direct mold creation by laser sintering

There was a thread on the possible reduction of cnc machining because of the growth in "3D" printing. It appears that a German
company [EOS] has developed a process to directly create plastic injection molds by laser sintering. Not only can you directly create the mold from a cad file, this process also allows very intricate coolant passages.
Thoughts and has anyone seen any molds made by this process? Materials? Surface finish?
http://memagazine.asme.org/Articles/2009/September/Technology_Focus.cfm {mold article starts about 1/4 the way down the page} <snip> Injection molding is the most widely used plastics processing technology. The process melts thermoplastics and forces them into a metal mold. After the plastics cool, the mold opens to reveal the finished part. To speed cooling, molders run liquid through cooling channels they drill into the mold.
Cooling channels work great when molding parts with regular features. Add curves and irregular geometries, and manufacturers run into problems. Straight drilled channels cannot follow the contours of the part. As a result, they remove heat unevenly, so operators must wait until the material farthest away from the cooling channel cools before they remove it from the mold. No wonder cooling time can account for up to 70 percent of each injection molding cycle. Uneven cooling can also warp parts and increase scrap rates.
This is where EOS comes in. The companys equipment produces molds from 3-D CAD data by direct metal laser-sintering, fusing metal powders into solids one layer at a time. The companys equipment has no problem creating cooling channels that curve, arch, and branch to conform to any shape, because channels are built into the mold as it is formed, not drilled afterwards. <snip> ------
Unka George (George McDuffee) .............................. The past is a foreign country; they do things differently there. L. P. Hartley (1895-1972), British author. The Go-Between, Prologue (1953).
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Jan 14, 12:36pm, F. George McDuffee <gmcduf...@mcduffee- associates.us> wrote:

Being a moldmaker for over 30yrs, I'm here to tell ya, laser sintered mold cavities are not all that great. The process has been around for quite some time. It kind if remindes me of SLA's only in metal. I worked for a Swedish company in the 90's & they had it then at mother company in Sweden. Probably the German machine. It does have a purpose though, for quick "bridge" or pre- production prototype tools. Its a powdered metal, so its weak & soft. Deep cavities are no go. We cracked'em in the the press due to the injection pressures sometimes upto 40k psi! They did cell phone housings for Erickson & Nokia. It worked ok to get real world injection molded parts, but longevity & accuracy was not there. They would wash out & were real finicky to run. Typical class A molds need have million shot life. With highly abrasive polymer you'd be lucky to get 50-100k. before the cavity is washed out. But, you could keep the sinter machine going 24/7 & just replace cavities as the wore out or broke?

Some of this is true & some is just caused from a poor selection of steel & cheap mold desgin On a good tooI running a 10sec cycle, injection time is less than a second, hold time=a couple secs?, the rest is cooling, so yes 70%is a fair estimate. Getting the cooling lines in around contours is cool, but not absolutely necessary.There are ways to cool "troubled" areas.By means of water bubblers/baffels - pressed in "cooling pins" or by material selection. Years ago the would use berrilyim copper inserts, now they have devolped an Aluminum Bronze? material called Amcoloy 940. $Good$ stuff for cooling. I've machined entire cavities out of it. Its costly stuff so no fuck-ups! Decreased mold cycle times drastically.Problem areas in molds have to be spotted before hand, buy the tooling engineer or mold builder. Mold Flow analysis is fairly good, but the best I've seen comes from years of experience. Problem is when those areas are spotted, most do not want to spend the extra bucks & time to tackle it. They always wait till the last second to build a mold, because product design/engineering are so far behind. Go figure. Its a rat race to build a tool & get it into the press in 4-6weeks. Most of the time on short lead times they build as the database is getting done-finalized. EC's up the ying yang. No part prints just pre release data base. Go MFer! <g>

Out of all the machinists trades (I've been in a few others these last 6yrs) Mold Makers got it the toughest.
I'm glad I'm outa that racket. Just a macheenist now man.<g>
--
___ ___
/ /\ / /\
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Thu, 14 Jan 2010 16:50:48 -0800 (PST), cncmillgil
<snip>

=======Thanks for the real world feedback.
As for the wear did anyone try a hard chrome plate or other coating, possibly like the newer carbide inserts have? Article mentioned "it was not until 2007 that EOS developed a maraging steel that it could use to make molds durable to withstand mass production."
Unka George (George McDuffee) .............................. The past is a foreign country; they do things differently there. L. P. Hartley (1895-1972), British author. The Go-Between, Prologue (1953).
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On 1/14/2010 10:36 AM, F. George McDuffee wrote:

It's being tested on aircraft engine blades as it's easy to put cooling passages in them for the hotter stages of the assembly. Using some sort of chromium alloy.
-- Bill
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

They have really come along way with this stuff ( 3D printing)- now DLMS

http://www.youtube.com/watch?v=wjSb51aEpWU

http://gpiprototype.com /
--
BB's #4
Our pitiful pride
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Polytechforum.com is a website by engineers for engineers. It is not affiliated with any of manufacturers or vendors discussed here. All logos and trade names are the property of their respective owners.