Additive manufacturing is a process of building three-dimensional objects by depositing materials in layers, which is typically used for creating prototypes and low-volume production parts.
On the other hand, subtractive manufacturing removes material from a workpiece to create an object with the desired shape. Many subtractive manufacturing processes produce high-precision parts, such as machining and computerised numerical control (CNC).
While subtractive and additive manufacturing processes have some similarities, there are also some significant differences.
Let's take a closer look at the differences between additive and subtractive manufacturing techniques to help you better understand each process.
How Do You Differentiate Subtractive Process From Additive Process?
The main difference between additive vs subtractive manufacturing is the way create the finished components.
As the name suggests, additive manufacturing techniques revolve around adding material to create an object, while subtractive processes involve removing material from a workpiece.
These two approaches result in different manufacturing processes and capabilities. Additive manufacturing is typically used to create prototypes and low-volume production parts, while subtractive techniques are better suited for mass production.
Here are some of the most common differences between additive and subtractive processes:
The material options for additive processes are fairly limited compared to subtractive techniques. This is because additive manufacturing generally relies on plastic derivatives, such as thermoplastics, metals, ceramics, resins, and biomaterials.
On the other hand, the material removal processes used in subtractive manufacturing can work with a broader range of materials, including metals, plastics, composites, wood, and glass. The process starts with a solid block of material, which can be machined to meet the desired specifications.
The speed of an additive manufacturing process depends on the volume of the build and the complexity of the design. However, additive manufacturing is generally faster for prototyping and small-scale production compared to subtractive manufacturing techniques.
This is because additive manufacturing does not require the same level of tooling as subtractive techniques.
In subtractive manufacturing, the machining process often requires dedicated tooling for each part. This means that there is a significant lead time to create the necessary tooling before production can begin.
Additive manufacturing, on the other hand, does not require tooling. This means that production can begin as soon as the design is finalized.
However, subtractive processes are generally faster for mass production. This is because the material removal process can be scaled up to accommodate high volumes. In contrast, additive manufacturing is typically limited to low-volume output due to the slower build times.
Additive manufacturing is more versatile when it comes to producing complex designs. Since the process involves adding material to create an object, there are no restrictions on the geometry of the design.
This means that additive manufacturing can be used to produce parts with complex shapes and features that would be difficult or impossible to create with subtractive techniques.
Subtractive manufacturing processes are more limited in this regard. Since the material removal process often relies on CNC machining, the designs must be able to fit within the constraints of the machine. This means that complex designs may need to be simplified in order to be machined.
In addition, the material removal process generally results in dimensional inaccuracies. This is because the cutting tools used in subtractive manufacturing are not always perfectly precise. As a result, the dimensional accuracy of a part produced with subtractive techniques may not be as tight as the accuracy of a part made with additive manufacturing.
So, additive manufacturing may be the better option if you need to produce complex designs with tight dimensional tolerances. If you need to quickly produce large quantities of parts, subtractive manufacturing may be a better choice.
The cost of additive vs subtractive manufacturing depends on several factors, including the type of process, the complexity of the design, the size of the build, and the number of parts being produced.
Here is a general overview of the cost of additive vs subtractive manufacturing:
The cost of additive manufacturing equipment has been falling in recent years, making it more accessible to small businesses and prototyping laboratories. However, the price of additive manufacturing machines is still higher than the cost of subtractive manufacturing equipment.
Additive machines are generally more complex than subtractive machines, which makes them more expensive. Additionally, the range of additive machines on the market is much smaller than that of subtractive machines. This limited choice drives up the cost of additive manufacturing equipment.
On the other hand, subtractive manufacturing machines are relatively simple and have been around for many years, resulting in a wide range of machines on the market which drives down the cost.
Post Processing Cost
Post-processing is the process of finishing a part after it has been machined. It generally includes polishing, washing, and removing excess material.
The post-processing cost is generally similar for additive and traditional manufacturing. However, parts produced with additive manufacturing (particularly parts used in precision mechanical systems) often require more post-processing because they often have more excess material that needs to be removed.
This can increase the cost of additive manufacturing, primarily if large quantities of parts are produced.
Additive manufacturing processes typically have higher accuracy compared to subtractive techniques.
As mentioned earlier, additive manufacturing builds parts by adding materials layer by layer. This process is controlled by computer software, which can precisely control the placement of each layer.
In contrast, subtractive manufacturing processes such as milling remove materials from a workpiece. The accuracy of these processes depends on the precision of the cutting tools and the skill of the machinist. As a result, there can be some degree of variability in the accuracy of the parts produced with subtractive techniques.
Additive manufacturing may be the better option if you need parts with high dimensional accuracy.
When to Use Additive and Subtractive Manufacturing
While additive and subtractive manufacturing differ in many ways, the two processes are not mutually exclusive. In fact, many manufacturers are using both additive and subtractive manufacturing techniques to produce parts. This is sometimes referred to as hybrid manufacturing.
An excellent way to think about the hybrid process is to consider the prototyping process.
Prototyping is the process of creating a model or sample of a product. It is often used to test the design of a product before it is put into production.
Prototypes are generally produced with additive manufacturing techniques such as selective laser sintering. This is because additive manufacturing is well suited for prototyping complex designs. Once the product's design has been finalised, production parts can be produced with subtractive manufacturing.
The choice of additive or subtractive manufacturing depends on the specific needs of the product being prototyped. In general, additive manufacturing is best suited for prototyping complex designs, while subtractive manufacturing is better suited for producing large quantities of parts.
Product designers and manufacturers should consider both subtractive and additive processes when designing a new product. Using both methods, they can produce parts with the best combination of accuracy, cost, and lead time.
Additive manufacturing, also known as 3D printing, is the process of creating a three-dimensional object by adding material layer by layer. This technology has been around since the 1980s, but it is only in recent years that it has become more widely used due to the advancement of technology and the decrease in cost.
Subtractive manufacturing is the process of removing material from a workpiece to create a three-dimensional object. It is the traditional manufacturing process and has been around for centuries.
The choice of additive or subtractive manufacturing depends on the specific needs of the product being prototyped. In general, additive techniques are used for more complex designs, while subtractive processes are better suited for producing less complicated parts in larger quantities.
Why Is Additive Manufacturing Better Than Subtractive Manufacturing?
Additive manufacturing has several advantages over subtractive manufacturing, including:
- Increased accuracy: Additive manufacturing can produce parts with very tight tolerances. Before a part is printed, the design can be verified using computer-aided design (CAD) software. This ensures that the finished product will meet the specifications of the design.
- Flexibility: Additive manufacturing can produce parts of various shapes and sizes. This flexibility allows manufacturers to create parts that would be impossible to make using subtractive manufacturing.
- Fast turnaround time: Additive manufacturing is a fast process. This is because parts can be printed directly from CAD files without tooling or moulding. However, additive manufacturing is generally slower than subtractive manufacturing when large quantities of parts are needed.
What Is an Example of Subtractive Manufacturing?
Subtractive manufacturing is a process that removes material from a workpiece to create the desired shape. The most common subtractive manufacturing process is machining. Machining is a process that uses a cutting tool to remove material from a workpiece. Other standard subtractive manufacturing processes include milling, turning, thread cutting, sawing, and grinding.
What is Subtractive Manufacturing Process?
Subtractive manufacturing is a term that refers to several controlled machining processes, including turning, milling, drilling and grinding. These processes typically create shapes or features on a workpiece by removing material. The workpiece is generally a block or sheet of material that is first machined to create the desired shape or feature.
What Are the Processes of Additive Manufacturing?
The most common additive manufacturing processes are:
- Stereolithography (SLA)
- Selective Laser Sintering (SLS)
- Fused Deposition Modeling (FDM)
- Electron Beam Melting (EBM)
- Binder Jetting
- Material jetting
- Direct metal laser sintering (DMLS) or Selective Laser Melting (SLM)
What Are Subtractive Manufacturing Processes?
There are several types of subtractive manufacturing processes, including:
- CNC machining processes: CNC machining is a process that uses computer-controlled machine tools to remove material from a workpiece. The most common CNC machining processes are turning, boring, milling, reaming, and drilling.
- EDM: Electrical discharge machining (EDM) is a process that uses electrical sparks to remove material from a workpiece.
- Water jet cutting: Water jet cutting is a process that uses high-pressure water to remove material from a workpiece.
- Laser cutting: Laser cutting is a process that uses a laser beam to cut material.