Leeds-based Kingfisher (Lubrication) has broken into the US specialist aerospace sector winning, for the first time as a non-American company, a contract to supply non-standard grease nipples out of Monel material. Solutions reports.

Such was the urgency for supply on the new contract that Kingfisher had only eight weeks to deliver initial components – but far from being a straightforward make and ship, the importance of production demand led to the purchase and installation of a new 20mm capacity machine from Citizen Machinery UK and a massive short term drive to develop the process. However, all the effort was rewarded as within four weeks of the machine being delivered, Kingfisher was able to successfully air freight parts to its customer.

The contract for a significant quantity of grease nipples (called Zercs in the US) was won with a tight delivery schedule and the customer agreeing to free issue supply the 7/16 inch A/F hexagon nickel-copper alloy material. However, the sting in the tail that could have caused embarrassment for Kingfisher was when the customer found the highly specialised hexagon material was on a six month delivery and it could only supply ½ inch round bar meaning existing machine tools, all set for volume nipple production, could not be used.

With the prospect of further contracts and the possibility of competing with the only other company in the world to produce Monel grease nipples, managing director John Fisher and technical director Richard Holt decided to purchase a CNC sliding head lathe and mill/turn the hexagon in-cycle. Initial discussions with potential machine suppliers drew the directors towards Citizen Machinery UK due to its ability to meet the demands of the project, delivery and installation within the tight time frame which resulted in a Citizen L20-VII turn-mill centre being ordered.

Single hit success

With this machine the single cycle operation involved the profile being turned and hexagonal flats milled and notched, the central bore drilled and the special taper thread cut. As a process monitoring and costing exercise has revealed, a payback equal to one third of the price of the machine was achieved within this one contract.

The move to the use of sliding head technology follows a recent installation of a Miyano BNJ-42S fixed head turning centre from Miyano Machinery UK, a sister company within the Citizen Group, which had been previously purchased to satisfy a long term contract for producing complex high pressure valves for off road tracked vehicles. Like the Citizen, the Miyano operates as a single cycle machine using the combination of main and sub-spindles. Normal production methods for Kingfisher are based on highly automated processes that are able to produce 2.5 million standard mild steel, case hardened and stainless steel nipples a week.

To achieve this level of production the company had spent over £4 million developing its 45 BSA Acme Gridley multi-spindle autos replacing the traditional mechanical gearbox with PLC control and direct drive systems in order to raise the level of reliability and process consistency.

Indeed, such is the level of productivity that these machines are able to produce grease nipples at a rate of 50 per minute. Kingfisher also designs, develops and builds its own fully automated assembly machines to insert and capture the spring and non-return ball in the nipple by swaging over the central hole which is carried out at a rate of 100 completed cycles per minute, per machine.

Says Mr Holt: “The Monel is a tough corrosion resistant material and despite being a free cutting specification it presented a real challenge as it is subject to work hardening. The material is also difficult to chip on a consistent basis and can ‘bird’s nest’ and cause tooling problems which means we have to be vigilant.” The incorporation of the Citizen CoolBlaster 2,000psi high pressure coolant system has significantly improved tool life and productivity while extending the period when manual intervention is required from a few minutes to between two and four hours’ continuous production.

More bang for your buck

Mr Fisher adds that this classification of grease nipple is very unfamiliar in the UK but there is room to use the flexibility of the Citizen to further develop this range of product. “We have worked closely with Citizen’s application engineers and tooling suppliers and have so far improved the cycle time from an initial 135 seconds to just 44 seconds,” he reveals.

“What we have found in the Citizen, which has a 4m bar feed, is that due to the consistency of process and lack of rejects, coupled with a shorter bar end than we originally estimated, we have enough material to produce a further 15% more parts.”

The Monel metal grease nipple is 19mm overall length with a radius and angled profile of 6.65mm that is necked down to 5.5mm diameter. Behind the 7/16 inch A/F hexagon, a special hydraulic sealing thread 1/8 inch x 27tpi with a 1:16 diametral taper is screw cut. So critical is the thread, that when it is screwed into position during assembly, the thread on the nipple finish shaves the mating internal thread form to create a totally leak proof seal. Within the Citizen single cycle the central hole for the ball and a counterbore is also drilled with a register 5mm diameter by 1.3mm deep turned adjacent to the thread.

Mr Fisher adds: “The speed and versatility of the Citizen sliding head machine will mean that we can now produce other standard steel long parts such as those required by one of the UK’s leading offroad equipment manufacturers, which are 12.5mm diameter by 50mm long. We can now produce these at twice the speed of a twin-spindle slant bed, fixed head machine.

Paving the way 

Mr Fisher is the fourth generation managing director in the 143 years the company has been producing lubrication devices in Leeds. Formed in 1867, it specialised blending oil and manufacturing grease soap. In the early 1900s it began development and production of screw-down lubricators and grease cups but it was 50 years later that Mr Fisher’s late father Adrian took maximum advantage when the American grease nipple patent expired and he started his own production in the UK. By the early 1960s helped by PERA at Melton Mowbray, the highly automated production of nipples was laid down which has led to Kingfisher becoming one of the world leader’s in its sector. Altogether, a range of some 350 different types of grease fittings are now being produced.

Employing 50 people today at the 10,000m² site in Leeds, the company is heavily export orientated with 90% destined for overseas customers through a network of distributors. North America is by far the biggest market taking 70% of sales especially in the offroad, agricultural and automotive sectors. As Mr Fisher explains: “While ‘sealed-for-life’ has progressively eroded the widespread use of grease nipples in cars, three quarters of American roads are in fact not paved, and a wide range of vehicles still require grease lubrication to survive.”

Three years ago the company invested in a new 1,500m² building adjacent to the existing production shop and while at present it only houses the Miyano and Citizen machines, it will form a CNC machine shop that will open the way for adding value from specialist production of grease fittings and other machined parts in relatively smaller quantities.

Citizen Machinery UK
www.citizen-miyano.co.uk

Kingfisher (Lubrication)
www.kingfisherlub.co.uk