Why Modern Product Designers Prefer Engineered Synthetics Over Traditional Metals and Glass

The case for engineered synthetics in modern product design

Choosing the right material has traditionally involved balancing the needs of the design against the capabilities of the process. For too long, metal and glass were often chosen by default, not because they were consistently the optimal materials. But that’s changed.

What designers were actually asking for

The familiar point regarding engineered synthetics is that we can tailor both their physical properties and manufacturing processes to meet the optimum requirements of a given product. Where an OEM once might have needed glass (often a custom size or composition-filling glass solution requiring special tooling), with an engineered synthetic, moulding the primary material for display applications might instantly produce the perfect ready-to-install product without any secondary tooling or finishing. Non-reinforced polymers are orders of magnitude less brittle than float glass. Floating polymers offer the same optical quality as float glass without the tinting. Heat treatment of plastically formed acrylic parts can vastly improve impact resistance (the drawing of many OEMs to polycarbonate) while maintaining very high optical quality.

And those are just design and manufacturing benefits; that doesn’t touch on the whole set of performance advantages (including weight savings) that polymers can offer if replacing traditionally metal components.

Weight reduction and what it actually changes

The difference in weight between glass and acrylic is not insignificant. Ordinary acrylic (PMMA) has an impact resistance that can be up to 17 times greater than that of ordinary silica glass of equivalent thickness, all while weighing roughly 1/2 as much. This statistic is important in ways that go well beyond the surface.

Lighter panels will lead to lower shipping costs – and not just a few dollars but significantly when your job is to transport large-format displays or signage installations over long distances. It will also demand less in support from the wall, ceiling, or frame that it’s mounted to. In retail, this means quicker installations and less damaging mounts. For those in the field tasked with the un/installation of large-format panels mounted high above, this can be a life or death circumstance.

In the world of product design, cutting weight gives you more options as to what is possible in the realm of portable and consumer products. A display unit which can be moved and positioned by one person is a different product entirely than one that requires a team and a dolly. Synthetics make that distinction possible without sacrificing the needed structural performance the application demands.

Geometric freedom and the limits of metal forming

Thermoplastics sound pretty mundane, but they can redefine the limits of what you can design, and how you can fabricate it.

Sure, you can heat and reform a ton of metal alloys too (it’s the most fundamental idea behind blacksmithing) but most of the rest of the standard workshop material palette isn’t nearly as formable as thermoplastics are.

Take a flat sheet of acrylic: you can heat and draw it down through a former, get complex 3 dimensional curves, compound angles, and make a seamless, single piece structure. Try that with sheet metal and you’re welding, grinding, filling, and refinishing; failing in each step to add heaps in potential failure points and labour. For glass, most organic curved geometries are either technically impossible at the scale required, or prohibitively expensive through any method that’s not “Xerox copy an existing one”.

Go further with injection molding; complex geometric motifs can be produced en masse, with exacting dimensional tolerances. You wouldn’t dream of asking a machinist to make most of the stuff you can injection mold. Single components to replace multi-part assemblies in metal also make sense, dropping assembly labour and potential weak points in the structure. Cleaner finished aesthetic is a nice bonus.

For an industrial or a product designer in consumer electronics, point of sale displays, or architectural installations, this geometric freedom isn’t a ‘nice to have’. It’s often the difference between your design being vaguely feasible, and not.

Optical performance in signage and display applications

A light transmission rate in the 88-90% range for standard float glass doesn’t sound particularly lower than your 92% value for high-grade acrylic, but factor in the greenish tint that results from iron impurities inside the silica and it gets a little more complicated. For almost all architectural applications, the green tint is generally irrelevant.

When you’re talking about a backlit panel, colored and illuminated text, or any other particularly special or business graphic, however, even the almost invisible hue presented by the iron in standard float glass simply won’t cut it. Up to 92% of visible light can be transmitted through the highest grade acrylic sheet materials. They also exclude the iron tint. The result is cleaner, truer color rendering. For perspex and similar acrylic sheet materials, laser cutting and CNC fabrication produce clean, polished edges that function as light guides in edge-lit signage – a capability that flat glass panels can’t replicate without specialty processing.

Impact resistance and liability in public environments

Glass is a terrible material when it fails. It shatters into sharp-edged, razor-sharp fragments that can endanger public safety in high-traffic retail, hospitality, and public installations and facilities. While tempered and laminated treatments mitigate this, it is still a liability issue.

Polycarbonate and high-grade acrylic have different, but safer, failure modes. Instead of shattering, they crack into dull-edged pieces when impacted over their performance limit. For schools, transport hubs, sports facilities, and public retail facilities, this can be the difference between a small maintenance issue and catastrophic failure with injury implications.

Aluminum fails by denting and deforming rather than shattering. However, the deformation is permanent and often structurally compromising as, for example, aluminum curtainwall framing systems aren’t designed to uselessly deform even in a modest wind load.

Its surface does fail if impacted but that is generally cosmetic, as any dented high-end car drivers know. A dented panel in a high-end retail environment isn’t just unsightly, it is a signal the installation is deteriorating.

Engineered synthetics have enough “give” in them to allow the absorbed energy of a minor impact to not show in the form of a deformed and dented panel. This also relates to useful life in that a well-installed sheet of polycarbonate should look as good 15 years in as the installation team made it look the day it was installed.

Weatherability and outdoor durability

The longevity of signage systems relies on the integrity of their components and their resistance to environmental degradation. The environment is particularly demanding on materials due to direct and indirect atmospheric interactions of wind, UV light, and precipitation. Airborne pollutants, which react with moisture to create acidic solutions, accelerate the breakdown of organic and inorganic materials. These conditions, coupled with the term of intended use for the end item, play a role in material selection and the evaluation of trade-offs. Climates with low UV load (for example, northern Europe) and locales which are nearly pollution-free through careful regulation may have less impact on material lifetime. With more extreme conditions (a desert locale versus an inland bay), attention to appropriate material selection and maintenance is critical, considering the greater swings of heat and humidity.

Cost structure from prototype to production

Metal cutting degrades tooling quite quickly. Subtractive methods of production – such as CNC milling of metal or thermoplastics – generate significant waste and result in frequent tool changes as they roughly cut out the shape of the final part. The relative economics of working in metal, and the accompanying level of waste generated, makes it more expensive to iterate a design, pushing product developers into shortening the iteration cycle and moving to production before the design is fully polished.

Thermoplastics sort of cheat the manufacturing cost structure at several points. They melt at a lower temperature, so less energy is required in forming them. Laser cutters and CNC routers wear out when working with metal an order of magnitude faster than when they’re cutting acrylic or polycarbonate. And while some processing methods (like 3D printing) produce parts that are effectively production ready, for the most part working with synthetics involves relatively minor secondary operations like thermoforming or cutting and bonding together panels.

Many of these processing methods involve little to no tooling, and for certain complex geometries, an investment in tooling for production in low volumes still isn’t strictly required. If you are a design team that needs to run multiple iterations of a part through a physical test or assembly process, or needs to change a part midstream though limited testing of the assembly, the per-iteration cost of doing that in a thermoplastic is significantly lower than it would be as a machined part.

Surface finishing without secondary processes

Metals often require finishing when they come off the production line. After aluminum or steel components are produced, standard secondary steps include powder coating, anodizing, wet painting, or polishing. Each additional step adds more time and cost, as well as a process handoff, which can create additional risk of quality variation.

Thermoplastic fabrication can involve similar finishing steps and risks, but an entirely different approach is possible if colors or finishes are either naturally in the material or applied as a part of the sheet or vessel production process. Pigments for different colors can be blended with the coloring compound for the polycarbonate resins during the polymer’s production process so that no painting is required as part of the sign fabrication.

Matte diffusion surfaces and anti-glare coatings can be created by applying vapor deposition at the sheet manufacturer, or by adding special powder coating at the fabricator during the forming process, as long as the paint adheres to the paintable surface and is laid down thick enough. Textured finishes also can be applied in either place.

Sustainability and the recyclability question

The conversation about plastics and sustainability isn’t a straightforward one, and we’d argue that if it sounds simple, then you’re probably not engaging with it enough. The honest picture is mixed (but it’s not the direction most of the critics are assuming when they’re working from decade-old information).

For instance: Modern engineered synthetics, and PMMA in particular, can be chemically recycled right back to the monomers it started from, and reprocessed with no appreciable loss of quality. In a closed-loop collection and processing system, the case for thermoplastics is, technically, straight-up circular. The quantity-to-quality advantage depends on a real-world collection and reprocessing infrastructure that is only just starting to rise to the challenge in a few isolated markets.

The transport carbon argument is also fairly hard and immediate on the math: if you’re shipping glass or metal installations over significant distances, you are burning a lot more fossil fuel than you are for the equivalent in synthetics. Over global supply chains and distributed installation programs, the weight difference compounds into an easier-to-calculate advantage in material transport emissions.

Finally, if you’re going to be comparing “natural” materials to synthetics, remember: smelting aluminum or steel is an energy-intensive industrial process. Acrylic sheet production doesn’t require the same energy inputs or generate the same process emissions. That doesn’t make synthetics carbon-neutral, but it does add a couple of convenient terms to the math for which seems to be the most sustainable choice.