Whether you call them blueprints, engineering drawings or just prints, a two-dimensional representation of the parts being made is an essential part of the fabrication process. Throughout the 19th and 20th centuries, these drawings were produced with painstaking care by draftsmen working at drawing boards. Since the late 1980s though, pencil and paper have been replaced by computer-aided design, otherwise known as CAD.
The change came about because CAD makes manufacturing easier. It improves communication and documentation, and today it’s a cornerstone of the Industry 4.0 digital transformation underway everywhere. This blog explains what CAD is and how metal fabricators put it to work. Benefits for customers are highlighted, some case studies show how it’s used, and the piece concludes with a brief look at CAD and digital transformations.
Drawings in Fabrication
Drawings are how designers tell the fabrication shop what to make. They provide the shapes, dimensions, and tolerances. They show where bends are needed, the angles and the radii, where welds are required, and how parts go together. Without drawings, it would be almost impossible to make anything, and there would be no possibility of making the same thing twice.
CAD in Fabrication
Early CAD systems replicated what draftsmen did on drawing boards: they produced 2D engineering drawings communicating part requirements. Then 3D CAD systems arrive where the engineer produces a model of what’s needed. This 3D model can be viewed from different angles and forms the basis of a digital record of the part and assembly.
Today, rather than sending a part print to the shop telling the people working there where to cut, bend, and weld, it goes into a computer-aided manufacturing (CAM) system. This generates CNC programs that guide machines like laser cutters, turret punches, and even robotic welding cells.
Some machines, such as saws and press brakes, are still set up by operators working from the print, but this is becoming less common. On most newer machines the CAD file generates the sequences of steps needed and operators just load, unload, and inspect.
The Impact of CAD on Fabrication
From being a tool that improved draftsman productivity, CAD has become essential to every aspect of the modern metal fabrication business. Benefits include:
- Higher precision and repeatability
- Fewer errors and less waste
- Enables more complex designs and part customization
- Streamlines the prototyping process
- Enhances communication
Here’s a look at each of these points.
Precision and Repeatability
Features are replicated automatically and consistently. Take holes or louvers required at a fixed pitch as an example. Copying and pasting ensures repeatability. Sheet thickness is taken into account, radii are reproduced exactly, angles are calculated precisely, and dimensions are rounded consistently to the specified level of precision. In short, CAD drawings are guaranteed to be accurate.
Fewer Errors and Waste
Engineering drawings produced by hand need careful checking. CAD software eliminates most errors, such as interferences between components in an assembly. They also ensure readability so no one mistakes a ‘5’ for a ‘3’. Integration with CAM software eliminates mis-keying errors and linkage to the BOM ensures part and assembly records remain up-to-date.
A CAD drawing provides a single source of truth for the part to be manufactured. Any changes to the drawing are implemented instantly and related adjustments are made automatically.
Customization and Complex Designs
CAD prints are quickly modified and saved with a different reference when sales agree to a new or modified feature. If, for example, a cable access hole needs to be larger, it takes just seconds to make the change.
Complex fabrications are easier to design with CAD, especially using 3D software. The ability to rotate and zoom lets the draftsman verify the relationships between components, check movement ranges, and more.
CAD is as effective for concept design work as for producing detailed prints. An engineer can quickly throw together a few concepts for sharing with colleagues. Any changes needed or improvements suggested take seconds to implement and are then reviewable at the same meeting.
Once the team settles on a concept the engineer can quickly translate this to detailed drawings with all the features, dimensions, and tolerances needed.
CAD facilitates collaboration between design engineers and manufacturing. A single source of truth, the document is easily reviewed and modified as needed. The ability to zoom, rotate, and show 3D views helps people without an engineering education understand what’s being proposed and what the finished result should look like. In addition, alterations are made in compliance with document control procedures, eliminating the risk of working from outdated versions.
1. Spiral material handling chutes
These have complex three-dimensional surfaces which are very hard to draw accurately and translate to 2D shapes for cutting. 3D CAD enables accurate extrapolation from 3D to 2D, ensuring individual pieces are cut and bent to the correct form and assembled without needing alteration.
2. Truck trailer apron plates
Each trailer manufacturer has different requirements and different designs. CAD simplifies communication and ensures fabricated components will fit with those from third parties. When replacement parts are needed, the CAD prints are quickly retrieved.
3. Part nesting
Maximizing sheet utilization is an important part of cost control. CAD can evaluate more options in a second than a human has time for in a day, leading to better layouts for laser and waterjet cutting and turret punching.
CAD and the Digital Transformation
There’s a lot of talk about how manufacturers should be embarking on a digital transformation. This refers to using technologies like the Industrial Internet of Things (IIoT), artificial intelligence, data analytics, and digital twins to boost productivity and metrics like OEE.
Much of this relies on having accurate CAD models of the manufacturing equipment and the parts being made. CAD is being enhanced with the addition of computer-aided engineering (CAE) capabilities that model responses to changing loads, pressures, and temperatures. In addition, simulation tools provide the ability to incorporate realistic motion into the models so they move like real-world mechanisms and achieve the same cycle times and part rates.
Incorporating these advances, and adding linkages to real-world equipment, turns CAD models into digital twins. These can be used for training operators and maintenance technicians, debugging faults, anticipating maintenance needs, and evaluating productivity improvements. But it won’t be possible without CAD.
Streamlining Fabrication With CAD
CAD is so deeply embedded in the way we work it’s hard to believe there was a time when engineering drawings were produced by draftsmen working on drawing boards. In metal fabrication it’s increasingly common to work directly from the CAD file, producing CNC programs as needed and never looking at a paper drawing.
At Wiley Metal Fabricating we’re experts in producing simple and complex parts and assemblies from sheet metal, section, and extrusion. We use CAD for concept sketches, prototyping, and full-scale production. If you’d like to learn more about our fabrication capabilities or have a project to discuss, please contact us.