Leaving nothing to chance

The DNM 6700 was installed at Cogsdill’s 27,000ft² facility in May 2018 where it is being used, primarily at this moment in time, to machine precision components for Cogsdill’s range of ZX facing and contouring head tooling systems. These components include different sized front-mounted cross slides, with slide ranges from 200mm to 900mm, which are machined from nitrided and carbon steel.

The decision to invest in the new Doosan DNM 6700 machine followed an internal review undertaken by Cogsdill into its existing CNC machine tool capabilities and, in particular, whether current milling machining resources were adequate to meet growing demand from customers worldwide for its large-capacity tooling solutions.

Lee Donaldson, executive director, Cogsdill UK comments: “We invest regularly in advanced CNC machine tool technologies and the audit and review highlighted a potential improvement opportunity within our existing CNC milling capabilities.”

With global demand for its larger tooling solutions on the increase it became clear to management and production staff at Cogsdill that an investment in a new, reliable and large-capacity vertical machining centre was required.

“To ensure we acquired a vertical machining centre that matched our needs and expectations we did our homework and created a key criteria checklist before investigating the market. In addition to the working capacity of the new machine, other requirements included its cutting performance, availability and price as well as the scope and scale of the technical back-up and aftersales support services provided by the machine tool supplier.

“This was our first Doosan machine,” Mr Donaldson adds. “We were aware of their reputation in the marketplace and that exclusive UK distributor Mills CNC are highly regarded in the industry.”

Cogsdill also had direct experience of working in collaboration with both Doosan and Mills CNC as a Technical Partner, supplying advanced tooling solutions to both. A recent example of this involved Cogsdill working in partnership with Doosan and Mills CNC to deliver a turnkey process for auto-loading facing heads, boring tools and splining tools, into a Doosan horizontal boring machine (a DBC 130) for a US-based oil and gas customer.

Following an extensive search into the market Cogsdill ultimately decided on investing in a new DNM 6700 vertical machining centre.

Capacity and capability

The DNM 6700 is a large-capacity vertical machining centre equipped with a generously sized worktable (1,500mm x 670mm) and impressive axis travels (X-axis:1,300mm x Y-axis: 670mm x Z-axis: 625mm). The machine also features a powerful, 118Nm high-torque direct-drive spindle (18.7kW/12,000rpm).

“The working envelope of the machine was of critical importance and the DNM 6700 enables us to machine larger components, as well as smaller parts in a single set-up. This means faster production and reduced part cycle times,” Mr Donaldson reveals.

“Similarly, the cutting performance of the machine was important and the DNM 6700’s powerful direct drive spindle technology gives us the ability to achieve high-volumetric removal rates when required as well as fine finishes. It is a very versatile machine.”

To increase its flexibility still further Cogsdill, as part of its investment in the DNM 6700, also ordered a 4th/5th axis unit to be supplied with the machine.

Ready and waiting

Mills CNC has at least 70 new Doosan machines at any given time in stock at its Technology Campus facility in Leamington. A significant proportion of these machines include its best-selling DNM vertical machining centres.

“The quick availability of the new machine was important. We attended MACH 2018 where we visited Mills CNC’s stand and supplied them with a letter of intent to purchase a DNM 6700. Just a few weeks after the event, once we had acquired external grant-based funding, the machine was delivered, installed and commissioned.”

DNM 6700 machines are competitively priced and this, in conjunction with their high-performance and reliability, explains their popularity: “I have to say that we were pleasantly surprised with the machine’s price. There is a lot of technology and functionality packed into the DNM 6700 and, whilst price isn’t everything, it clearly is an important factor when making any capital investment,” Mr Donaldson asserts.

All Doosan machines supplied by Mills CNC are backed by the company’s aftersales service and support. This was an important aspect for Lee Donaldson: “Mills CNC’s reputation in the market for its aftersales support is second to none in our opinion and we have direct experience of this having worked in partnership with Mills delivering a number of turnkey and process improvement projects for customers. For us, just knowing we have Mills’ technical, applications and service back-up at your disposal inspires confidence.”

The DNM 6700 in action

Since being installed at Cogsdill’s facility in Nuneaton the DNM 6700 has been used to machine front-mounted cross slides used in the company's ZX facing and contouring head tooling systems. These cross slides are rough machined from solid on the machine prior to stress relieving, and are then semi-finished, heat treated and ground before final finishing operations occur.

On average machining times for roughing, semi-finishing and finishing are 60 minutes, 90 minutes and 30 minutes respectively.

Cogsdill’s ZX facing and contouring head systems increase the capabilities of machine tools with live spindles, such as horizontal boring machines. The heads have a single front-mounted tool slide onto which top tooling is mounted into qualified locating holes.

The systems facilitate the machining of large castings and components that are difficult and awkward to hold and rotate, and enable a range of different machining operations i.e. external turning. grooving, taper boring, radius forming, chamfering, recessing and threading to be performed in a single set-up without moving the workpiece from the machine table.

Mills CNC www.millscnc.co.uk

Cogsdill-Nuneaton www.cogsdill.co.uk