Manufacturing processes

After the creation and signing off of the elease drawings (see p.109), the tooling required to manufacture and design is built and long lead-time components are ordered. It is very common that the tooling required is outsourced to specialist toolmakers. The tooling is subjected to extensive testing and modifications to iron out any glitches and ensure that the tools can effectively produce components and parts that meet the intended aesthetic, functional requirements, quality, volume, and dimensional accuracy. It is at this stage that beta prototypes are produced using parts that represent the actual intended manufacturing processes and components. After extensive user, reliability, and performance field-testing, where the general public tests products, the manufacturer will be able to confidently begin producing the product for sale/use.

There are essentially five ways of making things: take something away, add something, cast something, form something, or grow something. Within each way there is an infinite variety. To add to this, there are many techniques to finish the product, such as painting, coating, and engraving. Below is an introduction to some of the most common manufacturing processes and techniques.

Cutting

Cutting is the separation of a physical object, or a portion of a physical object, into two portions, through the application of an acutely directed force such as a blade or saw.

Machining

This is the collective term for the numerous processes of cutting or removing material from a solid piece, such as boring, drilling, milling, shaping, and turning. These are collectively referred to as chip forming. The production of chips of material result from the cutting processes in which power-driven machine tools, such as lathes, milling machines, and drill presses, are used with a sharp cutting tool to mechanically cut the material to achieve the desired form.

Machining offers the advantage of being a highly versatile technique to produce a wide variety of complex shapes, in virtually any solid material, and to a high degree of accuracy. However, the process can produce a large amount of wastage, especially when having to use stock sizes of material.


Costs

Low tooling costs and low unit costs


Quality

High


Production scale

One-off to medium-volume manufacture


Alternatives

Laser cutting


Drilling: A drill is a tool with a rotating bit (cutting off thin shavings of material or crushing and removing material) used to make holes. Cutting fluid is often pumped to the cutting area to cool the bit, lubricate the cut, and to sluice away the unwanted debris and waste resulting from the process, which is known as swarf.

Boring: This process involves enlarging a hole that has already been drilled (or cast), by means of a cutting tool. Boring is used to achieve greater accuracy of the diameter of a hole, and can be used to cut a tapered hole.

Milling: A milling machine is a machining tool used for the shaping of metal and other solid materials. Like drilling, a rotating cutter rotates about an axis commonly known as a spindle axle; however, a milling machine can perform a wide range of tasks such as planing, drilling, routing, and engraving due to its ability to multi-axis cut. Milling machines may be manually operated, mechanically automated, or digitally automated via Computer Numerical Control (CNC).

Shaping: This material removal process involves a single-point cutting tool moving across a stationary block of material to produce a shaped or sculpted surface.

Turning: This process involves rotating a material around an axis on a lathe, and employing a cutting tool to produce “solids of revolution.” Turning is restricted to producing circular profiles, but can be used for low- or high-volume production runs for a variety of materials and has low tooling costs.

Die cutting

This process involves a formed sharpened block, known as a die-cutting tool, making a predetermined incision when pressure is exerted, cutting or creasing a thin material. Die cutting is ideal for batch production due to its low set-up costs, but if the process is used to produce 3D products then the flat die-cut forms will need expensive hand assembly or secondary processes.


Costs

Low tooling costs and unit costs


Quality

High


Production scale

One-off to high-volume manufacture


Alternatives

Laser cutting, water-jet cutting, punching and blanking


Punching and blanking

This process involves a hardened steel punch cutting through sheet materials, and allows for a variety of profiles to be cut out.


Costs

Low to moderate tooling costs and unit costs


Quality

High, but the cut edges often require finishing


Production scale

One-off to high-volume manufacture


Alternatives

CNC machining, laser cutting, water-jet cutting


Bent, designed by Stefan Diez and Christophe De La Fontaine for Moroso, 2006. These tables are fabricated out of laser-cut perforated aluminum sheets.

Water-jet cutting

This technique employs a tool capable of slicing into metal and other solid materials such as glass and stone using a high-pressure jet of water, enabling very fine details to be cut. It is a cold process that doesn’t heat up a material and risk deformation. However, as the cutting jet splays the farther it gets from the nozzle, the thicker the material cut, the more the cut edge is deformed. To ensure the back of the material being cut is not damaged from splash-back, it is common practice to use a sacrificial layer of plastic to protect the piece.


Costs

No tooling costs and moderate unit


Quality

Good


Production scale

One-off to medium-volume manufacture


Alternatives

Laser cutting, die cutting, punching and blanking


Laser cutting

This process involves cutting metals or other non-reflective materials using a high-powered, computer-controlled laser. The process allows for intricate patterns to be cut and leaves a clean, high-quality finish. While the process has the advantage of not requiring expensive tooling to cut materials, its low speed means that it is best suited for one-off and batch production.


Costs

No tooling costs but medium to high unit costs


Quality

High


Production scale

One-off to high-volume manufacture


Alternatives

CNC machining, punching and blanking, water-jet cutting


Etching

This process uses acid to cut into the unprotected parts of a metal surface to create a design in the material. Photo-etching uses a photosensitive coating that is then exposed to light to etch metal.


Costs

Very low tooling costs but moderate to high unit costs


Quality

High


Production scale

One-off to high-volume manufacture


Alternatives

CNC machining and engraving, laser cutting


Garland Light, designed by Tord Boontje for Habitat, 2002, and Artecnica, 2004. Made from a continuous etched metal strand that is wrapped around a lightbulb, the charming floral forms of this shade have led to the popular rediscovery and use of decorative motifs in recent years.

Micro World, designed by Sam Buxton, 2003. This is part of a series of fold-up metal sculpture business cards, where each scene folds from a flat sheet of photo-etched stainless steel just 0.005in (0.15mm) thick. All are packaged flat with folding instructions for buyers to complete the sculpture.

Joining

Joining is the mechanical, structural, or chemical bonding of different components to form a larger object.

Fasteners

A variety of removable or permanent fastenings are often used in assembly, such as rivets, pins, screws, staples, collars, and snap-fits.


Costs

No tooling costs but may require jigs; unit costs can be moderate to high depending upon the complexity


Quality

Low- to high-strength fixings available


Production scale

One-off to high-volume manufacture


Alternatives

Adhesive bonding, welding, joinery (wood)


Adhesive bonding

This is the process of joining two or more parts by using an adhesive. A form of mechanical fixing such as a clamp or bracket to prevent misalignment is often used to ensure a secure bond. Most commonly used in bonding plastics, this method has begun to be used to bond metals.


Costs

No tooling costs but may require jigs and additional fasteners


Quality

High-strength bond


Production scale

One-off to medium-volume manufacture


Alternatives

Mechanical fixing, welding


Soldering and brazing

This process involves adhering metal components together using a metallic soldering or brazing alloy that melts below the temperature of the metals being joined to avoid thermal distortion of the components. The metallic soldering or brazing alloy is essentially a type of “glue.” The difference between them is that the melting point for soldering is much lower.


Costs

No tooling costs but may require jigs; high unit costs


Quality

High-strength bond


Production scale

One-off to high-volume manufacture


Alternatives

Welding


Welding

This is the process of joining metal parts by applying heat and/or pressure. The process results in a joint as strong or stronger than the parts themselves. The two basic categories are fusion welding (where the temperature of the metal is brought to its melting point and joined, with or without filler material) and solid state welding (where the metal is joined at a temperature below the melting point of the material, without the addition of a filler material). The most common example is friction welding, where two rods or pipes are rubbed together, with the heat generated causing the two parts to weld together.


Costs

No tooling costs but may require jigs; low unit costs


Quality

High quality


Production scale

One-off to high-volume manufacture


Alternatives

Mechanical fixing, adhesive bonding


Kelvin 40 concept Jet, designed by Marc Newson, 2004. The partially riveted, welded, and bonded structure is shown (above), while (below) the designer completes his final check on the canopy latch system.

Joinery

This is the term used to describe woodworking techniques to join wooden parts with glue or without, known as dry joints. These can be constructed by hand or machine-made. They offer a variety of structural and aesthetic qualities suitable for a wide range of applications, from furniture and cabinet-making to the construction industry.


Costs

No tooling costs but may require jigs; unit costs can be moderate to high depending upon the complexity


Quality

High-strength bond


Production scale

One-off to medium-volume manufacture


Alternatives

Mechanical fixing, welding


Weaving

This describes the passing of strips or strands of material over and under each other to form an intertwined structure. Traditional woven furniture was made from bamboo, rattan, and willow, but modern techniques enable a far wider range of materials to be woven together, from paper and plastic to wood and metal. Woven structures rely on mere friction (rather than the adhesives used in laminating) to create rigidity; by being more flexible they can easily be deformed and molded, enabling designers to produce complex forms impossible to develop through lamination. Hand-weaving is a relatively slow process that requires skilled labor, while machine weaving is a high-speed process.


Costs

No tooling costs


Quality

Dependent on which material is used


Production scale

One-off to high-volume manufacture


Alternatives

Upholstery for flexible applications or laminated wood or composites for rigid applications


Apollo, designed by Ross Lovegrove for Driade, 1997. This modern chaise lounge chair is made from rattan.

Togo, designed by Michel Ducaroy for Ligne Roset, launched in 1973. This was the first sofa to be manufactured without a frame, and simply made of multiple-density foam with generously quilted covers that are fully removable and available in a wide range of colors and textiles.

Pools & Pouf!, designed by Robert Stadler, 2004. These upholstered seating components in black leather with tufted details are like a traditional Chesterfield sofa. They deliberately blur the boundaries between functional furniture and design as art.

Upholstery

This is the process of bringing hard and soft components and materials together to create finished furniture. Typical chairs consist of structural wooden frames, foam padding, and a textile cover. This traditional approach has been complemented by design innovations, such as creating seating without a frame—for example, the first all-foam sofa, the Ligne Roset Togo, which reinvents the traditional Chesterfield.


Costs

No tooling costs but unit costs depend on complexity, and material selection and can be costly


Quality

Skilled upholsterers can achieve very high standards of quality


Production scale

One-off to high-volume manufacture


Alternatives

None


Casting

Casting involves pouring a liquid material into a mold, which contains a hollow cavity of the desired shape. The liquid is allowed to solidify and the solidified part, known as the cast, is then ejected or broken out of the mold.

In manufacturing, the terms tools or molds refer to a cavity in which a part is formed. Tools can be made from a variety of materials depending on the material to be cast. High-volume tools can be manufactured from exceptionally hard and brittle tool steel, while shorter-run parts can be produced from less durable wooden, plastic, or aluminum “soft” tooling.

Injection molding

The process of injection molding, in which granules of raw material are conditioned by heat and pressure to reach a fluid state and then injected into a steel mold, is frequently employed for the common polymers polystyrene, high-density polyethylene, polypropylene, and acrylanitrile butadiene styrene (ABS). A common technique for making multiple-color or component thermoplastic objects, such as toothbrushes, is multi-shot molding. This typically involves the injection molding of the first part, before inserting this into another mold in which a subsequent part is molded onto it. Injection moulding also enables decoration such as graphics to be added during the molding process through the use of printed foils being placed into a mold prior to the plastic being injected. Injection molding is a highly versatile process, enabling the production of complex forms very precisely. However, it involves considerable investment and is only really appropriate for high-volume production.


Costs

Very high tooling costs but very low unit costs


Quality

Very high-quality surface finish


Production scale

Only suitable for high-volume production runs


Alternatives

Rotational molding


Blow molding

This enables the production of hollow forms. Plastic is melted down before being forced into a mold by compressed air, pushing the plastic out to match the mold. Once the plastic has cooled and hardened, the mold is opened up to release the finished part. Blow molding demands high production volumes to be financially viable due to the high cost of making the moulds required. However, it does allow manufacturers to make simple hollow forms exceptionally fast and with a very low unit price.


Costs

Moderate tooling costs and low unit costs


Quality

High, enabling uniform wall thickness and a high-quality surface finish


Production scale

Only suitable for high-volume production runs


Alternatives

Injection molding, rotational molding


Algue, designed by Ronan & Erwan Bouroullec for Vitra, 2004. The brothers have created injection-molded interior design components and decorative elements here. Reminiscent of plants, the plastic elements can be linked together to form vine-like structures, from light curtains to thick, opaque partitions.

Dip molding

This is one of the oldest techniques for forming shapes, and simply involves dipping a shape into a melted material. Best known for producing rubber gloves and balloons, it is highly cost-effective for short production runs.


Costs

Very low tooling costs and low to moderate unit costs


Quality

Good, with no flash or split lines caused by two-part molds used by other methods


Production scale

One-off to high-volume manufacture


Alternatives

Injection moulding of sleeves and covers


Reaction injection moulding (RIM)

This is a similar process to injection molding, but rather than using thermoplastics, thermosetting polymers are used, which are cured within the mold. Typical applications are foam moldings for furniture and soft toys.


Costs

Low to moderate tooling costs


Quality

High-quality moldings


Production scale

One-off to high-volume manufacture


Alternatives

Injection molding


Glassblowing

This centuries-old process involves inflating molten glass with the aid of a blowpipe or tube. Hand-blowing can be used to produce a large variety of forms for one-off, batch, or medium-volume production, but the unit costs labor. Industrial glassblowing and blow molding offers the potential for low unit costs, but has very high tooling costs and the designer is limited to specifying comparatively simple forms only.


Costs

Low for studio glassblowing; high tooling costs but low unit costs for industrial mechanized production


Quality

High perceived value and quality


Production scale

One-off to high-volume manufacture


Alternatives

Blow molding if plastic is an acceptable alternative


Glassblowing is a technique that involves inflating molten glass into a bubble with the aid of the blowpipe and then manipulating the form using tools to create the desired design.

Rotational molding

Ideal for producing hollow shapes in low volume, this simple process enables designers to create large components cost-effectively. The process involves loading a hollow mold with plastic pellets or liquid, heating the mold externally and rotating it to distribute the plastic evenly on the internal surface of the mold. Rotational molding is a comparatively low-cost process due to its simple tooling requirements and is ideal for runs of up to 10,000 units, but is not suitable for producing small, precise products or components. Cycle times are long, and fewer parts can be produced than with processes such as injection molding.


Costs

Moderate tooling costs, with low to medium unit cost, but processes have long cycle time of, on average 30 minutes, which adds cost if volumes are high


Quality

Good surface finish; dimensional tolerances are subject to cooling deformation


Production scale

Low to medium-volume manufacture


Alternatives

Blow molding, thermoforming


Outgang XP, designed by Alex Milton and Will Titley, 2008. This multifunctional design, enabling the chair to be rotated into three different seating positions, provides maximum versatility from the one piece. Its faceted ergonomic form takes full advantage of the structural and manufacturing possibilities that rotational molding provides.

Rotationalmouldedshoe, designed by Marloes ten Bhömer, 2009. This innovative couture design was specifically created, using polyurethane rubber and stainless steel, for the “After Hours” installation in the Krannert Art Museum in Illinois, USA.

Chair_One, designed by Konstantin Grcic for Magis, 2004. An example of aluminum die-casting, the chair is constructed like a soccer ball with a number of flat planes assembled at angles to each other, creating the distinctive three-dimensional form that is then mounted on a cast-concrete base.

Die-casting

A high-volume, high-tooling cost, metal-forming process in which molten metal is forced into a mold or cavity under pressure. The process is ideal for complex shapes and produces an excellent surface finish and dimensionally accurate part.


Costs

High tooling costs but low unit costs


Quality

Very high-quality surface finish


Production scale

High-volume manufacture


Alternatives

Sand casting, machining


Compression molding

This process involves a measured amount of ceramic, thermoset plastic or elastomer being placed in a heated mold and compressed into the desired shape, before being left to harden and removed. Excess material, known as “flash,” can occur at the parting line, which will require trimming. First used in plastic manufacturing in the 1920s to produce Bakelite, the process is ideal for producing largely flat and simple parts that require large, thick-walled sections such as gum boots.


Costs

Moderate tooling costs and low unit costs


Quality

High-quality surface finish, with high-strength components able to be produced


Production scale

Medium to high-volume manufacture


Alternatives

Injection molding


Slip casting

This traditional method of producing ceramics involves pouring clay slurry (a thick suspension of clay solids in a liquid) into a plaster mold; as the water from the slurry is absorbed by the mold, the clay begins to gather on the surface of the mold. Once the desired thickness has been reached the excess slurry is poured out. The clay part is then removed from the slip-casting mold, dried, and fired in a kiln. The advantage of this low-cost technique is that it enables decoration to be integrated into complex forms easily.


Costs

Low tooling costs, but moderate to high unit costs


Quality

The surface finish is dependent on the quality of the mold, the ceramic glaze, and the skill of the worker


Production scale

Low-volume manufacture


Alternatives

Traditional clay-throwing on a wheel


Forging

This is the traditional process of deforming metal between dies or with hammers using impact or pressure. Blacksmiths use this approach of manipulating metal to make products.


Costs

Moderate to high tooling costs and moderate unit costs


Quality

Forged metals displayed an excellent structure


Production scale

One-off to high-volume manufacture


Alternatives

Casting, machining


Spinning

The manufacture of hollow rounded metal shapes is often achieved by forcing a spinning metal blank against a pattern. The process offers limited control over wall thicknesses and often requires surface finishing to achieve the desired quality.


Costs

Low tooling costs and moderate unit costs


Quality

The finish is dependent on the skill of the operator and the speed of spinning


Production scale

One-off to medium-volume manufacture


Alternatives

Deep drawing


Investment casting

This process, also known as lost-wax casting, enables the production of high-quality parts with complex shapes. An expendable wax pattern is created and then coated in a ceramic to form a mold. The mold is then heated to remove the wax, leaving a hollow mold into which molten metal is poured. Upon cooling, the ceramic mold is broken away to leave a high-quality part. Investment casting enables complex shapes to be produced without requiring any post-process machining, and it is possible to reduce the weight of large castings by forming a hollow core.


Costs

Low-cost wax tooling and moderate to high unit costs


Quality

Excellent


Production scale

Low to high-volume manufacture


Alternatives

Die casting, sand casting


The iconic Rolls Royce Flying Lady mascot, 1913 to present, is constructed using investment casting.

Sand casting

This traditional low-cost technique enables the production of cast metal by forming a sand mold using a wooden pattern and pouring molten metal into the cavity. The metal is allowed to cool and the casting is separated from the mold. The process produces porous components and can be highly labour-intensive, as parts may require a lot of finishing.


Costs

Low tooling costs, moderate unit costs


Quality

Poor surface finish


Production scale

One-off to medium-volume manufacture


Alternatives

Die casting


Pewter Stool, designed and made by Max Lamb, 2006. Cast into crude sand formations on a sandy beach, it takes shape as the incoming tide cools the molten metal.

Forming

Forming covers a set of manufacturing processes that involve the manipulation of sheets, tubes, and rods into predetermined forms.

Bending

This is the application of hand-controlled or CNC formers to fold flat metal sheets, tubes or rods into three-dimensional forms.


Costs

Standard tooling required, no cost; specialized tooling can incur significant costs; unit costs are low


Quality

High


Production scale

One-off to high-volume manufacture


Alternatives

None


Panel beating

This process requires highly skilled craftspeople to stretch and compress sheet metal to create almost any shape using a variety of tools and techniques.


Costs

Low to moderate tooling costs; high unit costs


Quality

Handmade process can produce a high-quality finish


Production scale

One-off to low-volume manufacture


Alternatives

Stamping


Stamping

This high-volume process enables sheet metal to be formed into complex shapes between two matched steel tools. The technique is used to produce a wide range of products from large-scale car bodies to cell phone cases.


Costs

High tooling costs; low to moderate unit costs


Quality

High


Production scale

High-volume manufacture only due to tooling costs


Alternatives

Panel beating


Leaf Lamp, designed by Yves Béhar with fuseproject for Herman Miller, 2006. The lamp is stamped using a tool before being bent to form the final shape. It uses LED (light-emitting diode) lighting, giving the user a variety of options such as intensity and color and enabling them to set a mood or a location. The LEDs use less than 12 watts of power and use 40% less energy than the compact fluorescent lights used in conventional Luxo lamps.

Sheet Steel chair, designed and produced by Max Lamb, 2008. First, it is formed from a single sheet of steel (above), then bent along the punched holes for assembly (top and left).

Thermoforming

This process involves heating a sheet of thermoplastic until it is soft and pliable, enabling it to be stretched over or into a single-sided mold until cooled. The most common method is vacuum forming, where air is sucked out of a chamber to force the draped thermoplastic to mold around the pattern. The process requires the molded sheet to be trimmed. Any form must not involve vertical sides but instead feature draft angles (tapered forms) that enable the pattern to be removed. Thermoforming tooling costs are comparatively low and the process is suitable for low- and high-production volume runs.


Costs

Low to moderate tooling costs and unit costs


Quality

Depends on material and pressure applied


Production scale

One-off to high-volume manufacture


Alternatives

Injection molding, composite laminating


Plywood forming

This process, commonly used in furniture, involves forming and bending plywood sheets made up from layers of veneered wood glued together by applying pressure through vacuum and patterns to produce laminated sheets. Bending plywood can only be done in a single direction but can be achieved through handmade jigs that help control the location and motion of a tool, as well as industrial tools such as presses. Thin plywood can also be pressed in a similar manner to plastic forming, although it is difficult to achieve deep impressions and forms.


Costs

Depends on complexity


Quality

Depends on grain variation of material


Production scale

One-off prototyping to mass manufacture


Alternatives

None


Steam bending

This process steams wood to soften it sufficiently so that it can be bent into tight bends. It combines traditional handmade craft skills with industrial techniques. It was first pioneered as an industrial process by Danish furniture manufacturer Thonet in the 1850s.


Costs

Low tooling costs; moderate to high unit costs


Quality

Good


Production scale

One-off to high-volume manufacture


Alternatives

CNC machining, wood laminating


Pigeon Light, designed by Ed Carpenter for Thorsten Van Elten, 2001. An urban souvenir, it is a successful example of using a low-cost vacuum-formed component to produce a commercially viable product. The playful and iconic light features a clothes peg foot, which enables the pigeon to perch on a wall fixing or clip itself to its own cable to be self-standing.

Gubi Chair, designed by Boris Berlin & Poul Christiansen of Komplot Design, 2006. This is the first industrial product based on an innovative technique of molding three-dimensional veneer. The organically shaped shell provides a friendly and comfortable form, while offering the unique possibility of reducing its thickness and consumption of natural resources by half.

Biomega MN bike, designed by Marc Newson, 1999. It makes use of superforming to create a bonded aluminum frame.

Superforming

The pace of technological change and adaptation of processes into new materials can be seen in the recent innovation of superforming. This process enables thermoforming processes to be applied to aluminum alloy sheets to produce complex forms within a single component.


Costs

Low to moderate tooling costs; moderate to high unit costs


Quality

Good surface finish and dimensional tolerancing


Production scale

Low to medium-volume manufacture


Alternatives

Stamping, thermoforming


Glass slumping

This forming process involves heating a sheet of glass sufficiently to soften it enough to slump into or over a mold. Slumping is a slow process, commonly used to produce bowls and plates. This requires a skilled technician, and often needs extensive trial and error to arrive at the desired result.


Costs

Low tooling costs; but high unit costs due to slow speed of production


Quality

Dependent on skill of operator


Production scale

One-off to medium-volume manufacture


Alternatives

None


CASE STUDY: the VENUS chair

Tokujin Yoshioka’s VENUS chair, 2008, is made by growing natural crystals on a substrate frame of spongelike polyester elastomer that is submerged in a tank of water saturated with minerals, the production process being half controlled by Yoshioka and half left up to nature.

(Left to right) The chair in the aquarium, and details showing the chair and minerals in water.

Finished chair as presented at the exhibition Second Nature, directed by Tokujin Yoshioka at 21_21 Design Sight in Japan.

Growing

Technological developments are provoking the biggest change in the nature of mass production since the Industrial Revolution, with processes like rapid prototyping enabling the production of parts without tooling.

Rapid prototyping (RP)

This is the process of constructing objects by taking virtual designs from CAD software and transforming them into data that can be laid down layer by layer using liquid, powder, or sheet material. Originally used to prototype parts, today designers are actively exploring the possibility of manufacturing production-quality, high-cost parts in small numbers.


Costs

No tooling costs but high unit costs due to slow speed of production


Quality

High quality is possible depending on process chosen


Production scale

One-off to low-volume manufacture


Alternatives

CNC machining


Fused Deposition Modeling (FDM): This is a process that extrudes a molten metal or polymer to create layers of material generated from CAD files. The cross-sectional layers are built up one at a time to complete the finished part.

Stereolithography (SLA): This is an additive fabrication process that uses a vat of photo-sensitive liquid resin that is cured in layers by a laser to build parts. SLA requires designers to add support structures to the CAD data to enable the creation of forms that would deform due to gravity. SLA offers unlimited geometric freedom, but is slower than many other rapid prototyping processes.

Selective Laser Sintering (SLS): This is an additive technique that uses a high-powered laser to fuse small particles of ceramic, metal, or plastic into a mass. The process allows highly detailed, lightweight, and high-strength components to be produced, but as with other RP processes SLS manufacturing has high unit costs.

Chair from the Solid collection, designed by Patrick Jouin for Materialise, 2004. Manufactured using the rapid-prototyping technique of stereolithography, the structural form is reminiscent of blades of grass or ribbons waving in the wind to create this unique design.

Finishing

Many manufactured parts may be subjected to additional processes to enhance their appearance, performance, or corrosion-resistance. Finishes can be additive—such as plating, galvanizing, painting, or applying adhesive labels—or subtractive, such as etching, engraving, polishing, and sanding.

Plating

This process involves covering a conductive surface with a metal, with common applications including chrome-plated car bumpers and plating base materials for jewelery and decorative items.


Costs

No tooling costs; high unit costs


Quality

Dependent on coating material


Production scale

One-off to high-volume manufacture


Alternatives

Galvanizing, spray painting


Spray painting

This common process involves applying a layer of paint, ink, or varnish by using a spray gun to atomize paint particles and spraying them though the air onto a surface.


Costs

No tooling costs; unit costs dependent on scale and complexity


Quality

Dependent on skills of operator


Production scale

One-off to high-volume manufacture


Alternatives

Powder coating


Powder coating

This process involves coating metal parts with a fine thermoplastic powder that is heated until it melts and forms a protective durable layer over the part.


Costs

No tooling costs; low unit costs


Quality

Glossy and uniform high-quality surface finish


Production scale

One-off to high-volume manufacture


Alternatives

Galvanizing, spray painting, dip molding if used as a coating


Subtractive processes

This set of processes includes polishing, sanding, and grinding components to achieve the desired surface finish.


Costs

No tooling costs; unit costs are dependent on the surface finish required


Quality

High-quality finishes are achievable


Production scale

One-off to high-volume manufacture


Alternatives

Spray painting or powder coating to finish a material, the various subtractive processes if different finishes are required


Anti-Theft Bike/Car Device, designed by Dominic Wilcox, 2008. These stickers are designed to deter thieves from attempting to steal a vehicle by making it appear old, damaged, and worthless.

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