Perfectly proportioned: Working to improve dry compaction and sintering

Nov 03, 2009
A new simulation technique helps to improve the sintering process: it calculates the best method for achieving an even density of the powder in the mold. (© Fraunhofer IWM)

(PhysOrg.com) -- The manufacture of parts by compaction and sintering involves filling a die with metal powder. Research scientists have simulated this process for the first time to achieve an evenly distributed powder density. This improves the cost-efficiency of sintering.

It all happens very quickly: the feed shoe, configured as an open-bottomed box, moves across a surface in which a recess forms the shape of the desired part. The fine-grained metal powder dropping from the feed shoe settles in the mold. Stamps then compact the loose powder grains at a pressure of several hundred megapascals to produce the “green body” - a preform in the shape of the finished part which now has to be sintered in a furnace at a temperature below the melting point of the material. This procedure ensures that the compacted grain structures become more compressed and harden.

Dry compaction and sintering are common processes in industry. They deliver precisely shaped parts that can withstand high mechanical loads. There is still potential for improvement, however, and Fraunhofer researchers aim to perfect the technique and avoid costly waste.

“Filling the die is a critical step in dry compaction,” states Dr. Claas Bierwisch from the Fraunhofer Institute for Mechanics of IWM. “The metal powder is not distributed 100 percent evenly in the mold. These inhomogeneous distributions of density could cause the part to warp or even crack, affecting its loadability, precision and service life,” the project manager explains. Up to now an expensive trial-and-error approach has had to be applied to obtain the best results, but this will no longer be necessary with a simulation technique developed by the research scientists for optimizing the filling process.

“By describing the powder numerically we can attach values to virtually every grain,” explains Bierwisch. The physical properties, size and shape of the grains as well as the shape of the mold are all taken into account. The research scientists then calculate how and where the powder grains flow into the mold and what the density distribution is like after filling. It is now possible for the first time to realistically simulate the production of three-dimensional parts such as toothed wheels in gear systems or washers in one-hand mixer taps for washbasins.

What’s more, the researchers can draw conclusions about the filling process, including how high the speed of the feed shoe needs to be and how it should move. In some cases the shoe only needs to move forwards and backwards. For other parts the die has to oscillate as well. The scientists can simulate the sintering events through to completion of the finished part and can therefore replicate the entire process chain. They are currently optimizing the manufacture of magnetically soft coil cores for wheel hub motors, which could play an important future role in electric vehicles.

Provided by Fraunhofer-Gesellschaft (news : web)

Explore further: Faster computation of electromagnetic interference on an electronic circuit board

add to favorites email to friend print save as pdf

Related Stories

Printing of components with functional ink

Apr 08, 2005

Time is money - even in component manufacturing. Researchers can continuously print out three-dimensional metal parts using a rapid manufacturing process. The unique feature is that they can vary the material ...

First powder injection molding process for pure niobium

Oct 17, 2005

Penn State researchers have developed the first powder injection molding process for pure niobium, a biocompatible material similar to platinum and titanium but cheaper. The researchers, who are based in the University's Cen ...

Engineers crack ceramics production obstacle

Mar 13, 2009

(PhysOrg.com) -- Engineers at the University of Leicester have invented a new technique in the manufacture of ceramics that has the potential to save the industry time and costs while reducing wastage.

Dental fillings without gaps

Sep 05, 2008

Tooth cavities are usually closed with plastic fillings. However, the initially soft plastic shrinks as it hardens. The tension can cause gaps to appear between the tooth and the filling, encouraging more ...

Hollow spheres made of metal

Oct 13, 2009

Producing metallic hollow spheres is complicated: It has not yet been possible to make the small sizes required for new high-tech applications. Now for the first time researchers have manufactured ground hollow ...

Recommended for you

A smart prosthetic knee with in-vivo diagnoses

Apr 22, 2014

The task was to develop intelligent prosthetic joints that, via sensors, are capable of detecting early failure long before a patient suffers. EPFL researchers have taken up the challenge.

Old tires become material for new and improved roads

Apr 22, 2014

(Phys.org) —Americans generate nearly 300 million scrap tires every year, according to the Environmental Protection Agency (EPA). Historically, these worn tires often end up in landfills or, when illegally ...

Students take clot-buster for a spin

Apr 21, 2014

(Phys.org) —In the hands of some Rice University senior engineering students, a fishing rod is more than what it seems. For them, it's a way to help destroy blood clots that threaten lives.

User comments : 0

More news stories

Jacket works like a mobile phone

A fire is raging in a large building and the fire leader is sending a message to all firefighters at the scene. But they don't need a mobile phone – they simply check their jacket sleeves and read the message ...

Is nuclear power the only way to avoid geoengineering?

"I think one can argue that if we were to follow a strong nuclear energy pathway—as well as doing everything else that we can—then we can solve the climate problem without doing geoengineering." So says Tom Wigley, one ...

Male-biased tweeting

Today women take an active part in public life. Without a doubt, they also converse with other women. In fact, they even talk to each other about other things besides men. As banal as it sounds, this is far ...

High-calorie and low-nutrient foods in kids' TV

Fruits and vegetables are often displayed in the popular Swedish children's TV show Bolibompa, but there are also plenty of high-sugar foods. A new study from the University of Gothenburg explores how food is portrayed in ...