IMAGINE manufacturing an intricate hearing aid with a number of demanding requirements such as high accuracy, thin walls with space for electronics and a feature detail to suit the human ear.
Instead of going through the time-consuming work of forming a flexible mould and casting it with resin, imagine being able to manufacture that part straight from the electronic data provided in the design.
In 2000, Swiss manufacturer Phonak Hearing Systems decided to improve its manufacturing process for hearing aids through laser sintering technology.
The process, which originated from rapid prototyping (RP), allowed the company to manufacture the hearing aid directly from digital data with improved accuracy and mechanical properties. Today, it’s slowly making its way into commercially viable avenues within Australian industry.
Craig Beechey, MD of Betta Machine Tools, says that one of the key benefits of laser sintering is the ability to create any conceivable part out of plastic or metal powder directly from electronic data, with no design constraints.
“The traditional way to manufacture something is to get a block of steel and take away what you don’t need. With laser sintering, it’s an additive technology. You start with a metal powder and you build up, layer by layer, what you do need.
“Recently, one of our customers conceived a job on Friday, designed it over the weekend, sent through the CAD on Monday and on Wednesday morning, he held a physical metal part, 82mm in height with elaborate detail within 20 micron accuracy, ready for use,” Beechey told Manufacturers’ Monthly.
This combination of speed and accuracy to the design means that parts that are too costly to manufacture by other means, such as “one-off” equipment for surgeons, visualisation models or prototypes for testing purposes, can be made using laser sintering.
Rapid prototyping bureau Solid Concepts uses selective laser sintering (SLS) to create test components and prototypes for clients. According to GM Adrian Burleigh, the process is extremely fast in terms of build time, particularly when prototyping large components or castings.
“SLS is used when a part is subject to environmental or consumer trials and strength is the requirement, as they tend to hold out better than some of the other technologies available,” explained Burleigh.
“Some of our clients actually utilise the parts for field testing. We’ve made the parts in SLS, sealed them and they’ve then been painted with UV paint for field trials up to 13-14 months, basically like a consumer test to make sure they work,” he said.
Mass customisation
This is good news for companies who require a prototype, but what about when it comes to making 100 for a special line of stock, or 1,000?
Although the process has been in development for approximately ten years, it has only been in the last couple of years that laser sintering has accelerated to speeds faster than 20 micron and utilised more “exotic” materials such as chrome cobalt, titanium and stainless steel.
Beechey says that such developments have increased the market potential of the technology outside of rapid prototyping, with Betta Machine Tools recently announcing a partnership with German based company Electrical Optical Systems (EOS), recognised as world leaders in laser sintering technology. He also highlights laser sintering as a sign of a new industrial age of additive machining.
“With the advent of faster processing, laser technology and commercially available powder materials, the process is becoming more commonplace for direct parts (the end product) and direct tools (the tool or mould inserts).
“Applications in medical, automotive and aerospace industries are therefore now frequent. We’re also seeing new solutions in the mass customisation of consumer goods, everything from football boots to sunglasses and hearing aids,” said Beechey.
However, not every application will see cost benefits with laser sintering technology, as it’s still a relatively slow process when compared to high speed milling or turning.
Both Beechey and Burleigh advise that the general equation is the more difficult a part is to manufacture by traditional means, the more cost effective laser sintering becomes.
“Generally speaking, if you have a part that looks like it can be manufactured by traditional means you’re better off with a machining centre, but if that block of steel has spiral grooves and all sorts of intricate details, then laser sintering would be cheaper,” said Beechey.
Betta Machine Tools 02 9829 1129.
Solid Concepts 08 9455 5377.