3-D printing and labour needs

 

The Straits Times

Published on May 27, 2013

 

Visitors examining sample products made with 3-D printers at an exhibition in New York on April 22. 3-D printing is currently constrained to making small-scale, specialised items, but the goal in the manufacturing and construction industries is to scale it up in terms of both size and output. -- PHOTO: AGENCE FRANCE-PRESSE

By Andy Ho

IN FEBRUARY, Finance Minister Tharman Shanmugaratnam announced a $500 million Future of Manufacturing programme, one focus of which was to create a 3-D printing sector over the next five years. The same month, US President Barack Obama announced a US$1 billion (S$1.26 billion) initiative to fund 15 hubs to develop 3-D printing "to revolutionise the way we make almost everything" and create jobs for Americans. Even earlier, in October 2012, British Minister for Universities and Science David Willetts announced a £7 million (S$13.4 million) national initiative in 3-D printing.

Will this technology transform manufacturing, or even construction? Or is it a rose-tinted fantasy to hope it will somehow create jobs for locals while offsetting the need for foreign workers, especially in these two sectors that, in 2011, together accounted for 56 per cent of foreign workers on work passes, excluding maids?

Layer by layer

IN 3-D printing, the object to be "printed" is laid down as "ink" in incredibly thin layers which are stacked up precisely upon one another to the desired size and shape as specified by a digital blueprint. The ink such printers use can be liquid thermoplastic to make a gun or liquid colloids to make hamburgers. The base of these inks can also be powder bed systems of steel, cobalt-chrome alloys, titanium, titanium alloys, aluminium, nickel-based alloys and even gold.

Or it could be filaments "very much like a fishing line that is fed into an extrusion head and heated into a semi-liquid, which is then extruded and deposited in ultra-thin layers, a layer at a time", according to Professor Chua Chee Kai, chair of mechanical and aerospace engineering at Nanyang Technological University.

The ink is squirted out of precision nozzles that build up the item to be assembled. The nozzles know exactly where and when to squirt line by line, and then layer by layer, as directed by computer software. As far as the nozzles are concerned, they do the same job whether printing a square, a curve or some complicated shape.

While this technology is already used in "rapid prototyping" to make high value-added one-off items in academe and sectors ranging from dentistry to aerospace, the industrial goal is to scale it up.

Presently, 3-D printing is essentially just the fabrication of unique replacement components or spare parts. Printing on an increasingly larger scale may lower labour costs and manpower requirements in manufacturing and construction.

Manufacturing

BECAUSE it adds precise layer by precise layer to the correct dimensions and geometry, 3-D printing is also called additive manufacturing. This involves much less wastage compared to traditional manufacturing, which basically involves splitting, sawing, shaving, drilling, milling and turning. Removing material this way uses up time and energy while leaving lots of metal or plastic shavings all over the shop floor.

With 3-D printing, however, parts can be printed out as, when and where they are needed. This could save time, energy and cost. There is also less retooling required to make variations of a widget.

Traditionally, one makes a prototype using injection moulding, in which hot liquid plastic is injected into a precise metal mould of the prototype, which itself requires very precise machining to fabricate. But these conventional techniques are hard put to make widgets with intricate designs.

With additive manufacturing, however, extensive and expensive retooling is unnecessary since the 3-D printer can be reprogrammed digitally to make variations of the basic widget. Currently, 3-D printers can already be used to make personalised dental crowns, for example. So 3-D printing may lead to more rapid product development through prototyping by the masses.

Because the widget is printed when required, inventories would be minimal. One could set up shop in a small space with a few tabletop 3-D printers - a factory in an office space as it were.

An innovative sector of small firms involved in customised and personalised manufacturing could well emerge. But this would be more like the neighbourhood photo shop that allows you to print your own digital photos and less like a factory making high-end digital cameras.

By being able to make things in small batches themselves, entrepreneurs and inventors would no longer have to depend on a large manufacturer that may be reluctant to fabricate the small batches of innovative widgets they dream up.

Moreover, by producing the widget very near to the consumer's home base - rather than importing it from China, say - product manufacturing would be decentralised, fans think.

With 3-D printing, most of what is moved around is just moved around on the Internet, namely the widget's digital specifications. These can be printed out on demand, at the customer's location. This would entail less transportation of raw materials, components or finished products over long distances. The carbon footprint of additive manufacturing could thus be smaller. It would also be easier to reuse any leftover raw material. Thus, the new sector could be eco-friendly.

Presently the main limitation to scaling up 3-D printing for large-scale manufacturing is the "build envelope". This is the product of the maximum dimensions of each of the three axes, namely: height, length and breadth.

This volume, which defines the printable widget size, is constrained by the size of the enclosed zone needed for depositing the ink layer by layer.

The enclosed zone is like an oven because the raw material has to be heated up to a liquid or semi-liquid form to be squirted out by nozzles.

Thus, most 3-D printing is confined to fabricating smallish components. What is called "big build envelope" today is only about 60cm to 80cm along each axis. Thus, with most 3-D printers, you need to print smaller pieces to be assembled into a bigger widget.

Print speed is also slow. The bigger the "build envelope", the slower the print speed. This is because when you double the dimensions of each of the three axes, the print volume goes up eight-fold. Thus, print times are currently clocked in terms of hours and days, not minutes.

Moreover, 3-D printing is not quite there yet in terms of precision, maximum resolution, consistency, reliability and maintainability that consumer products must have in today's market. At Prof Chua's lab, what one sees are just small-scale items like toys, figurines and jewellery.

How can 3-D printing be scaled up to massive sizes? One idea is to use a team of coordinated robots on heated platforms to print large structures sized in terms of metres rather than centimetres. Called Big Area Additive Manufacturing, multiple nozzles are used, each of which is responsible for a specified area. The nozzles can be mounted on gantries or moved around by robots.

In this manner, it might be possible one day to print very huge structures. The vision is to have a warehouse full of robotic nozzles working in concert 24/7 with little human input to print anything from cars to drones. But until 3-D printing can be scaled up for mass production, it is more likely to be integrated into commercial production in a way that complements rather than displaces conventional manufacturing.

Accounting for about 21 per cent of Singapore's gross domestic product, manufacturing here is focused on higher value-added and innovation-intensive activities such as aerospace. Thus, while 3-D printing could be an enabling technology for some parts of the value chain in high-end manufacturing, it is unlikely to reduce the need for manpower, especially in less value-added manufacturing for some time.

Construction

IN 2005, British scientists managed to develop a quick drying cement of the right viscosity that did not clog up the nozzles. Using gantry-mounted nozzles that sprayed cement, binders and a catalyst mixed with the sand, they printed out a small wall section that began hardening in 15 hours, and was totally solid by 24 hours.

In 2010, the University of Loughborough's Freeform Construction Project managed to print out a one metre by one metre, one tonne, free-form reinforced concrete panel with an undulating geometry reminiscent of the Microsoft Windows logo.

In the future, concrete walls could be printed with all the conduits and ducts for electrical, plumbing and air-conditioning in situ. You could also include any texture or feature on or within the walls, which could be customised to specific requirements.

A big hurdle, however, is that concrete printing is currently very slow.

At a construction site, robotic printers could be towed around by automated tractors. Operating them outdoors, however, would make it subject to the vagaries of the weather. Thus it is more likely that panels with complex geometries will be printed indoors to be transported to actual construction sites.

Of course, such robotic fabricators could be used to print out mundane flat parts for public housing projects too. But there might be no cost advantage over existing methods. All in all, 3-D printing may change the construction sector at the high end but probably not reduce overall manpower needs to any significant degree for some time to come yet.