A prototype is simply defined as an early version of a product. Prototypes are an extremely crucial part of the process of designing a product – they help people in a variety of fields test designs in an inexpensive, affordable way before committing large amounts of resources or cost to a full-scale production. Because emphasis is often placed on speed and affordability with regards to prototypes, plastic is very commonly used because of its combination of low cost and fast manufacturability.
This article will cover how to manufacture plastic prototypes using four different methods: 3D printing, vacuum forming, CNC machining, and injection molded. In addition to the manufacturing processes themselves, the situations where each type is most beneficial will be described.
3D Printed Prototypes
The process of 3D printing has gained much traction and popularity in recent years. A technical term for 3D printing is “additive manufacturing”, but this encompasses many different types of processes. One of the most popular is Fused Deposition Modeling.
FDM is the most popular and widely used type of additive manufacturing. It involves plastic extruded from a nozzle, depositing successive layers that eventually create an object. If you see a 3D printer available for consumers, it most likely works through FDM. That being said, FDM is also used in industry frequently with specifically designed printers that can manufacture plastic prototypes that are strong and high resolution.
Types of Plastics
One type of additive manufacturing material which is used by some plastic prototype manufacturers is known as Polylactic Acid. This produces colorful prototypes, however they are not very strong or durable.
Polylactic Acid, or PLA, is not widely used in industrial settings because it offers more form than function. ABS is another prototype plastic which is frequently used. The advantage of ABS is that it is functionally much better than PLA because it can withstand extreme temperatures and impacts of high forces. These factors make it a preferred prototyping material in automotive or aerospace settings.
When are 3D Printed Prototypes Used?
The biggest advantages of 3D printing over other forms of plastic manufacturing are its cost and relative speed. This means that 3D printing, or additive manufacturing, is the preferred method of creating prototypes in situations where many designs are being considered. This is because little manpower is required to operate 3D printers, and they lend themselves to creating many different kinds of prototypes in a short amount of time.
One example of a good application of 3D printing is early on in the design process when new ideas are being iterated through. 3D printing allows the design team to get their hands on something concrete without needing to spend a lot of time or effort to create the prototype itself.
CNC Machined Prototypes
CNC milling is another popular way to create prototypes out of plastic. This process involves taking a slab of plastic and applying various cutting tools to remove plastic over time until all that is left is the prototype itself. This process is quite the opposite of 3D printing, as instead of adding material to make the final shape, you start with a larger chunk of material and cut it down over time.
CNC milling allows for many various surface finishes, threads, and even tight tolerances among other advantages. It can be fast and time efficient, but this will vary depending on the prototype.
One process that Is frequently used to make final products out of plastics is called “Injection Molding”. This requires a mold to be created and molten plastic to fill the mold, which then hardens in the shape of the final product. The creation of this mold is an expensive process, so CNC machining offers plastic prototype companies a cheaper alternative to preview products which will be created through Injection Molding once their design is finalized.
When are CNC Machined Prototypes Used?
Many areas and situations exist where CNC machining is preferable when compared to additive manufacturing. For example, mechanical quality will generally be higher when using CNC machining. This is because a solid piece of material starts with certain mechanical qualities that are better than when the material is melted and fused back together, as is done with 3D printing. Because of this, functional prototypes usually use CNC machining.
Injection Molded Prototypes
As discussed previously, injection molding is frequently used for mass production. Despite this, in certain situations it may be used for plastic prototyping.
In injection molding, the first step is to create a die. This will be an inverted version of the product, which plastic will be injected into (hence the name) and solidified to create a prototype. Plastic pellets are pushed into a chamber which is heated, where they are heated and put under pressure so that they become molten. Next, they are injected into the die at high force before being cooled quickly to create a solid prototype.
When are Injection Molded Prototypes Used?
As discussed previously, injection molding is most popular for mass produced products. Because of this, its applications to prototyping mostly apply to large-scale prototypes, potentially to serve as one final test before production begins in full.
Vacuum Casted Prototypes
The last process used in plastic rapid prototyping which will be discussed in this article is vacuum casting. This involves three major steps.
The first step in this process is the creation of a design of the prototype using computer aided design (CAD) which will serve as a “master” from which all prototypes will be created. This is possible through additive manufacturing.
After a master is created, the next step is to develop silicone molds. Finally, these molds are filled with molten plastic, much like the injection molding process.
When are Vacuum Casted Prototypes Used?
This type of manufacturing is most advantageous for small productions. Each master can only create about 25 molds, so large scale prototyping operations are inefficient because so many masters would need to be made. Prototypes created through this process are best used for visual models that don’t need to serve a functional purpose.
All in all, if you want to succeed in getting the better plastic prototype, it is extremely important to choose the right manufacturing technology and material for your prototype. Wayken with years of experience is really happy to help you find the right process for your project, so if you want to know more our rapid manufacturing services how to make clear plastic parts, you may go here.