Focused on automotive injection mold and molding for over 10 years, YF Mold is capable of manufacturing the best molds for various automobile brands.
Our design team design automotive parts based on clients’ specifications and requirements. Upon completion, we evaluate and test every product design proposal. The analysis process is carried out by design and engineering experts in consultation with the client, which ensures that we deliver precise and high-performing parts. Here shares some experience we design plastic injection mold for Car Door Panel Audio Horn Cover.
Actually the mold design is not difficult when you make the key points clear. This time we will take the rear panel as a case, and provide some ideas how to design this type of mold.

The main jobs as following:

Part Analysis
Its automotive plastic molded part-real panel parts with horn cover as the picture shown,1*1 cavity and resin PP+ EPDM; the shrinkage is 1.012; part dimension: 811.5 X 716.2 X 123.2 mm; Surface: grain, no gating mark, welding lines, sink marks etc.

Product structure design (especially for lifter design)
There are 12 hook snaps on the part and have to make lifter for demoulding, see the picture.

There is hook snap long to 611.7mm on the side of the part and need to design 2 lifters with 331mm and 316mm to do demoulding, which is most challenging for this mold, since the hook almost covers one side of the product, and the packing force is very large.

There are two improvements have been made when lifter ejection without product pulling injury:
Improvement one: 6 through holes are designed under the button position to pull the product away from the lifter.

Improvement two: A push block is designed at the bottom of hook to cover the ribs.
The push block is positioned in the fixed mold and ejection at the same time with the lifter.
The purpose of this design is to keep the push block in control of the product and prevent the product from following the lifter. This is so important. It’s so well designed!

The 6 through holes on the push block are all designed as an elastic-insert pin structure. When the push block ejection, the insert pin moves backward under the action of spring force and breaks away from the product. Design reason: If the 6 through holes are always wrapped in the push block, it is difficult to take out the product. The design considerations are comprehensive.

The lifter, push block, and lifter tube position are designed independently of each other. The depth of push block tube position is longer, which is convenient for grinding and matching.

Push block and water cooling design
1. The push block is connected with water cooling and is transferred to ejection bottom plate.

2. Lifter water transport joint fittings

3. The lifter water pipe need to avoid enough space, just simulate the distance of the lifter.

3. Mold base size
The mold dimensions: 1200 X 1100 X 1006 mm, the total weight is about 10 tons, it’s medium and large injection mold.

4. Gating system design
The gating system is 2-point open hot nozzle to cold runner, 2 side gates from invisible surface of the middle of the door plate.
Disadvantages: 2 points open hot nozzle, it’s hard to control the parting line.

5. Ejection design
01. The ejection plate is ejected by 4 hydraulic cylinder ejection, and the distance between the oil circuit and the hydraulic cylinder is close to the same to ensure synchronous ejection.

02. The part is ejected by stripper block, ejection blade, and lifter. The maximum ejection pin is 16 mm and the minimum is 10 mm

03. The insert is made in the horn position of the door panel, and the ejector block and ejection blade are designed.

6. Cooling layout design
This mold adopts the design “straight through water pipe + well”, the water diameter is 12 mm, the well diameter is 20 mm, the distance between the waterline is 55-65 mm.

Assembly mold drawing

Review:
01. There is hook snap length to 611mm and lifter design is one of the highlights and difficulties of this mold. It is very practical
02. The method of lifter, push block, water line design is worth learning
03. Mold positioning pin design is very clever, whatever small size mold or large size injection mold can be used in this way.

We have extensive experience in designing and manufacturing tools for interior and exterior plastic car parts. Our staff is well-trained in specialized techniques which are essential in manufacturing plastic injection molds for automotive parts with a strong durable structure. Working with us would thus make your plastic auto parts industry-compliant by default.

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