Analysis of quality defects and causes of injection bottle caps

1, flash

Reason analysis: improper process adjustment (excessive injection volume, excessive screw temperature, high temperature of nozzle nozzle, high mold temperature, excessive injection pressure, excessive pressure, too small clamping pressure), mold forming Partial fit clearance is too large

Treatment method: reduce the injection amount, reduce the screw temperature, reduce the hot runner nozzle temperature, reduce the mold temperature, reduce the injection pressure, reduce the holding pressure, increase the clamping force, and clean and replace the corresponding mold parts.

According to the flashing parts, it can be divided into the following specific situations:

1.1 anti-theft ring axial flash:

Cause: The mating surface between the push ring and the thread core is worn or the clearance is too large.

Countermeasure: cleaning the mold and replacing worn parts

1.2 anti-theft ring radial flash.

Cause: The mating surface between the half module and the push ring is worn or the clearance is too large.

Countermeasure: cleaning the mold and replacing worn parts

1.3 anti-theft ring Huff block clamping line flash

Cause: The mating surface between the half module and the half module is worn or the clearance is too large, and the wedge block is worn.

Countermeasure: clean the mold and replace the half module wedge block

1.4 cover body radial flash

Cause: The mating surface between the half module and the cavity is worn or the clearance is too large.

Countermeasure: cleaning the mold and replacing worn parts

1.5 seal ring flash

Cause: Wear surface or excessive clearance between the threaded core and the push tube: Clean the mold, replace the core or push the tube

1.6 cap top edge flash

Cause: Cavity damage or cavity insert damage countermeasure: Replace the cavity or cavity insert

2, lack of material

Reason analysis: improper process adjustment (injection is too low, screw temperature is too low, hot runner nozzle temperature is too low, mold temperature is too low, injection speed is too large or too small, injection pressure is too small, pressure is too small, back The pressure is too small), the mold vent is blocked, the hot runner nozzle is blocked, the condensed water or the mold leaks, the hopper is not smooth, and the raw material flow is poor.

Treatment method: adjust the corresponding process parameters, clean the mold exhaust groove, clean the nozzle, check whether there is condensed water or water leakage on the surface of the mold, check whether the pump has any influence on the blanking, and check the performance of the raw materials (such as whether to replace the batch number).

The common shortages are as follows:

(1) The edge of the missing material is irregular

Cause: The mold is leaking or condensed too much

Countermeasure: Check if the dehumidifier is working properly and check the cavity and the core for water leakage.

(2) The edge of the material is smoother

Cause: Improper process parameters or blocked hot runner nozzle

Countermeasures: Adjust parameters and clean the nozzle.

3, note piercing

Analysis of the cause: small impurities are stuck in the gate position, resulting in miscellaneous molding

The quality is embedded to form a depression or perforation at the point of the spot.

Treatment method: clean the nozzle, control the cleaning of raw materials and mixing.

4, seal ring crush

Analysis of the cause: The main cause of the seal ring crush is that the push tube fixing plate and the support plate are opened and closed before the mold is opened. Since the opening distance is larger than the height of the seal ring, the seal ring is easily injured. The reason for this phenomenon is that the frictional force of the parting surface when the mold is opened is greater than the back pressure of the ejector plate.

Treatment method: increase the back pressure of the thimble, clean and maintain the mold, and ensure the normal weight of the bottle cap, so as to reduce the friction of the mold parting surface.

5, note point drawing

Analysis of the cause: gate wear, hot runner nozzle temperature is high, back pressure is too large

Treatment method: replace the worn gate, reduce the temperature, and reduce the back pressure appropriately.

6, note point bulge

Cause analysis: cavity gate wear, nozzle tip passivation or fracture

Treatment: Replace the cavity insert or nozzle.

7, black spots

Reason analysis: There are foreign objects, oil traces, etc. in the mold cavity, and there are “dead spots” in the hot runner nozzle and the head switch, which cause the plastic to degrade and carbonize to form impurities.

Treatment method: clean the mold, replace the worn nozzle, the throttle body, and the valve core.

8, note crack

Analysis of the cause: the cold material caused by excessive cavity overflow and the newly injected raw materials are not

Compatible, forming cracks. Treatment method: reduce the nozzle temperature, increase the distance after the screw is stored, and replace the wear cavity insert.

9, leaking

Reason analysis: 1. The seal ring is too small 2. Seal ring damage

Treatment method: 1. Adjust the cooling time and cooling temperature to ensure the stable size. 2. Replace the thread core or push tube.

10, imprint

Analysis of the cause: damaged or scratched mold forming parts

Treatment method: Replace the damaged parts.

11, adhesion

Analysis of the cause: the wear of the semi-module anti-theft ring is worn, and the core part wears with the semi-module

Treatment: Replace the worn half module or core.

12, color difference

Analysis of the reason: the color masterbatch and the raw materials are not uniformly mixed, and the raw material supply is broken, resulting in separation of the color masterbatch and the raw material in the lower feed port.

Treatment method: ensure the mixing time and effect of raw materials, and ensure the continuous supply of raw materials to the injection molding machine.