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Robots automate 3D printing factory

06 September, 2017

By combining collaborative robots with 3D printers, a US company believes that it can produce plastic parts in batches of up to 100,000 at prices that compete with injection-moulding. Contributing editor Tony Sacks looks at the company’s plans.

Additive (3D) printing has come a long way in the past couple of decades, but it is still a relatively expensive, time-consuming and labour-intensive way of producing parts. For these reasons, it has mainly been used so far for producing prototypes or high-value components.

But, a start-up US company, called Voodoo Manufacturing, believes that by combining 3D printers with robots, it can produce parts at a similar cost to injection-moulding techniques.

At its 167m2 (1,800ft2) premises in Brooklyn, Voodoo has already demonstrated the feasibility of its ideas and it is now implementing a project that will use a couple of robot arms to tend 160 3D printers, allowing them to operate around the clock, seven days a week, with little human intervention.

Voodoo was set up just over two years ago, and has already raised more than $6.4m in funding. The company has created a niche for itself producing plastic parts in runs of fewer than 10,000 items using an army of 160 3D printers. A production run typically takes less than two weeks, and some orders can be turned around in 24 hours.

It would normally be extremely difficult to operate so many printers effectively, so the company has developed a software platform that allows it to control and monitor them continuously, and to optimise efficiency.

Voodoo has so far produced items including marketing and promotional products, such as key-fobs, as well as engineering components. It has even produced protective eyewear for dogs, and more than 1,000 prosthetic hands for use by children around the world.

Conventional techniques for volume production of plastic parts, such as injection moulding, usually involve runs longer than 10,000 items. To offer a viable alternative, Voodoo will have to achieve much longer runs at a competitive price.

Although it is costly and time-consuming producing the tools needed to injection-mould a part, once the tools have been made, they can produce millions of identical copies. Voodoo has set itself the goal of being able to 3D-print 100,000 items at a competitive price within three to five years. This will mean cutting costs by an order of magnitude.

Crushing costs

Voodoo’s costs come from three main areas: material; machines; and labour. To achieve its target, it will need to reduce each of these – or a combination ¬– by 90%.

According to the company’s co-founder and chief product officer, Jonathan Schwartz, material is the easiest cost to reduce, because of the fierce competition between 3D material suppliers. It’s just a matter of time before the 3D material costs approach those of the raw plastic pellets used for injection moulding. Schwartz suggests that Voodoo could eventually produce its own materials in-house, eliminating the margins added by intermediary suppliers.

The next factor is machine cost, which determines how much Voodoo has to charge for each hour of printer time. This cost is a result of the machine price amortised over its expected lifetime at a given rate of use. Factors that can affect this include the machine’s operating lifetime, utilisation and output.

Voodoo expects 3D printer prices to remain fairly stable, but hopes to cut its costs by buying in bulk. It doesn’t expect printer lifetimes to change much. But, in any case, it is planning to update its machines every few years, whether or not they are still working.

Machine efficiency depends on production speeds, scrap rates, and equipment utilisation. Voodoo expects scrap rates to decline, and build speeds to increase, as high-end printing technologies filter down to lower-end systems. At present, with 160 printers and five full-time employees working eight hours a day, five days a week, the company is operating at about 30–40% utilisation. “We are hoping to push that to 90–95% over the next three years,” says Schawartz. This will require Voodoo to trim its labour bills.

At present, the company’s production process is labour-intensive, with human workers needed to change the printer materials, and to collect, pack and ship the finished prints. Even with this “somewhat inefficient” process, Voodoo has been able to compete on price with low-volume injection-moulded parts, but cutting these costs will be critical if Voodoo is going to compete with injection-moulding at higher volumes. This means eliminating wasteful parts of the process, and automating the remaining manual tasks.

According to Schwartz “the need to automate labour became clear as not only the key to our future success, but as a necessity for our survival”. And so the company set out to identify where it could introduce automation into its production process to increase its capacity, while maintaining or lowering costs. It named this quest Project Skywalker.

Identifying targets

When deciding what part of its manufacturing process to target first, Voodoo looked for:

• the easiest part to automate;

• the automated part that would have the biggest impact on its labour requirements; and

• proof that the business could scale well beyond where it is today, and potentially become a manufacturing giant.

It became clear that the first step it should attempt to automate was “harvesting” – the process of removing a printer’s build plate (the substrate onto which it prints) after a completed build, and replacing it with a clean plate, ready for the next print.

At present, Voodoo’s employees spend about 10% of their time harvesting the 3D printers. Automating this task would reduce the time spent on a low-value-added activity, and keep the printers running for longer. Schwartz describes harvesting is “a perfect and almost quantifiable task that we felt confident in being able to automate with speed, accuracy, and precision”.

Voodoo chose Universal Robots’ UR10 robotic arm for the harvesting task. This arm offered a low-enough price point, coupled with sufficient precision and payload capacity. Most attractive, however, was the fact that it was collaborative. “Rather than build a factory with caged-off areas and hazardous possibilities, we preferred the idea of a friendly workplace where continuous and spontaneous improvement and interaction are default,” Schwartz explains.

Voodoo built a demo system consisting of: nine 3D printers mounted on server racks; a custom-built “hopper” that feeds clean build plates to the robot; and a conveyor where the robot deposits the harvested plates for collection by an employee. Voodoo’s engineers planned the paths between all nine printers, the conveyor, and the hopper. Lastly, using software developed in-house, they established communications between the printers and the robot.

When a printing operation finishes, the software notifies the robot arm which removes the plate from the printer and places it on the conveyor. It then collects a new plate from the hopper and inserts it into the printer, notifying the control software and initiating the next printing cycle. After solving many edge cases and unforeseen problems, Voodoo has achieved what it believes is the first-ever robot-operated cluster of 3D printers.

After watching the system completing several cycles successfully, Voodoo’s engineers worked up the courage to run it overnight, without any human supervision. The next morning, they returned to find more than 30 completed prints for a real production job. “It was magical,” Schwartz recalls.

By being able to start new prints throughout the night, rather than being limited to the standard eight-hour shift, Voodoo tripled the output from its nine printers. Schwartz describes Project Skywalker as “a massive success,” adding that “even though we shouldn’t have been surprised by the results, we all had this strong realisation of how much of a game-changer this would be”.

Extrapolating from the demo cluster, Voodoo estimates that one robot arm will be able to tend about 100 3D printers in its factory, boosting its printer/employee ratio from around 40 at present, to around 400. It reckons that the robot arms will pay for themselves in about three months.

In the longer term, Schwartz envisages Voodoo scaling up its operation to around 10,000 3D printers. These printers will be able to use new materials and make items that you can’t tell are 3D-printed, as well as doing things that conventional forms of manufacturing cannot do – such as creating complex assemblies containing moving components.

In Voodoo’s 3D-printing factory of the future, it says that lead times will be short and iteration cycles will be fast. It will be easy to customise products, and production runs will be able to start small and to scale instantly as demands change.

To Schwartz, automation is more than simply a way of cutting costs. “It’s the only way we’ll survive to be a large company that employs hundreds, if not thousands, of people,” he predicts. “The path we walk is one that many companies have already started down. Those who choose not to, will fall behind and be faced with the choice of changing or fading. As a start-up taking on a massive and deeply entrenched industry, automation is our primary weapon.”

This article is based on a blog on Voodoo Manufacturing’s Web site (https://voodoomfg.com)

What is 3D printing?

3D printing builds up objects by adding material layer-by-layer. There are many different types of 3D printing, offering a choice of speeds, quality and compatible materials.

Voodoo uses a technology known as fused deposition modelling (FDM), which extrudes molten plastic out of a hot nozzle and lays it down on a flat surface, one layer on top of the next. FDM printers have minimum feature sizes that they can print. Voodoo recommends a minimum feature size of 0.1mm and warns that sections smaller than 1mm in diameter will be fragile.

Compared to traditional subtractive, moulding, or casting manufacturing methods, 3D printing offers several advantages:

Complex geometries are free Material and machine time are the only tangible costs, allowing designers to create things that are not possible to produce any other way.

Customisation 3D printers turn digital design files into objects. Because they don’t need any initial tooling or moulds for production, every 3D-printed object can be unique.

Digitisation The 3D printing process makes it easy to print, test, and iterate designs. Little upfront time and effort is needed for each new item, making 3D printing ideal for projects with tight deadlines.

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