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Emerald Group Publishing Limited
Copyright © 2008, Emerald Group Publishing Limited
Two citizens are worked as a team
Article Type: Aerospace world From: Aircraft Engineering and Aerospace Technology: An International Journal, Volume 80, Issue 4
To celebrate the first anniversary of his business in small part subcontract machining, William Bradley bought and installed a second Citizen M32-V CNC sliding head turn-mill centre – and the machine immediately gave Midland Precision Engineering the ability to meet a growing order book. He also now has the capability to run two machines unmanned as individual production centres enabling at least some parts to be produced continuously throughout the 24-h a day.
Utilising to the full his previous subcontract sliding head auto experience, William has one proviso for the (Derbyshire) Ilkeston-based operation – he wants to run his small business his way being answerable only to customers and his family. When he started just over a year ago, he rented a small unit and installed a new 13-axis, Citizen M32-V CNC sliding head turning centre supplied by NC Engineering of Watford.
Helped by his father with the initial funding, that also included tooling and a non-contact 3D measuring machine, he recounts how eight days after he started on this new venture his wife gave birth. Undistracted, orders built up rapidly and the company very soon was running flat out and producing all day and most of the night.
After his first 12 months, the only time the first Citizen machine was not running round-the-clock was when it was being reset. He recounts how exciting it has been and despite a few questions in the early days of “what have I done in setting up my own business?” He is positively bursting with enthusiasm.
William is just 34-years old and can often be found at the business unit for 18-h a day. He returns to the site at night to reset, or rebar the machines and has the automatic call out from each machine control to his mobile if it should stop for any reason when in unmanned mode. He also helps to clean up, does the accounts, delivers work, carries out all the buying functions, meets and spends time with his 20 or so customers, and runs all aspects of the business.
From a cold start in setting up the business, he does not look back especially with orders flowing in and work flowing out from his aerospace, autosport, hydraulic pump, printing and off-shore related customers in batches that range from 50 to 15,000.
In his early weeks, he was reliant for work on other subcontractors who were seeking a quality machinist. Although he found it very welcome, some was the type of work no one else in their right mind would take on. “That’s the start point and learning curve, and it certainly drew upon all the skills I had developed”, he said, and as other work began to flow in, his own position and confidence strengthened. He maintains he is eternally grateful to some of the early customers and said: “They were keen to support me, helped my cash flow and gave me confidence and useful advice. I’ll never forget them!”
At the same time, as William was installing the first Citizen M32-V, he also bought, through NC Engineering, a 3D non-contact measuring centre. “That was an absolutely correct decision that has helped beyond belief. It means there is no tie to the inspection bench. Once programmed, it will automatically collate measurement and SPC data that can then be sent with the batch of work to the customer”, he said.
However, there are still two spectres haunting this young machinist – the thought of failure before those that have helped him and concern over making a mistake and letting a customer down. “It is totally down to me to make sure it does not happen”, he said.
Having served an apprenticeship and worked up to production component technician before joining a subcontract company, he is a stickler for organisation. An immediate impact of his business efficiency is felt when you step through the door of the fairly new unit to see the two machines very clean, with all the bar material racked and labelled, off-hand grinders mounted on a clean bench next to a new vibratory finishing machine and component wash. All tools are organised and the clean and shiny components are packaged and boxed in the storage area on a small mezzanine floor alongside the measuring machine, and office equipment.
His first decision when he set up was to buy the Citizen as the core machine. He knew the M32 inside out and from previous experiences he understood what it could achieve. This targeted the type of parts that he knew he could use his programming and production skills to make very successfully – parts that would normally require turning and the addition of three or four machining centre or milling and drilling operations to complete. He said: “I knew most could be done in one highly productive and accurate cycle with the right equipment and the blend of functionality and flexibility of the M32 would give me what I needed in a single operation.”
Indeed, one early component quoted for the Citizen M32 enabled five normal operations to be combined into a single process. The customer could not believe the short lead time we had promised and was amazed when he received the delivery, and even more amazed when he found every part was easy to assemble. He revealed: “The customer always had issues with his previous supplier and because of the way my company performed, we are now growing the order book and still getting frequent compliments on the quality. That makes me very proud of what the business has been able to achieve”, he said.
He then picks up a range of parts, some are not difficult but nearly all have combined operations involving multiple features. “Holding them on the bar is the best fixture you will get”, he said, “so with the M32 it is a matter of being able to set the tools to do the task in the best order and minimise burrs and sharp edges because deburring by hand can waste a lot of time.” Often, for very complex parts, he arranges with a local toolmaker to wire EDM collets to suit the Citizen sub-spindle in order to accept a particular shape from the partially machined component out of the main spindle that enables the part to be completed in the same cycle.
He shows one aluminium component with multiple diameters, undercuts, slots, cross-holes and milled flats and with a hexagon form in the bottom of a counterbored hole to demonstrate the versatility of the M32 in saving the use, cost and delivery of special broaches. By using the Y-axis crossfeed to put small drills into the corners of the hexagon, he then drills out the core followed by the milling of the flats. “There is never any swarf compaction and the part may take slightly longer to machine but the hexagon is produced automatically with overlapped operations, it costs very little to do!”
The Citizen M32-V has two Y-axis crossfeeds, one for the ten-station turret, the other to the gang tool slide, enabling three tool simultaneous cutting. The machine can carry up to 72 tools, has a 7.5 kW, 8,000 rpm main and 3.7 kW, 7,000 rpm subspindle.
The second Citizen M32-V purchase followed a comparison of the alternative machines on the market. According to William some machine suppliers were pushing hard the argument for greater rigidity and the ability to cut metal faster but trials on parts he already produced on the Citizen could not be matched in terms of cycle time nor meet the machine’s flexibility for programming, tooling and setting.
“This second Citizen has transformed the business giving more time to manage day to day tasks because at least one machine is always producing parts”, he said. “There is no longer a need to have production stopped, when a machine is reset. A lot of work is made up of fairly small batches that repeat and the machine eats through those very quickly. So it is now left to run longer and build a small stock of parts for the customers to call-off when required, giving them the advantage of a quicker delivery.” That said, each M32 is reset at least once a day leaving common tools in the machine. And all the while the other Citizen is earning its keep so production is continuous.
Materials processed at Midland Precision Engineering include plastics, mild steel, stainless steels, aerospace alloys and 2014 aluminium. The company also machines plenty of EN24T which each machine copes with very well even with the materials inherent toughness. Here, he insists: “The tooling is critical and this is an area where I never skimp. Pounds could be saved buying cheaper tools but you need to be confident that the tool will do the job and be predictable. The last thing you want is machines stopping requiring a tool change because the tools have started going off prematurely or an edge chips. Also, having to keep changing offsets wastes time, introduces another source of error and it’s another thing to do to keep checking what’s going on.”
With the new machine William ordered Coolblaster II, the compact 2,000 psi high-pressure coolant system that sits under the barfeed. “Once the system is proven I will order another for the first machine which will add to confidence levels on the security of the machining process especially regarding swarf”, he said.
“Consistency of process is not an issue with these machines”, he maintains. “We regularly hold 0.01 mm on stainless and have even maintained eight microns over a batch of parts. But to do this you need a stable temperature so the workshop doors are kept closed and the machine will then run and run”, he says.
William has no ambition to be rich in his business activities but only to be comfortable in the knowledge he can support the family and lead a life where he can, to a certain extent, control his destiny. “I can then set the business to work for me producing the quality of work customers require and meet their deliveries. But I must admit, I will enjoy myself doing what I’m doing to get there”, he said.
Midland Precision Engineering Ltd, Tel: +44 (0)1159 304460.