Due to complex and changeable structure of automobile molds, expression of text and graphics is often abstract. For this reason, editor has collected and sorted out some typical cases of automobile molds for everyone to learn and watch, hoping to help majority of automobile interior and exterior decoration and mold industry personnel.

Car rearview mirrors are an important part of automobile exterior trims. They are located on both sides of car and are one of the most important exterior trims of car. Car rearview mirror is a device used to allow drivers to observe road conditions during driving. It can be said to be eyes of driver. Car rearview mirrors are generally composed of mirror rings, bases, mirror shells, brackets, rotating shafts, mirror seats and other parts.

Plastic material is PBT_GF30%, shrinkage rate is 1.005, number of mold cavities is 1+1, plastic part is a left and right mirror image. Mold adopts demoulding mechanism of "push rod + inclined top + spring + injection molding machine pull-back type", adopts lateral core pulling structure of fixed mold tunnel inclined slider and "inclined guide column + slider". There are many sliders and core pulling area is large. Slider glue surface needs to be treated with leather grain, and appearance requirements are high.

 

Automobile rearview mirror base
Plastic part material is PP+GF45%, shrinkage rate is generally 1.004, plastic part is a left and right mirror part, and number of mold cavities is 1+1. Plastic part is a non-appearance part and belongs to an internal functional part.

 

Automobile rearview mirror shell
Plastic part material is ABS, shrinkage rate is generally 1.005, plastic part is a left and right mirror part, and number of mold cavities is 1+1. Plastic part is an appearance part and is one of the most important exterior parts of a car. Mold adopts a demoulding mechanism of push rod + push block + inclined push block, which is a typical structure of automobile rearview mirror shell mold.
When designing this type of mold, it should be noted that this structure must be manually taken out. Manual taking out requires manually breaking out plastic parts when taking out parts. For this type of plastic parts, plastic parts must have room to swing. There are also many such plastic parts that rely on manual breaking out in automobile mold design, such as automobile steering columns, throttle covers, etc.

 

Automobile rearview mirror bracket
Plastic part material is ASA, shrinkage rate is generally 1.005, plastic part is a left and right mirror part, and number of mold cavities is 1+1. Plastic part is an appearance part and is one of the most important exterior parts of a car. When inner side of mold is designed as a push block structure, parts must be taken out manually, and there must be room to swing when plastic parts are taken out.

 

Automobile rearview mirror rotation axis
Plastic part material is ABS, shrinkage rate is generally 1.005, plastic part is a left and right mirror part, and number of mold cavities is 1+1. Plastic part is an appearance part and is one of the most important exterior parts of a car. As one of the most important exterior parts of a car, appearance requirements of automobile rearview mirror are extremely high.
Rearview mirrors of this car series are divided into high-end and low-end. High-end is a leather grain part (fine leather grain), and low-end is a spray-painted part, so mold requirements are extremely high. For automobile rearview mirror mold, the most difficult part in mold making is control of weld lines, appearance clamping lines and plastic part deformation. Mold flow analysis must be done before mold design to drive weld lines to non-appearance area.

 

Throttle cover refers to box on car for storing gasoline. Shape is generally square or round, generally made of plastic, and has good sealing. There is only a small round entrance, which is only as big as bottle cap, which is convenient for storing gasoline. It is usually placed at rear of car. Automobile throttle cover is generally composed of throttle decorative cover, throttle cover, fuel filter cover, throttle cover knob and other parts. Fuel filter cover is soft rubber, the rest of parts are hard rubber or other hardware materials.

 

Automobile throttle cover
Plastic material is PP+GF30, number of mold cavities is 1*1, and product surface is spray-painted. Due to structural limitations, inner side of product needs to be bent outward after position and lifter are disengaged. Therefore, it must be manually removed.

 

Structural motion analysis of automobile throttle cover

 

Automobile steering column is located on steering wheel of car and is a device for driver to control direction. When driver is driving, device where car key is inserted is steering column. Automobile steering column and automobile steering wheel belong to same series of main and auxiliary instrument panel assemblies. Automobile steering column is generally composed of two or three plastic parts. The most important plastic parts of steering column are: steering column upper guard and steering column lower guard.
Automobile steering column plastic parts are required to have excellent appearance quality, high clamping line requirements, and high requirements for mold making. Upper and lower steering columns are assembly parts. They cannot be misaligned after assembly, gaps are required to be small and uniform. Since plastic parts have multi-directional and multi-vertical concave structures, outer side of plastic parts adopts moving mold slider core pulling structure, and inner structure adopts lifter core pulling structure to achieve core pulling.

 

Car lights are mainly used for lighting, which can be said to be eyes of car. Headlights are a general term for all car lighting systems. Car lights have high requirements for appearance. Several important parts are transparent parts, electroplated parts, etc. It can be said that parts with the highest requirements for car appearance are headlights, so requirements for mold design and manufacturing are extremely high. Generally, main lighting parts of a car are front and rear headlights. Different car series have different configurations of headlights, same car series also has different configurations based on high and low configurations. Main parts that make up front and rear lights of a car are: left and right lenses, left and right decorative frames, left and right lamp shells, left and right reflectors, etc.
Car headlight lens
Car headlight lens (also known as light distribution mirror) is outermost transparent part of car headlight. Generally, car headlights are white and transparent, rear combination lights are red (or multi-color) and transparent. Surface of plastic part of automobile headlight lens is a Class A curved surface (i.e., gap between adjacent curved surfaces is between 0.001 and 0.005 mm, curvature change is less than 0.005 degrees, and shear rate change is less than 0.16 degrees.), with a super-hard coating on outer surface. Transparency requirements of inner and outer surfaces are extremely high, and it is the most important automobile exterior decoration.
Car headlight decorative frame
Car headlight decorative frame is a decorative part of automobile headlight lighting system. It is located on inner side of lens and assembled with the lens. Decorative frame can be seen from outside of headlight through lens. Material is PBT+30%GF. Material has good heat resistance and fluidity, is easy to process and form, and has strong adhesion of surface coating. It is generally used as a decorative frame on lamps. Appearance of plastic part is aluminum-plated, and some areas need to be frosted.

 

Car headlight housing
Plastic part material is PP+TD20, where PP is base of lamp housing cover, and TD20 is 20% talcum powder added to material, mainly to improve rigidity of lamp housing cover. It is not an appearance part, but an internal functional part.

 

It is easy for automobile lamp housing plastic parts to stick to mold. Early design and prevention of sticking to mold of automobile lamp housing plastic parts are generally:
1. Before designing mold, check whether demoulding slope of area with strong clamping force of plastic part is greater than 3 degrees, try to design it to be more than 5 degrees to avoid sticking to mold and dragging of plastic part.
2. Design undercuts on inner side of plastic part where it is easy to stick to mold and clamping force is large. Depth of undercuts is 0.5~1mm, and undercuts are designed near fillet of plastic part.
3. Design reinforcement ribs on inner side of corresponding plastic part where clamping force of plastic part is large, or design undercut hooks on push rod.

 

Automobile headlight reflector
Automobile headlight reflector (also known as reflector) is a part of automobile headlight lighting system that has a reflective function to avoid direct light. It is located on inner side of lens and decorative frame, and is assembled with lens. Reflector can be seen from outside of headlight through lens. Plastic parts are appearance parts, with aluminum plating on the surface. They are high-gloss plating parts with large-area patterns on outer surface for surface decoration and reflection.
Car lights are important safety devices and decorative parts that are indispensable for automobiles. Due to high-temperature working environment and reflective focusing function, reflectors need to be molded with prefabricated integral molding compound (BMC) thermosetting plastics with almost zero shrinkage, heat resistance, flame retardancy, and strong creep resistance. This material has been die-casting in the past. Due to low production efficiency and high scrap rate, and because material is harmful to human body, frequent manual material collection and weighing processes are required in die-casting production, which poses certain risks to health of operators. For this reason, it has become an inevitable trend to develop injection molding technology of BMC materials to replace die-casting technology.

 

Automobile side interior panel assembly includes: A-pillar upper panel, A-pillar lower panel, B-pillar upper panel, B-pillar lower panel, C-pillar upper panel, C-pillar lower panel, front door sill panel, rear door sill panel, D-pillar upper panel, rear side panel, etc. Side interior panel can increase comfort and beauty of passenger area, and also provide durable covering for body sheet metal, wiring harness, seat belts, etc.
Sedan side interior panel assembly series

 

 

Parts shown in above picture are side interior panel assembly of a certain brand of automobile. It can be seen from picture that this is a sedan side panel assembly and an SUV side panel assembly. It can be seen from picture that SUV side panel assembly has more parts than sedan side panel assembly, and product composition is also more complicated. By comparison, it is found that SUV side panel has an additional D-pillar, while ordinary sedans only have ABC columns. ABC pillars of automobiles are main parts of side wall guard plates. ABC pillars of automobiles are also called front pillars, middle pillars, and rear pillars.
ABCD pillars of automobiles
Left and right upper guard plates of ABCD pillars of automobiles are important components of automobile interior decoration. In automobile interior decoration, in addition to door guard plate assembly composed of door guard plates on both sides of car door, there are also mechanisms composed of upper and lower guard plates such as ABCD pillars on both sides of door. These mechanisms are collectively referred to as automobile side wall interior guard plate assemblies. Main function of side wall interior guard plate is to cover metal plate, provide a beautiful appearance, meet ergonomics, comfort, functionality and convenience. Provide appropriate energy absorption protection in the event of a side collision and provide shielding for noise outside car.
Low-pressure injection molding technology for automobile AB pillars
So-called low-pressure double-layer injection mold, also referred to as low-pressure injection mold, is a new type of injection mold technology. Traditional parts that rely on manual covering and vacuum adsorption of negative mold and positive mold are directly injected in mold at one time.
Main principle of low-pressure injection mold is: injection pressure is low and plastic flows on cloth. When opening mold, cloth should be hung on fixed (movable) mold hanging needle first, then mold is closed, injection is performed, and finally parts are taken out. Plastic parts produced by this technology have a special soft cloth on the surface, which greatly improves decorativeness, feel, and aesthetics. Therefore, low-pressure injection mold technology is widely used in mid-to-high-end cars, generally used in parts such as automobile AB pillars.