Metal 3D printing is transforming heavy industry, opening up opportunities that would have never...
As metal 3D printing becomes the buzzword in the additive manufacturing industry, many argue it can overtake traditional manufacturing. But is this the case? We look at the pros and cons of both metal 3D printing versus traditional manufacturing to determine which is the best or whether they both play their part in producing spare parts.
Metal 3D Printing
As the popularity of metal 3D printing grows by the day, there are several advantages companies are capitalising on. These are:
- Ability to Create Complex Parts
- Shorter Lead Times
- Freedom of Design
- Reduced Waste
- Good Mechanical Properties
Ability to Create Complex Parts
Perhaps the main benefit of metal 3D printing is it can produce complex parts with intricate geometries. By printing the part layer by layer, metal 3D printing can produce almost any part designed through a 3D CAD drawing with precise detail.
Shorter Lead Times
Although there may be more post-processing tasks with metal 3D printing, it’s still quicker at producing parts than traditional manufacturing. A part can be designed, uploaded and printed within hours.
This means the overall lead time for 3D printed parts is far shorter — usually up to 30 days. Not only does this mean customers can get their parts quicker, but it’ll also reduce the downtime of their equipment, saving overall costs.
Another benefit of shorter production time is it creates the ability to print on-demand. Metal 3D printing can quickly print complex parts in small volumes, making it a relied upon method for many industries.
Freedom of Design
As previously mentioned, there are hardly any limitations in the design of metal 3D printed parts. As long as it’s within a certain size limit, any design can be transformed into a 3D CAD model and printed into a physical part.
This opens up a wide range of possibilities, including the opportunity for design optimisation and rapid prototyping. With speed and design freedom comes the ability to rapidly verify and develop design ideas by tweaking a design, printing a prototype quickly and testing its capabilities.
The main benefit is companies can redesign spare parts to improve them, having a positive impact on the performance and reliability of a part and their equipment as a whole.
With sustainability becoming an increasing concern for all industries across the globe, wastage is a key focus for many companies. When comparing metal 3D printing and traditional manufacturing methods, the former tends to produce less waste and is, therefore, a more sustainable option.
With metal 3D printing, only the required material needed to build the part is used. Of the limited wastage, as much as 97% of the non-sintered raw material (e.g. metal powder) can be recycled and reused in another build, making 3D printing highly sustainable.
Good Mechanical Properties
The mechanical characteristics of a 3D printed metal part depend on the additive manufacturing technology used. Laser powder bed fusion (LPBF) is one of the most widely adopted metal 3D technologies and is capable of producing parts with near isotropic mechanical and thermal properties. LPBF printed parts can achieve densities of 99.5% – higher than those produced with investment casting – and yield strengths nearly equivalent to machined parts.
These mechanical properties can be further improved during the post-processing stages with surface and heat treatments.
Although there are many benefits of metal 3D printing, no manufacturing method is perfect. We’ll go on to discuss the drawbacks of metal 3D printing, which include:
Fewer Materials Available
While metal 3D printing can create almost any part, the number of material options available is limited. The materials available depends on the type of technology used and the model of the printer. LPBF still boasts the largest portfolio of materials, including steels, nickel-based alloys, aluminium, copper alloys and titanium. However, it’s important to note that the material portfolio will steadily grow as the use of 3D printing becomes more commonplace.
The metal powders needed for 3D printing are produced by a gas atomisation process and only represent a small proportion of the global metal production output. Because of this, the price of metal powders is more expensive than forged metals that are used for traditional methods such as CNC machining.
Not Suitable for Mass Production
Metal 3D printing naturally lends itself to producing complex parts in small to medium-sized production quantities. Although the initial investment for metal 3D printing may be lower, as you begin to scale the quantity upwards, the potential for unit cost reduction is less than metal injection moulding.
Restricted Build Size
We’ve previously touched on the size capabilities of metal 3D printing. This method is typically better suited for smaller parts due to the build volume restrictions of 3D printers. Current large-format LPBF printers can have build volumes as big as 400mm x 400mm x 400mm, whereas binder-jetting (BJT) build volumes can be even bigger. However, in the case of BJT, there may be part size restrictions due to the inability to prevent distortion during the sintering process.
Direct Energy Deposition (DED) printers – which consist of a printer head mounted onto a robot arm – are only limited to the mobility range of the robot and therefore have the potential to build very large parts. To find out more about how each technology works and the print sizes capable with DED, read more here.
As metal 3D printing technology advances and becomes more mature, this doesn’t mean we should discount traditional manufacturing techniques such as CNC machining or casting. Here’s why:
Better Suited to Mass Production
If repeatable large-scale production is required, traditional manufacturing methods such as casting or CNC machining would be the best route to take. This is because it is easier to leverage economies of scale, meaning you can produce parts faster and at lower unit costs.
More Material Options
Traditional manufacturing methods tend to use readily available bar stock to produce metal parts, so there is a high selection of different raw materials available. The cost of raw materials for traditional manufacturing is generally lower than metal 3D printing due to efficiencies associated with bar stock production.
Create Large Parts Easily
Like 3D printing, some traditional metal fabrication techniques – CNC machining or metal injection moulding – are also limited to size. However, manufacturing methods such as casting can produce large parts, as the only limitation is the size of the casting mould. Not only this, but it’s often cheaper to produce very large parts using traditional manufacturing methods.
Although traditional manufacturing is better suited to producing simple parts in large volumes, several drawbacks need to be acknowledged. These include:
- Often Not Suitable for Complex Parts
- Longer Lead Times
- More Waste
- Not as Cost-Effective for Smaller Quantities
Not Suitable for Complex Parts
There are certain geometries or features that cannot be produced using traditional manufacturing methods. These limitations need to be considered when designing parts. With traditional manufacturing, complex parts are often created by welding parts together, resulting in weak spots at the weld joints.
Longer Lead Times
The lead times associated with traditional manufacturing are often longer than metal 3D printing. Machining requires more set-up time than 3D printing and the cutting speed will vary depending on the material. When considering casting or metal injection molding, a mold must first be created before the casting process takes place, resulting in much longer lead times.
If the production batch is made of different design variations, this will also significantly increase the lead time, since each variation needs to be treated as a different production run.
Traditional manufacturing methods create a lot of waste, which needs to be melted down and reprocessed into bar stock before it can be used again for production. Many traditional manufacturing methods — such as CNC machining — are subtractive, so they remove material to produce a part, which is turned to scrap.
Not as Cost-Effective for Smaller Quantities
While traditional manufacturing benefits from economies of scale, it’s the less suitable option for smaller order quantities. This is because the fixed costs associated with traditional manufacturing are much higher and therefore need greater volumes to make the process economically viable.
A combined Approach
Metal 3D printing is more appropriate for certain types of production scenarios, whereas traditional manufacturing methods are more suited for others. The idea is that the two should be used in unison to create efficiencies and increase equipment reliability.
Although the development of metal 3D printing is advancing rapidly and is likely to become a more preferred method of manufacturing, it’ll never eradicate traditional methods.
There are many positives and negatives to both routes, so it’s essential to consider the individual requirements of a job to establish which would be the best method to use. As a general rule, for simpler parts in larger quantities, traditional manufacturing would be the route to go down. Metal 3D printing would be the best option for more complex parts in smaller production quantities.
Learn More About the Possibilities of Metal 3D Printing
We’ve created a guide to help you gain a deeper understanding of metal 3D printing, the technologies used, the process and the opportunities it prevents for heavy industry. Simply click the link below to get permanent access to our helpful resource today.