Manufacturing process is also an important aspect of quality of decorative lighting besides design and material selection. Each production process from forming the brass arms and processing the glass, to surface finish and final assembly has a direct impact on the structural strength, decoration, service life and production cost of the fixture.
High-end residential developments, commercial buildings, and hotels are all examples of projects where a knowledge of the characteristics of various manufacturing processes aids the buyer and designer in determining the product’s quality and choosing the production solution for a particular project. Thispostmodern lighting article covers the typical manufacturing process and common manufacturing methods for decorative lighting, and discusses the impact each process has on product quality and project delivery.
1. What Is the Manufacturing Process for Decorative Lighting?
The design to delivery of a decorative lighting fixture generally involves a number of stages such as raw material preparation, component manufacture, surface finishing, assembly and quality checking. Decorative fixtures are different from mass-produced fixtures in that they may be of irregular shape, have thin wall construction, or be designed in an artistic manner, and so may require other operations to be performed, such as precision shaping and customizing the surface finishes.
Lighting Fixture Manufacturing
1) Raw Material Preparation
The first step in the manufacturing process is to prepare raw materials. Depending on the product design, the materials selected by manufacturers are Brass, SS, Aluminium Alloy, Glass, Crystal, Marble and Wood. Materials are subsequently checked for dimensions, composition, surface defects and colour uniformity.
Brass is typically tested to ensure that the proportion of copper to zinc is correct. Natural Marble is tested for grain pattern and cracks and Glass is tested for bubbles, inclusions and light transmission uniformity.
Choose materials for metals based on the forming process, structural strength requirements and service environments. For example, 6063 aluminum alloy is suitable for extrusion profiles, while 304 stainless steel is commonly used for indoor structural components. Under the condition of sea or high humidity, consider the use of 316 stainless steel based on the project needs. Glass parts are usually made with high transparency ultra-clear glass, whose light transmittance is more than 91%. Stone pieces are typically made of natural marble and/or engineered quartz.
2) Component Fabrication
Once the materials are inspected, they continue on to the process of their intended fabrication. Common parts of regular geometries are produced by mechanical techniques like sheet metal fabrication, CNC machining and tube bending. The irregular artistic structure is usually made by casting, metal spinning or hand forging. The components of light-transmitting parts are produced by hot bending, glass blowing and glass pressing, and stone parts are cut, drilled and polished.
Each part can be manufactured with a specific geometry, machining accuracy and cost, depending on the chosen manufacturing process. In some cases, complicated decorative brass components are casted, and normally metal connectors are CNC-machined to obtain better dimensions.
3) Surface Finishing and Product Assembly
The process of assembling the fixture determines the stability of the finished product, and the surface finishing determines the appearance and protection of the fixture. These are the major processes that set these lighting products apart from standard lighting products. Once the components are made, they may be surface treated by electroplating, powder coating, brushing, polishing or antique finishes.
It then moves on to final assembly, which involves mechanical assembly, electrical wiring, light source installation and functional commissioning. Pre-assembly is also necessary for large chandeliers, to ensure that all parts are in place and properly aligned before being disassembled to be packaged and shipped.
4) Quality Inspection
Once built, the final product is typically subject to an appearance, electrical and structural examination. These include dimensional measurement, power-on testing, insulation testing, grounding testing, visual inspection, and packaging inspection. The manufacturer is also required to perform the necessary tests and/or provide the necessary certifications according to the destination market requirement for export products. Only products which have been passed on the final inspection are allowed to go to packaging and shipping.
The surface should be free of any visible color variation, coating runs, and scratches that are obvious to the naked eye. Color difference of the same production batch should be within the range of ΔE < 2. Structural inspection: Full load and deformation tests. Optical inspection: Ensure that correlated colour temperature (CCT), colour rendering index (CRI) and light output are within an approved specification. Weather resistance inspection: Outdoor use products or high humidity environment products are weathered by high temperature aging and salt spray test as per project requirements.
2. What Are the Common Metal Manufacturing Processes Used in Decorative Lighting?
The basic parts of decorative lighting fixtures are metal constructions. Design complexity, structural strength, machining accuracy and production cost are directly influenced by the manufacturing process. Casting, sheet metal fabrication, CNC machining, tube bending, metal spinning or using more than one of these methods are the usual methods that manufacturers use to produce the fixture depending on the product design and the volume of products that will be produced.
1) Casting
Casting is one of the most popular metal forming methods utilized in the decorative lighting industry, particularly for brass and aluminum alloy parts. The advantage of pouring molten metal into a mold is that complex 3-D shapes can be achieved in one step. This is especially appropriate for sculptural shapes and decorative features of lighting fixtures.
The casting process can produce openwork design, irregular curved surface and one-piece integrated structure without welded joint, which is better than welding and machining. It is commonly used for decorative ornament, animal shaped part, irregular connector and European style lamp arm. But there is a relatively high initial investment in the development of molds, which makes casting more appropriate for medium and high volume production.
Lighting Fixture Casting Process
Process Parameters: The normal melting temperature of brass is around 1100–1150°C and for aluminum alloys, it is approximately 660–700°C. The dimension precision of cast decorative parts is usually ±0.5-1.0mm.
These can be used with any Crystal, European, Brass or large chandeliers in hotel lobbies.
2) Sheet Metal Fabrication
Sheet metal fabrication is the creation of metal sheets into various forms using techniques such as laser cutting, stamping, bending and welding.
Compared with casting, the cost of tooling for sheet metal is low, and the production efficiency is high, especially suitable for the production of contemporary minimalist lighting fixture.
Lighting Fixture Sheet Metal Fabrication
Because sheet materials have uniform thickness and provide high machining accuracy, many modern wall lights, ceiling lights, and linear pendant lights use sheet metal structures. The main advantages are controllable production cost and excellent batch consistency. The problem is that it is not possible to make complex curved surfaces directly. Irregular shapes typically need several pieces to sew together and have small lines of seams.
Process Parameters: The precision of the laser cutting is generally about ±0.1 mm, and the deviation of the bending angle is generally about 0.5° for the CNC bending.
Inspect after bending and welding for the general dimension, hole locations, perpendicularity and welding deformation.
Products it can be applied to include wall lights, ceiling lights, linear pendant lights and modern decorative light fixtures.
3) CNC Precision Machining
CNC machining is the process of using computer-controlled machine tools to machine the parts with a high degree of dimensional accuracy and excellent surface quality. It is widely used in connectors, mounting parts, lamp holders, precision parts and other parts that require precision. The advantages of CNC machining are that processing costs are relatively high, but it can effectively control the tolerance during the assembly process, and the product can be made more consistent, so it is widely used in high-end custom lightings.
Process Parameters: Repeat positioning accuracy ±0.02 mm, dimensional tolerance ±0.1 mm, surface roughnes Ra ≤ 1.6 μm.
Application: High-quality brass lighting fittings, custom lighting fittings and precision connectors.
Lighting Component CNC Machining
4) Tube Bending
Tube bending involves the use of special machinery to bend metal tubes into various angles and curves. It is one of the most widely adopted methods of manufacturing decorative lighting today. One-piece bent tubes offer smoother lines and fewer welded seams as compared to a series of straight tube sections welded together.
The bending radius and accuracy of production will directly influence the overall appearance and installation accuracy of the fixture. The problem with manual tube bending is that it can easily lead to uneven and thin walls in the bend. The automatic tube bending mandrel support with CNC is significantly enhancing the bends’ quality and retaining the clean and flowing appearance needed for a sleek and elegant lighting fixture.
Useable Products: Contemporary chandeliers, floor lamps, reading lamps and creative decorative lamps.
In structures with continuous curves, the lack of bending accuracy is easy to lead to the lack of symmetry and the deviation of installation after multiple lamp arms are assembled. High-end projects therefore normally include an additional trial assembly process.
Lighting Fixture Tube Bending
5) Metal Spinning
Metal spinning is a process that uses a rapidly spinning mandrel to gradually form sheet metal into the desired cross section. This process is especially well suited to the production of round, cone and hemispherical lampshades. Relative to casting, spun parts offer superior material usage, superior surface quality and lower weight. Metal Spinning is however, best suited for axisymmetric structures. The more complicated the geometry the more parts that will be needed to fabricate.
Use for metal lampshades, pendant lights, restaurant pendant lights and industrial style metal lamps.
Lamp holder metal spinning
3. Processing Technologies for Glass, Stone, and Other Decorative Materials
Decorative materials for decorative lighting can also consist of either glass, natural stone, crystal or metal structures. The manufacturing process for each material will vary, with implications not just on the look of the fixture, but also its light transmission, weight, durability, and price.
1) Blown Glass
Blown glass refers to the natural, flowing shapes of glass glass formed by blowing, either by hand or by machine, the molten glass into a desired form. Blown glass comes in slightly different variations, thus it is used, in high end custom lighting and artistic decorative fixtures.
Blown glass can create freer curves, varying wall thicknesses, and natural textures, when compared to pressed glass. It provides a lower dimensional consistency, slow production speeds and is dependent on highly skilled craftsmanship, however.
Use: Artistic chandeliers, modern glass chandeliers, and custom chandeliers for hotel projects.
Blown glass is a handcrafted product. Minor variations in thickness, texture, and bubble distribution within the same production batch are normal process characteristics rather than quality defects.
Blown Glass Manufacturing
2) Pressed Glass
Pressed glass is created by pressing it in just one press, using a mold. It is suitable for the use of patterned glass shades, louvered light diffusers and other uniform glass parts with high dimensional uniformity. Pressed Glass: Pressed Glass can be manufactured in large quantities, has good dimensional accuracy, high production efficiency and low manufacturing cost compared with blown glass.
Compatible Applications: Wall light, ceiling light, hotel guestroom light and large volume project applications.
Pressed Glass Manufacturing
3) Bent Glass
Bent glass is created by taking flat glass and applying heat to it until it’s soft enough to bend into the desired shape. This process can develop curves, wave shapes and other complex surfaces. Bent glass is more designable than flat glass, and is very popular in contemporary art lighting and decorative lighting applications.
Glass cutting, drilling, and other machining operations must normally be completed before thermal bending. Therefore, all dimensions must be fully verified before production begins to avoid costly rework of an entire production batch.
Products Usage: Modern chandeliers, decorative lighting for artistic purposes, and commercial lighting fixtures.
Bent Glass
4) Marble Cutting and Polishing
Most often, natural marble is cut, drilled, chamfered and polished prior to being made up into lampshades, bases or decorative finishes. As each natural stone slab has its own grain pattern, colour and veining is bound to vary. In this way, physical samples are usually required for approval for high end projects. It is also recommended that a protective sealer be used to ward off staining, yellowing or discoloration over time.
The process flow is: CNC waterjet cutting, chamfering and edge finishing, coarse grinding, fine grinding, final polishing and protective sealing treatment.
If the stone component has a flatness, the finished flatness can be controlled within 0.3 mm/m generally. Polished surfaces can be made with a gloss level of more than 85 GU without any scratches and without edge chipping.
The lighting products that can be used are table lamps, wall lights, floor lamps, and high-end decorative lighting fixtures.
5) Crystal Processing
There are a few types of decorative lighting that are typically made with K9 crystal, optical crystal, and natural crystal. Cutting, edge grinding, polishing and drilling are required for each material. Improving the accuracy of the machining process leads to the creation of light refraction and brilliance, but also raises production cost.
The processes include CNC precision cutting, manual beveling, multi-stage polishing and ultrasonic cleaning.
The finished product of high quality K9 crystal can provide light transmittance greater than 90%, and can transmit the light without any color impurities, without darking.
Use the chandelier in Crystal, Banquet Hall and Hotel Lobby.
When buying crystal lighting, be sure to look at the cutting precision, polishing quality and crystal material. The quality of crystal will have a more even light refraction, whereas the low-grade crystal will be cloudy, have poor light dispersion, or have variable color.
Crystal Manufacturing
4. Which Manufacturing Processes Still Require Manual Work?
Although most of the components required to manufacture a decorative lighting fixture are being replaced by laser cutting, CNC cutting and automated welding, traditional light manufacturing still requires skilled artisanal skills to guarantee the detail, finish and assembly.
1) Hand Welding
Hand welding is still the most popular method of joining components for fixtures with complex geometries or for low volume production. According to the material and structure property requirements, the welding expert should select the appropriate welding method to reduce the welding distortion and ensure that it is kept to a minimum and the structural integrity is not affected.
Hand welding is better for curved and irregular surfaces, openwork joints, difficult to reach areas and precision thin-wall components than robotic welding.
It also requires a much higher level of operator skill, however.
Applicable Products: Brass chandeliers, artistic lighting fixtures, and custom hotel lighting.
Hand Welding
2) Hand Grinding and Polishing
Grinding and polishing directly affect the level of gloss and surface texture in metal parts and is one of the most difficult processes to be fully automated. There are still areas to be hand carved, and complex curved surfaces, decorative carvings, and intricate structures that require a highly skilled technician.
If products are electroplated or PVD coated, the poor polishing will still be evident after the high quality coating has been applied. Some surface irregularities (ripples, pinholes, irregular reflection) can remain.
Refining edges and curved surfaces, blending welded joints and finishing complex brass lighting fixtures can be a longer process than the welding itself. These preparation processes also affect the flatness and finish of the final electroplated or PVD finish.
Hand Grinding and Polishing
3) Hand Assembly
Large chandeliers, crystal chandeliers, and custom chandeliers are the most popular styles. The last chandelier type is typically hand made. Technicians assist in installation of metal structure and in installation and fine-tuning of the crystal pendants, glass shades, electrical wiring and decorative elements.
With multi-tier chandeliers, the entire assembly is also required to be done during a trial fit to see how the components fit together, how the chandelier is arranged vertically and how the fixture is balanced, ensuring it is installed correctly during the job.
Large chandeliers are normally completely installed at the factory and the installation sequence is documented and recorded. The fixture is then taken apart and shipped to the installation site and put back together based on the fixture Identification numbers, which cuts down on installation time and greatly helps to avoid assembly mistakes.
Lighting Fixture Assembly
4) Hand-Applied Decorative Finishes
High quality decorative lighting fixtures can be finished using antique patina, color rubbing, hand gilding, and antique brass finishes, to give more depth to the lighting and a more refined artistic look.
These processes of finishing are not fully automated like the other finishing processes such as electroplating or powder coating. Some differences in the individual products are to be expected and one of the hallmarks of high-end custom lighting.
Experienced manufacturers will often send a sample finish to the customer for approval prior to mass production for finishes like antique brass and antique gold so that the final product looks as per the design intent approved by the customer.
Lighting Fixture Decorative Finishing
5. What Are the Common Surface Finishing Processes for Decorative Lighting?
Surface finishing affects the color, texture, corrosion resistance, wear resistance and overall lifespan of a lighting fixture. Various finishing methods can be used in the different materials and application environment.
1) Electroplating
Electroplating involves the process of coating a component with a metal to enhance its surface properties such as its appearance, corrosion resistance and wear resistance. Bright chrome, nickel, gold, rose gold and gunmetal are all common finishes.
One of the most sought after surface treatments in decorative lighting is electroplated finishes which give a smooth surface and a high-end metallic look. But the quality of the last coating is strongly dependent on surface preparation. However, if the grinding and polishing are not done well even using the same plating process, it can also be likely to suffer from pitting, surface waviness, and uneven color.
Use: For application in the following products: Brass chandeliers, modern chandeliers, hotel decorative lighting and high-end custom lighting.
2) Powder Coating
Powder coating is the process of applying powder to the metal surface using electrostatic charge and then heating the surface at a high temperature to form a protective coating.
The thickness of the coating, its wear and corrosion resistance are better than conventional liquid paint. It has a stable color and high production efficiency, and is widely used in modern lighting in the industry and large-scale production engineering projects. It is especially recommended for use in public areas and areas of high humidity in long term use.
Applies to: Modern chandeliers, wall lights, outdoor decorative lighting and commercial lighting.
3) Painting
Painting has a variety of color choices and increased design flexibility. It has the ability to create matte, gloss, metallic and gradient finishes, making it suitable for custom lighting fixtures.
Painting is easier to obtain special colors than electroplating, but in general the paintability is not as good as that of electroplating in terms of durability. For large production projects, it is important to manufacturers to verify the standard color references (RAL, Pantone etc.) and to approve color samples before producing in order to reduce batch-to-batch colour variation.
Use for Custom lighting fixtures, artistic lighting fixtures, modern decorative lighting.
Lighting Canopy Painting
4) Brushed & Polished Finish
Brushing creates a uniform surface grain through mechanical treatment, reducing the visibility of fingerprints and minor scratches. Fine polishing is applied to create a highly reflective surface, adding a cleaner and more upscale modern look to the fixture, which is called mirror polishing. Both processes are applied as a base treatment before electroplating or PVD and can also be directly used for the final treatment. Mirror polishing gives a high visual effect but the surface will be more vulnerable to scratching when being hauled and installed. For high-end projects, the protective film is usually left on until the time of installation.
Use for products: Brass, stainless steel and modern decorative lighting.
5) Antique Finish
Antique finishing is a technique that applies chemical coloring, hand rubbing or the aging process to give the appearance of naturally oxidized metal, like antique brass, antique gold and antique silver effects. Many of these operations are manual, so there will be variations between products. This is also a characteristic of antique finishes.
The final antique color is difficult to confirm accurately from photographs alone. Therefore, the manufacturers must obtain the approval of a physical finish sample, prior to formal production, to prevent colour disputes after mass production.
Useful Products: European style lighting fixtures, American style lighting fixtures, hotel lobby lights and artful decorative lights.
6) PVD Vacuum Coating
PVD (Physical Vapor Deposition) is a vacuum coating process that provides a high hardness protective coating via a physical deposition process. Compared with conventional electroplating, PVD provides better wear resistance and color stability. However, in the last few years, manufacturers are increasingly using PVD on top-notch brass and stainless-steel decorative lighting for high-end finishes like gold, black titanium and champagne gold.
Not all metals are suitable to be coated by PVD. PVD’s advantages over electroplating are not always considered as the reason for choosing PVD, manufacturers usually choose PVD or traditional electroplating according to the base material, color needs and project budget.
Ideal for luxury lighting for residential projects, hotel projects, and bespoke lighting for commercial projects.
6. How Do Different Manufacturing Processes Affect Decorative Lighting Quality?
A fixture’s manufacturing processes impact its appearance and more. They also affect the strength of the structure, the accuracy of assembly, surface quality, long-term stability and the cost of production. In the case of hotel and commercial applications, these differences can impact the quality of the installation, maintenance down the road and service life.
1) Impact on Structural Strength and Load-Bearing Performance
Casting produces fewer joints and is more appropriate for complex one-piece arms for lamps and decorative parts, but may have porosity, shrinkage cavities and ununiform wall thickness that affect local strength. Welded joints can be used in bent and welded sheet metal structures, but the section and wall thickness control is easy; however, the welding distortion and stress concentration should be minimized for large frames.
These are spun components, which are lighter, have smooth surfaces, and are better for lamp shades and housings, and less suitable for structural purposes. Because of the size of the chandeliers, often a combination of a welded main frame, cast decorative parts and CNC-machined connectors are used, rather than just one of the manufacturing processes.
2) Impact on Dimensional and Assembly Accuracy
Accuracy ranking, from highest to lowest: CNC precision machining > sheet metal laser fabrication > metal spinning > precision casting > fully handcrafted fabrication.
The accuracy of the CNC machining is ±0.02 mm and the assembly of zero clearance can be completed. In batch production, sheet metal fabrication ensures that the components are produced consistently and with an accuracy that meets strict standards. The casting is suitable for irregular forms and gives an adequate level of accuracy for decorative applications. The dimensional variation of handcrafted fabrication is the largest and is primarily used for artistic custom work and not for high precision assembly applications.
3) Impact on Surface Texture and Decorative Effect
Artistic look: The look depends on the process used. Natural variations occur when the glass is hand-blown and/or finished in antique. Casting can be used for relief detail, decorative patterns and 3-D shapes. Metal spinning is ideal for producing smooth, continuous circular surfaces, while sheet metal fabrication and CNC machining are ideal for modern designs that require clean edges and precision. The decorative effect needs to be in line with the design intent, a more handcrafted process does not necessarily result in a higher grade.
The lighting effect: The precision finishing of high-transmission glass and precision processing of K9 crystal can achieve the maximum uniform light transmission and the maximum visual depth. They may be irregularly processed light-transmitting materials that can create irregular light spots and light attenuation, disturbing the decorative of the space directly.
4) Impact on Product Consistency and Long-Term Stability
Batch consistency: Highest batch consistency for automated sheet metal fabrication, CNC machining and pressing. Casting offers the next level of consistency and fully handcrafted production is the greatest variation in color, texture and dimensions.
Long term stability: Coatings such as PVD coating, powder coating and heat treatment of cast components can effectively remove the stress of the structure, and enhance the weather resistance. Conventional painting, non-annealed castings, and manually joined fixtures tend to deform, pull away from the casting, and oxidize over time.
5) Impact on Production Cost and Lead Time
Different manufacturing processes have significantly different cost structures and production efficiencies. Based on a manufacturer’s internal mass-production records for comparable standard lighting fixtures, if batch sheet metal fabrication is taken as a cost index of 1.0, CNC precision machining is approximately 1.8, metal spinning approximately 1.5, precision casting approximately 2.0, and labor-intensive handcrafted production approximately 3.2.
Under similar conditions of material, structural complexity, and production capacity, the component processing lead time for 100 standard lighting fixtures can be referenced as follows: approximately 3 days for sheet metal fabrication, 5 days for CNC machining, 6 days for metal spinning, 7 days for casting, and 15 days for labor-intensive handcrafted production. These lead times cover only the corresponding manufacturing process and exclude material procurement, surface finishing, final fixture assembly, testing, and packaging.
In real mass production, the standard project order usually puts emphasis on sheet metal fabrication, stamping or pressing to control the unit cost and lead time. When a fixture is complex with irregular shapes, use casting to finish it, and when it is a threaded connector, locate part or other high tolerance parts, use CNC to finish.
7. Need Help Manufacturing Custom Decorative Lighting?
We can offer recommendations of suitable manufacturing processes based on your design drawings, materials required, budget considerations and target markets and make feasibility assessments and quotes for a new decorative lighting product or for a reliable manufacturing partner for hotel, commercial or high-end residential projects.
From high-end decorative lighting crafted from brass, crystal, or marble designs, to OEM, ODM, or customization, Postmodern Lighting has the expertise to optimize the product structure, manufacturing process, and surface finishing solution to ensure the product is both high quality and low cost with an optimized delivery time. Please feel free to contact us.
