Manufacturing Process
Fabrication is the process used to manufacturing steelwork components that will, when assembled and joined, form a complete frame. The frame typically uses readily available standard steel sections that are purchased from a steelmaker, together with protective coatings and bolts.
Although a wide range of section shapes and sizes are produced, the designer may find that the required section size is not available. In this case, built-up girders may be fabricated from plates. Sections and plate girders may also be strengthened by stiffening the web or flanges depending upon the load to be carried.
Most modern steelwork fabrication factories have computer aided design and detailing (CAD) machines linked directly to factory floor Computer Numerical Control (CNC) machinery. This means that a computer turns a 3D design into numbers within an X, Y, and Z coordinate system. The three coordinates control the movement and direction of the cutting machine. Using this approach, a volumetric material can be cut in 3 dimensions. The design is produced by Computer Aided Design (CAD) software program. The software is used to produce 2D and 3D precision drawings and technical illustrations. The accuracy of the computer generated details being transmitted directly to the Computer Aided Manufacturing (CAM) machinery increases the quality standards of production. Building Information Modeling (BIM) enables the fabricators to perform scheduling, and cost estimation throughout the process of manufacturing the steel systems.
To increase the speed and efficiency of manufacturing, three types of prefabrication are common: kits-of-parts approach, panelization, and modularization. The advantage of offsite fabrication allows for fast, accurate, and repeatable production. Design and logistical planning play a major role in deciding on the appropriate type of steel prefabrication.
1. A Kit-of-parts Approach:
In this approach, simplification is the key. Here, the components are standardized so they can be easily interchanged to create speed on both ends of the production line and during on-site installation. The advantage of this system is that the parts are demountable, they are able to be disassembled and reused in a different project.
2. Steel Panelization:
Manufacturing light-gauge-steel framed panels offsite allows time and money savings compared to building the individual pieces onsite. This construction system is used for different components of a building such as partition walls and bay flooring, including decking. The panelsare built in the factory, shipped, and quickly erected on the site. They can be completed prior to erection, with finished surfaces already preinstalled in the factory.
Figure 3.16 The panelization production system is comprised of 4 steps: Figure A) (1) Engineering: Drawings are converted by CAD to a list of components that comprise the panels. (Figure B and C) (2) Roll Forming: The data is connected to the roll-formers. The roll-formers create all the pieces with the specification given to them. The material are lifted to panel carts. (Figure D, E and F)(3) Assembly: The pieces come together and are attached through a welding and punching system. (Figure G, H, I and J) (4) Finishing: Post welding and sheathing on panels take place. The completed panel is inspected and stacked. (Figure K, L and M)
Modular Steel Building Manufacturing Techniques
There are several techniques used in the factory to create a seamless shell, a seismic structure, a weather and water resistant system, and an easy to install system. These techniques are punching, clipping, usage of splices, weather-tightening, usage of flexible ridges, etc.
