2D To 3D CAD Avails State Of The Art Fabrication Processes
Start-up ventures, inventors, and small companies may have product ideas, concepts, patents, or core technologies that are the basis of a new product development effort. Accordingly, many product development programs begin without either 2D (three dimensional) or 3D (three dimensional) CAD models. It is typical in these environments not to have professional CAD capabilities. Many business success stories tell of conversations over coffee sketching on a napkin. Good ideas can come from anywhere and anyone including from people with diverse backgrounds that do not necessarily include product or business development experience. At some point, people with entrepreneurial aspirations will seek the services of professional CAD designers, engineers, for prototyping and manufacturing capabilities.
When CAD services are required tight budgets will cause the developer to gravitate to hand drawings or free or inexpensive 2D CAD programs such as Draft It, CadStd, Concepts Unlimited, Cadvance, CAD X11, PowerCAD, or the popular AutoCAD LT. While these programs are easy to learn and serve to get designs on printed paper, they are only a preliminary step to developing professional production ready data for prototyping, machining, tooling, and manufacturing. 2D programs can be very useful for building breadboard level testable units to validate the fundamental design and engineering for a product but when it comes time for complex geometries 3D CAD services from professional CAD designers and engineers is the gateway to world class product development.
Often the need for the professional CAD designers and engineers is identified when a developer seeks the services of a prototype service company. The developer is typically looking for SLA (stereolithography) generated parts. This process requires STL file formats which are easily exported by 3D CAD software that convert surface data into a tessellation mesh of triangulated planes. In the stereolithography process prototype parts are "grown" in a tank wherein a liquid is solidified in thin successive layers according to the cross sections of the part building from bottom to top. It is literally a process of layering, or printing hence the term lithography which is building up a part by layering cross sections. Advances in SLA materials provide for simulated properties of various polymers.
The need for SLA parts may be the first point at which the developer is requested to supply 3D CAD data. Typically this is an unanticipated snag in the developer's schedule. Many prototype service companies make referrals to CAD service professionals. The upside of this is that the developer is introduced to a professional CAD service provider who can offer much more than just 3D part files. CAD service professionals can work with whatever engineering data, prototypes, notes, or sketches that the developer may possess. Professional CAD service providers work daily with prototyping and manufacturing companies and offer a bridge to the developer in moving from and idea, breadboard, patent, or technology to manufacturable delivered products.
Contemporary 3D CAD services are parametric solid modelers. Solid modeling mean that the computer software recognizes the exterior skin of the modeled part, knows the density of the material it represents, and can calculate its volume, surface area, and part weight. In addition, it can calculate its center of gravity and moments of inertia. Visualization features allow for the program to remove materials and reveal sections through a part or assembly. Such view will appear as if the product were cut on a saw. Solids functionality changes the way that drawing are created. Drawing rather than being lines and arcs on a sheet are actually virtual camera shots of the solid model from any defined angle or section view. Parametrics mean that dimensions in a solid model can be modified and the model will automatically adjust the volume of the solid to reflect the new dimension. Parametric solid modeling is highly efficient versus 2D drafting and certainly manual pencil drawing. Solid modeling offered enormous advantages resulting from mass property data. The solids data allows the software to be aware of the respective position of all of the mass within an assembly. This allowed for clearance and interference checking.
Converting 2D to 3D CAD typically involves importing 2D geometry into a 3D CAD program file. Importing is commonly done with IGES (Initial Graphics Exchange Specification) files or AutoCAD's DXF (Drawing Exchange Format). Once imported, 2D sections can be given volume by: 1.) extruding a section to a fixed dimension, 2.) revolving a section around an axis, 3.) sweeping a section along a trajectory, or 4.) sweeping and blending multiple sections along multiple trajectories. Once a solid model form is enclosed it can be shelled which means that volume is removed by offsetting the outer surface by some dimension resulting in a thin wall part. This makes the part suitable for casting or molding by some process for metal or plastic manufacturing. A professional CAD designer or engineer will apply drafts and corner radii appropriate for a particular manufacturing process. This expertise is not to be underestimated as design for manufacturing and assembly (DMFA) is the most valuable contribution of the professional CAD designer or engineer. The results of a job well done is quality parts delivered on-time and at the right price whereas failure to employ properly trained and experienced professionals may save the developer money on the front end but cost the developer dearly on the delivery end for error corrections and rework, cost overruns, and schedule delays.
Conversion to 3D CAD data carries another great benefit to product development. It facilitates communication. Rendering capabilities make solid modeling a virtual reality theatre of design. The ability to apply colors and finish to parts for realistic shaded images allows the CAD modeler to visualize parts and assemblies as they would appear as manufactured. This is useful for design and especially useful as a communications tool for others who are involved in the project. Shaded views combined with software conferencing tools such as gotomeeting.com and Skype conferencing enable effective remote meetings. The ability to hide parts of an assembly and displace section views enables the CAD modeler to easily evaluate parts and assemblies. Multiple display conditions can be defined and called up quickly to facilitate discussion. Screen captures are easily converted to JPEG file formats and imported into presentation programs such as Powerpoint for slide presentation with annotation.
Once a product design database is completed, prototype validated, and approved the next step is to release parts for tooling and subsequently manufacturing. Some manufacturers are equipped to take in native CAD files, others require export file formats. CAM (computer-aided-manufacturing) programs routinely import IGES (Initial Graphics Exchange Specification) and STEP (Standard for the Exchange of Product model data.) STEP is a later development than IGES which includes more product data information notably (PDM) Product Data Management information.
Failure to get the qualified professional services can ruin a project plan and cost the developer the market opportunities that they are seeking. Business opportunities are not unlike catching an airplane flight. The plane will leave without you if you are late. Unlike the airlines where there will be another flight in a few hours, business opportunities often have limited windows of opportunities. Professionalism is the key to success. The product development world is very different today than it was two decades ago. Today development is typically done in a highly decentralized organization using the power of the internet to link service provides globally. While a developer today may not have to pay premium prices to receive high level professional services, bargain hunting for CAD services can often lead to business disasters. Internet network tools allow a project manager to orchestrate the service of all of the disciples required to turn an idea into a business success. A virtual development network today can outperform in time and cost the larger brick and mortar companies that must carry heavy overhead burdens.