A small group of journalists was recently conducted around the Leipzig and Zerbst plants of the Emag Group. The visit brought home the versatility of the vertical pick-up spindle machine tool. If you can pick up the job in a chuck, a wide variety of operations can be done in one or two set-ups in a vertical pick-up spindle machine (VPSM).
Nor are VPSMs dedicated to large batch or continuous production.
The visit to the Zerbst plant, not so far from Magdeburg, brought home the true versatility of these machines in a typical small batch production environment - machine tool building.
Emag's Zerbst plant machines about 60% of mechanical parts for the Emag Group.
The other 40% are produced at the headquarters plant in Salach, south Germany.
In the machine shop at Zerbst, five Emag VPSMs share production with two Heckert CWK 1600 and one CWK 500 horizontal machining centres (HMCs), two Hardinge VMC1000II vertical machining centres (VMCs), a DM3m (GBP1m) Dixi 410 TPA three-pallet HMC cell, two Karstens K51 cylindrical grinders, a twin, gantry-served CNC lathe cell, a small number of radial arm drillers, a horizontal borer and other supporting machines.
Perhaps of all the components being machined in the Emag VSC VPSMs the biggest surprise was the production of 12-face machine tool turrets in two set-ups.
The turrets are mounted on tooling plates for pick-up by an Emag VSC 400 MT.
Total machining cycle time for the two set-ups is 260 min.
Zerbst used to machine these in six operations, in three separate machines - two ops in a HMC, two in a CNC chucker and two in a CNC grinder.
Total machining cycle time was 486 min.
Emag has built two VSC 400 MT variants so far; the second is working in France.
The machine has a substantial trunnion-type manipulator fitted with a 30kW tool spindle in the inside of the 'U'-beam and a six-station turret mounted on the beam at 90 degrees to the tool spindle.
The U-beam swings from in front of, to underneath, the vertical spindle chuck.
A twin-arm carrier serving a disc-type magazine at the side of the machine effects automatic tool change into the tool spindle.
A simple conveyor delivers the turrets to the pick-up point.
The other four VSCs ranged from the 250 to a large 500 model.
These were machining various flanges, bushings, main spindle flanges, spacers, housings and the like.
The plant machines some 400 varieties of mechanical parts at an average output of some 1600 parts/week.
Zerbst is tooled up to produce any Emag or Hardinge Emag mechanical part.
VSCs, VL3 and 5s and HSCs are generally built inside four weeks, order to delivery.
One week is spent on assembly.
Two weeks before, sub assemblies are produced, and three to four weeks before, machining commences.
Some 70% of the parts are made within one week.
Production management of parts progress is largely by visual observation and is backed by a PPS system, electronic data processing and Kan Ban control of stocks and work-in-progress.
Next door to the machining hall is the assembly area where the more customised VPSMs are built.
For example, there was a 250mm chuck size 'Trio', which has three vertical pick-up spindle heads in one VSC, each with its own tool turret.
Nearby was a 'Duo' twin-spindle version.
The two pick-up stations are separated by a turn-over unit.
For GKN, USA, Zerbst was building a VSC 315 KBG to hard turn spheres and hard mill ball tracks for CR joints.
The machine uses two 4000 rev/min milling spindles on a B-axis.
These use Sumitomo CBN tooling.
One of the more recent developments is the HSC type for shaft machining.
The pick-up head has a horizontal chucking spindle and live centre assembly and picks up shafts from a conveyor.
It transfers across to present the shaft to a variety of turning, grinding and machining heads.
The basic HSC 250 or 450 has one disc-type turret with static and live tooling.
The machines can be equipped for ID and OD grinding, abrasive band finishing and peel-grinding.
For the DaimlerChrysler and ZF Batavia project, HSCs for hard turning and finish grinding will save 75% of machining time when compared with existing methods.
Emag said it had sold 20 HSCs straight from the machine concept 'sketch'! In another shop is Emag's 'Mineralit' polymer concrete casting bay.
A local sheet metal fabricator makes up the machine bed endo-skeletons (for want of a better word!) and supplies them through a 'hole-n-the-wall' on demand.
After setting up a batch of endo-skeleton moulds, pouring commences at 21.00h.
At present some four hours' worth of pouring satisfies current demand.
Curing is complete by the next day, ready for the location faces, dowel holes, bolt holes and so on, to be machined in a large Russian portal machining centre in a bay next door.
The Zerbst plant, by the way, used to be Wema, which used to build large facing lathes - up to 15m diameter, I was told.
The two-day visit had begun in Leipzig.
The arrival at the airport was very different compared with my last visit in 1988.
The exit was no longer through a narrow winding lane in a nearby housing estate.
There are now new roads avoiding that.
The air terminal is a very clean modern affair, replacing the sheds of 13 years ago.
Under build is a new high speed railway from Berlin to Leipzig, running past the airport.
All was very different! The Emag group had acquired the former East German Drema plant (a former member of the old '7th October Kombinat') from Tornos Pittler in September 1999 to add on more assembly capacity.
It was incorporated into Emag Leipzig Maschinenfabrik (Machine tool factory).
Drema was a producer of multi-spindle automatics, having taken over the plant in 1949 - it was the original Pittler plant.
Pittler had re-established itself in Langen, near Frankfurt.
Then in May 2000, Emag entered into a joint venture with Hardinge US, to build 'leaner' versions of the pick-up spindle VSCs - the VL Series - for the general jobbing shop market.
Production of the VLs is also done on the Leipzig site.
The two assembly shops in Leipzig had been considerably modernised and re-equipped.
Hardinge Emag commenced building the VL3 in October 2000 and the larger VL5 in April 2001.
To-date (early October), the company had shipped some 300 VL3s and VL5s.
Juergen Hannig, managing director of Hardinge Emag, said that the VL5 was going 'very well' with 60% of machines sold going to Europe and 40% to the US and the UK.
One diesel fuel injection manufacturer had bought 14 VLs to machine parts.
The VL flowline assembly area had become crowded, and Hannig said that the area was going to be remodelled and would include a nearby vacant building.
It takes about 90-100h to build a VL.
There are 42 people engaged in the plant and there are 17-18 VLs in the flowline at any one time.
About the VL design, Hannig said that from a user's standpoint, the machine uses 'air space' and not floor space.
Under development with Heilig Automation (acquired by Emag in March 2001) is machine inter-linking equipment for the VLs.
Next door, the VSC machines were being assembled and tooled up by Emag Leipzig, which employs 75 people.
On the floor were three linked VSC 200 types for Volkswagen's Salzgitter works to machine grey cast iron water pump housings.
Cycle time for each operation is 40 sec/machine, providing three components/2 min.
Earlier, 30 VSCs had been delivered to Volkswagen, Argentina.
These machines had been supplied partly automated and could be upgraded as demand rose.
Dieter Fischer, managing director of Emag Leipzig, mentioned that the Salach plant has delivered some 30 to 40 machines to CV joint manufacturers for hard turning of the spherical bearing and hard track milling in one operation on hardened steels of 62 HRC.
VSCs had also been supplied to Visteon's Swansea, Wales, plant for machining ring gears of 39mm ID and 80-85mm OD in 70 HRC hardened steel.
A VSC 250 UR features a hydrostatic bearing on the main pick-up chuck spindle.
This arrangement provides 50% longer tool life when hard turning using PCBN tooling, so reducing the price per cutting edge.
Under build too was a VSC 250 Duo, twin pick-up spindle machine for machining ring gear blanks in forged steel to within general tolerances of 8 - 10 microns.
The rings have to be machined all over, so the second spindle is equipped with a Heinbruch collet operated by the CNC via a pressure proportional valve.
Requirements include Cmk of 1.69 and Cm of 2.55.
A development of the VSC 200 features a gang tool slide instead of a turret, in this case, to machine prehardened helical gear and boss components using Sandvik Coromant and Sumitomo tooling.
Requirement is to hold +/-14 microns on a 36.1mm diameter bore and a surface finish of 2.5rootRc.
Under development is a four-station machine to press-fit assemble, C02 laser weld, clean and finish machine automotive parts.
Still on the 'secret' list, more details will be announced later.
A most interesting visit.
I would like to express my thanks to Manfred Hekeler, Marketing and Communications at Emag, and Tom Moriaty of Thomas Moriarty, for organising the tour - Mike Page