Product Details

Plastic injection molds for Automotive bumper is one of the most important exterior parts of an automobile. There are front bumper and rear bumper in an automobile.

ADM Group has rich experience in designing and building both front and rear bumpers. We have been exporting our molds to Europe, America, Asia including South and Southeast Asia,

Welcome you to contact us for any inquiry of auto bumper molds.

1. What’s auto bumper and what’s its feature?

The car bumper is one of the most important exterior parts of a car. It must have sufficient strength and rigidity. It can cushion the car in the event of a collision, protect the car body, pursuing harmony and unity with the car body shape. In order to make bumpers light in weight while remaining its rigidity, currently it is most popular to form the bumpers by plastic injection molds.

The front bumper of the car is shaped like a saddle. Generally, the material was PP+EPDM-T20 with shrinkage rate at 0.95%. PP, short for polypropylene, is the main material of the auto bumper, while the EPDM rubber can improve the elasticity of the bumper cover, and the T20 refers to the addition of 20% talcum powder to the material which can improve the rigidity of the auto bumper cover.

To design and build molds for auto bumper, it is critical to pay attention to the molds complexity, molds size and to keep plastic flow fill well considering bumper wall thickness is relatively thin.

2. Molds design and structure

3. Parting line surface

Usually for front auto bumper molds, it is important to keep PL in non-cosmetic surface area by using inner parting surface technology, so that there’s no visible PL after bumper assembled on car.

However, this technology is relatively more complicated and structurally more difficult than the external type bumper, and the technical risk is also high. The molds cost and molds price are also higher than the external type bumper, but because of the beautiful appearance, it is widely used for middle and high-end cars.

4. Auto bumper molds steel

Generally, about the front bumper molds making, molding part and the template are integrated, considering molds size and molds safe consistency, we usually suggest to use 1.2738HH Gröditz steel imported from Germany with original steel certification provided to customers.

5. Feeding system of auto bumper molds

For auto bumper molds, it is highly recommended to use integrated-hot-runner-system. Because it is much easier and convenient to assemble or disassemble the feeding system, with less requiring for processing, less risk of plastic leakage, higher accuracy in assembly, lower maintenance cost.

6. Cooling system design of bumper molds

Considering the bumper molds size and structures, cooling system has a great influence on the molding cycle time and product quality. The cooling system takes the form of “straight-flow cooling water pipe + inclined cooling water pipe + cooling water well”.

The design points of the cooling water channel of this molds are as follows:
● The more complicated molds structure is, and the more concentrated on cooling should be. However, the cooling water channel must be at least 8mm away from the push rod for molds safety concern, preferring straight top and inclined top hole.

● Better to keep 50~60mm distance between cooling channels, and keep channels 20~25mm away from the cavity surface.

● Prefer cooling channels to be straight hole to slant hole. Change to straight hole if a inclined hole less than 3 degrees.

● Keep the length of all cooling channels to be similar so that the molds temperature is roughly even.

7. Ejecting system

Auto bumpers are big and thin-walled parts, it’s important to keep knock out smooth and safe in balance. In the middle of the molds, it adopts a straight pushing rod and ejecting pin with diameter of 12 mm. Because the touching area for ejecting is small and difficult to return, it is easy to cause the ejecting pins to collide the cavity surface.

Therefore, the inner part of the auto bumper should be designed as straight as possible to reduce using of ejecting pins.

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