Metal fabrication encompasses various techniques vital for creating custom parts and components across industries. The multiple techniques used in metal fabrication account for some of the fundamentals of simple to complex metal structures. Metal fabrication includes old processes like metal casting, sheet metal fabrication, and machining and newer technologies like 3D printing.
Understanding the specifics of each technique is essential for manufacturers seeking optimal solutions for their fabrication needs. This article explores four standard metal fabrication techniques their pros and cons. We also discussed how to distinguish workpieces fabricated by each method before surface finishing.
CNC Machining
Description
CNC machining is a subtractive manufacturing process that uses computer-controlled machines to remove pieces from a workpiece to create custom-designed parts. These machines interpret digital instructions (CAD files) to precisely control the movement of cutting tools, allowing for the creation of simple to complex shapes with high precision. CNC machining operations include a series of cutting processes, including milling, turning, drilling, and grinding, making it a versatile solution for part fabrication and manufacturing.
Pros
The pros of CNC machining include the following:
- High Precision: CNC machining offers unparalleled precision and accuracy. This makes it the go-to process for achieving tight tolerance specifications and fabricating complex shapes that may be challenging for other manufacturing methods.
- Versatility: CNC machines can work with an extensive range of materials, including metals, alloys, plastics, polymers, and composites. This feature allows machinists to fabricate various parts and components for different industries.
- Efficiency With Less Error: CNC machining processes are mostly automated, requiring little to no human interference. This results in efficient production cycles and consistent part quality with little to no error. Once the device is programmed correctly, the cutters can function independently, minimizing downtime and enhancing productivity.
- Cost-Effective for Bulk Volume Production: While CNC machining requires capital investment for the machine set-up, it is cost-effective when manufacturing large volumes. The cost per product is distributed across the large volume, making it a valuable investment for companies running a fabrication service.
- Customization: CNC machining is a suitable process for fabricating parts with complex geometries while maintaining the intended precision and accuracy. Therefore, it is ideal for creating rare parts and customizing specialized designs.
Cons
Below are the cons of CNC machining
- Programming the CNC machine may be complex, requiring an experienced technician to assist.
- The high initial investment for the machine setup makes it a turn-off, especially for small-scale businesses.
- Material wastage is almost unavoidable, especially when creating parts with complex geometries or intricate designs.
Sheet Metal Fabrication
Description
Sheet metal fabrication is a manufacturing process that involves cutting, shaping, and forming thin metal sheets to create specific products and components. The process typically begins with the cutting of the sheet metal into the desired size, followed by various specific operations that suit the intended applications. These operations may include laser cutting, bending, folding, and stamping to achieve the desired shape and dimensions.
Pros
The advantages of sheet metal fabrications include the following
- Lightweight Fabrication: This metal fabrication process utilizes thin metal sheets, suggesting a reduced weight, even though the components possess significant strength.
- Versatility: Sheet metal fabrication allows machinists and manufacturers to fabricate diverse shapes and designs for different applications. It enables the creation of an extensive range of products with various shapes, sizes, and functionalities.
- Strength and Durability: Although sheet metal is thin, it is nevertheless quite strong, making it a durable choice for lightweight metal fabrications.
- Quick Turnaround Times: In today’s manufacturing world, sheet metal fabrication processes are automated, resulting in rapid turnaround times and efficient production cycles. This advantage makes it ideal for meeting tight deadlines and high-volume production requirements.
Cons
Below are the shortcomings o sheet metal fabrication
- Since the process creates thin metal parts, they may not suit thicker or applications that call for sturdy materials.
- Sheet metal fabrication encompasses various methods, requiring multiple machinery. Therefore, it requires an enormous capital investment.
- Forming complex shapes and designs with sheet metal may be challenging, requiring the services of experts.
Metal Casting
Description
Metal casting is a manufacturing process that involves pouring molten metal into a pre-made mold cavity, where it solidifies into the desired shape. This technique is one of the oldest metal fabrication processes; however, it’s still suitable and ranks among the most versatile for part fabrication. It offers an extensive range of possibilities for creating metal components of different sizes and complexity. A typical example of metal casting is die casting, which is still used in fabricating precision parts for various industries today.
Pros
Below is a brief overview of the benefits of metal casting.
- Design Freedom: Metal casting affords manufacturers the freedom to create complex geometries and intricate designs typically challenging for other manufacturing methods. It just requires creating a mold that suits the intended fabrication.
- Cost Effectiveness for Large Production Runs: Metal casting is significantly cost-effective for bulk volume fabrication. As the number of parts fabricated increases, the cost per unit decreases, making it cost-effective.
- Material Versatility: The process is suitable for fabricating structures and parts from an extensive range of metals and alloys. Materials like steel, aluminum, iron, bronze, brass, etc., are compatible with metal casting.
Cons
The disadvantages of metal casting includes the following
- Compared to other metal fabrication processes, metal casting may have longer lead times. The operation requires first creating a suitable mold, which may be time-consuming and slow down the process.
- While surface treatments and finishing may not be compulsory for other processes, they are essential in metal casting.
3D Printing
Description
3D printing is an additive manufacturing process; that is, it involves creating a component by depositing material layer by layer till the desired shape, dimension, and structure is achieved. The technique turns out to revolutionize the manufacturing industry, as it differs from other traditional processes, which are subtractive. The method essentially uses powdered and pellets of the material it intends to fabricate. Guess what? It supports an extensive range of materials, including plastics, metals, ceramics, and composites.
Pros
Here are the pros of 3D printing to metal fabrication.
- Rapid Prototyping: 3D printing is soon becoming the go-to option for rapid prototyping and manufacturing intricate designs, which allow engineers and OEMs to test and refine a concept before final production.
- Design Freedom: The technique just requires creating suitable digital files that the computer can understand. Afterward, it is capable of creating almost any structure or shape with high precision and dimensional accuracy, regardless of design complexities.
- Minimal Material Waste: Since it’s an additive process, the device essentially utilizes only the material it requires, generating little to no waste.
- Cost-Effective for Low Production: This advantage is why 3D printing suits rapid prototyping. There’s no complex or expensive tooling and setup in 3D printing, so it suits low-volume fabrications.
Cons
The cons of 3D printing includes the following
- The process for bulk volumes is relatively slow. The printing speed for one fabrication is essentially the same for each fabrication, resulting in a longer manufacturing time.
- Parts produced by 3D printing may have a rough surface finish compared to other methods.
Table Showing the Differences Between Four Techniques in Metal Fabrication
The table below helps provide apparent differences between the four common metal fabrication techniques.
| Feature | CNC Machining | Sheet Metal Fabrication | Metal Casting | 3D Printing |
| Manufacturing Principle | Subtractive | Subtractive | Additive | Additive |
| Process Complexity | Moderate | Moderate | High | Moderate |
| Surface Finish | Smooth, precise | Varies depending on operation | Rough | Variable depending on resolution |
| Material Thickness | Highly versatile, suitable for vast material options. | Thin metal sheets | Often thick | Variable depending on specific tech |
| Setup Time | Requires setup for each job | Setup time per part may vary | Time-consuming | Minimal |
| Post-Processing | Minimal, may require surface finishing for specific finishes | It may require bending, stamping, or other forming operations | Requires extensive surface finishing | Minimal surface finishing required |
How to Distinguish Workpieces Made by the Four Metal Fabrication Processes Before Surface Finish
The different metal fabrication processes may suit fabricating identical parts and structures. Therefore, distinguishing workpieces made by any of the four metal fabrication processes before surface finish requires an understanding of the unique characteristics. Below, we discuss some markers that can help differentiate them.
CNC Machining
CNC-machined parts and components typically exhibit precise, sharp edges and intricate detailing. The surface finish is usually smooth, consistent, and uniform, with visible tool marks aligning with the cutting path. Therefore, even before surface treatments, CNC machined parts may not require any post-processing, as some products are even released to the market as machined.
Sheet Metal Fabrication
One of the main distinctive features of sheet metal fabrication products is the thickness of the metal, as it utilizes thin metal sheets. They often exhibit uniform thickness and consistent bends or folds, depending on the specific process used. The edges of sheet metal parts are usually sharp and clean, with minimal distortion or warping. Also, depending on the forming process used, sheet metal parts may display characteristic grain patterns or textures on the surface.
Metal Casting
Parts fabricated using any metal casting typically possess a rougher surface texture compared to other fabrication methods. Therefore, upon the first appearance, you know the components require significant surface finishing to trim the edge and smoothen the appearance. In addition, many castings may exhibit their typical defect, which is surface porosity. However, you could also examine irregularities like flash or gate marks, which are remnants of the casting process. In addition, cast parts may feature a parting line or seam where the mold halves meet.
3D Printing
The main distinctive feature of 3D printed parts is the easily seen layer lines or striations on the surface, resulting from the additive layer-by-layer deposition process. That said, depending on the particular printing technology and parameters used, these layer lines may be more or less pronounced. Another common feature is that 3D printed parts may have support structures or rafts attached, serving as anchors to the part during printing, requiring removal upon post-processing.
Conclusion
The world of metal fabrication offers a diverse array of manufacturing techniques, each with its own advantages and limitations. Whether it’s CNC machining for precision, sheet metal fabrication for versatility, metal casting for complex geometries, or 3D printing for rapid prototyping, manufacturers have several options. Therefore, understanding the intricacies and applications of each method is important for making informed decisions to meet specific fabrication needs efficiently and effectively.
