Leading micro additive manufacturing (AM) platform developer, Nanofabrica, has 3D printed micro moulds that have been used to shoot dozens of parts in a variety of materials. The results of the company’s work has been ground-breaking in the fact that hitherto unattainable levels of precision demanded when manufacturing parts with micro-level tolerances have been achieved for the very first time through the use of AM produced soft tooling. There is a compelling drive towards the use of AM to manufacture mould tools, and this article discusses the reasons why, and looks at the results of Nanofabrica’s initiatives in this area.
Jon Donner, CEO, Nanofabrica
As AM matures as a process not just for prototyping but for true production applications, there is an excitement about what the future may hold for manufacturing. There has recently been increased interest in using AM for the production of mould tools themselves, so called Direct Rapid Soft Tooling (DRST). DRST is especially well suited to scenarios when the goal is small series production where the cost of a traditionally manufactured tool is prohibitive, and it is also much easier and inexpensive to apply design changes. In addition, increased tool complexity can be accommodated at no extra expense, increased complexity with traditional micro tools invariably leading to exponential increases in associated time and cost.
THE NANOFABRICA PROCESS
The time and cost associated with the fabrication of conventional micro tooling for micro injection moulding recently led Nanofabrica to assess the viability of creating AM produced DRST for short run production parts and functional prototypes.
Nanofabrica’s AM process encapsulated in the Terra 250 AM platform uses an ultra-high resolution Digital Light Processor (DLP) engine, achieving repeatable micron levels of resolution by combining the DLP engine with adaptive optics. In conjunction with an array of sensors, this allows for a closed feedback loop, which is at the heart of why the technology achieves very high accuracy while remaining cost-effective as a manufacturing solution.
Nanofabrica is consistently experimenting in the area of AM mould tool fabrication as it recognises the huge potential benefits for manufacturers, and is consistently achieving ground-breaking improvements in mechanical capabilities, mould designs, materials, and the accuracy and integrity of parts injected using the AM mould tool.
THE TRIAL RESULTS
In its recent experiments, Nanofabrica (which can achieve ultra-precise 1 micron resolution on the Terra 250) succeeded in injecting PP, PE, and ABS into a 3D printed mould, which was manufactured with a new material that the company is currently developing. Excellent surface finish was also achieved with an Rz of 0.8 micron in the hardest direction, and an Rz of better than 0.1 micron in the Z plane.
In the initial experiments, the moulds lasted for 20 shots with a moulding pressure of 400 bar at 230°C. It took Nanofabrica an hour to additively manufacture one mould at the cost of under $20. The materials were injected using an Arburg 35-ton machine.
Nanofabrica is fine tuning the manufacture of its DRST through a combination of design optimisation and improvements in materials. While the company is getting a good 20 shots off this preliminary testing, it is working on improving both the material (giving it much higher temperature resistance and strength) as well as the process (focusing on improving the impact pressure and stiffness of the printed soft tool) with the aim of handling tougher injection conditions and a bigger array of injected materials. The aim is to last 1000 shots in the coming months accommodating temperatures of 350 degrees C and pressures of 800 bar.
This unlocks new business possibilities for mould makers and manufacturers who up until this point have been restricted to the use of long lead time and expensive traditionally manufactured mould tools for the achievement of any volume of moulding, from prototype runs all the way through to mass manufacture. The Nanofabrica trials should stimulate the business case for a process chain that includes DRST, with a dramatically shorter lead time of about 2 hours from file to injected part and at costs reduced from thousands of dollars to tens.
Using Nanofabrica’s Terra 250 precision AM platform to produce DRST capable of manufacturing upwards of 1000 parts per tool opens up the possibility of small and even medium batch manufacturing. This is a product of Nanofabrica’s platform that is able to accommodate the manufacture of multiple small tools in each build, and so manufacturers will be able to produce numerous replacement tools at extremely low cost. In the future, for the cost of one aluminium precise mould which costs about $10K you could manufacture 500 soft moulds on a Terra 250, leading to about 500K final parts through a significantly faster process. In addition, each tool can be adapted as required, opening up the possibility of speed to first part out, and the ability to correct during the manufacturing process according to market and customer needs.
It is usually the case that when AM produced DRST and traditional injection moulding are compared, the savings in terms of product development time and cost are seen as the most compelling benefits for using AM. However, the fact that AM is relatively agnostic to complexity means that AM produced DRST could also stimulate innovation in product design and manufacture. AM can achieve geometries impossible using conventional processes, and as such is positioned as a key enabling technology driving the production of cutting-edge products as well as shortening the product development cycle. This is because it is quite often the case that product design updates are shelved by manufacturers due to the cost of new traditional moulds.
Until Nanofabrica’s results, the demand for AM produced DRST has been held back by perceptions that AM is limited in terms of surface finish, precision, accuracy, and repeatability and also in terms of the limited number of materials that can be processed. Nanofabrica’s AM process reaches micron-level resolution enabling high surface finish, and when applied to manufacturing of mold tooling for the very first time the requirements of tooling can be achieved without the time-consuming and costly need to cut steel. Uniquely, the high resolution that Nanofabrica’s technology achieves means that it can create extremely precise and micro features, and this is a key attribute that manufacturers are also keen to take advantage of.
SUMMARY
The fact that AM can produce extremely accurate moulds in a matter of a few hours instead of the weeks and months associated with conventionally produced tools means that the technology can improve manufacturing margins, and this is also coupled with the fact that AM allows design engineers to take advantage of nearly limitless creativity to improve mould design.
Using AM makes it more economical to optimize tools for enhanced end-product performance, and when coupled with shorter production cycles, the creation of more complex geometries, and the ability to rationalise final manufacturing costs it means that manufacturers can create a larger number of personalized tools which supports the manufacture of truly customised parts. This is a key advantage associated with the use of AM produced moulds, and heralds the achievement of true mass customisation.
www.nano-fabrica.com
