The headlight housing is part of the headlight base and wiring harness before installation. It belongs to the internal functional components, and the external components have many assembly dimensions.
The lamp holder has high precision and the installation harness has a large size.
The lamp mold is part of the headlight lamp cover part, the material is PP+TD20, wherein PP (polypropylene) is the base of the lampshade, and TD20 means adding 20% talcum powder to the material to improve the rigidity of the lampshade. This part is not the appearance part, but the internal function. The average wall thickness of the plastic parts is 3.00 mm, and the maximum size of the plastic parts is 320.9*228.4*344.3 mm. The characteristics of plastic parts are as follows:
1. No spot is allowed on the surface of plastic parts. Defects such as shrinkage holes, weld marks and burrs are not allowed.
2. The plastic part is an internal functional part, and the lamp cap hole and the back cover hole have many assembly dimensions and high precision.
3. The shape of the plastic parts is complicated and the parting surface is complicated.
4. There are two inverted buckles on the outside of the plastic parts, and the parting surface is complicated.
5. In addition to the asymmetrical aperture of the lamp head, the left and right lamp housings are asymmetrical.
Since the lamp mold is a large mold, the parting surface is complicated, and the mold part and the template adopt an integrated structure, that is, the fixed mold a plate is a fixed mold forming part, and the moving mold B is a moving mold forming part. The structure has the advantages of compact structure, high strength, good rigidity, small mold volume, and avoids complicated procedures such as opening a frame, arranging a frame, and manufacturing a groove.
Since the plastic parts are PP+TD30 and no parts are present, the fixed and movable mold steels can be P20 or 718.
Since the push mechanism is on the movable mold side, the plastic parts must be held on the movable mold side after the mold is opened. Due to the complex shape of the plastic parts, the plastic parts may stick to the fixed mold after the mold is opened. Therefore, when designing a lamp mold, it is necessary to prevent the occurrence of a fixed mold phenomenon. The specific measure is to design the ribs and the reverse buckle type on the side cylinder of the movable mold to the area where the plastic parts are strongly stressed. If it is still fixed, design a buckle on the push rod to keep the molded part on the side of the movable mold.
Pay attention to the design of the lamp holder during design. The left and right of the lamp hole is a translational relationship, not a mirror relationship. This is one of the mistakes that lamp mold designers can easily make. Pay attention to the dimensional accuracy of the lamp cap hole. The ventilation angle must be within 0.5°, otherwise it will affect the installation of the lamp holder. The lamp housing plastic part has a plurality of ribs, and the boss has a plurality of columns. There are many fixed, movable molds that are inserted into the injection mold and push tube. Fixed and mobile mold inserts should be positioned with a mushroom head to tilt. Screw as far as possible from the front and copper at the bond.
In other respects, the design of the injection molded part should pay attention to the insertion angle. In the design of automobile molds, in order to improve the service life of the mold and avoid the insertion position of plastic parts, all the insertion positions are designed to be more than 7 degrees.
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
Head Lamp Features and Development Trend
Head lamps usually described as the language with developing trend of times, follow people’s aesthetic tendency, all kinds of high technologie will reflect on the head lamps at first time. Including high beam lights, low beam lights, turn lights, position lights and daytime running lights, now the light source of headlamps transition from halogen, xenon to LED, matrix and Laser source. The product modelling developing in the direction of thin strip and ring shape.
Head Lamp Mold
Eye-catching shapes put forward more and more challenges to head lamp mold, headlamp lens are developing in the direction of double-color mold, mold drop becomes ever larger, the drop of around 600mm-750mm is becoming more common. Thin strip and ring shapes make the mold gating system complex, multi-gate and sequence valve are widely used. Light guide mold and thick wall mold are getting more and more, electroforming core and diamond cutting techniques are used to ensure the optical requirements.
With rich experience in headlamp mold design and manufacturing, our products are widely distributed in most popular models. We are familar with the headlamp products feature requirement, design difficulty and have the corresponding design standards, could flexibility to meet the difficult head lamp mold development.
Explanation of car lamp mould design Car headlight reflector (also known as mirror) is a part of car headlight illumination system that reflects function to avoid direct light. It is located inside lens and decorative frame, assembled with lens. Lens can be seen from outside of lamp through lens. Plastic parts are appearance parts, surface is plated with aluminum, which belongs to high-gloss plated parts. Outer surface has a large area pattern for surface decoration. Lamp is an important safety device and decorative part essential for car. Mirror need to adopt a pre-formed integral molding compound (BMC) thermosetting plastic molding with a shrinkage rate of almost zero and heat resistance, flame retardancy and strong resistance. This material has been used in die-casting process. Due to low production efficiency and high scrap rate, and because it is harmful to human body, process of manual feeding and weighing is frequently required in production of die casting, thus bringing certain risks to health of operators. For this reason, it has become an inevitable trend to develop an injection moulding process for BMC materials instead of a die-casting process.
The lights in modern cars do more than illuminate dark roads. They’ve become a design signature of many OEMs. Audi started this trend in 2004 with the LED daytime running lights fitted onto the A8, and lighting technology has advanced rapidly since then, making auto lamp mold production a critical part of automotive manufacturing. Today LED lights are commonplace in both the front and rear ends of the vehicle, active lighting is throwing light around corners, and even laser high beams are emerging.
Front and rear light clusters go through rapid design cycles as manufacturers make styling changes every few years. Producing these assemblies of injection molded plastic components requires complex mold tools and their long lead times can easily constrain or delay model facelifts. Inevitably, designers and die makers are under increasing pressure to accelerate auto lamp mold production.
Iterating Faster
Product development typically follows a pattern of: design; prototype; test and validate; freeze or modify design before it moves into scalable manufacturing. True design validation often calls for complex auto lamp mold production tools that might take weeks or months to finish, dragging out each iteration and risking a launch or program delay.
Advanced 3D computer modeling and ray tracing software lets designers conceive and evaluate more alternatives but there’s still no substitute for physical prototypes. The key is to reduce auto lamp mold production lead time so they can be made faster.
Why Prototype at All?
In the case of auto lamp mold production, physical prototypes are essential, for five reasons:
Cost evaluation
Fit assessment
Prove-out of overmolding/insertions
Material performance assessment
Optical testing
1. Cost Evaluation
Only by molding parts is it possible to determine actual cycle times and actual yields. Lessons will be learned about the mold temperatures and pressures needed, cooling and shrinkage rates, distortion and so on. From these, tool modifications will be identified that bring down ultimate manufacturing costs.
2. Fit Assessment
After metalizing, molded reflectors are bonded to the clear or colored housings to create lamp clusters. Fitting together in the computer is no guarantee the actual parts will go together the same way, so prototypes are essential. The completed assemblies are then mounted on vehicle mock-ups and sculpted models for evaluation of fit and appearance under a range of lighting conditions and viewing angles.
3. Prove-Out of Overmolding/Co-Molding and Insertions
Many automotive lamp assemblies need different color plastics molded together, such as orange and clear or red, orange, and clear, and these are made by overmolding or co-molding. Male and female threaded inserts are needed for mounting in the vehicle as well as holding the bulbs and associated electrical components. Only by actually making the parts is it possible to verify the integrity of these overmolded and sometimes co-molded assemblies, and the insert bond strength and position.
4. Material Performance Assessment
Auto lamp assemblies are expected to last years in all kinds of environmental conditions without substantially diminished output. Plastics manufacturers continue to improve the grades available and prototyping lets development teams evaluate their performance under a wide range of conditions.
5. Optical Testing
Output, intensity, visibility, and beam shape are the subject of many regulations. Additionally, as manufacturers put greater efforts into adaptive lighting, it becomes even more important to track critical performance metrics. Regardless of how much modeling is done, only a functional prototype can ”bring to light” the actual performance achieved or delivered, validate the modeling, and demonstrate conformance to tighter regulations.
Tooling Lead Time Reduction
Production injection molding tools are typically machined from steel before hardening. Milling is slow and usually followed by hours of grinding to blend radii and surfaces. EDM can take hours to spark-erode complex pockets and cavities, after which more grinding is needed. The whole process, from design initiation to delivery, can take months.
Additive manufacturing methods using metal may one day reduce development time but today their chief contribution is producing SLA patterns as a basis for urethane molds. These allow pouring of liquid acrylics that take on the shape of the part needed, as described in this case study of an automotive tail lamp prototype, but aren’t directly usable in injection molding.
An alternative is to harness the speed and precision of modern CNC machine tools to shape molds from aluminum. Aluminum can be machined without slow grinding and EDM processes. Lifetime, measured in quantity of parts produced, will be less than that of steel tools, but that’s not a concern when making prototypes. In addition, the heat flow characteristics of aluminum can be of benefit when molding small quantities.
All About Speed
The lamp clusters used on modern cars have almost become fashion accessories and that means frequent design changes and intense pressure to get new designs to market. Computer modeling lets designers explore far more alternatives than was possible before but physical prototypes remain essential. Consequently, launching face-lifted car models depends on the speed of auto lamp mold production, which, in turn, depends on quality, time-sensitive prototyping.
Car headlight reflector (also known as mirror) is a part of car headlight illumination system that reflects function to avoid direct light. It is located inside lens and decorative frame, assembled with lens. Lens can be seen from outside of lamp through lens. Plastic parts are appearance parts, surface is plated with aluminum, which belongs to high-gloss plated parts. Outer surface has a large area pattern for surface decoration. Lamp is an important safety device and decorative part essential for car. Mirror need to adopt a pre-formed integral molding compound (BMC) thermosetting plastic molding with a shrinkage rate of almost zero and heat resistance, flame retardancy and strong resistance. This material has been used in die-casting process. Due to low production efficiency and high scrap rate, and because it is harmful to human body, process of manual feeding and weighing is frequently required in production of die casting, thus bringing certain risks to health of operators. For this reason, it has become an inevitable trend to develop an injection moulding process for BMC materials instead of a die-casting process.
Car lights are mainly used for lighting, which can be said to be eyes of cars. Car lights are collective name for all car lighting systems. Automobile lamps have high appearance requirements. Several important parts are transparent parts, electroplated parts, etc. It can be said that the most demanding parts of automobile appearance are automobile lamps, so requirements for mold design and manufacturing are extremely high.Main lighting parts of a general car are front and rear headlights. Different cars with different lights have different configurations, and same car has different configurations based on height. Main parts 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 reflectors, etc. Appearance requirements of car lights are extremely strict car headlight assembly effect
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.