Glasgow-based Linn Products Ltd, which designs and manufactures ‘state of the art’ music systems, recently installed (April 2017) a five-axis machining centre to produce a range of high-precision parts; these include machined-from-solid aluminium enclosures for its range-topping Klimax systems.
The machine, a Doosan VC 630 5AX, was supplied by Mills CNC Ltd, Leamington Spa (
www.millscnc.co.uk) — the exclusive distributor of Doosan machine tools in the UK and Ireland.
Prior to buying the VC 630 5AX, the machining of these enclosures was sub-contracted; and while that situation was more or less satisfactory, it was always considered to be temporary.
Linn Products’ Fraser Crown said: “The more of our manufacturing processes we can bring in-house, the better able we are to manage, control, optimise and ultimately improve them.
“Linn does not mass-produce products; everything we make is built to order. This can cause scheduling and delivery issues when relying on sub-contractors, who are generally structured to handle larger and more-predictable batch-type work.”
Linn is no stranger to CNC machining, having earlier bought a three-axis Doosan DNM 650 VMC from Mills CNC to manufacture a variety of parts.
However, its ‘milled from solid’ enclosures necessitate some distinct machining capabilities, being precision-machined (internally and externally) from individual aluminium billets.
Internal features include a number of separate and isolated chambers (divided by walls) where audio/electronic circuitry and power supply units are housed, while the back of the enclosures contains a variety of machined holes for output and input connectors and ports.
Furthermore, all exterior faces of an enclosure are machined to a mirror-like finish, with the top and bottom being finished using a large-diameter tool that can mill the entire surface in one pass to ensure a completely uniform finish.
“Surface-finish imperfections — however small — are not acceptable, as they would show up after the enclosures have been anodised,” said Mr Crown.
With regard to machine choice, he said: “We wanted a machine that would meet our immediate and future requirements, which is why we looked at large-capacity five-axis vertical and horizontal machining centres.
Although we do not machine parts in high volumes, flexibility, reduced set-up times and cycle times are the advantages of five-axis machining that are important to us.
“We finally decided on a VMC with full five-axis simultaneous-machining capability, because this allows each side of the billet to be machined continuously without the need to remount the job.
Furthermore, for certain machined features — most notably where the front panel display is located on the enclosure lid — we knew that five-axis simultaneous machining would provide the accuracy we required and the faultless finish needed on the ‘Klimax smile’, which is a particular characteristic of our products.”
Having a large-capacity machine means that Linn can produce a wide range of components, while the decision to opt for the Heidenhain control (as favoured by mould-and-die makers) was made for its ease of use and onboard functionality — in particular its ability to help machine complex three-dimensional surfaces and curved contours.
The VC 630 5AX has a work envelope of 650 x 765 x 520mm and a 32kW 12,000rev/min direct-drive spindle.
The skill and experience of Linn’s operators and programmers — combined with the technical and applications support (including training) provided by Mills CNC — have helped the company develop a secure and reliable machining process for its enclosures.
In conclusion, Mr Crown said: “The new machine is working well, and we have found that having a five-axis machining capability in-house makes us more productive and flexible.
“We are also able to respond — from a machining perspective — much more efficiently and effectively with regard to product design upgrades and modifications.”