From the initial discussion and concept phase to the industrialization of your product, the 3D modeling of the machine and its parts can help you optimize your design, bringing speed, precision, and enhanced visualization to each stage of the manufacturing process. This adds additional benefits, such as reduced lead times and manufacturing costs.
3D modeling using computer-aided design (CAD) allows engineers and CAD services to build realistic computer models of the product. From a simple one-piece component to a multifaceted system such as a Formula 1 racing car, using 3D CAD modeling enables the product to be brought to life in a virtual environment. From here, many "what-if" scenarios can be performed, design changes can be implemented on the fly, and design enhancements can be implemented in real time at a vastly reduced cost compared to building multiple physical prototypes.
Solid models are created by developing a mathematical representation of an object in three dimensions. This representation is a virtual physical body that defines the volume of the object it represents. Typically, the designer envisages the process by which a singular component is to be manufactured and applies the processes using the CAD software being utilized.
While there are subtle differences between the different CAD packages on the market, the procedure is similar and involves the designer creating primary, secondary, and tertiary features of the model.
The primary features of a machine component consist of the main bodies of the component – bodies that define the primary dimensions of the component by either extruding shapes (creating a sketch on a defined plane and "stretching" the sketch in the desired direction to form a solid body); revolving a shape (similar to extruding but revolving the said sketch around a pre-defined axis); sweeping a shape along a predefined sketch path (a curved extrusion such as the curved neck of a tap faucet), and lofting different sketch profiles to form a complex component (such as a structural component of differing widths).
The inverse is true for removing material on primary features. A revolved shape can be utilized to remove material from a primary body (such as would be used in a typical CNC manufacturing process). Changing the dimensions of the primary bodies will alter the component shape and often necessitates the recalculation of the load or stress factors on a component to see if it meets with the required factors of safety.
Secondary features of a machine component consist of features that typically assist with the assembly of components to one another. These can include holes, threads, spigots, etc., and are generally available to the designer through menus in the software. The modification of these features may have some bearing on the design of the component but would not be considered as critical during analysis (they are, for the most part, removed during finite element analysis).
Tertiary features consist of the components that have no real influence on the design and the modification of said components is considered to be trivial from a design perspective. An example here is the removal of sharp corners (chamfers) for handling or the engraving of a part number on the component surface.
If the manufacturing process is understood for a particular component, there are other tools to assist the designer in the definition of her component. Sheet metal or forming add-ons allow the designer to create manufacturing-specific processes such as bending, punching, notching, or the ability to "flatten" or develop the component. With processes such as forming or injection molding design, the ability exists to create forming or press tools by simply using Boolean functions such as "subtract" to create an accurate representation of the designed part in its inverse state.
If the component is to be printed (such as with laser sintering), it's common-use tools to automatically create latticework on structural members to reduce mass, an intricate process difficult to accomplish by normal methods. A recent implementation is generative design – the designer specifies parameters such as material, loads, constraints, design space, and the software generates a 3D geometric solution.
For the more aesthetic components of a machine component such as molded covers, rubber fixtures, handles, or the parts of the assembly that consist of a more free-form or organic shape, a methodology called surface modeling is used. Surface modeling represents components with a technique called wireframe modeling.
While giving the designer more freedom regarding shape definition, the ability to modify the basic profiles is more complicated later on in the design process. Once the wireframes are complete, the model can be closed to form a solid and form an integral part of the machine component or assembly. It is not uncommon for both solid and surface modeling to be utilized in a 3D model.
Assembly modeling allows for all the individual components to be assembled as one. The 3D modeling of machine parts will, for the most part, form part of the assembly. The onus is on the designer to determine if this should be part of a "top-down" or "bottom-up" design principle, where "top-down" design allows for components to be designed in the context of an assembly where, for example, space constraints dictate where and how components must work.
It is possible to work on a component individually in the assembly and rules can be set up in the software to notify the designer when these constraints have been breached. Bottom-up design allows for existing components to be utilized or designed and then assembled as required. With the ever-increasing availability of tools, fasteners (such as screws, washers, etc.), and supplier part online repositories, it is not uncommon for 3D assemblies to utilize these generic models, which can save a great deal of time.
Applying material properties to the modeled component allows for the design simulation of the 3D model within the modeling software and the ability to see if the design conforms to currently valid standards (such as ANSI, DIN, ISO, AGMA, etc.). To ensure the design meets its product life parameters, the assembly interference checks can be performed to ensure that all components fit.
The machine design process is iterative. From concept review and preliminary design review to critical design review and even up to full industrialization, there is only one constant – change.
Utilizing the advantages of 3D modeling and design can shorten the process of the prototyping design service.
Even today, the keystone of a design is the manufacturing data pack, which consists of a 2D representation of the designed components, documentation, and assembly instructions. Utilizing the speed and simplicity of the latest modeling tools, it is possible to create a full parameterized and associative data pack. A 3D model that has well defined "mates" linking the faces, edges, or primary features will, by association, update its corresponding components automatically.
Similarly, the 2D drawings that are automatically generated from the corresponding 3D model along with the defined attributes such as material types, dimensional tolerances, geometric dimensioning and tolerancing (GD&T), surface finishing, notes, and special instructions are also updated. The design intent is therefore captured automatically without the need for user intervention ensuring revision control is seamless.
It is common for manufacturing companies to make use of generic 3D models generated by the CAD designer, especially in the prototyping stage to generate CNC code to assist with the setup and manufacturing of the component. Utilizing the correct 3D modeling software can also ensure associativity between changes in the model and the subsequent CNC generated code or 3D printing files alleviating possible revision mismatches.
As an additional benefit, photorealistic rendering of the 3D CAD design communicates the design intent to the end user or client much earlier in the design cycle.
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