Preliminary mechanical design may be performed in either interactive or generative mode by use of a CAD system on the basis of the data calculated from SCORPATH. Traditional CAD systems are limited to the representation of geometric data and other types of information relating to geometry such as constraints, parametric information, features, etc. However, implementation of function, behaviour and structure of a specific machine such as compressor is not accounted for in them.

The engineering design community has been developing new classes of tools to support knowledge-based design, product data management (PDM) and concurrent engineering. When contrasted with traditional CAD tools, these new systems are improved but still mainly database related. Also, although these systems can represent some kinds of non-geometric information such as design process details, bills of materials, etc, the representation of the design object itself is still generally limited to geometric considerations. Evidence of this may be found by reviewing the projects described on the IAI web page. Due to these limitations, further interoperability is required to enable full interaction between any CAD system and performance calculation programs such as SCORPATH.

Any detailed mechanical design, that is to be performed later, may be conducted with a different CAD system to the one used in the previous design phase. As a result, manufacturing drawings can be produced and a numerical basis for manufacturing process generated based on information exchange between them through standard IGES, STEP or likewise integration. Available standards can be reviewed on either the IAI or the ISO web pages.

Part of the CAD system should be related to the selection and/or calculation of mechanical properties of compressor elements. Some of these are: bearing selection based on life theory, selection of bolts and screws, checking of shaft deflections and strength, selection of keys and key-ways, dowels etc. The majority of CAD software allow such calculation through integrated CAE components.  However, these generally require substantial action by the user in order to set up and relate loads and restraints calculated outside the CAD system with geometry created within the CAD system.

SCOCAD therefore organises output data from SCORPATH into a standardised database, with unique structure for all screw machine designs available, to be implemented to an arbitrary CAD system. These data are provided as the coordinate points for rotors, ports and the manufacturing tool. Since these are automatically transferred to the CAD system, the 3D solid model can be built in a short time. Additionally, parametric organisation of the data interchange through the external data base enables the design to be easily modified not only from the CAD system itself but also from both the external database and the SCOCAD environment. Being incorporated in DISCO, SCOCAD then enables the design changes to be introduced to other applications also integrated in DISCO. In addition, it permits the calculation and/or the selection of the machine elements from a database independent of the CAD system. The 3-D solid model obtained from the CAD system serves as a basis for rapid prototyping, while drawings are automatically provided to support more conventional manufacturing methods.