In recent years, additive and subtractive manufacturing has made a noticeable impact globally. Due to technological advancement, many industries now benefit from their inventive production of different parts.
Even though there is a difference between additive and subtractive manufacturing implementation methods, they both rely on each other because of their overlying application modes. However, the process used in manufacturing a prototype or part is dependent on other factors such as production volume and stage of product development.
This informative article tends to compare additive manufacturing vs subtractive manufacturing. We also highlight the major differences between the two manufacturing processes, their pros and cons, and their main applications.
What’s Additive manufacturing?
Additive manufacturing, commonly known as 3D printing, is an industrial computer-controlled process that produces 3D objects by depositing materials in layers on the base material.
The main core of this method is the addition of material together to create a new object. Furthermore, additive manufacturing uses various materials depending on the printing process. These materials also range between metal alloys, thermoset polymers, composites, and thermoplastics.
Additionally, the application of AM technology started with just aerospace and medical industries but has now expanded into other industries. What’s more, end industries like automobiles, oil, gas, and heavy equipment are examples of its ever-expanding reach.
Types of Additive Manufacturing Processes
Generally, the standards that classify Additive manufacturing divides its processes into 7 different categories, and they include:
This is a process under additive manufacturing that involves depositing a binder selectively onto a powder bed to form solid layers. Furthermore, the materials used for this type of 3d printing process must be in granular form and include metals, sand, and ceramics.
Additionally, binder jetting works using a roller to spread a powdered material evenly on the build platform. The next step in the process is the selective deposition of binder adhesive on the powdered material. The roller then spreads another layer of powder over the previous layer with adhesive, and the process repeats until the formation of the entire object.
Directed Energy Deposition (DED):
This method is a complex process to construct 3D objects. And the material used is usually a powder or metal wire. The material melts through a focused energy source like a beam or laser and is then poured precisely into the building platform. The liquid hardens to form a layer, and the process repeats itself until the final phase.
The process works with the aid of a glue gun. This feature shoots the material into the printer through a coil. The nozzle tip melts the material with heat, and it’s then placed on the build platform layer by layer to solidify and form the object. This type is the most expensive form of additive manufacturing, although with some limitations.
Powder Bed Fusion (PBF)
PBF includes diverse AM processes like Direct Metal Laser Sintering (DMLS), Selective Laser Sintering (SLS), Selective Heat Sintering (SHS), Electron Beam Melting (EBM), and Direct Metal Laser Melting (DMLM). Besides, this method uses lasers, beams, or print heads to melt and fuse fine layers of material in 3D. It shoots off excess powder from the product afterward.
The two main sheets of lamination methods are Laminated Object Manufacturing (LOM) and Ultrasonic additive Manufacturing (UAM). UAM joins thin metal sheets by ultrasonic welding, while LOM uses adhesive-coated paper sheets as original material, the best for visual and aesthetic modeling objects.
VAT Photopolymerization produces an object in the vat of a liquid resin photopolymer. The photopolymerization process now cures the microfine resin layer with the help of Ultraviolet lighting. Afterward, these light rays then direct towards the object using a mirror.
This method is just like binder jetting, only that it uses wax. The operation follows a similar layering of material to create an object instead of using adhesive on the powder bed. MJ deposits wax on a building platform. Most producers prefer MJ because it is cheaper and gives high-quality surface finishes with better accuracy.
Pros and Cons of Additive Manufacturing
Here are some of the advantages of additive manufacturing.
- Highly efficient and eliminates waste
- Faster route from design to production
- Create complex designs easily
- Has a limited range of materials compared to other processes
- It can be expensive when it involves the use of metals
- Not ideal for large quantity production
What’s Subtractive Manufacturing?
As the name implies, subtractive manufacturing entails the removal of object parts to create a new product. Besides, it could be cutting away parts of a solid block of metal, plastic, or wood. A good example is a milling machine hollowing a metal or plastic.
Furthermore, this manufacturing technology allows designing, prototyping, and manufacturing in end-use materials. It is also the perfect option for small and big volume productions to get specific mechanical properties or finishes. It works with metals or resin-like aluminum, brass, ABS, Delrin, Nylon, PEEK, PVC, plexiglass, PCA, Polypropylene, as well as wood.
Additionally, it is easier to match the design in subtractive manufacturing techniques with material for strength, flexibility, chemical resistance, or other dielectric properties.
Types of Subtractive Manufacturing Processes
The common types of subtractive manufacturing include cutting, machining, and abrading. Below are some details of each.
This process uses a laser to cut different materials to shape. Furthermore, materials derived from this process are commonly used in industrial and artistic sectors.
In the laser cutting process, Computer Numerical Control (CNC) and optics help direct the powerful laser beam on the material. A motion control system helps ensure CNC follows the desired pattern when cutting the material. Afterward, vaporization or high-pressure jet gas ensures a high-quality surface finish.
CNC machining is a type of production in which a pre-programmed computer software guides industrial tools and machinery. This subtractive manufacturing type completes three-dimensional cutting jobs with just one set of commands.
However, before turning on a CNC system, it is necessary to program the necessary cuts into the software which in turn dictates to the appropriate equipment and machinery how to carry out the dimensional duties as defined.
Despite the likelihood of errors, which is larger when a CNC machine cuts in more than one direction at the same time, the code generator within the numerical system will frequently presume mechanisms are flawless in CNC programming. A set of inputs known as the part program determines the placement of a tool in a numerical control system.
The Abrading process involves using an abrasive to grind or brush away parts of a material. Abrasives are rough substances that grind, sand, or polish material. Besides, they can remove material parts through constant rubbing or smoothen their surface. You can also attach an abrasive to a hard surface or add it to a liquid as a suspension. For more efficiency, they should be harder than the material they want to remove.
EDM (Electrical Discharge Machining)
EDM is a subtractive manufacturing technology that uses electrical discharges to achieve the desired shape. Also termed spark machining, spark eroding, die sinking, wire burning, or wire erosion.
Additionally, it works using a series of quickly recurring current discharges between two electrodes (tool and workpiece electrodes) separated by a dielectric liquid and subjected to an electric voltage. The culmination of the EDM process is the removal of materials from the workpiece. What’s more, the tool and workpiece also do not make physical contact in this process.
Pros and Cons of Subtractive Manufacturing
- It applies to various materials like metal, plastic, wood, and composites
- Used for all shapes like holes, cylinders, screw threads, or flat surface
- Ideal for obtaining a smooth surface
- Produces high accuracy with 0.0025 mm close tolerance
- Wastes material and chips formed. The chips are recyclable though but are still waste
- It takes more time than additive manufacturing
Additive Manufacturing Vs Subtractive Manufacturing: What Are Their Differences?
Additive manufacturing processes build products by adding materials layer by layer, while subtractive manufacturing removes parts of a solid material to create the product parts.
Although additive and subtractive manufacturing processes have their way of developing prototypes and products, they approach production differently.
Here are some of the notable differences between additive and subtractive manufacturing below.
Comparing Additive vs Subtractive manufacturing, material options is one major difference between additive and subtractive manufacturing. A narrow range of materials is available for use in the additive manufacturing process. Furthermore, the materials for this process are mostly plastic derivatives. These include ceramics, biochemical, thermoplastics, metals, and resins are also some other materials used in the additive manufacturing process.
On the other hand, subtractive manufacturing begins with a single piece of solid material. Additionally, this material could be glass, metal, plastic, wood, composite material, or plastic derivative.
When it comes to complex design between additive vs subtractive manufacturing, Additive manufacturing is ideal, while subtractive manufacturing is best suitable for less complex designs. But subtractive manufacturing edges out when there is a need to produce complex designs in large batches.
In comparison with machines used for additive manufacturing, subtractive ones are more accurate. Besides, machining has to take place after printing to achieve high accuracy using additive manufacturing.
Properties Of Finished Parts
Products made using additive manufacturing often have tiny pores on their surfaces. Moreover, these pores often lead to structural weakness and could result in food contamination or infection for products used in the medical field. Hence, products manufactured with additive processes require cleaning and finishing to achieve better product properties and appearance.
On the other hand, products manufactured through subtractive processes using computer numerical control (CNC) machining produce stronger parts. What’s more, these parts are also more tolerant and have better finishing than parts produced using Additive manufacturing.
Surface Finish Choices
Surface finish option is also a factor to consider when comparing subtractive manufacturing vs additive manufacturing.
Additive manufacturing results in poor surface finish when combined with powder bed fusion. Often, partially fused powder and deposition layers are visible on the product, making the surface rough.
Besides, a product with a rough surface performs poorly in terms of fatigue and is prone to fracture. Surface machining or shot-peening produces a smoother surface, but they do not often consider internal surfaces and small features.
Conversely, CNC subtractive manufacturing produces smoother surface finishes and better tolerance.
The batch size and use case of design determine the speed of an additive manufacturing process. Furthermore, one of the advantages of additive manufacturing over subtractive manufacturing is that 3D printing makes prototyping and the total time needed for small volume production faster. But compared to subtractive manufacturing, it takes a longer time to print a single part using 3D printing. Besides, 3D printing is not as fast for the mass production of plastic parts.
Comparison Table Between Additive Manufacturing Vs Subtractive Manufacturing
|Additive Manufacturing||Subtractive Manufacturing|
|Material Options||Works with a narrow range of materials, mostly plastic, plastic derivatives, biochemical, resin, and some metals||It uses a wider range of materials, including; stone, glass, wood, foam, metals, and plastics|
|Achievable Complexity||Better than 5-axis CNC machining in the development of complex and intricate designs||Ideal for use with simple geometry|
|Accuracy||The products produced using this process are less accurate than the traditional process. The most accurate additive manufacturing process has a tolerance level of 0.100mm||It produces products with more dimensional accuracy. With Tolerance levels as tight as 0.025mm|
|Properties Of Finished Parts||Parts produced using this technique might have structural weaknesses. The reason is that the production occurs through layering, and this compromises some properties||Parts produced have excellent heat resistance and are structurally sound|
|Surface Finish Choices||Finishing is an important aspect of parts produced using this technique||Finishing is not compulsory for parts produced using this method|
|Speed||Faster and less costly when the prototype and batch production are small||Faster and less costly when the prototype has large parts or production batches are large|
Subtractive Vs Additive Manufacturing Cost: Which Is More Expensive?
Machinery and Tooling Costs
It is quite expensive to acquire and install precision additive manufacturing equipment. This makes an investment in machines the highest contributor to additive manufacturing costs.
For additive manufacturing, tooling expenses are accountable for 5% of the total cost of production and are one of the advantages of additive manufacturing over subtractive manufacturing.
Besides, layer-by-layer printing makes the additive manufacturing process very adaptable for different products, thereby saving cost. On the other hand, designing the tool is important for each subtractive manufacturing process.
Due to the highly automated nature of both methods, labor costs account for a small proportion of the total cost. Simplifying parts in both additive and subtractive manufacturing helps reduce labor.
Moreover, simplification involves redesigning a product to reduce the required number of parts. This redesign would also help to reduce production, assembly, and post-processing costs. Generally, labor cost accounts for less than 10% of production costs in additive manufacturing.
Materials used in additive manufacturing often cost higher than those used in subtractive manufacturing. According to the international cost estimating and analysis association, materials for additive manufacturing are more expensive than those used for subtractive manufacturing by a factor of 8 on a per-weight-basis.
What’s more, the exact material and additive process is used to determine the exact cost of additive manufacturing.
Post Processing Costs
Manufactured parts often also require post-processing to reach their final state. This often involves washing or polishing to improve the sheen for metal parts. Furthermore, products manufactured additively, especially using the precision mechanical system, involve removing the surplus material.
Above all, post-processing costs are similar for both manufacturing processes and inevitable.
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Applications of Additive vs Subtractive Manufacturing
Additive Manufacturing Application
With more companies adopting additive manufacturing techniques and finding creative ways of combining them with subtractive manufacturing, it has a wide range of applications, including:
- Jewelry production
- Aerospace industry
- Energy use improvement
- Model Fabrication for industries
- Robotic and Electromechanical systems
- Solid Freeform Features
- Metamaterials, Electromagnetics, and 3D electronics
- Dental and Medical elements
Subtractive Manufacturing Application
This manufacturing process is ideal for production in large batches, and its application includes:
- Contoured profile and textured surfaces fabrication
- Cutting features for household use, automobile, electronics, aerospace, dental and medical industry.
Hybrid Process: Implement Design To Prototype
Hybrid systems tend to maximize the advantages of additive manufacturing over subtractive manufacturing and vice versa. Moreover, they combine the advantages of subtractive and the versatility of additive manufacturing. Special machines handle both systems, and it works great for repairs of broken parts. Hybrid manufacturing makes it easy to produce complex parts as they can be layered and then finished using milling tools.
RapidDirect is a certified company (with a standard registration number ISO 9001:2015) that implements these manufacturing processes from design to prototypes. We also produce the best quality parts to meet our customers’ needs while maintaining the required standards.
Moreover, we provide instant quotes and guarantee the best-automated DfM analysis. What’s more, we achieve these processes with strong manufacturing capabilities merged with our diligent workforce to ensure the timely delivery of the best quality parts.
The world is tilting towards less waste, making additive manufacturing a better option. Besides, additive manufacturing imitates natural processes in creating a finished product by layering. It is less wasteful than subtractive manufacturing. It is also faster and produces complex designs better.
Is Injection Molding Additive Manufacturing? No, Injection molding is neither additive nor subtractive manufacturing. Instead, it is a manufacturing process that aids mass production. In addition, the production here occurs by injecting molten material into a mold. This mold would have the shape of the intended finished product.