available DMLS materials

—–Original Message—–
From: A. Simchi [mailto:simchi@sharif.edu]
Sent: Wednesday, September 23, 2009 3:32 PM
To: White, Owen
Subject: RE: available DMLS materials

Hi Owen:

I see! The post processing is to achieve full density. Certainly, protective atmosphere is required to prevent excessive oxidation of the powder.

You are welcome if any other questions rise.

Best regards,

Arash

—–Original Message—–
From: White, Owen
Sent: Wednesday, September 23, 2009 12:30 PM
To: A. Simchi [mailto:simchi@sharif.edu]

Arash,

Thank you this is great. I read in:

http://cat.inist.fr/?aModele=afficheN&cpsidt=17832087

a fairly clear description of where to obtain HSS powder and how to combine with copper. I might explore this option.

I am confused about something I read in your article (Journal of Materials Processing Technology 141 (2003) 319-328) you performed post processing by raising to 1250 degrees under vacuum. Is this required or just meant to improve the densification?

Also, will it be useful to build a DMLS chamber to maintain a nitrogen atmosphere?

I promise no more questions after this mail message,

Owen

—–Original Message—–
From: A. Simchi [mailto:simchi@sharif.edu]
Sent: Wednesday, September 23, 2009 3:32 PM
To: White, Owen
Subject: RE: available DMLS materials

Hi Prof. White:

I see! I was the main developer of LaserTool. Actually, preparing a DMLS material is not very difficult if full densification is not a main object.

Simply by using fine and spherical powders (average size of about 30 micron) and employing a relatively high laser power (for CO2 250 W and for Nd:YAG 100 W) you should be able to reach density of 85-90 % theoretical for Bronze and Stainless steel powders. Please keep layer thickness as 50 micron and hatch spacing to 0.3 (25% overlap). Also, please use short scan vector. The other problem you may involve could be part cracking due to the thermal stresses. You may preheat the platform to reduce this problem.

Full densification is feasible if you use higher laser intensity to attain full melting of the powder bed.

Best regards,

Arash

—–Original Message—–
From: White, Owen
Sent: Wednesday, September 23, 2009 12:30 PM
To: A. Simchi [mailto:simchi@sharif.edu]

Dr Simchi,

Thank you for responding. For now, my application is not particularly complicated. There is interest here to simply see if we can set up DMLS capability to rapidly prototype parts with bronze or steel based powders. We have some equipment on hand and are prepared to purchase other parts of the system to create an initial prototype.

Were you involved in the construction of LaserTool? How difficult was it to make?

Thanks very much for your help,

owen

—–Original Message—–
From: A. Simchi [mailto:simchi@sharif.edu]
Sent: Wednesday, September 23, 2009 2:26 AM
To: White, Owen
Subject: Re: available DMLS materials

Hello Prof. White:

Thanks for your e-mail and your interest on DMLS powder. We have
patented LaserTool on 2001. At first EOS attracted our patent right
but later purchased it then shutdown the production (!) because the
price of this powder is less than 10% of the current available
materials produced by the company. It is understandable because as
the low amount of the material are used worldwide the high price
guarantee the benefits of the company.
You should enable to purchase the materials from EOS; you may send a
mail and ask. If it does not work, you may contact Dr. Frank Petzoldt
(fp@ifam.fraunhofer.de), the deputy director of Fraunhofer Institute
IFAM, Germany, and request the materials (either LaserTool or other
type which they have developed).

I don’t know in which application you intend to use the material. If
you give me more information I would be pleased to help.

Sincerely,

A. Simchi

—–Original Message—–
From: White, Owen
Sent: Wednesday, September 22, 2009 12:30 PM
To: A. Simchi [mailto:simchi@sharif.edu]

Dr. Simchi,

I have read a number of your publications that evaluate the properties of DMLS materials and I was wondering if you could answer some questions.

I am considering construction of a custom made DMLS machine using a 250 watt C02 laser but I do not know of a source for DMLS powder. Your 2003 publication “On the development of direct metal laser sintering for rapid tooling” you describe the properties of LaserTool , is it possible to obtain this material?

If it is not available, do you have suggestions of how I could obtain DMLS powder from commercial manufacturers, or to fabricate DMLS powder from raw materials? I am assuming that EOS does not supply any of their DMLS powder to people that do not own one of their systems, perhaps this is an incorrect assumption.

Owen

Owen White, PhD

PI, Data Analysis and Coordination Center for the Human Microbiome Project
Director of Bioinformatics, Institute for Genome Sciences
Professor, Department of Epidemiology and Preventative Medicine
University of Maryland School of Medicine
801 West Baltimore Street, Room 661
Baltimore, MD, 21201

Advertisements

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s


%d bloggers like this: