Within just two months of changing its business from being a component-oriented cell production operation to a Group Technology and Skill Centre (GTSC) based on machine type, precision gear specialist FT Gearing Systems has been able to increase the collective output from its Citizen CNC sliding-head turn mill centres by 20%.

Moreover, the immediate success of the ‘Citizen GTSC’ in one of FT Gearing’s newly acquired facilities in Aldershot shows a company can benefit by analysing how its business best functions.

Set up by Des Fitzgerald in 1978 as a two-man operation, the company is now run by his two sons — Graham (managing director) and Nigel (technical director) — and has become a specialist supplier of gears, miniature gearboxes and assemblies to the aerospace industry with a turnover of £7 million. It has 80 employees and has invested over £4 million in the last four years.

Graham Fitzgerald says: “We felt we were efficient before; we focused on how parts were produced and set up a number of manufacturing cells where, for instance, we had a lathe, machining centre, broach and grinding machine grouped together with a setter/operator having total responsibility for all the different pieces of equipment.

"The operator went from machine to machine; on first appearance, that gave good job satisfaction due to the different technologies involved, but it resulted in the operator becoming a ‘Jack of all trades’ who rarely mastered one!”

Benefits of GTSC

Although FT Gearing has also applied the same GTSC strategy to fixed-head mill-turning, four- and five-axis vertical machining centres, gear cutting and grinding, the company uses its sliding-head machines from Bushey-based Citizen Machinery UK Ltd (www.citizenmachinery.co.uk) as a prime example of the benefits provided by its GTSC venture.

Graham Fitzgerald says: “We had eight Citizen machines in three separate factory units on the industrial estate that was our base. We now have all the Citizens — another is on order — in Unit 14; we have also created a Citizen working team that is developing an active interest in the business, as well as a little competitiveness between themselves. When we took over Unit 14, the team we put together really saw it as their domain; they even volunteered to come in over a weekend to help remove an internal wall, paint the rest of the walls and seal the floor prior to the machines being installed.

“The team collectively decided on the location of each machine and specified where the material, tool and spare-parts stores were to be located — and where the Citizen Wizard programming and inspection area would go. They even persuaded us to set up a mini training area where they can help each other to improve their sliding-head skills,” says Graham Fitzgerald.

FT Gearing runs an overlapping double day shift from 4am to 9pm, with the team working the inspection area between them. As a result of the changes, output from Unit 14 is now up by 20% compared with the previous arrangement, producing over 7,000 parts a week in difficult-to-machine materials that include a wide range of stainless steels, titanium, copper-based aluminium bronze and maraging steel — a low-carbon high-strength steel with 15-25% nickel (it is used in the manufacture of aircraft undercarriage and wing fittings). This material is very unstable when being machined and has a tendency to creep, so FT Gearing’s engineers have written a macro for the Citizens that ensures they consistently achieve the required size.

Aerospace applications

The company supplies eight OEM and Tier One aerospace customers with complex small assemblies and critical ‘Class 1’ components. These parts are all used in wing surface actuators, engine controls, instrumentation, epicyclic fuel pumps and thrust-reversing units.

Graham Fitzgerald says the selection of Citizen Machinery UK as FT Gearing’s supplier of sliding-head machines was down to their ease of setting and ability to provide a totally consistent level of size, geometry and surface finish. “In addition, Citizen Machinery UK provides a high level of service and applications support when we need it.”

FT Gearing has two top-of-the-range 14-axis Citizen M32s and two B12s, as well as an L20E, an A20 and a B16E. A Citizen L20 VllE-1X is on order; this features a Y axis, 20-tool capacity and a short bar feeder. Quality and consistency are priorities for FT Gearing’s two directors.

Nigel Fitzgerald says: “We are always assured of consistent quality from the Citizen machines. Indeed, on certain components we can maintain tolerances as tight as 5µm. We have installed air conditioning in several of our units, including Unit 14. Within minutes of switching on a Citizen, we have found that it quickly stabilises and will hold size. It is rare to put in offsets, except to account for tool wear when machining particularly difficult materials.”

The Citizen B16E is frequently used for producing spur-gear blanks in a single cycle. All faces have to be perfectly flat and the OD held to a 5µm tolerance; the bore is held to a tolerance of 4µm. Meanwhile, the Citizen L20E will machine S143 stainless-steel shafts to a tolerance of 5µm, which would normally be considered the equivalent of being precision-ground.