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product development | Prototyping

tools. However, he sees AM offering an alternative tooling route as CNC can be quite and time consuming given it is frequently outsourced to external sub-con- tractors. “Using an in-house 3D printer to produce moulds for injection moulding using newer and more robust 3D printed materials, gives companies flexibility in the production of injection moulded parts. Companies can print tools on their 3D printer overnight and with a significant cost saving.” Sella cites the example of ice cream spoons moulded in PP on a six-cavity mould. A tool insert in P20 steel would cost $3,200 and would have a turnaround time of 30 days, he claims. In aluminium the cost would be $1,400, with the same turnaround time. An insert made in an ABS-like material on a Objet260 Connex Multi- Material 3D Printer from Stratasys would cost $785 and would be ready overnight. “The option of printing a tool instead of producing a

metal tool cannot be used in all cases, and is not intended to replace CNC and metal tools altogether, but having this option can save both money and moreover precious time when more than one design iteration is needed,” says Sella. Stratasys aims to demonstrate this AM to moulding concept at the K show this month. As Sella says, AM could be a potential option for fast

tooling but CNC is the established– and very effective - option as companies such as Proto Labs (“Real Parts, Really Fast”) and Star Prototype (“The Best of the West in China”) demonstrate. Both have turnaround times that are often measured in a few days if not hours, and

neither has AM in-house. Gordon Styles is owner and managing director of

Star Prototype. “Prototyping companies either special- ise in one particular area or have a large number of strings to their bow with the intention of achieving across-the-broad success,” he says. “This second approach is the one I used with Styles Rapid Prototyping in the UK in the 1990s and reverted back to when I came to China to set up Star Prototype in 2005. Today our service covers everything from Stereolithography (SLA) and Selective Laser Sintering (SLS) through to CNC machining, polyurethane casting and even vapour polishing.” Styles says there is now a huge range of SLA materials

with very good mechanical properties. Star mainly uses DSM Somos 14120, which he says closely simulates ABS and is used mostly by the company to make SLA models as Master Patterns for production of silicone rubber moulds for vacuum casting in polyurethane. “The work we recently did for Nomiku is a prime

example of the expertise an RP bureau can bring to the table. We helped transform an innovative design idea into a workable product with the potential to turn sous-vide into a global home cooking phenomenon,” he says. Star was approached by California-based Nomiku with initial designs and some general ideas for a portable sous-vide device that could be sold at a price that would make it an affordable option for amateur cooks everywhere (popular in the catering industry, sous-vide involves cooking food in a water bath within a

Inserting an element of competition

EOS says with increasing competition from eastern Europe and Asia, German plastics processors need to make as much use of innovative and economic processes as they can. One German processor, FWB Kunststofftechnik, in Pirmasens, has been working closely with LBC LaserBearbeitungsCenter, a producer of metal parts using AM to make tool inserts for injection moulding components. One recent project was to manufacture mould cores for a 16-cavity

production tool. FWB wanted a fast and inexpensive method of developing and producing moulds, suitable for use in highly automated, independently operating production cells. FWB needed to produce a hybrid blank for a mould insert with the maximum possible volume. First, LBC calculated the structure of the cavity to fit the capacity of their EOSINT M 270. After integrating and configuring a new EOSINT M 280 unit (an updated and improved version of the EOSINT M 270), the project was recalculated and two of the 16 tool cores to be made for the new production tool were constructed on the new system. The all-AM method for the tool inserts turned out to be 25 % more

economic for FWB than the original hybrid solution. The new laser sintering system saved it four weeks in production time. Moreover, the component structures displayed improved stability compared with hybrid components, which would have been made up of two parts.

30 INJECTION WORLD | October 2013

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