Aerospace Industry Utilizes Laser Sintering

Polyamide PA 2210 FR, produced by EOS for use in its laser-sintering machines, is specifically designed to meet the flammability, smoke and toxicity standards for the civil aerospace industry. Airplane manufacturers like Boeing, Dassault, Embraer and others have successfully tested the new material and PA 2210 FR typically qualifies for "flying hardware" with wall thicknesses down to 2mm.

UK-based rapid manufacturing and prototyping specialist Ogle Models now offers PA 2210 FR in the range of materials used to produce components for customers. Sales and Marketing Director David Bennion believes Ogle is one of the first RM/RP bureaus in Europe to run the fire-resistant material in its machines and it has already produced two sets of parts for the cabin and fuel tank of an aircraft, in quantities ranging from 50 to 200.

Additional Ogle customers include the telecommunications industry, where for some time they have been producing a fireretardant, fiber-optic tray for communications towers using a combination of stereolithography (SLA) and vacuum casting. However, that process used to be time consuming and relatively expensive, but now the same part is laser-sintered in one operation using PA 2210 FR in quantities up to 180, without the need for tooling, resulting in a 30% cost savings for the customer.

A FORMIGA P 100 plastic laser-sintering machine is capable of 10µm layer definition.

The first EOS plastic laser-sintering machine installed in 2000, an EOSINT P 385, has been working to capacity 24 hours per day for the last 18 months. Ogle's Rapid Prototyping Director, Steve Willmott, comments that the machine has been upgraded twice by EOS to take advantage of improvements in laser-sintering – resulting in a 30% increase in productivity and a 50% improvement in component quality.

Addressing the need for more machinery, two additional EOS machines were added during a recent $1.8 million investment at Ogle's product development service center. Since then it has seen a near doubling of floor area, giving more space to develop both the traditional model making and CNC prototyping sides of its business.

A step-change in performance came with the installation of the two latest machines, a larger EOSINT P 730 with 700mm x 380mm x 580mm build volume and a smaller 200mm x 250mm x 330mm capacity FORMIGA P 100.

The chassis (center) that supports the screen and electronics of thermal imaging cameras went into full production using laser-sintering.

"New control software makes these machines much easier to operate, as no guesswork or experience is needed to set the scaling factor that allows for shrinkage of the part," says Willmott. "There is less of a problem in the X- and Y-axis as shrinkage is linear, but it is non-linear in Z. The latest EOS software applies compensation in all three axes automatically, making it quicker to set up a new job.

"The twin-laser P 730 is 40% faster than earlier machines, producing components that look as though they have been molded, and providing better dimensional accuracy and surface finish. Key to the improvement is the 0.12mm standard layer thickness, down from 0.15mm on the P 385. Similarly, the FORMIGA P 100 does everything that the large machine is able to, but within a smaller work volume, and to even higher accuracy thanks to the 0.1mm layer thickness."

Series production of laser-sintered plastic components is becoming the norm at Ogle, in addition to ones and twos for prototype applications. A good example is the manufacture of parts in batches of several hundred for a thermal imaging camera used in search-and-rescue work. From a CAD model supplied by the customer, laser-sintering is used to make the chassis that supports the thermal imaging screen and the electronics. No hard tooling is required, so any alteration in design is easily accommodated without additional expense.

A big advantage of additive layer manufacturing by laser-sintering is that the process is fully self-supporting, allowing parts to be built within other parts and with complex geometries that could not be realized any other way. These attributes lower the cost of production and at the same time offer unfettered freedom of design. Moreover, the resulting components are strong and rigid enough to be used in places where they may be subjected to mechanical and thermal stress.