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Five years ago Dave Malin set himself up as a one-man subcontract machinist having bought a Citizen L20 CNC sliding head lathe to perform one-hit machining cycles on parts up to 20mm diameter.

Soon after setting up DJM Precision Engineering Malin was working all hours of the day and night and quickly became confident enough to install a second Citizen from NC Engineering, now Citizen Machinery UK, of Watford.

On the back of the Citizen installations the business has gone from strength to strength and following a move to a larger unit that is double the size of his first production shop, turnover has tripled.

The company now employs five people, has six Citizens running around the clock, a fixed head bar lathe and runs two vans to service customers.

Such has been the progress of DJM Precision Engineering that with the strong possibility of winning a contract for almost a million components a year, Malin took the day off and went to Mach 2008 at the NEC Birmingham in May to check out the viability of the Citizen A20 sliding head lathe.

Convinced this machine would improve competitiveness even further, he sat down with Citizen’s application engineers at the show, costed out the cycle time and price per part, ordered the machine on the stand and subsequently won the business.

The Citizen A20 VII, which was delivered in June, is permanently set to run 24 hours a day, seven days a week, to meet the current 80,000-parts-a-month schedule, and apart from replenishing the bar feed and strictly timed tool changes – never stops.

Malin was sure the new machine would be more productive on this component than his existing three Citizen L32 and two L20 machines due to higher rigidity, latest control software and shorter axis strokes.

DJM Precision has 20 regular customers and Malin attributes much of the success and growth of the company to the decision to expand his machine bar size from 20mm to 32mm, with the installation of the three Citizen L32s and a long workpiece adaptor.

Again, the result of thinking ahead on capacity, the long adaptor has brought in a considerable amount of extra business from existing customers such as the one-hit cycle production of shafts up to 400mm long.

Also, new customers have been secured, due to the larger bar size, from areas as far away as Lancashire and Yorkshire and across to Cambridgeshire.

Indeed, DJM are now working on other long-term contracts involving JIT supply to an automotive customer.

Malin recounts how he opened the door to his new unit without even an Allen key to his name following the decision to ‘go it alone’ from working as a machine setter with a local subcontractor.

It was there he learned to set Citizens instead of cam autos and still admits how the technology initially scared him.

However, with his first Citizen L20 installed he has never looked back.

He was quickly producing a wide range of connectors, shafts, spindles, special screws and valves in batches as small as 250.

A Citizen Alarm Alert calls Malin whenever a machine stops, needs replenishing with bar feed or resetting when running unmanned.

Customers now range from automotive, agriculture, office furniture, brewing, marine and shoe industry sectors including many that appeared on his early customer list that still ply the company with work and one in particular that has a regular call-off of 50,000 parts.

Initially most components were produced from mild steel but now brass, aluminium, high grade steels and stainless steels in 303, 304 and 316 are on the bar racks in the factory for processing on the sliding head lathes.

One of the attractions of the seven-axis Citizen A20 VII machine was its availability as a ready-to-run package with bar feed, workpiece conveyor, delivery, commissioning and training.

The machine will carry up to 21 tools and with its X-2 axis on the subspindle and back tool post enables two tool simultaneous cutting on the front and reverse of the component.

The 8,000rev/min main spindle is powered by a 3.7kW motor and the subspindle by a 1.5kW drive with the same speed capability.

Full C-axis is available on each spindle.

There are four driven tool positions powered by 0.75kW motors giving up to 6,000rev/min and all rapid traverse rates are 32m/min.

Central to the lowering of non-cutting times on the A20 is the inclusion of Citizen’s Streamline Control software.

It is an ultra-fast processing system and enables the operational sequences of a standard part program to be overlapped to reduce positioning times.

As part of the DJM package the machine included a 3m lemca bar feed, a workpiece conveyor applauded by Malin for ensuring parts are not damaged, plus Sandvik Coromant’s QS quick-change tool system, developed in conjunction with Citizen, which enables a tool to be changed in under 40 seconds.

The Citizen/Sandvik QS system is another area appreciated by Malin who programs a complete tool change every 7,000 parts.

‘All you need to do is release one tool holder and replace it with the next that is already prepared with an insert to be positioned against the deadstop,’ he said.

The business has come a long way in the last five years, increasing machines from one to six Citizens plus a fixed head bar lathe that was installed to produce larger components up to 42mm diameter.

Citizen Machinery

Citizen is the world leader in CNC sliding head ‘one-hit’ turn-milling technology. It has a range of machines having a maximum bar capacity between 4 mm on the compact micro-machining capable Citizen R04 to 32 mm on the top of the range Citizen M32-VII which has the added capability of two Y-axis cross-feeds.   

The M32 can carry up to 80 tools, of which 20 can be driven, and can cut with three tools simultaneously giving low cycle times and high levels of productivity.  Also, fully automated unmanned cycles can be utilised through an integrated gantry option and conveyor system that helps ensure damage free parts during uninterrupted batch production.  A high pressure 2,000 psi CoolBlaster coolant system is a further option to optimise swarf control, tool life and machining difficult materials.

Following the acquisition in Japan in 2008 of 65 per cent shares in Miyano, the fixed head turning centre specialist, the two companies are maintaining their separate high profile brand names utilising a single sales operation.  However, turn-milling solutions from bar up to 64 mm diameter can now be provided.  In addition, with the Miyano range of turning and turn-milling machines for chucking operations, cell-type applications can now be accommodated with a wide range of automation options.   

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