Metal Prototype: Exploring Four Metal Rapid Prototyping Methods

medical metal prototypes

A prototype is a physical model or a sample that is made to verify a new design, concept or process at an early stage. It is widely used in an array of industries including automotive, aerospace, medical device, electronics, and architecture.

Metal prototypes can never get enough credit for their roles playing in our society. They are so crucial that every product we use in our daily life begins with them.  Because the prototyping process is the step between the evaluation and the finalization of a new idea.

What is a Metal Prototype?

A metal prototype is an object used as a sample or model of a new product. The prototype allows manufacturers and designers to transform an idea or concept into a physical object. The item can then be used as part of the product development process for testing, demonstration, or further design work.

A metal prototype can be made using a variety of methods, including 3D printing, CNC machining, casting, sheet metal prototyping and etc. While these prototypes can be made from many different materials, aluminum, carbon steel, sheet metal, brass, copper, and bronze are the most widely used.

The Application and Function of Metal Prototypes

aluminum metal prototype

1. Metal prototypes are used in a wide variety of industries from different metal materials . They can be used in the construction industry to build models of new buildings or bridges, or in the automotive field to sample cars or trucks.

2. Manufacturing processes also use liquid metal to create prototypes or test models of new tools, fasteners, electronic devices, or household items.

3. Manufacturers can use the Prototyping process to test and refine new tools before full-scale manufacturing and fabrication begin. A metal prototype can take many different forms, depending on the developer’s goals. It may simply act as a physical representation of the proposed object, without actual functionality.

Some prototype models may have full functionality and may perform exactly the same tasks or actions as the proposed object. For example, a metal prototype for a new handheld rig may consist of only a hollow casing that can be used to make detailed prototypes.

4. Metals prototypes offer many advantages to manufacturers and designers. They can be used to test designs or features so that the manufacturer can improve the product before starting production. They can also be used to get investors or potential buyers excited about a new product.

Why Choose Making Metal Prototypes?

After deciding to make a rapid prototype, another question will pop up: should I make a metal prototype or a plastic one? Compared to plastic, metal rapid prototyping shows a few competitive edges. To know the advantages, let us have a look below:

1. Excellent Strength

Stainless steel, aluminum, titanium, and magnesium alloys carry a few outstanding properties, one of which is their strength and durability.

If the designed part is going to be exposed to extreme conditions like immense heat, wind, and having to withstand heavyweights, is a perfect solution because most plastic parts are just not as strong and durable.

2. Incredible Cost-Effectiveness

Intuitively, we may think plastic is cheaper than metal, which, to some extent, is correct. However, plastic components are easier to wear out and should be replaced sooner.

Another reason that makes it more cost-effective to have the part made in metal instead of plastic is the unique structure. Therefore, the metal prototype is more potential and competitive over plastic in some cases. 

3. Metallic Surface

If you are looking for a metallic, smooth, and bright surface finish, is definitely the way to go. In addition, metal prototypes can be anodized to achieve a corrosion-resistant finish while plastic prototypes can only be painted. This also makes metal prototyping unparalleled.

4. Versatile Applications

The material metal itself allows more design freedom and can be used in a variety of fields. In both prototype and production phases, metal is preferable for both functional and aesthetic purposes.

4 Methods to Make Your Metal Prototypes

CNC machined metal prototypes

There are different methods to make metals prototypes and just like every coin has two sides, different methods show different advantages and disadvantages. In metal rapid prototyping, these technologies include CNC machining, metal 3D printing, sheet metal fabrication, metal casting method, and other processes. Now let’s have a look at the ins and outs of each one.

1. CNC Machining Metal Prototypes

CNC machining (computer numeral control machining) refers to a computerized manufacturing process that uses common techniques for pre-programmed software to control the whole movement of the production equipment.

Materials that are suited for CNC metal machining include aluminum alloys, copper, steel (especially stainless steel), titanium alloys, zinc alloys, and magnesium alloys. While it is a popular manufacturing method, the pros and cons still remain unknown to some.

Some CNC machines work on only X and Y planes while others work on three dimensions (X, Y, Z planes). Typically, you can see 3, 4, 3+2 and 5 axis machines in a CNC machine shop with the best solution.

Key benefits:

No MOQ– Since no mold is needed for CNC machining, there is no such thing as MOQ. Therefore, the unit price for 10 pieces and 30 pieces is very close. If you are looking to make metal components in low volume, CNC machining will be your perfect option.

More Material Options– As mentioned above, there is a wide range of metal blocks to choose from when it comes. However, aluminum, steel, and copper are the most commonly chosen ones because they offer great mechanical and thermal characteristics.

High Precision– Medical, aerospace, and robotic industries often involve high-tech, and the components used in the fields have to be high precision. It can be complicated, high precision, and strong.

Disadvantages:

Higher Unit Cost– Although high precision can be manufactured on CNC machines, it can be time-consuming for complex projects. Unlike casting or printing, it is costly when the quantity is substantial. In such cases, CNC machining is not recommended if there are no requirements on the surface and precision.

Material Waste– it is a subtractive manufacturing method for mass production, which means some material will be removed from the metal blocks so material waste is inevitable. 

2. 3D Printing Metal Prototypes

3D printing metal prototypes

Metal 3D printing, also known as additive manufacturing, is a technology that builds physical objects by printing layers of adhesive materials like metal powder or plastic powder, using digital model files.

Rising as a new star in the manufacturing industry, 3D printing functions as additional or alternative technology and it enjoys rapid growth in recent years. It is typically useful for lightweight and complex one-off pieces with a short life cycle.

Key Benefits:

Design Freedom– Undercuts and inner structures are unattainable by CNC machining, so 3D printing is the only method to make very complex features. It allows designers and engineers to create a physical prototype without design constrictions.

Quick Turnaround Time– Besides allowing design freedom, 3D printing has another benefit: manufacturing a metal prototype in a short time. It is suitable when production time is requested to be short, especially for design projects.

Disadvantages:

Rough Surface Finish– Compared to CNC machined parts, 3D printed metal prototypes are less strong, with a rougher surface finish. You can feel the coarse touch and see the uneven surface.

Low Cost-effectiveness– Although you can see that 3D printed plastic products are pretty frequent nowadays, 3D printing metal is not as common in that the metal powder used for printing is expensive. This is against the business model where profit is the most important thing.

3. Metal Casting Prototypes

casting metal prototype

It is a process of forming rigid metal cast parts. Molten metal is poured into a mold and when the metal and mold cool down, the metal part will be removed from the mold and move on to the next round.

This process has been used for thousands of years and it is still growing. Investment Casting is an inexpensive way to manufacture big volumes with complex shapes and designs.

With the development of technology, nowadays people can 3D print or CNC machining the mold, which makes it cheaper and quicker to make prototypes.

Key Benefits:

Production Quality– sometimes our customers may reach out to us for a metal prototype, but they will ask for metal casting when proceeding to mass production. So if the end products will be made in casting, prototypes provide production quality. You will get something functional and solid, which makes it worthy of what you pay for.

Size and Weight– If you are looking to build a 20ft metal prototype, casting will be your only choice. It is simply too big so it is unlikely to make it through CNC or 3D printing. Size and weight is not limited to casting. It can be used to create everything from a small tabletop gadget to a factory version desalination tank.

Disadvantages:

Expensive Mold Cost– Although the mold can be reserved for future use, the cost of the mold is too high for low volume metal prototype project. It is more of a technique for mass production.

Corse Surface Finish– Metal casting prototypes have a relatively rough surface finish and hence wider tolerance should be taken into consideration. This is not suitable for prototypes with mating interfaces.

4. Sheet Metal Prototypes

sheet metal prototypes

Sheet metal fabrication is another method to make prototypes. During the sheet metal prototyping, sheet metalwork with the standard thickness (usually thin) is placed on a desk where a laser cutter performs patterning with the aid of a program.

Next, different forming processes including spinning, bending, punching, and welding will be undertaken, depending on the geometry requirements. The sheet metal prototype is suitable for enclosure, casing, and structural frames.

Key Benefits:

Cost-effective– Due to its quick turnaround time, sheet metal prototyping is a metalworking method that offers good quality parts.

Replaceable- One of the biggest advantages of sheet metal is that when it can be replaced. When several components are utilized for assembly, the individual part or parts can be removed and replaced by new ones. This will save costs, especially new changes or adjustments that need to be made.

Production Quality– Since prototyping is a step between design and end product, the production quality is important to test the product and sheet metal prototypes are usually end-products quality

Disadvantages:

Limited Design Freedom– Unlike CNC or 3D printing, sheet metal prototyping doesn’t allow as much design freedom.

Wider Dimensional Tolerance– Compared to other metalworking methods, sheet metal prototyping can’t achieve as tight dimensional tolerance.

In short, if you need a fast turnaround time and low cost, 3D printing is the best option. However, if you need a high degree of accuracy or complex geometry, CNC machining is a better choice. Metal casting and sheet metal prototyping are good options for large or complex parts. Whichever method you choose, make sure to work with a qualified prototype manufacturer to get the best results.

6 Key Considerations for Metal Rapid Prototyping

low volume metal parts

1. Material properties: When prototyping with metal, it is important to consider the material’s mechanical and physical properties. Different metals have different strengths and densities.

Material for metal rapid prototyping can be produced by using CNC machines, direct metal laser sintering, laser cutting, or printed parts to design perfectly.

2. Machinability: The machinability of a metal refers to its ability to be cut or shaped using machine tools. Some metals are more machinable than others, meaning they can be more easily shaped into the desired form.

3. Tooling: In order to produce a metal prototype, you will need to use special tooling. This tooling can be expensive and may not be readily available. It is important to consider whether the cost and availability of tooling is an issues before choosing a metal for prototyping.

4. Surface finish: The metal parts’ surface finish can be an important consideration when prototyping. Some metals have a rougher surface finish than others, which can affect the appearance and function of the prototype.

5. Cost: The shape and subtractive or additive process nature of a prototype defines its lead time, complex design takes more time. The cost of prototyping with metal can be significant, especially if special tooling is required. It is important to consider the cost of materials and manufacturing before choosing a metal for rapid prototyping.

6. Volume and budget: The volume of mass production can be adjusted according to your budget and the suitable method above mentioned.

Conclusion

In conclusion, metal prototypes are an important step in the product development process. They allow you to test your design and make any necessary changes before moving on to manufacturing.

Additionally, they can help you save money and time by identifying potential problems early on. By understanding the benefits of metal prototypes, you can ensure that your product development process is as efficient as possible.

With advanced equipment and a highly trained professional team, WaKen specializes in plastic and metal rapid prototyping. From tight tolerance CNC with custom finishes to 3D printing with complex geometries and low-cost rapid tooling, we can help you increase agility at every stage of the product life cycle. Contact us today for more guidance on your projects!

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