There are still many injection molded parts for automobile lights. The more representative ones include headlight masks, headlight decorative frames (transition plates), taillight masks, ellipsoid lenses, light guide strips (plates), etc. Each product has its own processing technology characteristics. Today we will briefly explain headlight mask.
1. Definition of two-color injection molding
Multi-color and multi-material injection molding process refers to combination of several plastics into multi-functional components in one manufacturing process or one production unit. This technology uses a variety of materials for injection molding production, combines characteristics of different materials during molding process for assembly or other suitable bonding methods to improve functionality and aesthetics of product, providing meaningful savings potential and new design possibilities for product manufacturing.
2. Necessary conditions for multi-color injection molding
Paired materials for multi-color injection molding must meet two basic compatibility conditions, namely bonding compatibility and processing process compatibility. Multi-color injection molding also puts forward new requirements for injection equipment. As far as injection unit is concerned, parallel and parallel, parallel and opposite, horizontal and vertical L-shaped, and Y-shaped single-cylinder injection structures can be used. As for mold, standard type, vertical turntable type, horizontal turntable type, rotating shaft type, robot rotating type and other mechanisms can be selected. As for oil circuit, ACC pressure accumulation, high-speed injection and closed-circuit designs can be provided.
One of key factors in multi-color injection molding is variability of computer control programs. Because even for same type of multi-color products, if different mold designs are used, different electronic control programs must be used. After customers purchase a multi-color injection molding machine, if they encounter a new mold design, an excellent multi-color injection molding machine supplier can quickly modify and upgrade existing machine to make it meet injection molding requirements.
3. Multi-color molding technology for car lights
Automobile industry has become a pillar industry of country. Rapid development of current automobile industry has put forward increasingly higher requirements for automobile lighting.
Quality of automotive lighting is very important to driving safety. Therefore, regulations in various countries around the world have strict requirements for automotive lighting. Design of lamps must not only comply with regulatory safety requirements, but also meet some other requirements. For example, appearance must be integrated with appearance of the entire car, be beautiful and practical, comply with aerodynamic requirements, make driver and passengers feel comfortable and convenient. Therefore, design technology of car lights is also changing with development of automobile industry.
4. Processing characteristics of car light mask products
Product name: Headlight lens (LENS)
Product features: white transparent PC in main functional area, black PC in periphery, shrinkage rate 7/1000, average wall thickness 3mm. White parts use a rectangular gate to feed glue from side, and black parts use a double-sided dot gate to feed glue from side.
Processing technology: two-color injection molding, two products on the left and right in one mold, sprayed with UV paint on the surface.
Car lights generally consist of a mask and a lamp shell. Material of mask is generally PC for headlights and PMMA for taillights. Lamp shell can be made of PP, ABS and other materials, usually in two or three colors. In terms of two-color car lamp production process, special attention should be paid to injection part of two-color injection molding machine. Center distance of two screws should correspond to center distance of two-color mold.
5. Car light mask equipment (injection molding machine)
Main equipment parameters of NEGEL1700T two-color injection molding machine
Pick-up distance = robot width (fixed) + clamp width (design size) + pick-up distance (forward distance) + safety width (5-10cm)
6. Headlight mask mold
Main structure introduction:
1. Two-color mold, high-gloss mold. 1# cavity white piece, 1 rectangular side gate for each left and right piece. 2# cavity black piece, two point gates on the left and right parts respectively.
2. Mold adopts a hot runner self-sealing valve structure, with 12 sets of hot runner temperature controls for white piece and 26 sets of hot runner paths for black piece.
3. 2# cavity black piece uses a large internal pumping structure and side guide pillar is reset.
4. Fixed mold bone blocks 1# and 2# adopt a guide block structure.
5. White piece of cavity 1# is ejected by a spring and forced back. Finished product of cavity 2# has a neutron ejection structure.
Mold level one maintenance operation guide
Main focus:
1. Clean wear-resistant sheet, guide pillar and mold parting surface with alcohol and non-woven cloth, check whether there is black dirt on mold parting surface.
2. Add high-temperature lubricating oil to mold parting surface, wear-resistant sheets, and guide pillars.
3. Clean top of mold with a non-woven cloth soaked in alcohol.
4. Check whether there is black dirt on the top block of mold and clean it.
5. Add high-temperature lubricating oil to top of mold, wear-resistant sheet, and guide pillar.
6. Use bamboo pieces wrapped with cotton to clean oil stains on the sides of mold core.
7. Use bamboo pieces wrapped with cotton to clean oil on friction surface between inner pump and mold cavity.
8. Add high-temperature lubricating oil to friction surface between mold core and inner pump, clean and polish oil stains on mirror surface.
7. Commonly used materials for headlight masks
Introduction to PC (PC2405, PC2447)
Typical applications: electrical equipment (computer components, connectors, etc.), appliances (food processors, refrigerator drawers, etc.), transportation industry (vehicle front and rear lights, instrument panels, etc.). Our factory is mainly used for headlight lenses and aluminized transition plate products)
Chemical and physical properties: PC is an amorphous engineering material with particularly good impact strength, thermal stability, gloss, antibacterial properties, flame retardant properties and anti-pollution properties. Notched impact strength of PC is very high, and shrinkage rate is very low, generally 0.1%~0.2%. PC has good mechanical properties but poor flow properties, so injection molding process of this material is difficult. When choosing what quality PC material to use, it should be based on final expectations of product. If plastic part requires high impact resistance, then use PC materials with high melt index; otherwise, use PC materials with low melt index, which can optimize injection molding process.
Because PC contains strong polar groups, it is very sensitive to moisture. When PC contains a very small amount of moisture, silver threads will form on product in mild cases. In severe cases, moisture will react with PC under high temperature and high pressure, greatly reducing molecular weight of plastic, which will greatly affect performance of plastic and make product very brittle. Therefore, PC must be strictly dried before molding.
Molecular chains of PC plastic are very rigid and can easily cause stress concentration. At the same time, because PC materials are not too sensitive to temperature, higher temperatures and lower pressures can be used during molding.
Injection mold process conditions:
Drying treatment: PC material is hygroscopic, and drying before processing is very important. Recommended drying conditions are 100℃-120℃, drying time: 3-4 hours. Humidity before processing must be less than 0.02%.
Melting temperature: 260~340℃.
Mold temperature: 70~120℃.
Injection pressure: Use high injection pressure.
Injection speed: Use low speed injection for smaller gates, use medium and high speed injection for other types of gates.
Gud Mould 