3D printing using Memjet printheads

US 2014/0345521 A1
Printing system for forming three dimensional objects
3D Systems, Inc.

This is a continuation patent dating back to 2011 and filed by Kia Silverbrook. However the assignee is 3D Systems, the leading 3D printing machine manufacturer. The basic idea is to use stationary Memjet printheads to deposit layers of material to build up structures. The printhead technology proposed is not the bubble jet system which has been commercialised, but a moveable element system. Nov-14aFor instance Silverbrook has demonstrated a moving nozzle prototype in the past. A wide range of materials can be deposited up to a viscosity of 10 centipoise. The printhead is heated so that low-melting point metals such as indium (156C) and alloys of indium and gallium can be used, polymers with melting points of 120-180C, and sacrificial waxes with melting points above 80C.

Printheads 402 and 404 deposit drops onto a moving conveyor. Multiple printheads are used to deposit separate materials. In the figure 4 printheads 402a-402d are being used to deposit 4 different materials on the first layer. Some materials may need some form of processing, for instance forced cooling, evaporative drying, UV curing, precipitation reactions etc. Here the first two materials are processed by curing station 406. The second two materials have a different curing requirement and so a second curing system 408 is used. The second layer is built using seven diff erent materials by printheads 404a-404m. In this case 3 different curing systems are used.

Nov-14bNote also that the layers are off set slightly from each other. This enables small cavities to be constructed that are self-supporting and do not need a sacrificial support material. This avoids the extra processing and complication of removing the support material later.

The pitch of drop separation and the height of a layer is 10 microns. Larger cavities can be created to allow the insertion of dies such as integrated circuits, memory, LED and so on.

The process speed envisaged is 208 mm/sec. and the print width 295 mm. Up to 1,000 layers are envisaged allowing products to be printed up to 10 mm thick. This requires a minimum of 1,000 printheads, but if multiple materials per layer are used something like 8,000 printheads may be needed.

The patent application talks of applications such as flat panel TVs and PDAs, perhaps dating the document and also demonstrating how fast product development has been. Production speeds are 0.37 and 432 per second respectively for those two examples.

Although this process sounds incredible and optimistic, remember the patent application has been acquired by a market leader. It will be interesting to see what comes of it.