Fast and economical laser finishing of glassforming moldsPublished on September 29th, 2011 | By: Eileen De Guire
Laser manufacturing usually conjures images of high energy welding, rapid prototyping or precision cutting. A recent press release from Fraunhofer Institute for Laser Technology describes a laser manufacturing method that offers advantages for more pedestrian applications, too.
Mold making, for example, is tedious, time-consuming work involving hand polishing with grinding stones and polishing pastes. The old adage, “Time is money,” applies, and the finishing step of mold making is expensive. Also, according to the press release, “companies are struggling to find new recruits for such a challenging yet monotonous task.”
Fraunhofer ILT has developed a laser process that is capable of finishing simple or complex surfaces. The resulting surface finish is rougher than is achievable with hand polishing but, as researcher Edgar Willenborg says, “many applications – for example molds for glassmaking, forming and forging tools – a medium-quality surface is all that is needed.”
Hand polishing removes material layer-by-layer. The laser process differs in that materials is not removed, but is melted in thin layers of 20 to 100 micrometers. Because of surface tension, the liquid metal solidifies evenly. Willenborg also noted that exploiting surface tension means that component quality is not dependent on the machine’s rigidity, such as in a polishing process. Average roughnesses of 0.1 to 0.4 micrometers have been demonstrated.
Working with Maschinefabrik Arnold and S&F Systemtechnik, Fraunhofer ILT has built a 5-axis gantry system with a 3-axis laser scanner, which allows the workpiece to be accessed from all sides. The machine finishes surfaces up to ten times faster than is possible with hand polishing, and feed rates of more than one meter per second (even on small components) have been achieved. The system incorporates conventional CAD/CAM technologies that will be familiar to technicians. The press release says the process “is an excellent option for serial production and for polishing small batches.”
No mention is made of environmental advantages, but the absence of cutting fluids may be an added benefit.
The institute will be rolling out the laser polishing system at the 2011 EuroMold exhibit Nov. 29-Dec. 2 in Frankfurt, Germany.
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