Headlights generally have 4 bulbs: high beam, low beam, turn signals, and position lights. However, there are also cases where high beam and low beam are combined into a single dual-filament bulb, in which case there are 3 bulbs on headlight assembly.

 

2. Lamp Holder Hole
Lamp holder hole is where lamp holder is installed into lamp body. If lamp holder hole is too small, lamp holder will be difficult to install. If lamp holder hole is too large, lamp holder will not be firmly secured in lamp holder hole, resulting in looseness. Special attention should be paid to dimensions of lamp holder hole, including inner diameter C, outer diameter B, groove length A, and wall thickness D. In addition, insertion surface of lamp holder hole must be smooth and flat to ensure sealing of lamp body.

 

3. Insertion of Lamp Holder Hole
Lamp holder hole has four notches (though there may be more than four). These four protrusions serve a sealing and error-proofing function. Error-proofing: Because widths of these four protrusions are different and there are angle requirements, lamp holder will not be able to be inserted if insertion direction is incorrect! Sealing: Groove on lamp holder interlocks with lamp holder, and there is a sealing ring in the middle. Insertion surface of lamp holder hole should be smooth and flat to ensure seal of lamp body. Therefore, dimensions of groove on lamp holder and lamp holder should also be noted.

 

4. Inserting Lamp Holder into Hole
After lamp holder is inserted, an anti-rotation device is necessary to prevent it from rotating inside lamp holder hole. This device may be located on lamp holder itself or on lamp holder hole.

 

5. Rear cover hole (1)
Rear cover hole has a sealing function. Outer diameter of inner circle should be noted, outer diameter surface of inner circle must be smooth and flat, because after rubber is installed in rear cover, outer diameter surface is what plays a sealing role.

 

6. Rear cover hole (2)
② Assembly type of this type of rear cover hole is not a compression type, but a screw type, which is similar to installation method of lamp holder. Inner circle side wall of rear cover hole should ensure size and smoothness. Because this surface is the one that plays a sealing role after rear cover is installed in rear cover hole. (There is a sealing ring on rear cover) Above two types are round holes. ③ Rear cover can also be fixed with screws, with a rubber seal inside. However, this type of rear cover is not suitable for complex lamp body structures, because if you want to replace a bulb, it is impossible to unscrew all screws. ④ Fixed with clips, also with a rubber seal wire harness fixing clip.

 

7. Wire Harness Clip
Wire harness clip serves to secure wire harness. It only needs to hold wire harness in place. Therefore, there are no large size requirements, but it must not have sharp edges to prevent cutting wires when the wire harness is secured, which could create a potential hazard.

 

8. Hook and Loop
Hook and loop is part that connects lamp body and lens. Therefore, quality of hook and loop manufacturing affects assembly quality of lamp body and lens. Required dimensions include internal length and width of hook and wall thickness of hook.

 

9. Clamping Pin
Clamping pin is part that connects lamp body to automobile during assembly. Therefore, clamping pin must extend from lamp body. Thus, packaging process should be designed to ensure product is not damaged during transportation!

 

10. Adhesive Application Groove
Adhesive application groove is a crucial part that seals connection between lamp body and lens. While there are no strict dimensional requirements for groove, it must not be deformed to prevent damage to spray gun during adhesive application. During production, groove must be kept free of oil stains to avoid poor sealing and affecting lamp body assembly.
Positioning ribs within adhesive application groove serve to secure lens, preventing misalignment after installation in lamp body.

 

11. Screw Holes
Screw holes are divided into mounting screw holes and dimming screw holes, can also be divided into hot-fix screw holes and threaded screw holes. In comparison, size requirements for hot-fix screw holes are lower. For threaded screw holes, attention should be paid to bottom hole. If bottom hole is too small, screw is easy to crack when it is screwed down. If it is too large, thread will strip, creating a potential danger.

 

12. Dimming Screw Holes
Since there is a certain gap between screw holes, sealing ring on screw head and inner diameter surface of screw hole are responsible for sealing. Therefore, this surface should be smooth and flat to ensure lamp body's seal.
Ps: Dimming is divided into manual dimming and motor dimming. Manual dimming can adjust in four directions, while motor dimming can only adjust in two directions: up and down.
Through-hole size of screw hole should be carefully considered. If size is too small, screw cannot be inserted; if size is too large, screw will swing inside hole after insertion, affecting airtightness.
Dimming structure of lamp body can be broadly divided into two types: one is dimming via screws, and the other is dimming via a dimming screw. Thickness of upper and lower surfaces of screw hole should also be considered.

 

13. Vent Hole
Vent hole is a device used to stabilize temperature inside lamp body. When lamp body starts working, temperature inside rises, and vent hole prevents certain materials from undergoing physical or chemical changes that could cause softening or deterioration.
Vent hole is generally oriented downwards or to side to prevent moisture from entering and affecting lamp's illumination.

 

14. Wiring Harness Arrangement
Wiring harness arrangement on lamp body falls into two main categories: 1. Wiring harness is arranged inside lamp body and connected to power supply through a sheath. 2. Wiring harness is arranged outside lamp body and connected to power supply through a single harness.

 

15. Decorative Ring Positioning
Decorative ring positioning groove is used to position decorative ring when assembling it with lamp body. Attention should be paid to height and width of groove.

 

16. High-Intensity Discharge (HID) Pack
Installing a high-intensity discharge pack allows headlight to emit a strong light, resulting in relatively high temperatures and placing certain requirements on materials used in headlight assembly.

 

17. Reinforcing Ribs
Reinforcing ribs are not part of product assembly process, but based on principles of trigonometric mechanics, they protect product from damage.

 

Rearlights, as name suggests, are lights installed at the rear of a car. While not as important as headlights, they are still an indispensable part of a vehicle.
Many of functions and structures of rearlights are same as those of headlights, such as wiring harness clips, screw holes, lamp holder holes, and vents.

2. Sealing of Lamp Body and Lens
Hot Friction Method
Sealing of rear lights differs from that of headlights. Rear lights use a hot friction method to melt mating surfaces of lamp body and lens, which then cool and solidify, creating a tight bond between them. (An adhesive application method is also used.) Mating surfaces of lamp body and lens must be free of oil stains. On hot-friction rear lights, mating surfaces of lamp body and lens should also be smooth and flat.

 

3. Lamp Body Sealing
Lamp body is sealed using a sealing rib around lamp head hole, with a sealing ring installed on top. After taillight is installed in car, lamp body is sealed directly by lamp head through compression, in same way as headlight.

 

4. Aluminum Plating
Unlike headlights, taillights have a decorative ring inside, with aluminum plating applied to the ring. Taillights, however, have aluminum plating directly applied to lamp body. Therefore, although taillights are not as important as headlights, their manufacturing requirements are higher.

 

Lens is representative of the overall appearance of front and rear lights, and its appearance requirements are much higher than those of light body. Therefore, lens must be aesthetically pleasing, free of silver streaks, weld lines, and shrinkage. If defects are unavoidable due to injection molding or mold structure, they must be minimized or moved to non-critical parts of lens.

 

2. Heat-sealed Rib
Heat-sealed rib is used to seal rear light body. It uses a heat friction method to contact adhesive groove of light body. Its thickness and shape are important; excessive or insufficient thickness, or an incorrect shape, can lead to poor sealing during assembly with light body.

 

3. Ultrasonic Ribs and Hot-Filmed Screw Holes
Ultrasonic ribs and hot-filmed screw holes are used for assembling lens and lamp body, serving a fastening function. Their dimensions have very strict requirements!

 

4. Internal Beam Filter
As name suggests, internal beam filter is a decorative element inside lamp body, directly attached to decorative ring. It is used to adjust light quality of individual bulbs (as shown in picture above). Its connection with decorative ring is mainly achieved through a clasp (as shown in picture on the left).

 

Purpose of decorative panels is to adorn lamp body, preventing internal structure from being exposed and affecting its aesthetics. They come in two forms: unfinished and assembled, meeting only the most basic requirements for plastic products. Assembly relies on fasteners and screw holes on the back. Exterior must be free of defects such as burning, burrs, shrinkage, and deformation.

 

High-mounted brake light is used to indicate to vehicles behind that vehicle has braked. Because this light body is separate from taillight body and independently mounted on rear windshield, it is named a high-mounted brake light. Exterior should be free of burrs, with a smooth, uniform surface, free of bubbles, flow marks, and cracks.

 

2. Components of High-Mount Brake Light (1)
As shown in diagram, the empty slot in the middle is for mates with high-mounted brake light's lens. Wiring harness slot is for installing wiring harness, so strict size requirements apply. Empty slot can hold light bulb! Wiring harness fixing clip is used to fix wire; there are no strict size requirements, but it must not have sharp edges to prevent sharp edges from cutting wire and causing accidents such as leakage!

 

3. Composition of High-Mounted Brake Lamp (2)
In above diagram, holes 1 and 2 are used to position lens. Remaining holes and ribs are used for high-mounted brake lamp body to fit with other parts on vehicle. Therefore, size and thickness of holes and ribs must meet product size requirements!

 

High-mounted brake light's lens is representative of the entire high-mounted brake light's appearance, and its appearance requirements are much higher than those of lamp body! Therefore, lens must be aesthetically pleasing, free of silver streaks, weld lines, and shrinkage. If defects are unavoidable due to injection molding or mold structure, these defects must be minimized or relocated to non-critical parts of lens.

 

2. Positioning of Lens
Lens assembly relies on the bottom clips, screw holes, and heat-sealing ribs for positioning. Therefore, all of these must meet dimensional requirements. Heat-sealing ribs, in particular, must not deform to ensure proper sealing during assembly.

 

Reading lights are installed inside car for illumination. They are generally located on the roof between driver's and passenger's seats. Because their surface requires an aluminum plating, there must be no defects such as grease, shrinkage, or weld lines. Assembly dimensions must conform to drawings.

 

2. Positioning of Lamp Body
Positioning of lamp body mainly relies on various mounting screw holes and clips, so they must meet required dimensions.

 

Identification lights are undoubtedly used for identification. Their body surfaces must be aluminum-plated, therefore defects such as weld lines, shrinkage, and grease are not allowed! Lens must be aesthetically pleasing, free of silver streaks, weld lines, and shrinkage! Assembly between light body and other components relies mainly on various fasteners and clips! Therefore, their dimensions must meet requirements to avoid problems during assembly!

 

Beaded rings, commonly known as "cold light" rings, are used to refract and reflect light. As you can see from picture, the entire beaded ring is aluminum-plated! Requirements for aluminum plating surface of beaded rings are extremely high! Deformation, shrinkage, and other defects are not allowed! During production, oil stains must be thoroughly wiped clean! Because oil stains and aluminum plating do not fuse, they will create many pits on the surface, affecting light transmission!

 

2. Assembly of Bezel
Bezel mates with lens flare primarily through latches and clips shown in diagram. Therefore, dimensions of latches and clips must meet dimensional requirements to prevent loosening or misfitting during assembly.

 

Fog lights are used in foggy weather because they contain nitrogen gas, which has strong penetrating power and can effectively prevent traffic accidents in foggy conditions. Assembly mainly relies on latches and heated screw holes, as shown in picture.

 

2. Fog Light Lens
Fog light lens is a key element of fog light's appearance, and its aesthetic requirements are much higher than those of light body. Therefore, lens must be aesthetically pleasing, free of silver streaks, weld lines, and shrinkage. If defects are unavoidable due to injection molding or mold structure, they must be minimized or relocated to less critical areas of lens. Assembly relies primarily on clips and latches; therefore, its dimensions must conform to product requirements.

 

lamp holder is product that connects bulb to lamp body and also serves a sealing function to prevent moisture from entering lamp body, affecting use and lifespan of vehicle lamp.

 

2. Fitting Lamp Holder and Lamp Body
Top left image shows lamp holder hole, and bottom image shows lamp holder. This lamp holder is a screw-in type. When using it, touch screw-in handle by hand to allow retaining ring to enter slot, then rotate it. Retaining ring acts as a positioning element. Therefore, retaining ring size must meet product requirements to avoid loosening or inability to install after lamp body is installed!

 

Based on optical principles, when designing automotive headlights, to achieve better optical effects, part of bulb's light source is shielded, preventing direct light from shining into center! Instead, light is scattered from all sides and then reflected by cool light to achieve the best effect! This is where sun shield comes in! Because its surface needs to be aluminum-plated, surface requirements are very high! Surface must not have defects such as ripples, shrinkage, silver streaks, or oil stains!