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The surface baking printing and light and shadow of the mold

• 2025-08-04

The surface baking printing and light and shadow of the mold

Surface baking and printing：

    Phenomenon: During the production process of the product, whitening and baking marks often appear on the surface.

    Analysis: The surface temperature setting of the mold is unreasonable. The cooling time of the mold surface texture is too short, causing the product to shrink. The pressure setting in the fourth section is too low.

（1）Characteristics of injection molding machines

    Grade: Haitian, Clamping force :120t, Plasticizing capacity :152g

（2） Mold characteristics

    Mold ejection number :1×2, glue injection method: point gate, ejection method: Ejection by ejector pin, mold temperature: 76 ° C (constant temperature machine)

（3）Product characteristics

    Material :ABS, Color: Black. Product weight (single piece) : 42.6g, sprue weight :7.3g

（4）Analysis of causes of defects

    1. The main runner of the mold is thin and long. The method of feeding the molten material is point-in feeding. Due to the slow speed and pressure, the molten material flows near the feeding port

The force is large, causing an increase in product stress and obvious baking marks.

    2. The mold temperature is set too low for the front mold and too high for the rear mold.

    3. The pressure at the end and the cycle time are unreasonable.

（5）Countermeasures

    1. Utilize multi-level injection and position switching.

    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 proceed to the second section Just fill the area near the rubber inlet at a slow speed and in a very small position. In the third stage, fill 90% of the mold control with a medium pressure quickly to prevent the high-temperature molten rubber from cooling. In the fourth stage, fill the mold cavity slowly to completely expel the air inside the cavity. Finally, switch to the pressure-holding switch position.

    3. By setting the mold temperature at 85 °C for the front mold and 73°C for the rear mold, the cooling time has been increased from the original 4 seconds to 47 seconds.

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

Injection molding process table

	/	73	Holding pressure	Pressure-holding position	87	90	92	98	Injection pressure
	/	3	Holding pressure time	12	15	21	63	73	Injection pressure position
Residual amount of injection glue		/	2.0	/	55	78	20	65	Injection velocity
7.8		/	/	/	15	21	63	73	Velocity of fire position

Light and shadow：

    Phenomenon: During the production process of the shell, light and shadow are prone to occur at positions with structural differences and at a distance from the glue inlet.

Analysis: The thickness of the product meat is inconsistent. The differences in product cooling shrinkage and internal stress decomposition: The injection pressure and holding pressure are relatively small.

（1）Characteristics of injection molding machines

Grade: Haitian (Jiangsu), clamping force :160t, plasticizing capacity: 200g

（2）Mold characteristics

Mold ejection number :1x2, glue injection method: point gate, ejection method: Ejection by ejector pin, mold temperature: Mold cavity 85℃ (constant temperature machine), rack row position 70℃ (constant temperature machine)

（3） Product characteristics

Material: ABS PA757 37784, Color: Black (fine texture surface), Product weight (single piece) : 27.1g, spout weight 7.6g

（4）Analysis of causes of defects

The glue injection method is single-point injection. After the glue flow enters the mold cavity, it requires sufficient time to fill to saturation. Within a unit of time, if

If the pressure is too low, the product will cool and shrink unevenly. Uneven heating of the mold itself and insufficient temperature can also cause the product to cool and shrink unevenly

Consistent

（5） Countermeasures

1. Utilize multi-level injection and position switching.

2. In the first section, fill the flow channel to the glue inlet at a relatively fast speed and find the corresponding switching position. Use medium speed in the second section Just fill a very small area near the glue inlet. The third section is filled with 90% of the mold cavity at medium speed to cool the molten rubber material that is not yet warm Inconsistency creates light and shadow. In the fourth section, fill the mold cavity slowly to completely expel the air inside the cavity, avoiding trapped air and charring, etc Adverse phenomena. Finally, switch to the pressure-holding switching. position.

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

Injection molding process table

/	100/	120	Holding pressure	Pressure-holding position	100	100	110	125	Injection pressure
/	1.3	1.5	Holding pressure time	"End	/	15	45	70	Injection velocity
Residual amount of injection glue	/	/	/	/	12	25	35	45	Velocity of fire position
7.8	/	/	/	/	5	/	/	/	Injection time