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Solutions to the problems of hard rubber indentation, row position demolding and inconsistent product dimensions in molds

• 2025-08-29

Solutions to the problems of hard rubber indentation, row position demolding and inconsistent product dimensions in molds

Hard rubber indentation of the mold

Phenomenon: Hard rubber surface indentations appeared on the volume keys of communication products during the production process.

Analysis: The product mold is designed for the secondary injection molding of hard and soft rubber (that is, one set of molds first injects the hard rubber product, and then inlays the hard rubber into the soft rubber mold to inject the soft rubber). During the injection molding of the soft rubber, due to the small space at the insert position, the surface of the hard rubber product is indentations.

（1）Characteristics of injection molding machines

Grade :HT-50T, clamping force :50t, plasticizing capacity: 60g

(2) Mold characteristics

Mold ejection number :1x2, glue entry method: lap water outlet, ejection method: Ejection by ejection pin, mold temperature: 60℃ (constant temperature machine)

(3) Product characteristics

Material :TPU85 degrees, Color: black, Product weight (single piece) : 1.5g, nozzle weight: 1.2g

(4) Analysis of causes of defects

1. The product mold is designed for secondary injection molding of hard and soft rubber. Due to the product structure, the rear die of the soft rubber mold is sealed with inserts

Due to the small space at the insert position during the injection molding of soft rubber, indentations occur on the surface of hard rubber products.

2. The thickness of the 1×4 hard rubber product mold varies due to the loosening and fading of the inserts during injection

(5) Countermeasures

Clean the surface of the soft rubber mold and keep the surface of the hard rubber free of dirt.

2. Raise and level the tail of the hard rubber mold part to prevent it from receding during injection molding.

Automobile parts mold Manufacturer in China (jfmoulds.com)

Demolding of the row position of the mold

Phenomenon: During the production process of the knife pick-up and dispensing table for electrical products, there is a phenomenon of mold dragging or burning in the line position.

Analysis: The product mold is designed as a 1×2 side large row position structure, and during demolding, it performs row drag mold/burn.

Characteristics of injection molding machines

Grade :HT-800T, clamping force: 80t, plasticizing capacity: 130g

(2) Mold characteristics

Mold ejection number :1×2. Glue injection method: Water dispensing port ejection method: Ejection by ejection pin. Mold temperature: 85℃ (constant temperature machine)

(3) Product characteristics

Material: ABS PA757, Color: White, Product weight (single piece) :7.5g, Spout weight: 8.5g

(4) Analysis of causes of defects

The product mold is designed as a 1×2 side large row position structure. Due to the design, the two small row positions on the side holes are embedded into the large row position slide grooves

It is not fixed. When demolding, the small row position is prone to sliding, causing the row position to drag the mold or burn.

(5) Countermeasures

1. The FI mode of the row position cooperates smoothly with the sliding.

2. Fix the small row position of the hole into the large row position slide groove with M5 countersunk screws.

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

The product sizes of the molds vary

Phenomenon: During the production process of the outer knife and inner box of electrical products, there is a phenomenon of inconsistent product sizes.

Analysis: Due to the shrinkage of the raw materials of the product, it is easy to cause an impact on the product size.

Characteristics of injection molding machines

Grade :HT8OT, clamping force: 80, plasticizing capacity: 130g

(2) Mold characteristics

Mold ejection number :1×2, glue injection method: point gate, ejection method: Ejection by ejector pin, mold temperature :80℃ (constant temperature machine)

(3) Product characteristics

Material: POM M270, Color: Grey, Product weight (single piece) : 2.9g, Spout weight: 3.6g

(4) Analysis of causes of defects

The mold design adopts a one-point injection of glue. Due to the influence of the shrinkage of the raw materials after the product and the unreasonable control of the production process, the product size is reduced Not exactly the same inch

(5) Countermeasures

Adjust the stability of the raw material molten material return and increase the residual amount.

Increase the temperature of the first section of the barrel.

Position switching is adopted to adjust the production process.

The injection molding process ensures that the production cycle is basically stable and consistent.