Sheet Metal Design and Manufacturing Process

1. Overview of the Sheet Metal Manufacturing Industry

Sheet metal parts are components with specific shapes, dimensions, and performance characteristics that are produced through stamping processes. Owing to the high production efficiency and suitability for mass manufacturing inherent in cold stamping, sheet metal parts are extensively used in industries such as aerospace, automotive, shipbuilding, machinery, chemical engineering, and food-processing equipment, gradually becoming an essential component of today’s parts-manufacturing sector. Traditionally, sheet-metal part design involves engineers mentally conceptualizing a three-dimensional product and then using geometric projection to represent it on two-dimensional drawings. A substantial portion of the engineer’s workload is thus devoted to the iterative conversion between 3D solid models and 2D engineering drawings, as well as to time-consuming tabulation and calculation. Meanwhile, manufacturing workers must mentally reconstruct the 3D geometry from the 2D drawings before proceeding with operations such as layout and unfolding, material cutting, forming, joining, and assembly—tasks that are labor-intensive, time-consuming, and demanding. By integrating computer-aided design and manufacturing into the sheet-metal-part industry, particularly by applying UG software to the design and fabrication of sheet-metal parts, the design process can be greatly expedited, and manufacturing and assembly efficiency can be significantly enhanced.

Main Steps for Applying 2UG Software to Sheet Metal Part Design and Manufacturing

2.1 Design of Sheet Metal Parts

When humans design parts, their initial impulse is inherently three-dimensional; the outcome of the design process is a three-dimensional entity that encompasses such interrelated concepts as color, material, hardness, shape, dimensions, positional relationships, associated components, and manufacturing processes. Yet in traditional design practice, the information transfer between these two levels is entirely mediated by two-dimensional graphical representations. Due to the limitations of earlier tools and methods, designers were compelled to adopt standardized conventions for presenting two-dimensional orthographic projections in the third quadrant (in the U.S., this corresponds to the third quadrant), using a limited set of interconnected 2D projection views to convey their three-dimensional design intentions. This mode of information representation is profoundly incomplete, and both the creation and interpretation of such drawings require specialized training.

If design can begin directly in a three-dimensional conceptual framework—especially with the support of UG software—it becomes possible to express all geometric parameters of the design concept more intuitively and accurately, allowing the entire design process to be conducted entirely within the 3D model. UG software provides the UG/SheetMetalDesign module for sheet-metal design, which helps sheet-metal engineers adopt an integrated design-and-manufacturing perspective to streamline the design process, progressively creating sheet-metal parts from blank generation through each manufacturing operation. This module can be regarded as a virtual environment for machining sheet-metal parts: engineers can perform part design and assembly directly on the computer screen, with the product-development process virtually indistinguishable from actual manufacturing. The product displayed on the screen is, in essence, a three-dimensional representation of the future product.

After the design of a single sheet-metal part is completed, the 3D models of multiple parts can be subjected to virtual assembly. In the assembled model, the parts are interdependent: if one part in the assembly is modified, the other parts are automatically updated accordingly, thereby significantly shortening the product design and manufacturing cycle and enhancing the accuracy of product design.

2.2 Unfolding of Sheet Metal Parts

After the design of sheet-metal parts is completed, they must be converted into development drawings to facilitate manufacturing and to determine the required sheet-material dimensions and shapes. Traditionally, sheet-metal part development has been performed manually, relying on empirical calculations. This approach has three major drawbacks: (1) it involves a heavy workload and a cumbersome development process; (2) it is inefficient and prone to errors, especially for average engineers; and (3) it yields low accuracy, as most developments are based on experience, leading to substantial waste of materials and labor costs.

In UG, the automatic unfolding function of the UG/SheetMetalDesign sheet metal module enables fully automated unfolding of sheet metal parts. The shape and dimensions of the unfolded blank can be obtained through automatic calculation, offering advantages such as high speed, high precision, zero error rate, and simple operation.

2.3 Simulation of Sheet Metal Part Manufacturing Processes

By leveraging the automatic unfolding and arbitrary angle transformation features in the UG/SheetMetalDesign module, the manufacturing process of sheet metal parts can be simulated to determine the optimal fabrication route and conduct a manufacturability analysis. During the simulation of the manufacturing process, bending tool selection can also be finalized.

2.4 Output of Sheet Metal Part Machining Processes

The powerful 2D drafting capabilities of the UG/Drafting module enable convenient, rapid, and accurate generation of various required process drawings, facilitating subsequent manufacturing and inspection. Thanks to UG’s single database architecture, 2D engineering drawings are fully linked to the 3D solid model; for instance, any modifications to the sheet-metal geometry automatically propagate to the corresponding 2D views, thereby significantly enhancing the accuracy of the 2D drawings and improving drawing-generation efficiency.

2.5 Sheet Metal Part Nesting

The UG/SheetMetalNesting module enables multi-variant, multi-objective nesting of various part types on a single blank sheet. Users need only input the part types, the quantity of each type, and the specifications of the sheet material, after which the system automatically performs nesting and selects the optimal layout from among multiple configuration options. This module also optimizes the stamping process by reducing tool changes and minimizing the number of sheet repositionings during stamping. Additionally, users can perform nesting directly on the sheet in an interactive graphical environment.

2.6 Preparation and Output of CNC Machining Programs for Sheet Metal Parts

The UG/Manufacturing module provides a comprehensive suite of programming tools for programmers to choose from. These include two- to five-axis CNC milling, two- to four-axis CNC wire EDM, three-axis CNC electrical discharge machining, turret-type multi-station stamping, and various other machining processes. Programmers can perform CNC programming as needed, and the UG machining simulation module allows them to simulate the programmed toolpaths. If the machining results are not satisfactory, adjustments can be made promptly, ensuring *optimal machining outcomes.*

2.7 CNC Machining of Sheet Metal Parts

Using the appropriate post-processing files, the tool-path file is converted into an NC code program that the machine tool can recognize, which is then input via a serial interface to the corresponding CNC machine for CNC machining of sheet-metal parts.