In the production of auto parts, dashboards are one of the most common auto parts requirements. Nowadays, the design of automobile dashboards is mostly produced by plastic manufacturing. With the development of automobiles in terms of safety and environmental protection, people's requirements for safety and environmental protection of automobile trims are also increasing; at the same time, more and more dashboards adopt the appearance design of seamless airbag doors, which puts forward higher and higher requirements on the manufacturing process of the dashboard.
Take Chevrolet's dashboard as an example. The total weight of the dashboard system is about 17KG. Its component structures mainly include: dashboard body, airbag frame, dashboard lower body, sub-instrument panel body, interior trim panel, decorative panel, wind pipe, mobile ashtray; main materials: general-purpose plastic PP+EPDM-T20, PP-T20, ABS, PC+ABS, HDPE; engineering plastic PA+30GF%, POM, etc., based on a rough calculation, the amount of modified PP accounts for 80% of the plastic used in the dashboard. If you want to improve the product quality of the car dashboard, you must pay attention to the process of injection molding in automotive industry.
The dried plastic particles are cut in the injection molding machine through the screw and the barrel is heated and melted and then injected into the instrument panel mold to cool to obtain the finished product. Used to manufacture rigid plastic instrument panel body, blister and soft instrument panel skeleton and most other related parts. Hard plastic instrument panel materials mostly use PP, and the materials of instrument panel skeleton mainly include modified materials such as PC/ABS, PP, PPO (PPE). For other parts, ABS, PVC, PC, PA and other materials are selected according to different functions, structures and appearance requirements.
The injection molding processing of the instrument panel can be further divided into: gas-assisted injection molding, sequence valve injection molding, compound injection molding, insert injection molding, two-color injection molding, two-shot injection molding, etc.
1. Gas-assisted injection molding
Gas-assisted injection molding is an injection molding process in which molten plastic particles are injected into the mold while a certain amount of inert gas is injected, and a specific area of the part is formed into a hollow structure through the design of the gas path, structure and process control. The hollow structure not only enhances the mechanical properties of the parts, but also reduces the wall thickness of the parts, improves the appearance of the parts, and reduces the material cost and forming cycle.
2. Sequence valve injection
Through the valve interlocked with the equipment, the opening and closing of different gates of the mold hot runner are controlled to control the injection molding process of the material flow. This process is suitable for thin-walled and long-process products, reduces the requirements for the clamping force of the equipment, optimizes the surface quality, and shortens the forming cycle.
3. Composite injection
Place a sheet that matches the shape of the mold or a shapeless sheet on the side of the movable mold of the injection mold, and then injection molding, so that the product has a two-layer structure while using the mold to give the shape. The advantage is that the processing procedures are reduced, the product appearance is good, and the adhesion between parts is strong.
4. Instrument panel insert injection molding
It is more popular in the home appliance industry, and this process is used in the manufacture of electrical switches in the production of instrument panels. It is to place the metal parts that need to be embedded in the injection molded parts in the mold before injection molding, and the molten plastic after injection molding partially wraps them into parts.
5. Two-color injection molding for dashboard
On the two-color injection molding machine, different colors/types of raw materials are injected into the special injection mold at the same time/sequentially in the same production cycle, so that the product has different appearance/performance, but it is gradually being repaced by the two-shot moulding because of the huge investment in equipment and molds.
6. Double injection of instrument panel
Over-injection is an insert injection where the injection part is an insert. It is mainly used for parts with high mechanical performance and appearance requirements. Injection molding materials selection is the key to this process.
With the continuous exploration of the automotive industry in the research and development of instrument panel materials and process improvement, automotive instrument panels will gain more and more beautiful and ergonomic appearance and experience design.