Autodesk has moved to a subscription-based model. While the 2018 version is an older release, you can typically access it through these official channels: Log in to autodesk.com.
Choose "Download Now" or "Browser Download." Autodesk AutoCAD Mechanical 2018 Free Download
System automatically places items on correct layers. Autodesk has moved to a subscription-based model
Generate live parts lists that update as the design changes. Autodesk AutoCAD Mechanical 2018 Free Download