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Top tips for designing for additive – 12 April 2018

Designing for 3D print can be an innovative and highly creative process as you are free of the limitations that traditional manufacturing methods bring to the design board. 3D printing can be an ideal option for those in the Rapid Prototyping, Architectural, Mechanical, and Engineering and Automotive industries, with the ability to create specific products that meet the needs of your application. However, bear in mind that whilst 3D printing provides a highly flexible and innovative way of designing your product, there are certain design factors you need to be aware of to ensure you don’t experience any chinks in your production chain.

Here at Cadspec, we have gathered up some of our expert team members to give you some advice when designing in Autodesk software for 3D print.

What Software Should I Use?

Whether you’re an experienced 3D designer or you’re taking your next steps from TinkerCAD, Autodesk Fusion 360 is a great software tool for designs you’re going to 3D print. Fusion 360 is a comprehensive product design tool that allows you to work with sketches, Booleans and sculpting to create intricate scale models and complex geometry designs. You can import and export over 50 different file types as well as being able to collaborate with other team members if desired from one central dashboard.

Other software options which are great for when you want to 3D print the design include Autodesk Netfabb; ideal for reducing build errors during the additive manufacturing design process, and Autodesk Inventor; ideal for product development as there’s a software simulation too, allowing you to see how your product will move within the physical environment.

The decision of what design software to use ultimately comes down to what your application is. If you’re unsure which software to use, why not take advantage of our design consultancy services. Our team specialise in Advanced Manufacturing, Construction, BIM, Electrical Engineering, Mechanical Engineering and product design applications, in which we have over a decade’s worth of industry and software knowledge.

Our Five Most Important Design Tips

Whichever software you decide to use, here are some general guidelines to follow to ensure your design comes out of the printer the way you expected…

The 45-Degree Rule

Remember, overhangs greater than 45 degrees will need to be supported. The more support your model requires, the more material you will use, therefore it’s in your best interest to create as little overhang as possible. If you have a complex model, you could use your own support or bridge objects using cones and other supports in the design.

Software such as Netfabb will identify critical areas on your model that need support and will automatically generate a support pathway. To find out more about generating support contact our specialist team.

Minimum Supported Wall Thickness

Problems linked to wall thickness are by far the most common reasons why some 3D models are not printable. In some cases, wall thickness is too thin. Walls that are too thin make small parts on the model unable to be printed or very fragile and could break off easily. In other cases, walls that are too thick generate too much internal stress and could cause the item to crack or even break.The minimum printable wall thickness primarily depends on the material you choose. However, other factors, such as the alignment, size, and overall design of your 3D model, can also influence the recommended minimum wall thickness.

One of the common mistakes make is trying to migrate an existing design that was previously injection moulded or machined to a 3D printing process. The geometries with these traditional methods can be much thicker or much thinner than a 3D printed part; therefore, it is best to adapt the design rather than simply transferring the previous one.

Autodesk Inventor and Revit Pro both have built in software called finite element analysis (FEA). This software provides a computerised method for predicting how a product reacts to real-world forces, vibration, heat, fluid flow and other physical effects. It shows whether a product will break, wear out or work the way it was designed so that you can predict what will happen when the design is used. This tool is ideal for testing out different wall thicknesses’ before the design is sent to the printer. 

Level of Detail

When you are creating a 3D model with intricate details, it is important to keep in mind what is the minimum feature size each 3D printing process can produce. The minimum level of detail is connected to the capabilities and mechanics of each 3D printing process and to the selected layer height.

The process and materials used will have an impact on the speed and cost of your print, so determining whether smaller details are critical to your model is an important design decision.

File Resolution

Choosing the right resolution for your file is important to ensure a good quality print. STL is the most common format; therefore, it’s best to export your file as an STL. Most software including Netfabb, Fusion 360 and Inventor will allow you to do this. By exporting your design as an STL file, the surface of the model with be tessellated, and this is where you need to watch out for a few things.

Be aware when exporting the STL file that the resolutions are not too high or too low. Low-resolution means that the triangles in your STL file are large and the surface of your print will not be smooth; this will therefore lead to a pixilated print. A file with a resolution too high will make your file too big and sometimes impossible for the printer to handle due to it containing an extreme level of detail.

The solution to this? In most 3D modelling software, when exporting it will more than likely ask you to define the tolerance for the export. The tolerance is defined as the maximum distance between the original shape and the STL mesh you are supporting.

Build Orientation

With Autodesk’s 3D design software, you have the ability to choose from multiple build orientations, although the type of orientation can affect the cost of the print. The orientation of the model will affect part accuracy, manufacturing time, strength and surface finish of your 3D printed parts. Parts under tension should be printed with the build direction parallel to the load.

Consider which desired qualities are most important for your part before selecting the build orientation. It’s always best to chat with the manufacturing team before printing your design as a wrong build orientation can increase build time, be less cost effective and negatively affect the structure of your part.

 

By following our expert team’s handy advice, your 3D print is sure to come out of the printer in top-notch form! If you would like any more advice on our designing for 3D print tips, give the team a call on 01905 458000.

 

 

Top tips for designing for additive

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