Dashboard is a very unique component in car, integrating safety, functionality, comfort and decoration. In addition to requiring good rigidity and energy absorption, people have higher and higher requirements for its feel, leather grain, color and tone.
Due to its unique spatial position, more and more operating functions are distributed in it. In addition to reflecting basic state of vehicle driving, control of air vents, audio, air conditioning, lighting, etc. also gives driving more safety and driving pleasure. Therefore, in car, dashboard is a very unique component that combines safety, functionality, comfort and decoration. First of all, it needs to have a certain rigidity to support attached parts to ensure normal operation under high speed and vibration; at the same time, it needs to have good energy absorption to reduce impact of external forces on driver and co-driver in the event of an accident. As people's understanding of cars goes beyond their functions, feel, leather texture, color and tone of dashboard have gradually become important criteria for judging level of the entire vehicle.
Dashboard usually includes dashboard body (shell), instrument, air conditioning control system, air duct/duct, air outlet, operation panel, switch, audio control system, defrost vent, defog vent, glove box, left cover, decorative panel and other parts. Most dashboards also include: storage box, driver's side glove box, speakers and other accessories and clocks, metal reinforcements, ashtrays, cigarette lighters, cup holders and other functional parts; some mid-to-high-end cars are designed with satellite navigation systems, mobile phone intercom systems, temperature sensor systems, USB-SD card interfaces and other high-end products.
Dashboard is referred to as IP (Instrument panel), which is an important part of car interior.

 

a. Dashboard can be divided into dashboards without airbags and dashboards with airbags according to safety.
As people pay more attention to safety, customers have a greater demand for dashboards with PAB and KAB (knee airbags), and OEMs have also used this as one of their selling points. While airbag is open to protect passengers, it may also hurt passengers, especially children. Therefore, design of dashboard airbags has begun to add airbag shielding switches. In order to ensure normal opening of airbag, an airbag cover is often designed above airbag to release airbag when it is opened. However, there is a visible wiring at matching point with dashboard, which affects appearance of the whole vehicle. For this reason, in recent years, more and more models have dashboards designed as seamless airbag dashboards. It can not only ensure normal opening of airbag, but also have no visible wiring.
b. Dashboard can be divided into hard plastic dashboard and soft dashboard according to comfort.
Dashboard body is made of injection molding process, which is a hard plastic dashboard. It is widely used because of its simple process and low investment, especially in low-end and medium-end vehicles. Soft plastic dashboard is adsorbed and bonded to outside of injection molded skeleton or skin is compounded during injection molding to make it look leathery. At the same time, polyurethane foam is filled between skeleton and skin. A layer of foam can also be directly attached to the back of blister skin, which not only improves touch but also increases ability to absorb energy. At present, skin mainly includes vacuum thermoformed skin and slush molded skin. The former is made by traditional imitation leather technology; the latter has been widely used in recent years due to its uniform pattern, no internal stress, high design tolerance and other characteristics, has been highly recognized by customers, and has become leading mid-to-high-end car.
c. According to driving direction, dashboard can be divided into left-hand steering wheel dashboard and right-hand steering wheel dashboard.

For different instrument panels, processes and procedures involved are also quite different, which can be roughly summarized as follows:
1. Hard plastic instrument panel: injection molding (instrument panel body and other parts) → welding (main parts) → assembly (related parts);
2. Semi-hard plastic instrument panel: injection molding (instrument panel skeleton) → blister (skin and skeleton) → cutting (holes and edges) → assembly (related parts);
3. Soft instrument panel: injection molding skeleton → vacuum forming (female mold blister skin)/slush molding (skin) → foaming (foam layer) → cutting (edges, holes, etc.) → welding (main parts, if necessary) → assembly (related parts)

Dried plastic particles are sheared by screw in injection molding machine, heated and melted by the barrel, then injected into mold for cooling and forming. It is the most widely used processing technology for instrument panel manufacturing. It is used to manufacture hard plastic instrument panel body, blister, soft instrument panel skeleton and most other related parts. Hard plastic instrument panel materials mostly use PP, and the materials of the instrument panel skeleton are mainly modified materials such as PC/ABS, PP, PPO (PPE). Other parts are selected from ABS, PVC, PC, PA and other materials according to different functions, structures and appearance requirements. After rapid rise of injection molding process in the 1940s and 1950s, it has been vigorously developed. After continuous increase, modification and selection of equipment for different purposes in equipment and molds, injection molding process has formed a variety of sub-processes, such as gas-assisted injection molding, insert injection molding, two-color injection molding, etc.
① Gas-assisted injection molding is abbreviation of gas-assisted injection molding. It was invented in the early 1980s and promoted in the 1990s. It is an injection molding process that injects a certain amount of inert gas into mold while injecting molten plastic particles, forms a hollow structure in a specific area of part through design of gas path, structure and process control. Formation of hollow structure enhances mechanical properties of part while reducing wall thickness of part, improving appearance of part, reducing material cost and molding cycle. Therefore, this process is not only used in automotive manufacturing industry, but also has made great progress in home appliance manufacturing industry. It is mainly used in structural parts, especially those with appearance requirements. In recent years, research and application of using water instead of inert gas has also achieved certain results;
② Insert molding is popular in home appliance industry. This process is used in manufacture of electrical switches in dashboard production. It is to place metal parts to be embedded in mold before injection molding, and molten plastic will partially cover it to form parts after injection molding;
③ Two-color injection molding: On a two-color injection molding machine, different colors / types of raw materials are injected into a special injection mold simultaneously/sequentially in same production cycle, so that product has different appearance/performance. However, due to huge investment in equipment and molds, it is gradually replaced by secondary injection molding. Secondary injection molding is insert molding where injection molded part is an insert. It is mainly used for parts with high mechanical performance and appearance requirements. Material selection is the key to this process.

 

 

 

① Requires to meet convenience and convenience of operation;
② Comprehensively consider shape of the whole vehicle;
③ It is required to include driving control subsystem, information system, and comfort system (such as air conditioning controller, radio, switch, wiring harness module);
④ Various information systems should be arranged within driver's line of sight;
⑤ Provide a comfortable internal environment together with other interior systems;
⑥ Provide collision protection;
⑦ Provide some storage areas and convenient and useful tools (such as ashtrays, coin boxes, cup holders, etc.);
⑧ Provide installation carriers for other subsystems.

 

Main demoulding direction of dashboard is determined according to outer surface of dashboard and position of air outlet. Generally, it is between 20 and 30 degrees. Demoulding direction of auxiliary dashboard is vertical. According to this direction, analyze whether various places on outer surface of dashboard can be demoulded smoothly. Demoulding angle of large parts such as dashboard body is at least 7°, and specific depth should also be determined according to surface leather grain depth of dashboard. Demoulding angle of invisible area should not be less than 3°. If it is less than 3°, it may damage surface of part and produce marks. In addition, try to avoid using sliders when choosing demoulding direction and later layout plan, because use of sliders will first affect appearance and produce parting lines on the surface of part. Secondly, it will affect mold life and mold cost will increase accordingly.

Table above is a comparison of thickness of hard plastic instrument panels of several Chery S series cars. Due to difference in materials, thickness of instrument panel that meets same strength requirements will also vary from supplier to supplier. Thickness of domestic injection-molded instrument panel is generally 3.0-3.5mm. Thickness of instrument panel skin of positive mold blister is generally 2.0-3.0mm. Because skeleton uses alloy material (harder and more brittle), thickness can be 2.0-2.5mm, such as A15 instrument panel skeleton. For soft instrument panels, thickness of slush-molded skin\PU spray-coated skin\negative mold blister skin is generally 0.8-1.2mm, foaming layer is 4-8mm, skeleton thickness varies depending on material and process. T21 is 3.5mm, and B12 is 3.0mm.