[Industry knowledge sharing] Several common quality defects in bottle blowing process products(Part 1)

Introduction: Bottle blowing is one of the main plastic containers in cosmetic packaging materials. Its molding methods are also diverse, including injection blowing, injection stretch blowing, extrusion blowing, etc. Commonly used blowing materials include HDPE, LLDPE, LDPE, PP, and EVA. , PETG, PETP, etc., bottle blowing products are widely used in skin care and cleaning products. This article follows Chamsmetic to analyze several common quality defects in bottle blowing process products for the reference of Chamsmetic€™s customers and friends:

 

1. The bottom is not fully formed (concave feet)

 

Symptom:

 

The bottom contour of the petals is not ideal, especially the bottom corners are sunken. Although the incomplete bottom molding has little impact on filling, it does affect the stability of the bottle.

 

Factor:

 

1) Caused by insufficient high-pressure air.

 

2) The temperature in the area where the bottom corner is located is not enough.

 

3) The high-pressure blowing time is too short (the pre-blowing time is too long).

 

4) The pre-air intake is too late.

 

5) The vent hole of the bottom mold is blocked.

 

Solution:

 

1) Check whether the high-pressure intake air reaches 28BAR or above.

 

2) Check whether the high-pressure filter on the side of the mold is smooth.

 

3) Check the working condition of each valve to ensure accurate positioning of the stretch during pre-blowing and high-pressure molding.

 

4) Check the pre-blow and high-pressure blow control components to ensure correct setting values and smooth internal flow.

 

5) Ensure that the pre-blowing does not take in air too late and the time cannot be too long. Otherwise, the high-pressure blowing time is too short and the effective cooling time of the bottles in the mold is not enough.

 

6) Make sure the exhaust hole in the bottom mold is clear.

 

7) Increase the heating percentage of the area where the bottom corner is located or increase the number of lamps to increase the temperature of the area.

 

8) According to the actual condition of the bottle (bottle partition weight, thickness). Reduce the temperature of the thinner areas so that the material in the bottom corners is distributed to these areas.

 

PLA bottles-Chamsmetic

 

2. Bottle mouth expansion (thread expansion)

 

Symptom:

 

The thread area expands, which starts from the bottle mouth and is transmitted to the anti-air groove, which is more serious when the weather is hot. Due to the high temperature, it will occur during bottle blowing, and you can hear the popping sound of high-pressure air leaking.

 

Factor:

 

1) The temperature of the furnace cooling water is too high.

 

2) The flow of furnace cooling water is insufficient.

 

3) The position of the furnace cooling plate is incorrect.

 

4) The stove is poorly ventilated.

 

5) The height of the stove lamp frame is not adjusted well.

 

6) The temperature in zone one is too high.

 

Solution:

 

1) Check the temperature and flow rate of the furnace cooling water.

 

2) Adjust the position of the cooling plate so that it can protect the threaded area of the bottle mouth. (Make the cooling plate 1.5mm away from the front and rear of the bottle preform and 2mm above the plane of the bottle preform support ring.

 

3) The furnace blowing and exhausting can be increased to lower the ambient temperature. Or open the side door of the heating furnace to enhance air convection so that the heating furnace can dissipate heat well.

 

4) Decrease the heating percentage in a lower zone or reduce the number of lamps.

 

5) The cooling plate design is unreasonable.

 

The skin care bottles and jars created by Chamsmetic have avoided the above problems; Chamsmetic has its own factory and bottle blowing production line to effectively ensure the quality of the products.

 

3. Neck curvature (crooked neck)

 

Symptom:

 

Usually the neck is tilted and bent to one side. The convex ring under the thread of the bottle mouth is deformed and is not perpendicular to the center of the bottle body. This bottle seriously affects filling and capping.

 

Factor:

 

1) Caused by mechanical reasons.

 

2) The mold body temperature is too high.

 

3) The mold body flow is not enough.

 

4) The temperature on both sides of the mold body is inconsistent.

 

5) The material on the neck of the bottle is too thick.

 

Solution:

 

1) The convex ring is clamped too tightly in the recess of the mold top plate. The size of the preform must be fixed while it is still hot. It needs to have a gap of 0.25mm.

 

2) Check the mold body flow (insufficient flow causes the temperature to become high) and temperature (cooling water temperature or mold temperature machine temperature). The flow rate on both sides of the mold body is inconsistent, resulting in different temperatures on both sides. If the temperature is inconsistent or too high, when the bottle is shaped after it comes out of the mold, the neck will be crooked due to uneven shrinkage.

 

3) The mouthpiece is misaligned with the mold.

 

4) The material on the neck of the bottle is too thick, which will increase the temperature of the area (increase the heating percentage of the area or increase the number of lamps).

 

4. The bottom line turns blue (hot bottle)

 

Symptom:

 

There are pearlescent stripes along the bottom cut line, and the areas with pearlescent stripes on inferior bottles are thinner than those on good bottles.

 

Factor:

 

1) The pre-blowing pressure is too high.

 

2) Extension is too slow.

 

3) Pre-blow air intake too early.

 

Solution:

 

1) During pre-blowing, the bottle is blown up too quickly (this is often a problem with the pre-blowing solenoid valve, and high-pressure air leaks in during pre-blowing).

 

2) The pre-blow pressure is too high.

 

3) The control pressure of the extension cylinder is insufficient, the solenoid valve is dirty, the sealing ring of the control valve is worn or the coil reel is broken, causing air leakage.

 

4) There is resistance to the extension mechanical movement (the extension cylinder seal is worn or too dirty, the extension guide rail is not installed correctly or the linear bearing is worn).

 

5) The exhaust of the extension cylinder is blocked (the exhaust muffler is blocked or the air path is not smooth).

 

6) Adjust the pre-blowing air intake angle.

 

PLA jars-Chamsmetic

 

5. The bottom is damaged

 

Symptom:

 

There is often a small section of fine cracks where the material accumulation at the bottom is too thick, and they always pass through the pouring point or are close to the pouring point.

 

Factor:

 

1) Mechanical reasons.

 

2) The temperature at the bottom of the preform is not enough (especially for bottles with a flat bottom mold).

 

Solution:

 

1) Check the gap between the stretching rod and the bottom of the mold (the gap is: 2/3 of the bottom thickness of the preform used)

 

2) Check the extension buffer.

 

3) Increase the heating percentage of the bottom area and increase the number of lamp tubes in the area (the temperature at the bottom of the preform is low. When stretching, the stretching rod runs against it toward the bottom, and cracks will form at the bottom. But the bottom temperature cannot If it is too high, the bottom will be convex).

 

Chamsmetic€™s carefully crafted skin care bottles and jars are made of 100% biodegradable materials. Experience the benefits of eco-friendliness, reliability and versatility in your daily skin care routine with skin care packaging from Chamsmetic.

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