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The trapped air adjustment of the mold is difficult, and the deformation and the bottom row position pulling mold treatment method of the face shell

• 2025-08-12

The trapped air adjustment of the mold is difficult, and the deformation and the bottom row position pulling mold treatment method of the face shell

It is difficult to adjust the trapped air in the mold

Phenomenon: During the production of the product, there is a deep cavity where both the front and back sides are trapped with air, resulting in fusion marks.

Analysis: The technician believes it is caused by cold material. No matter how the process is adjusted, it cannot be completely eliminated.

Characteristics of injection molding machines

Grade: Haitian, Clamping force: 160t, Plasticizing capacity: 200g

(2) Mold characteristics

Mold ejection number: 1×2, glue injection method: direct water inlet, ejection method: Ejection by ejector pin, mold temperature: 75°C for front mold, 55°C for rear mold (water temperature machine)

(3) Product characteristics

Material: ABS PA757 37784, Color: black, Product weight (single piece) : 40.3g, spout weight: 8.65g

(4) Analysis of causes of defects

1. There is a gap in the product structure itself, and the glue position here is relatively thin.

2. The trapped air at this part of the mold cannot be expelled.

3. The temperature and process were not set properly.

4. The materials used in the product are fireproof materials.

(5) Countermeasures

1. By applying multi-stage injection and position switching, the front mold is equipped with a pin arrangement.

2. In the first section, fill the flow channel to the glue inlet at a relatively fast speed and find the corresponding switching position. Then, in the second section, fill the area near the glue inlet at a slow speed and a very small position. In the third section, slowly charge through this part of the product that is prone to trapping air. In the fourth section, fill the mold cavity slowly to completely expel the air inside the cavity, avoiding trapped air and charring and other adverse phenomena. Finally, switch to the pressure-holding switching position.

Auto Mould_Taizhou Jiefeng Mould Co.,Ltd. (jfmoulds.com)

Deformation of the mold

Phenomenon: The transparent lenses bend and deform during the production process, and the deformation is severe after strengthening.

Analysis: The thickness of the product's adhesive positions is inconsistent. The adhesive position of the product is too thin. The pressure-holding time is too short.

Characteristics of injection molding machines

Grade: DEMAG, clamping force: 50t, plasticizing capacity: 80g

(2) Mold characteristics

Mold ejection number: 1×2, injection method: fan-shaped gate, ejection method: Ejection by ejector pin, mold temperature: 90°C (constant temperature machine)

(3) Product characteristics

Material: PMMA, Color: Transparent, Product weight (single piece) : 1.12g, nozzle weight: 5.28g

(4) Analysis of causes of defects

Due to the thin and hollow glue position of the product, the product deforms in the rear mold, making it difficult for the mold constant temperature machine to control.

(5) Countermeasures

Two mold temperature control units are used. The temperature difference between the front and rear molds is set at 110°C for the front mold and 70°C for the rear mold

2. In the first section, fill the runner opening to the glue inlet at a relatively fast speed and find the corresponding switching position. Then, in the second section, fill the area near the glue inlet at a slow speed and in a very small position.

3. Then, fill it rapidly to 95%, first lowering it to the first holding pressure, then increasing it to the second holding pressure, and increase the holding pressure time by 0.5 seconds to prevent product deformation.

Commodity Mould_Taizhou Jiefeng Mould Co.,Ltd. (jfmoulds.com)

Pull the die at the bottom row position of the mold face shell

Reason: The mold temperature is relatively low. The injection pressure and injection speed are insufficient.

Characteristics of injection molding machines

Grade: HT120T, Clamping force: 120t, plasticizing capacity: 152g

(2) Mold characteristics

Mold ejection number: 1×2, glue feeding method: large water inlet glue feeding, ejection method: Ejection by ejector pins and inclined ejectors, mold temperature: 90°C (constant temperature machine)

(3) Product characteristics

Material: ABS+PC HI-1001BN color: black product weight (single piece) : 6.22g, spout weight: 14.38g

(4) Analysis of causes of defects

1. The mold temperature is relatively low.

2. Due to a punch hole at the bottom of the product, when the material flows through this position, the speed is too slow, resulting in excessive local pressure on the product. It causes the formwork to be pulled on both sides of the perforation position.

(5) Countermeasures

1. Utilize multi-level injection and position switching.

2. Appropriately increase the mold temperature.

3. Increase the injection pressure and speed, especially in the third stage.