It can be said that the most demanding part of car is lamp, so design and manufacturing requirements of lamp mould are extremely high. Main components that make up front and rear lights of car are: left and right lenses, left and right decorative frames, left and right lamp housings, left and right mirrors, and so on.

 

Lens is a transparent piece with a pattern on inner side with a high requirement of appearance.

 

Appearance of decorative frame is aluminized and some areas need to be frosted.

 

Lamp housing is an internal functional part of lamp mould, and assembly requirements of lamp cap hole and back cover hole are high.

 

Mirror are electroplated parts, have strict light distribution requirements, and appearance surface is aluminum plated.

 

Lateral core pulling mechanism is the most important core structure of plastic injection mold for auto lighting. Mold cleverly adopts inner core pulling mechanism of “T-slot guide block + oblique inner slide” to successfully solve solutions of lateral division of transparent part leave traces on the surface of plastic part.
Mold adopts a common pouring system and is fed by a fan-shaped gate tower. Compared with previous hot runner casting system, cost is not only greatly reduced, but also light transmittance of lamp lens is better.
Auto light lens mold adopts combined cooling system of “vertical cooling water pipe + inclined cooling water pipe + septum water well”. Water channel is arranged along cavity, and molding cycle is successfully controlled within 35 seconds, which effectively ensures precision of plastic parts and labor productivity of auto light lens mold.
Plastic parts are pushed out by push blocks, which are not only stable, but also leave traces that have no effect on the appearance.
Since production of mold, movement has been stable and smooth, and quality indicators of plastic parts have met injection mold design requirements. It is a successful example of large, complex and long-life injection mold design.

Headlight decorative frame of car is one of the most important parts on lamp, appearance is strict, and mold needs to be plated. For car headlight decorative frame mold, pay attention to following points when designing:
(1) Electroplated parts must first avoid weld line, because any weld line of electroplated parts will appear, affecting appearance of plastic parts. When designing gating system, avoid weld line. If weld line is unavoidable, try to drive it to non-appearance areas, gating system should be verified by mold flow analysis before design.
(2) Surface of decorative frame is generally designed with pattern. When designing mold, attention should be paid to depth of plastic pattern, which is generally prone to flow pattern.
(3) Molding process of plastic parts is small, and surface of plastic parts is easy to produce bright spots and difficult to control. When mold casting system is designed, flow path should be thick and large, and gate adopts a fan-shaped gate. Maximum width of gate is about 35~40mm, which is favorable for melt filling.
(4) Plastic parts of decorative frame are prone to phenomenon of sticking and fixing mold. Pre-design solution of solving plastic parts from adhering to mould is as followed:
a. Reverse buckle should be desiged on the inner side of plastic part that is easy to stick and has a large clamping force, with a depth of 0.5~1mm, and it is designed near rounded corner of plastic part.
b. Reinforcing ribs should be designed on the inner side of corresponding plastic parts which plastic molding is tightly packed with, and inverted hook is designed on push rod. According to characteristics of plastic parts, reinforcing ribs and BOSS column (commonly known as cylinder column)should be designed on the inside of plastic parts in 6 LED lamp areas to avoid deformation of plastic parts.
In injection mold design, area with large clamping force of plastic part is designed to have a slope of more than 5 degrees, and a 0.5mm deep reverse buckle pattern is designed on movable mold side, so that mold is released and mold is smoothly released, and movement of each mechanism is smooth. Mold is safe, stable and reliable, and mold has no sticking mold phenomenon, which successfully solves the problem of fixed mold of such plastic parts. After model trial, loading effect is good and size is stable. Redesigned headlights auto show has been recognized and praised by customers, creating certain economic benefits for customers.

For automotive lamp mirror molds, main design points are:
(1) Special plastic molding equipment is required, and plastic molding machines specializing in production of BMC plastics are required. Requirements for plastic molding equipment are very strict.
(2) BMC material is a special hard plastic. In injection mold design, it is necessary to design a heating system and a parting surface design discharge system. Molded parts must be quenched to improve wear resistance and mold life.
(3) Reflector plastic parts are used in car lights to prevent direct light, reflect light and avoid direct light, and light distribution requirements are strict. Plastic parts are the most important appearance parts of automobiles. There are many patterns on the surface of plastic parts for purpose of decorative beauty.
(4) Ejector System from injection mold design of BMC material should be balanced. Specifications of push rod should be designed as large as possible, and quantity should be as large as possible. Otherwise, mold release will be difficult.
(5) Because stripping angle of high-gloss plating part is too small, it will cause difficulty in demoulding. Therefore, drafting degree of side wall of mirror plastic part should be designed as large as possible, generally recommended to be 5°~10°. Of course, premise is that it cannot affect function and shape of plastic parts.
(6) Plastic parts can not have sharp edges, all corners need to be designed as rounded corners, because molded parts of plastic molding are susceptible to stress cracking after quenching.
(7) Note that head holes of left and right mirror lamp, surface of plastic part are left and right translation, and can not be designed as mirror symmetry, because bulb and lamp head are not divided into left and right, and other features are mirror symmetry.