Prototype Tooling: How to Choose the Best Option?
Nowadays, there are abundant of prototype tooling options, which sometimes makes designers a little hard to choose. What exactly is the most suitable option?
The most common prototype tooling options are CNC machining, 3D printing, urethane-vacuum casting, and rapid injection molding. These processes have their own characteristics, some can achieve tight tolerance requirements, some can meet a variety of test requirements, and some can show pretty cosmetic surfaces.
If you know what kind of function you need the prototype to realize, you can choose the best option.
CNC Machining
When we use CNC machining, we also definitely use CNC machining tools. The CNC machine tool is programmed and controlled by the CNC machining language, which can control the feed speed and spindle speed of the tool, as well as the tool converter and coolant.
Since CNC machining does not require much manual operation, its quality is stable and it can achieve high precision. In addition, CNC machining can reduce the time for production preparation and machine tool adjustment, as a result of the high produce effective. What’s more, CNC can process complex profiles that are difficult to process with conventional methods. Because of these advantages of CNC machining, it has become the most widely used processing method.
Of course, CNC machining also has many limitations. For example, because the tools of CNC milling machines are rotated at high speed, some radii will inevitably be left in some corners of parts. Also, when the quantity is large, CNC processing will lose its price advantage.
3D Printing
3D printing is also known as additive manufacturing, which is based on digital model files, using powdery metal or plastic and other adhesive materials to construct parts by printing layer by layer. This way can provide a fast turnaround.
Among them, the most widely used 3D printing process is Stereolithography (SLA) and selective laser sintering (SLS). SLA is to fuse the photopolymer resin layer by layer by ultraviolet laser. SLS is the same to SLA. There is only one differece is that SLS needs to uses a carbon dioxide laser to fuse a thin layer of metal, plastic, glass, or ceramic powder. In addition, SLS has a wider selection of materials, and its materials are closer to formally produced materials.
From a functional point of view, these processes also have limitations. Their current accuracy is not precise enough. And the material is expensive, so it is only suitable for very low quantities.
Urethane Vacuum Casting
Urethane-vacuum casting is a low-volume production method. First, we need to get the masters by CNC machining or 3D printing, and then wrap the masters with a silicone mold to form a cavity, finally, it enters the production stage, using polyurethane plastic as the raw material to process the prototype parts. Its molds are usually quite cheap, so between 20–100 pieces, this method has a large cost advantage.
However, the material of polyurethane is limited, and there are usually some differences from the material properties of formal products. And the degree of automation of vacuum casting is low, requiring a lot of manual operations, such as mold opening and closing. Therefore, the accuracy of the parts will not be much high, and there may be some differences between the parts, it is difficult to provide exactly the same quality
Rapid Injection Molding
Unlike formal injection molding, rapid injection molding usually involves more manual operations, and when the demand is not so high, materials such as aluminum or mild steel are usually used as molds. But the injection molding materials used is usually exactly the same as the formal injection molding materials, so parts in this way can also be used for formal products.
Rapid injection molding is also a common method for low-volume production. It has a much higher processing accuracy than vacuum casting and the consistency of parts is relatively better. However, it is not cheaper. Usually, the number of parts needs to be greater than 200 sets, then there is a certain price advantage. The larger the number of parts, the more advantageous the price of this method will be.
But rapid injection also has its shortcomings. For example, once the mold is completed, it is difficult to modify the design or profile, and processing development will also be limited. Once the mold needs to be redone, this will be a huge expense, so when using rapid injection molding, the design is usually stabilized and there will be no major changes.
Conclusion
The above are the characteristics of the 4 most common processing methods for manufacturing prototypes. When you design a prototype, it is important to know what kind of functions you need it to achieve. Do you need a pretty appearance or tight tolerances?
Or need to do functional testing? Meanwhile, the quantity requirements will also limit the choice of processing methods, because cost and delivery time are also important factors to be considered. I hope this article can help you choose the best processing method.
If you want to know more details about the 4 processes, please contact Wayken. Wayken is a prototype manufacturer specializing in prototype and low volume production, providing a variety of processing methods to achieve your prototypes.