XLS Production Diaries #2: More on Titanium

This is a slightly nerdy love letter to titanium and CNC technology and an expansion to the previous production diary on prototyping, you can read it here.

Like the Dream Gen. 1, the XLS’s chassis is made of titanium. It's quite nearly the perfect metal to be worn in the ear, light, hypoallergenic and durable, lending itself to be treasured for years to come. It also possesses its own unique acoustic qualities, letting us pack both smoothness and resolution into a single earpiece. 

The manufacturing of the Dream XLS entails the shaping of titanium using Computer Numerically Controlled (CNC) Machining, where material is removed by a machine using a range of tools milling the product into shape.

We've always loved the idea of filming our own CNC process, but owing coolant and bits of metal flying willy-nilly in multiple directions doesn't exactly make for compelling viewing.

So we're falling back on this video by MDA Precision in hopes that it gives you a better idea of what CNC machining entails. A cutting tool moves across the material, milling it into its desired shape. 

As much as we've loved titanium since the Dream Gen. 1, also what is known as a "sticky material" in engineering circles — it's a challenge to mill. Getting hard with applied heat, lots of which is generated in the milling process. 

As such, titanium is prone to chatter, where the CNC tool pings off the material with a loud, vibrating sound, affecting the look of the finished product.

A troublesome characteristic, especially given the black mirror finish we wanted to go for in the Dream XLS.

Titanium's inherent hardness also poses a threat to tool life, especially on the delicate, thin tools DITA uses for manufacturing our chassis. When tools snap in the middle of the milling process, it throws off the chassis' precision. 

The CNC process is a process that goes beyond the computer, requiring the operator or machinist to carry out precise calculations and years of experience in determining feed rates and spindle speeds. Minimising cutting time and increasing tool life while still maintaining the fine surface finishing that is needed in order to begin the tedious polishing process.  

This picture of a screen above illustrates part of the planning stage that the CNC machine operator must think through in order to maximise the abilities of the machine, reduce machining time and ensure a quality finished product. At this stage, the machinist or operator is also considering tolerances and offsets required in post processing.

It takes a whole working day to polish and carve the chassis of a single pair of the XLS, not including driver installation, tuning or matching. An arduous but necessary process that DITA Audio undertakes to ensure precision, consistency and consequently DITA’s signature build quality.

Previous: Prototyping 
Next: Manufacturing