The Portsmouth-based sub-contractor DKW Engineering (www.dkwengineering.co.uk) prides itself on value-engineering complex components and investing in new equipment to fulfil production economically.

A good example is the re-engineering of a family of 316 stainless-steel parts that go into flow meters used in the medical industry.

This application resulted in DKW winning a prestigious long-running contract to produce an increasing variety of the components and entailed the installation of a German-built Index C200 turn-milling centre from UK agent Geo Kingsbury Ltd, Gosport (www.geokingsbury.com).

The business came from an existing DKW customer that was putting the work out to a different sub-contractor, which was machining the parts from stainless-steel castings; they then had to be sent out for polishing, which was costly and often revealed porosity on the surface, making them unusable.

At the end of 2014, DKW was awarded the contract and initially followed suit by machining similar castings. However, it soon became clear to managing director Nick Iacobucci that the designs could be changed to allow the parts to be machined from round stainless-steel bar instead.

He also saw that it would be possible to omit the insertion of a pin into the component, doing away with an assembly operation; and the higher level of surface finish achievable when machining from bar would eliminate the need for polishing.

Mr Iacobucci approached three potential suppliers of turning centres that would be capable of producing the family of components, which have a variety of diameters ranging up to 65mm.

Geo Kingsbury was the chosen supplier, as it demonstrated that an Index C200 turn-milling centre could produce the parts to the required dimensional tolerances of ±0.05mm and achieve a 0.8Ra surface finish.

Moreover, the new process route allows the components to be produced in one hit rather than the previous five operations, improving accuracy and reducing work in progress.

In conjunction with DKW, Geo Kingsbury ran off 45 samples in its Gosport technical centre, and they all passed every test. An Index C200 fed by an Iemca Master 80HF bar magazine was duly installed at DKW’s factory in October 2015, complete with a gripper arm for picking each finished part out of the counter-spindle and placing it onto a conveyor.


The bottom line is that while the manufacturing cost per part is 8% more when using solid bar rather than castings, the yield of good parts is more than double. Overall, cost and lead time per part are reduced considerably across the range of nine different flow-meter components currently being produced; and as the value of each part is several hundred pounds, the savings are substantial.

Mr Iacobucci says: “Part of the reason we are able to machine the components so economically from bar is that we are using a triple-turret twin-spindle lathe. Two turrets can operate at either spindle, and three tools are in cut simultaneously during large sections of the cycles, which include a lot of balanced turning and milling.

Repeatability is excellent, partly due to the Index system of W-groove quick-change tooling, as well as refrigeration and filtration of the coolant.”

Geo Kingsbury’s application engineers also recommended the use of trochoidal milling to produce a slot in the component. The process involves running a Delcam Vortex milling cycle in the machine’s Fanuc 31i-model B control and using an Iscar solid-carbide 6.5mm-diameter side-and-face milling cutter to produce the feature, which has a tolerance on its width of ±0.1mm. If a cutter were to mill the full width of the slot in a linear pass, vibration would compromise accuracy and shorten tool life significantly.

Mr Iacobucci says: “A feature that sets the Index lathe apart from others on the market is the kinematic actuation of the three turrets, rather than via standard compound slides. This results in fast movements both in and out of cut, as well as high stiffness and rigidity, helping us to hold tight tolerances and the fine surface finish that our customer requires.”

Stainless steel accounts for around 60% of DKW’s throughput, with titanium and nickel alloys also frequently machined. The robustness of the Index C200 makes it ideally suited to processing these difficult materials. There is considerable potential work for the machine in the oil and gas, petrochemical, nuclear and aerospace industries.

Around a fifth of the ISO 9001:2008-approved sub-contractor’s turnover is already derived from the aerospace sector, and the company is now actively pursuing the AS9100 quality management standard relevant to that industry to elevate it to Tier One supplier status.