What is Additive Manufacturing?
Additive manufacturing is commonly known as 3D printing. 3D printing is a computer-controlled process that creates three-dimensional objects by depositing materials layer by layer through a fine “nozzle” controlled by the computer. These materials can be anything from plastic to actual metal.
The process “builds” a component from a flat surface of virtually nothing to a fully finished component via this deposition process, or, in the case of metal, by fusing a metal alloy powder in the same manner as the deposition process. In this case, a laser is fed through the nozzle rather than the material itself to fuse the powder.
Unlike traditional “subtractive” methods that cut away from a solid block, it builds parts directly from digital CAD models, drastically reducing material waste and enabling highly complex geometries. But choosing among additive manufacturing, subtractive manufacturing, and investment casting comes down to the distinct advantages each offers.
Additive Manufacturing Applications
Additive manufacturing encompasses as many as seven core layer-by-layer production methods. Common examples include Material Extrusion (like plastic FDM/FFF prototyping) and Powder Bed Fusion (like DMLS/SLS) used to fuse metal alloys.
Additive manufacturing applications are many, and the process is used because of its low cost over many, many components required, and its ability to produce highly complex parts, including the following industries where the process is used extensively in modern times :
Aerospace
NASA uses additive manufacturing to build complex engine parts for the many space exploration vehicles and engines they build. This is due to the complexity, low weight requirements, and unique metal alloys required in the industry.
Aircraft manufacturers such as Airbus uses FDM techniques for overhead cabin spacer panels, making them 15% lighter than traditionally manufactured components.
Automotive
Electric vehicle manufacturers leverage additive manufacturing for mass customization and weight reduction. For instance, the luxury Cadillac CELESTIQ features over 130 3D-printed parts to help preserve and optimize battery range.
Healthcare & Dentistry
The medical field utilizes 3D-printing to create custom titanium artificial jawbones and highly precise, patient-specific prosthetics modeled directly from individual bone structures.
What is Subtractive Manufacturing?
Subtractive manufacturing can simply be described as the REMOVAL of material from a larger mass of metal to produce the final component that remains after the removal of the excess metal is completed. The most widely recognized application of subtractive manufacturing is machining.
“Machining” is an all-encompassing process of cutting metal using specialized machinery such as milling machines, lathes, drills, grinders, and other metalworking tools.
Subtractive Manufacturing Applications
There are as many applications for subtractive manufacturing as there are components that need to be produced. Except for rare cases where a casting can form internal pathways that machining operations cannot, most any component is a candidate for subtractive manufacturing via machining.
Aside from the typical metalworking machinery used for a century, modern technologies, including CNC control, EDM (Electrical Discharge Machining), Laser Cutting, and Waterjet Cutting, have made the subtractive manufacturing process more versatile and economical for the end user.
Advantages of Additive and Subtractive Manufacturing
There are advantages of both additive and subtractive manufacturing techniques; the main distinction between the two processes lies in how the final object is made. While subtractive manufacturing removes material from a larger piece of the same metal alloy blank to reach the final component’s geometry, additive manufacturing or 3D printing builds parts from the ground up by applying stacks of raw material and fusing it together layer by layer.
Niagara Investment Castings utilizes additive manufacturing to enable our customers to take advantage of the additive process while maintaining the quality and integrity of an investment casting by building disposable PATTERNS from wax or plastic materials, which are then used to produce investment castings.
What is Investment Casting?
Additive manufacturing uses digital models to create objects layer by layer. This approach allows for complex geometries and faster manufacturing of small metal parts; the integrity of the metal matrix formed by fused powder is weaker than that of a mass of metal formed from a liquid state. Subtractive manufacturing, especially with today’s CNC technologies for controlling metalworking machinery, allows for virtually limitless external geometries; however, it can be restrictive when forming internal details.
In contrast, casting involves pouring liquid metal into a mold. Once cooled, the metal takes the mold’s shape. Casting is an ancient manufacturing process, but it remains vital for mass production. Investment casting utilizes disposable patterns dipped into liquid ceramic slurry to build up molds layer by layer. When dried and fired, these ceramic molds convey the features of the pattern to the casting once the molds are filled and allowed to cool and solidify.
Investment Casting Applications
Applications for using investment castings are limitless.
Investment casting is a highly versatile and cost-effective manufacturing process that can be used to produce any metal shape from virtually ANY metal alloy. That said, the process offers advantages over other manufacturing processes that make it more favourable for certain applications, but it also has some disadvantages that limit its appeal to the end user, both economically and physically.
Disadvantages of the investment casting process tend to be centred around when the castings get overly large and/or heavy, if the castings are extremely small or have walls that are under 0.100” thickness, or if dimensional tolerances are so tight for most of the features that only machined finishes could meet those requirements. Otherwise, there are unlimited potential applications for investment castings in today’s industry.
Advantages of Investment Casting
Additive manufacturing uses digital models to create objects layer by layer. This approach allows for complex geometries and faster manufacturing of small metal parts; the component’s integrity differs from that of a casting.
Engineers and designers are often confused about the advantages and disadvantages of additive manufacturing, subtractive manufacturing, and investment casting. The truth is that many geometries can be made using either method. However, the advantage of investment casting is that the component’s metallurgical structure is formed. Additive manufacturing “fuses” metal particles together, while investment casting allows the component to form from a molten alloy that retains its inherent strength and other important properties.
Some of the other advantages the investment casting process offers are as follows:
Intricate Internal Designs
Investment castings enable designers to produce complex internal designs that cannot be achieved by other methods, such as the flow path deep inside an enclosed impeller, a vital component in the pump industry. The curved shape of this space cannot be obtained by conventional machining.
Superior Surface Finish and Smoothness
Investment castings typically possess a smooth surface finish of 125 RMS or better, far ahead of the surface finish attainable by any other casting method used for high-melting-point temperature metal alloys.
Cost Efficiency
Investment castings can be produced to incredibly tight tolerances, allowing the casting of details that often do not require machining to finish the component. The term “near-net-shape” is therefore synonymous with the process. This provides machine manufacturers with a unique and cost-effective method for producing many multiples of the same metal part.
Material Versatility
Investment castings offer the design engineer the ability to cast challenging geometric shapes to tight tolerances. This means that rather than “removing material” from a generic shape, the geometry can be formed by flowing molten metal in the desired shape. This feature is especially important when the metal being cast is difficult to machine in its solid state.
Low or High Volume Run Versatility
Investment casting utilizes a disposable pattern at the heart of the process. Whereas higher volume castings are most economically produced from wax patterns obtained through the use of a wax injection die to produce these patterns, we are also able to use a 3D printed PLASTIC pattern for one-off prototype samples or low volume jobs, meaning that the advantages of the investment casting process are not limited to those manufacturing high numbers of parts only.
Different Types of Metal Manufacturing
Aside from additive, subtractive, and investment casting to manufacture components, there are also many other techniques, including the following processes :
Sand Casting
Similar to investment casting in that molten metal fills a void in a refractory mold formed by a pattern. The surface finish and accuracy, however, are quite different, and sand casting can be used for much heavier castings, whereas investment casting is typically used for lighter ones.
Forging
Performed either with cold metal or metal heated to over 2000 degrees F, forging is a process of “hammering” a larger piece of metal down to a near net final size and shape. This can take place using hand tools like a blacksmith would use, or it can involve machinery with several hundred tons of force being applied in each stroke of the hammering tooling.
Weldments
Considered an assembly, a weldment is generally a composite of 2 or more metal pieces produced by various manufacturing processes and welded together to form the final shape.
Choose Niagara Investment Castings for YOUR investment Casting Requirements
At Niagara Investment Castings, we offer the best of both additive manufacturing AND investment castings. Our clients have the ability to “tool up” with injection wax dies to produce their components as investment castings. When they need multiple pieces per order, we also offer the flexibility of additive manufacturing for low-volume requirements and rapid prototypes.
Manufacturing today requires resourceful out-of-the-box thinking to stay competitive in a global market. Choosing between additive manufacturing, subtractive machining, or investment casting isn’t always straightforward, especially when selecting from hundreds of unique alloy options. That’s where we come in. The team at Niagara Investment Castings helps you navigate the trade-offs to find the precise, cost-effective solution your components require.
Let’s explore what’s possible for your parts. Reach out to our team today to discuss your requirements.
