Manufacturing Process of Car Headlights: A Detailed Research Report

This report provides a detailed analysis of the car headlight manufacturing process. It begins with an introduction to car headlights and their essential components, including the bulb, reflector, and lens. The report explains the function of each component, with the casing serving as a frame, the bulb providing illumination, the reflector optimizing beam range, and the lens protecting the interior. It then delves into the manufacturing processes for each component, including the casing, different types of headlight bulbs (LED, halogen, etc.), reflector design (parabolic and free-form), and lens materials (polycarbonate). The report also covers the bezel and its role. The report highlights the importance of material selection, design considerations, and the application of technologies such as injection molding and vapor deposition in the manufacturing of these components. It also explains the manufacturing processes for reflector and lens. The report concludes by summarizing the key aspects of car headlight manufacturing, emphasizing the integration of these components to ensure functionality and aesthetics. This report is useful for students studying engineering and automotive design.

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CAR HEADLIGHT MANUFACTURING
A Research Paper on Headlights By
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INTRODUCTION
A car headlight is a lamp coupled to the front of an automotive to light the road ahead.
The car headlight components are highly controlled products that must conform to the standards
of performance during its manufacturing. The major components making up the car headlights
include bulb, reflector, and lens. The bulb is used in the production of light for illumination and
it is located in the focal point of a parabolic reflector through standard holders secured on the
headlight assembly casing. The concentric beams impact the reflector after being generated by
the bulb which then directs light to lighten road. The figure below shows the basic components
of the car headlight:
Figure 1: Car headlight components (Ashby, 2011)
The totally integrated headlight shape is attained by producing a continuous surface
curvature with front fenders of the car. The method of surface construction depends on the cures
of the surface on the surface of the front fender which propagate across the enclose profiles with
the conditions of curvature continuity.
Figure 2: The car’s front fender surface (Dashchenko, 2012)

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The components required in the manufacture of the car headlights include casing,
reflector, bezel, headlight bulb, and lens. These components used in the manufacturing of car
headlight together with their manufacturing are explained below in detail:
Casing
The casing provides a frame for mounting all the headlight components. The lens is
sealed hermetically to the casing through adhesion. The casing is composed of a reference plane
for mounting reflectors and bulbs and is used in maintaining the relative accurate positions. The
bulb holder is fixed on the bracket to assist in proper positioning on the bulb, while the reflector
is screwed on the bracket of the casing by the use of adjustable screws. The casing design is
based on a plane and also the conceptual models of the bezel, reflector, and lens (Dashchenko,
2012).
Headlight Bulb
The bulb is the source of light for the headlight and it depends on the requirements of
illumination for the particular market. The major breakthrough regarding the manufacture of
bulb includes a light emitting diode (LED), high-intensity discharge tube, Halogen lamps, and
incandescent lamps (Engineers, 2009).
Reflector
The reflector is used for the collection of light from the source so as to attain optimum
beam range. The reflector shape normally originates from a surface that is parabolic. The shape
of the reflector from the paraboloidal surface is varied by the focal depth of the reflector. The
current technology of reflectors is composed of numerous configuration such as free-form
reflectors or stepped reflectors based on the technology of optical imaging like the system of

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Poly-Ethipsoid. Materials used in the manufacture of reflector should not be distorted when high
radiation and temperatures are applied (Stadtler, 2014).
The process of manufacturing reflector starts with deep draw moulding and then powder
coating or galvanization. Painting is then done on the reflector to produce smooth surface after
which the reflective layer of aluminium is made by the technique of vapour deposition. The
manufacturing process of plastic reflectors is performed by the process of compression moulding
or injection moulding and then followed by reflective layer coating. The construction of the
paraboloidal surface is performed for the parameters of dimensions such as K, height, and width
value (Shimokawa, 2012). The technique of acquiring the reflector dimension from the boundary
curve during manufacturing is as shown below:
Figure 2: Technique of obtaining reflector dimension (Happian, 2010)
The reflector design of a car is controlled by the parabolic expression in which the
reflector shape depends on the K value which denotes the parabola constant and is a parameter
that is predefined by the manufacturer.
Height reflector = Aspect ratio × Width reflector (Motor, 2009)

Manufacturing of Car Headlights 5
Lens
The lens is involved in the protection of the interiors of the headlight from external
forces. It is positioned at the exterior surface of the headlight and plans a significant role of
beautification of the car. It is a translucent or transparent surface that covers the source of light
and enables conformance with the calorimeter and photometric requirements. The lens is applied
in filtering colours that are unwanted from the reflector emitted white coloured light. The lenses
are manufactured from a glass of high purity and free from streaks and holes. The current cars
use clear lens specifically made from plastic because of its cost advantage and lightweight
(Shimokawa, 2012).
The materials used in the manufacture of the lens should be easy to manufacture, durable,
good optical properties, and resistance to heat. Polycarbonate is applied in the majority of the
headlight application as a lens material since it can withstand temperature up to 171oC. The
process of injection moulding is normally used in the manufacture of lens followed by coating to
protect the surface from scratches and ageing. During manufacturing, the characteristics of the
lens are categorized into a material feature, rib feature, and surface feature. The rib feature
control mating with casing and certifies alignment with the vehicle’s front fenders (Motor,
2009).
The surface feature governs the shape of the exterior and is also as a free-form feature.
The purpose of curvature continuity of the surface within the curve boundary implemented
during manufacturing of lens and can be reused in the development of lens for any shape of the
car. The figure below shows the template that encapsulates the design and support re-use
(Shimokawa, 2012).

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Figure 3: Product template for lens design (Ashby, 2011)
Bezels
This is not a major component of the headlight, but it plays a significant role during the
operation of the reflectors. Some manufacturers coat bezel with a layer of reflection and
performs as a secondary reflector. There is anchoring of the reflector to the headlight casing by
the use of adjustable screw and it has to be able to move freely for the purposes of aiming
through vertical adjustment. Bezel acts as a spacer between the lens and the reflector and it
normally attached to the ribs lens hence enabling disassembly during inspection or maintenance
of the headlight. During manufacturing, the bezel is coated and polished with the metallic film.
The conceptual design of the bezel begins from the boundary profiles similar to the lens and
reflector (Chang, 2013).
Conclusion
The major components making up the car headlights include bulb, reflector, and lens. The
casing provides a frame for mounting all the headlight components. The lens is sealed
hermetically to the casing through adhesion. The bulb is the source of light for the headlight and
it depends on the requirements of illumination for the particular market. The reflector is used for
the collection of light from the source so as to attain optimum beam range. The lens is involved

Manufacturing of Car Headlights 7
in the protection of the interiors of the headlight from external forces. Bezel acts as a spacer
between the lens and the reflector and it normally attached to the ribs lens hence enabling
disassembly during inspection or maintenance of the headlight.

Manufacturing of Car Headlights 8
Bibliography
Ashby, M., 2011. Materials Selection in Mechanical Design. Melbourne: Butterworth-Heinemann.
Chang, K.-H., 2013. Product Manufacturing and Cost Estimating using CAD/CAE. Colorado: Academic
Press.
Dashchenko, A., 2012. Manufacturing Technologies for Machines of the Future. Perth: Springer Science
& Business Media.
Engineers, A., 2009. Automotive Engineering International, Volume 110. New York: Society of
Automotive Engineers.
Happian, J., 2010. An Introduction to Modern Vehicle Design. California: Elsevier.
Motor, I., 2009. Assembly Plant Performance and Changing Market Structure in the Luxury Car Segment.
London: International Motor Vehicle Program.
Shimokawa, K., 2012. Transforming Automobile Assembly. Sydney: Springer Science & Business Media.
Stadtler, H., 2014. Supply Chain Management and Advanced Planning. Melbourne: Springer.