Finding the additive sweetspots of the guitar

The excitement around additive manufacturing comes from the transformative nature of the additive process. The ability to ‘print’ – or ’add’, rather than subtract from solid material, means internal structures can be made with new levels of complexity, therefore making end products and components more fit-for-purpose.

Harald Kissel, R&D Manager at Sandvik Additive Manufacturing.“Additive manufacturing is a dramatic advancement, and its progress is only likely to be held back by the limits of our imagination. And that’s to be expected. Engineers have historically been taught to think and design with subtractive technologies in mind”, says Harald Kissel, R&D Manager at Sandvik Additive Manufacturing.

But far from all components are relevant for additive manufacturing. It should not be seen as a replacement to subtractive methods. It should rather be viewed as a complementary technology that is only suitable for certain applications or components.

Finding the additive sweetspots

“The real value in additive manufacturing today comes from understanding what should be printed, and what should not. Whether the choice is motivated by functional improvements, efficiency, or individual customization, the decision should be part of a holistic process and a fact-based business case”, says Harald Kissel.

So how do you decide if a component is relevant to print?

“Using a checklist is a good starting point”, says Harald. “Is the component being produced with a complex shape? Does it need to be made from an expensive material? And is low weight an essential characteristic of the end part? If the answer is Yes, then the component could be a good candidate for additive manufacturing.”

Other questions come into play. Is the component likely to come in a number of variations through mass customization? And is there the potential to merge sub-parts into one component? Finally, is there a strong need to reduce assembly time and increase productivity – or reduce inventories?

“Again, if the answer is Yes, then ‘building’ the component could be the solution. But in the end you will need a fact-based business case to verify your project”, explains Harald Kissel.

The additive sweetspots of the smash-proof guitar

In the guitar project, Sandvik decided to use additive manufacturing for the body of the guitar, which was printed in titanium.

“The reason for selecting the body for additive manufacturing was that the shape was extremely complex – and additive manufacturing allows tremendous design freedom. By using 3D printing we could build complex internal lattice structures, impossible to mill, with the purpose to make the body of the guitar both light and strong”, says Harald Kissel.

Powder Bed Fusion Laser was selected as printing technology for the body of the smash-proof guitar. This method is ideal for design of very complex geometries. Laser technology is used to melt and fuse the titanium powder together. The melting process is repeated, layer by layer, until the last layer is melted and the printing is complete. Then the body is removed from the build plate and post-processed according to requirements.

The guitar nobs and stoptail were also printed, since these structures also were quite complex – and only a few pieces of each should be produced. They could all be printed on the same building plate, even if the designs were completely different. Another advantage of metal additive manufacturing.

The guitar nobs and stoptail were also printed, since these structures also were complex – and only a few pieces of each should be produced. They could all be printed on the same building plate, even if the designs were completely different. The surplus powder could be reused for another print job.

Always unbiased advice from Sandvik

The smash-proof guitar is a very good example of when subtractive and additive technologies complement each other in an excellent way.

“Sandvik Group’s leading capabilities within both additive manufacturing and traditional, subtractive manufacturing through CNC machining, is unique”, says Harald Kissel. “Additive manufacturing is fantastic for certain components, but for others, subtractive manufacturing will remain more cost-efficient. Sandvik has the competence in-house to offer products and advice related to both areas.”

Harald Kissel says the initial discussion with customers around manufacturing method is central.

“Ask a metal cutting company and then a printing company, and you will get completely different answers to the most suitable manufacturing method for your component,” he says. “As we have leading competence in both methods within Sandvik, our customers will get unbiased recommendations, always.”

Here is Sandvik’s checklist for additive manufacturing. If a component meets any of the criteria below it is likely to be a good candidate for printing.

• Complex shape
• Expensive material
• Low weight is essential
• Revolutionary design
• Individual variations (tailored)
• Spare-part (to reduce lead-times, inventories and Net Working Capital)
• Potential to merge sub-parts into one component
• A need to reduce assembly time/increase productivity
• Smaller series