Robert Musselle, customer engineering manager EMEA at Protolabs shares what you need to consider with 3D printing and plastics prototyping.
Protolabs
Prototyping is essential when producing plastic parts - where medical device manufacturers must assess the ergonomics and functionality of surgical instrument designs, for example, before delivering them to practitioners.
As a technology for rapid prototyping, 3D printing has evolved over recent years, becoming an increasingly popular way to increase the speed and efficiency of the design process. It does have some limitations though, which are important to consider when deciding how to iterate your product.
The advantages of prototyping
Prototyping is the most effective way for businesses to keep costs low during a project. Planning for and producing multiple iterations of a design helps to reduce the risk of the project failing in the long-term and ensures the optimal part design is delivered before going into production.
However, before the prototyping phase begins, it’s important to understand what purpose it will serve. Does your designer simply need a concept model for a visual representation of a part or product, or are they looking for a more functional prototype to work with and test with target users, for example?
- Concept model - This is likely to be one of the first parts produced during a product cycle and is intended to provide a visual representation of the part or product. 3D printing technologies such as stereolithography and fused deposition modelling are typical manufacturing methods for concept models.
- Functional prototype - This gives a design team the ability to test the form and fit of a part, providing an accurate representation of the final part’s material properties. CNC machining or 3D printing technologies like Multi Jet Fusion are often used during this process.
Once you’ve settled on your initial requirements, you then need to choose your preferred method for producing the prototype - be that 3D printing, CNC machining or injection moulding.
Each method offers advantages and limitations, which can help businesses determine the one that best suits their needs. Part size, surface finish quality and feature size/resolution requirements should all be factored in as part of the decision-making process.
Benefits and limitations of prototyping
Benefits
- More cost-effective - Because there are no fixturing or cutting tools with 3D Printing, part costs are generally lower than the alternatives. The process simply involves the raw material, machine time, and whatever secondary post-processing is needed.
- Fast lead times and quick iterations - The elimination of tooling and traditional “setups” that are typical of injection moulding means quicker turnaround times. Many printers also have sufficient build volumes where designers can produce multiple iterations in the same build.
- Fewer design constraints - Many manufacturers use 3D printing to produce complex assemblies in one print, reducing part count and simplifying their supply chain. Ensuring the design can be manufactured at production quantities via injection moulding is key if this is the end goal.
Limitations
- Mechanical properties - Resins and powders used in 3D printers are “like” materials. They approximate their moulded and machined counterparts, so they can’t be considered direct replacements.
- Surface finish - Due to the layer-by-layer build process, on a practical level all 3D printed parts suffer some level of “stair-stepping”. Surface finishing techniques such as vapour smoothing can add time and cost - however, they are great at removing imperfections.
- Limited colour options - As a rule, 3D printing delivers white, black, grey, or translucent parts. Dying or painting a prototype will require additional post-processing steps.
When it comes to 3D printing, manufacturers today can choose from a range of technologies, including Selective Laser Sintering (SLS) and jetting processes such as PolyJet and Multi Jet Fusion (MJF). All are excellent for producing prototypes – and several are fast enough to support low-volume, end-use part production.
3D printing is a perfect option for medical parts design, which often require small runs of individual pieces. If you’re looking to produce larger quantities of plastic parts, however, there may be more cost-effective methods, such as CNC machining.
The prototyping phase is critical in the success of a product, ensuring it is feasible and reducing costs and risks before production. It’s important that you take time to consider the best manufacturing methods for your project and for each phase of it.