# CAD Export Rules **URL:** \ **Category:** Using SimScale\ **Created:** [February 9, 2018, 2:23pm UTC](https://www.simscale.com/forum/t/cad-export-rules/81633 "2018-02-09T14:23:57Z")\ **Posts on this page:** 2\ **Page:** 1
**Author:** ![Reynnoldsnumber](https://www.simscale.com/forum/letter_avatar/reynnoldsnumber/32/5_5575768a8748004e209b776fc1b2916d.png) [@Reynnoldsnumber](https://www.simscale.com/forum/u/Reynnoldsnumber)\ **Post date:** [February 9, 2018, 2:23pm UTC](https://www.simscale.com/forum/t/cad-export-rules/81633/1 "2018-02-09T14:23:57Z")
HI I’m just beginner of simscale and some trouble makes me crazy these days I definetly make my CAD ( there is three parts in my CAD ) but when i export my CAD as stl ( or iges) and if i upload my CAD on simscale It becomes one stuff ( there is no more part anymore) So is there any rules when export CAD files ? I’m using NX version 6 ---
**Author:** ![1318980](https://www.simscale.com/forum/user_avatar/www.simscale.com/1318980/32/9637_2.png) [@1318980](https://www.simscale.com/forum/u/1318980)\ **Post date:** [February 9, 2018, 4:10pm UTC](https://www.simscale.com/forum/t/cad-export-rules/81633/2 "2018-02-09T16:10:21Z")
Hi @Reynnoldsnumber, this is a common problem with STL. You can export as a .step file and this will preserve faces and solids, however, a better workaround is to export each part individually then merge them as described in this workshop: > [@Step-by-Step Tutorial Session 4 - Design Process](https://www.simscale.com/forum/t/step-by-step-tutorial-session-4-design-process/80476): > > Recording [[CFD in Formula Student and Formula SAE - Session 4: Design Process] ](https://www.youtube.com/watch?v=puJoco1inSA)Homework submission Your homework for this session is to design your own front wing for a Formula SAE car, and test it using SimScale by following the same setup and steps as in the 2nd session. Submitting all four homework assignments will qualify you for a free Professional Training (value of 500€) as well as a SimScale Certificate of Completion. To submit your homework assignment, please generate a … Good luck, Darren