With operations at more than 200 locations in 70 countries around the world, Wärtsilä is a global leader in ‘complete power solutions’ for the marine and energy-generating industries. The company has invested in advanced CNC manufacturing technology — and bespoke work-holding solutions — to improve productivity and efficiency.
A global business with some 18,700 employees, Wärtsilä last year achieved sales of nearly £4 billion. At its UK facilities in Havant, around 200 staff specialise in the manufacture of new and replacement sealing solutions for ship machinery (propulsion and manoeuvring systems), as well as special applications that include tidal-power equipment.
Seals for power output shafts —mostly ranging from 35mm to 1m in diameter — are used in a variety of craft, including commercial passenger and freight vessels, naval ships and inland-water river boats. At Havant, the company also specialises in submarine seals; these require a temperature-controlled environment for accurate production, as well as specialist grinding and lapping equipment to meet the required tolerances.
Installed during September 2013, the company’s Mazak 1060 V machining centre is equipped with a 10-pallet changer; moreover, there is the option of adding a further 10 pallets as business grows — and further machining centres to create an FMS.
Production engineer Russell Silcox says: “The aim is to feed the spindle to keep it turning and to reduce the number of set-ups to increase efficiency. Currently, two of the pallets are fitted with six-jaw chucks, two feature cubes that elevate the workpiece to allow the spindle of the Mazak machine to fully access the component, and three are fitted with four-jaw chucks.”
Range of components
Both of the six-jaw chucks — manufactured and supplied by Tamworth-based Leader Chuck Systems Ltd (
www.leaderchuck.com) — have been designed to hold a range of components.
With the jaws reversed, components of around 400mm in diameter can be held; with the jaws located on the outside face, parts up to around 630mm in diameter can be securely fixed.
The shopfloor at Havant mainly machines Inconel, nickel, aluminium and phosphor bronze for the seals and bearings. Raw material can be cast or billet; and with a lead time on the raw material of around six months, secure work-holding is crucial.
The varied product range means that change-overs are a regular occurrence — a situation further complicated by the fact that many parts feature thin walls and are “somewhat flexible”. Furthermore, many of the cast parts are split and then bolted together.
Mr Silcox says: “We machine the faces and bolt the two halves together, so it is not round but slightly elliptical. This is not a problem, because we can release three of the six jaws and use the Leader solution as a three-jaw chuck that allows us to centre the workpiece.
"Using a four-jaw chuck would result in just two of the jaws touching the part, which would not provide the security required to machine it.
“For a round machined component, the machinist will use all six jaws so they can tighten it up without any distortion by applying equal pressure from all sides. The Leader chuck is superb at holding both these types of parts.”
Moreover, the chucks have been designed to lift the material, thereby allowing the spindle head to access the areas that need to be machined all the way around, making the machining cycle as complete as possible.
Leader’s southern-area sales engineer, Jason Hutt, says: “To provide such a complete solution, we worked with the staff at Wärtsilä to engineer a chuck that addresses the needs of the production team. Even the T-bar was manufactured to allow it to fit inside the guarding of the Mazak machine.
All points of swarf ingress have been covered to ensure that the chuck will operate effectively for many years; some of these covers did require modification, as Wärtsilä needed to open the jaws further than originally specified.
As well as the sub-plate to mount the chuck to the pallet, ancillary parts supplied with the chuck included soft jaws, plus nip jaws that allow the part to be lightly located before internal jaws bring the required load onto the part to hold it. These work like a ring of vices (rather than a traditional chuck), which is ideal for thin-walled components.
Once the set-up is complete, the usual machining cycle is around 3hr. Most components are coming off completely machined, with just finishing operations — such as impregnation — required. “The bottleneck is the set-up station, so anything that makes that more efficient — such as the six-jaw chuck — is doubly important,” concludes Mr Silcox.