RE: [rp-ml] Sinterstation 2000 problems!!

Don't forget to check the nitrogen heater! Most I've seen out there are not working properly, which allows cold gas to flow into the center of the part bed. Setpoint is 150°C +/- 5°C.
 
Roger Spielman
Technology Development Manager
Solid Concepts
Valencia, Ca. 91355
Tel. (661) 257-9300

-----Original Message-----
From: David K. Leigh [mailto:dkleigh@harvest-tech.com]
Sent: Tuesday, September 07, 2004 7:25 AM
To: Kiran; rp-ml@rapid.lpt.fi
Subject: RE: [rp-ml] Sinterstation 2000 problems!!

Comments below.
 
1. Part strength are not what they should be? We are using Laser Power as required.( We have used a maximum Laser Power of 6.2Watts for PA and 6.0 watts for PA-GF). I am comparing the part strength to to that of Vanguard HS parts. Can you shed some light on this.
[David K. Leigh] Are you using the GUI display to calculate your wattage? The SLS system does not have active power calibration and you may have to increase your laser power setting in order to get the right wattage at the part bed. Also, if your part bed is too cold, it will also result in lower than normal density.

2. Part warpage. There is no sign of Curling during initial sintering of heat shield but the parts will get warped..In one of the cases the parts warped after 75mm of build, and the warping was so sevcere that the build was aborted)
[David K. Leigh] See above. . . you may want to increase your part bed temperature until it is hard to break out, then decrease a little at a time. The thermal characteristics on the SLS2000 are mixed. You will see a bit more curl, partly due to the smaller build area - therefore a smaller "sweet spot." But, overall our 2000 yields the most consistent temperatures.

3. The actual time taken for the build is more than 50 - 60% of the estimated time in case of multiple parts and in most other cases it is more by 20 -30%. But in some cases we have obeserved that it completes exactly as per the estimated time.
[David K. Leigh] This is really not a big deal. The scanning system on the 2000 is quite a bit slower, so it will take much longer for thick cross section parts.

4. We are not using Outline scanning. If we use Outline scanning then the machine will run forever :( ....Typically, we have observed that the parts quality as well as strength is better when we use Outline scanning. But a 23 hr build took around 58h to complete!!
[David K. Leigh] Sounds like you made the right choice. . .

5. We have disabled the downdraft in the system. Is that correct or wrong ?
[David K. Leigh] Downdraft is not necessary on Duraform. It does help even the part bed temperature out, but duraform has a decent operating range.

Good Luck!

*********************************************
David K. Leigh (254)933-1000
Harvest Technologies fax(254)298-0125
Rapid Prototyping Services dkleigh@harvest-tech.com
Received on Tue Sep 07 17:50:29 2004