Fasteners are widely used across all industries. In mechanical engineering, bolts, screws, and studs are commonly employed to connect parts, while rivets are frequently used in shipbuilding and aviation.
Designing and drawing fasteners in NanoCAD Mechanica frees designers from routine drafting tasks. Fasteners are easily integrated into part assemblies and can be edited or replaced as needed.
NanoCAD Mechanica enables the creation of both detailed and simplified bolted connections. In assembly and general view drawings, it is often necessary to display fasteners without sectioning. These images are generated in NanoCAD Mechanica by selecting the desired insertion type. The software supports creating multiple connection views—front, side, top, and bottom (if structurally feasible). The presence of sectioning and the type of fasteners in the connection are automatically adjusted.
The “bolt connection” tool in NanoCAD Mechanica is designed to create connections with bolts, screws, and studs. It allows technical documentation developers to connect part assemblies of varying thicknesses. Note that overly thin or thick assemblies may not be connectable with the selected fasteners if such a connection is structurally unfeasible.
The software automatically determines the number of parts to be joined and the position of holes in the parts. It supports creating smooth holes, threaded through holes, blind threaded holes, or universal holes commonly used in assembly connections, as well as adding standard bolt and screw placements to the connection.
When designing a bolted connection, parametric relationships are established between fasteners and other connection elements. For example, the thread diameter of a nut will match and depend on the thread diameter of the screw it is attached to.
To obtain high-quality connection views that do not require manual refinement, proper overlap is essential, which NanoCAD Mechanica provides automatically. For instance, in front and side views, the nut will overlap the bolt axis, while in the bottom view of the same bolt connection, the bolt axis will be higher than the nut. This results in structurally accurate images.
Detailed and Simplified Connections with Hex Bolts and Nuts
The image shows detailed and simplified connections with hex bolts and nuts. The software assists users in selecting an appropriate bolt length for the chosen assembly thickness (considering the nut’s position) from a standard range corresponding to the selected diameter, while automatically eliminating unsuitable lengths for the assembly thickness.
When connecting component assemblies with countersunk screws, contact surfaces from the database must be used. Once such a surface is created in the assembly, the countersunk heads of standard screws will automatically align with it, forming the connection.
Countersunk Screws
If a blind threaded hole is present in a screw connection, the software assists in selecting thread eccentricity and undercutting per ISO standards. The user only needs to select the required length and diameter, with other dimensions automatically determined based on the thread pitch.
Blind Threading
NanoCAD Mechanica supports designing various bolt connections. If the selected stud standard is a tie rod, it will behave accordingly in the connection: positioned at the center of the assembly, expanding and contracting symmetrically. For screwed studs, a different logic applies, specific to their design. Unlike tie rods, these studs can be screwed into threaded holes.
Critical bolt connections can be secured not only with a locknut or spring washer but also with a cotter pin or special lock washer, which automatically engage with the corresponding connection parts.
Critical Bolt Connection
When automating fasteners with cotter pins, issues may arise due to inconsistencies in standards. Typically, holes for a cotter pin in most standards are shown parallel to a face of the bolt’s hexagon. However, how should these fasteners be depicted in drawings of a bolted connection with a slotted or castle nut? Conversely, ISO 737893 clearly specifies that cotter pin holes should be perpendicular to the hexagonal face of the bolt, not parallel. In NanoCAD Mechanica, cotter pin holes are created per ISO 737893, not individual fastener standards, resulting in technically superior connection images.
Cotter Pins per ISO 737893
Due to the wide variety of fasteners and frequent lack of clear guidelines on bolted connections in standards, designing a bolted connection in NanoCAD Mechanica is left to the user’s discretion.
In addition to the bolted connection tool, NanoCAD Mechanica includes a similar tool for creating riveted connections, simplifying the creation and editing of various representations of these connections in drawings.
The database includes standard and precision rivets with various standard heads. Like bolted connections, rivets can join assemblies of multiple parts with different thicknesses, with unsuitable rivet diameters for specific assembly thicknesses automatically excluded.
Rivets have their own behavioral logic. For standard precision rivets, standards do not specify the shape of the closing head or provide clear recommendations on the riveting rod length, leaving these choices to the user. Users can also select any parameter for the closing head geometry. Rivets can be shown unriveted in drawings, with any clearance in the connection, and displayed in section or non-section views.
Standard Precision Rivets
The database includes hollow and semi-hollow rivets, which can be represented in section views.
Hollow and Semi-Hollow Rivets
When numbering multiple instances of the same fastener, NanoCAD Mechanica creates a common line with vertical position numbers. Standard fasteners are automatically placed in the appropriate section of the bill of materials, with their names filled in per the respective standards.
NanoCAD Mechanica users can create custom fasteners based on those in the database, with similar behavior.
Additional database editing options are available. For example, if a company or supplier only stocks specific fasteners, and only these should be used in projects, the database can be restricted using a special nomenclature filter tool. This allows hiding all parts in the database by unused standard numbers or selectively hiding individual part sizes to prevent their use in designs.
Thus, in the CAD software market, NanoCAD Mechanica’s functionality for designing bolted and riveted connections is currently among the most efficient. The database accounts for a wide range of standards, and thanks to the specialized logic of fastener behavior in connections, designing part connections requires significantly less time.