speed (flow control) is unstable.
(8). Plastic varieties that are not suitable for molds are used.
(9). Consider the influence of mold temperature, injection pressure, speed, time and holding pressure on the product.
3. Remedy
(1). Check whether there is sufficient cooling water flowing through the hopper throat to maintain the correct temperature.
(2). Check for inferior or loose thermocouples.
(3). Check that the thermocouple used with the temperature controller is of the correct type.
(4). Check the injection volume and plasticizing capacity of the injection molding machine, and then compare with the actual injection volume and hourly injection
Plastic usage for comparison.
(5). Check whether there is a stable molten hot material for each operation.
(6). Check whether the backflow prevention valve is leaking, and replace it if necessary.
(7). Check whether the feed setting is wrong.
(8). Ensure that the screw is stable in the return position of each operation, that is, the change is not more than 0.4mm.
(9). Check the inconsistency of operation time.
(10). Use back pressure.
(11). Check whether the hydraulic system is operating normally and whether the oil temperature is too high or too low (25-60oC).
(12). Select the type of plastic suitable for the mold (mainly considering shrinkage and mechanical strength).
(13). Readjust the entire production process
shrink marks
1. Characteristics of defects in injection molded parts
Usually associated with surface marks (see the "Voids" section) and are formed when the plastic shrinks away from the mold surface.
2. Possible causes of problems
(1). The melting temperature is either too high or too low.
(2). Insufficient plastic in the mold cavity.
(3). During the cooling stage, the surface in contact with the plastic is overheated.
(4). The runner is unreasonable and the cross section of the gate is too small.
(5). Whether the mold temperature is compatible with the plastic properties.
(6). The product structure is unreasonable (the reinforcement is too high, too thick, and the thickness is obviously not good enough)
one).
(7). The cooling effect is not good, and the product continues to shrink after demoulding.
3. Remedy
(1). Adjust the temperature of the injection cylinder.
(2). Adjust the screw speed to obtain the correct screw surface speed.
(3). Increase the injection volume.
(4). Make sure to use the correct gasket; increase the screw forward time; increase injection molding
Pressure; increase injection speed.
(5). Check whether the stop valve is installed correctly, because abnormal operation will cause pressure
power loss.
(6). Reduce the mold surface temperature.
(7). Correct the flow path to avoid excessive pressure loss; according to actual needs, properly expand Large section size.
(8). Properly control the mold temperature according to the characteristics of the plastic used and the product structure.
(9). Improve the product structure if allowed.
(10). Try to let the product have enough cooling.
Stain marks and injection marks
1. Characteristics of defects in injection molded parts
Usually associated with the gate area: its surface is dull and sometimes streaked.
2. Possible causes of problems
(1). The melting temperature is too high.
(2). The mold filling speed is too fast.
(3). The temperature is too high.
(4). Related to plastic properties.
(5). There is cold material at the mouth of the nozzle.
3. Remedy
(1). Reduce the temperature of the first two areas of the injection cylinder.
(2). Reduce the injection speed.
(3). Reduce the injection pressure.
(4). Lower the mold temperature.
(5). Most of the parts produced by PE will have shot marks, which can be used according to the requirements of use
Modify the inlet position.
(6). Avoid cold material as much as possible (control the temperature of the nozzle).
Sprue sticking
1. Characteristics of defects in injection molded parts The nozzle is held by the nozzle sleeve.
2. Possible causes of problems
(1). The sprue sleeve and the nozzle are not aligned.
(2). The plastic in the sprue sleeve is too stuffed.
(3). The nozzle temperature is too low.
(4). The plastic is not completely solidified in the nozzle, especially the nozzle with a larger diameter.
(5). The arc surface of the sprue sleeve and the arc surface of the nozzle are improperly matched, and there is a similar appearance.
Runner of "Winter Mushroom".
(6). The runner is not enough to pull out the slope.
3. Remedy
(1). Align the nozzle and nozzle sleeve again.
(2). Reduce the injection pressure.
(3). Reduce the screw forward time.
(4). Increase the nozzle temperature or use an independent temperature controller to heat the nozzle.
(5). Increase the cooling time, but a better way is to use a nozzle with a smaller nozzle
The sleeve replaces the original nozzle sleeve.
(6). Correct the matching surface between the nozzle sleeve and the nozzle.
(7). Appropriately expand the pull-out slope of the runner.
hole
1. Characteristics of defects in injection molded parts
Can be easily seen in "air traps" in transparent injection molded parts but can also occur in opaque plastics.
This is thickness related and is often caused by shrinkage of the plastic away from the center of the injection molded part.
2. Possible causes of problems
(1). The mold is not fully filled.
(2). Abnormal operation of the stop valve.
(3). The plastic is not completely dry.
(4). Pre-molding or injection speed is too fast.
(5). Some special materials should be produced with special equipment.
3. Remedy
(1). Increase the injection volume.
(2). Increase the injection pressure.
(3). Increase the screw forward time.
(4). Lower the melting temperature.
(5). Reduce or increase the injection speed. (For example, for non-crystalline plastics, add +45% speed).
(6). Check whether the check valve is cracked or not working.
(7). The drying conditions should be improved according to the characteristics of the plastic, so that the plastic can be completely dried.
(8). Properly reduce the screw speed and increase the back pressure, or reduce the injection speed.
Injection molded parts bend
1. Characteristics of defects in injection molded parts
The injection molded part shape is similar to the cavity but is a distorted version of the cavity shape.
2. Possible causes of problems
(1). Bending is due to excessive internal stress in the injection molded part.
(2). Mold filling speed is slow.
(3). Insufficient plastic in the mold cavity.
(4). Plastic temperature is too low or inconsistent.
(5). The injection molded part is too hot when it is ejected.
(6). Insufficient cooling or inconsistency in the temperature of the moving and fixed molds.
(7). The structure of the injection molded parts is unreasonable (such as the reinforcing ribs are concentrated on one side, but the distance is far ).
3. Remedy
(1). Reduce the injection pressure.
(2). Reduce the screw forward time.
(3). Increase cycle time (especially cooling time). from within the mold (especially Thick injection molded parts) Immediately after being ejected, immerse in warm water (38oC) to make the injection molding The pieces cool slowly.
(4). Increase the injection speed.
(5). Increase the plastic temperature.
(6). Use cooling equipment.
(7). Appropriately increase the cooling time or improve the cooling conditions, as far as possible to ensure dynamic and fixed The mold temperature of the mold is consistent.
(8). According to the actual situation in the permitted situation.
Post time: May-10-2023