Product category:
CNC automatic lathes
News Release from: Traub Heckert UK | Subject: Traub TNL 12/7 CNC sliding headstock automatic
Edited by the Manufacturingtalk Editorial
Team on 03 July 2002
CNC sliding head auto solves stock
problems
Model railway kit builder's busines was restricted by volumes of bought-out machined parts held in stock, until it acquired a sliding headstock CNC lathe and brought parts machining in-house.
Derbyshire based Slater's Plastikard is a company that will be very familiar to model railway enthusiasts around the world Until recently, most of its turned components were subcontracted which became very restricting on the business due to the volumes of parts that had to be ordered and then stocked in order to maintain a reasonable price
This article was originally published on Manufacturingtalk on 22 May 2001 at 8.00am (UK)
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However, since the company has installed a Traub TNL 12/7 CNC sliding headstock lathe, the business has never looked back.
It now has better control over stock and lead time and, most critical for the future of the company, it has been able to extend its product line and is able to produce parts totally under its own control.
The Matlock company has been providing quality products for railway modellers since 1956 and is credited with pioneering the use of Plastikard sheet, which is a reinforced polystyrene material, as a construction medium for buildings and wagons.
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Since that time, it has progressively expanded its range of scale model wagons, coaches and locomotive kits which are produced in a variety of gauges.
Following the installation of the Traub TNL 12/7 by Traub-Heckert (UK) of Brackley, Slater's Plastikard has been very busy multi-axis turning its model railway parts which include axles and bearings.
Managing director David White explains how prior to the installation of the Traub they had to order much larger quantities than required to get a good unit price and store the surplus.
"Whereas our demand was say between 2,000 and 3,000 parts a year for certain items we had to order at least 10,000 at a time.
That works out to around four or five years worth of stock.
On average, we were spending around GBP 35,000 on subcontract turned components a year," he says.
Eventually, the company decided to purchase a fast and flexible sliding head CNC lathe to handle all turning operations for its parts up to 12.7mm diameter.
After a thorough study of the turning market, the decision was made on the five-axis Traub TNL 12/7 equipped with FMB Minimag magazine bar feed.
With a requirement for fairly short cycle times, even when producing complex parts and tolerances down to five micron, the main production demand was for fast set-up and rapid changeover to meet batch sizes which were being rescheduled to range between 200 to 2,000 parts.
Says David White: "It was here that the TNL 12/7 really came into a class of its own, because it was by far the quickest machine to set for complex turned parts." He follows on to explain: "On a driving wheel axle, which involves milling, drilling and tapping operations, a complete set-up from scratch only takes us around two hours on the TNL.
On several of the other machines we looked at, such a complete breakdown and reset would take in the order of six hours to complete.
And when we run similar profile shaped components, the Traub can be re-set and be in production in just 30 minutes." The company also liked the speed and ease with which programs can be generated using background mode, on the TX8i RISC control on the Traub and that all of the 10 tool stations on the machine could accommodate driven tooling.
"With up to three large changeovers required each week, the savings made become quite substantial," claims David White.
He reflects his early concern over programming the machine and having only one employee with CNC experience and that was on milling.
"I'm surprised how quick we took it but the training and support by Traub Heckert certainly played an important part," he says.
The company sent the CNC miller and another employee for an initial five-day course at Brackley and once the machine was installed Traub's two-week training programme was followed which involved a week of theory and a week practical at the Matlock factory.
As David White outlines: "Over the two weeks the course covered all the component features that we are likely to have to make which not only quickly built-up our confidence, it has meant we have had no problems at all." Built on modular principles, the Traub TNL 12/7 lathe is supplied with a 12,000 revs/min spindle with options of one or two turrets, a sub-spindle, front and rear gang type working attachments and with up to nine axes under its CNC control.
All variants of the machine feature overlapped cutting cycles to give higher production rates and to help maintain consistency of production, digitally coupled axis drives and control have absolute measuring systems so that axes do not require referencing.
A thermal compensation system also helps to provide a stable process.
To meet production demands for some 200 model kits each month, Slater's Plastikard specified a five-axis TNL 12/7 lathe with a single six-station, 0.3 seconds chip to chip indexing tool turret with Y-axis cross- feed and four-station front linear tool slide.
The machine produces a range of mainly slender parts such as axles, buffer bodies, bearings, crankshaft parts and hand rail knobs in both mild steel and brass in sizes from 1mm to 6mm diameter by between 20mm to 55mm long.
These are used on the 70 different types of wagon, 16 types of coaches and 10 locomotive kits currently being produced and results in the lathe being run for around 10 hours each day with the magazine bar feed allowing limited manning.
One of the company's latest products is a crankshaft kit for locomotive engines and all eight parts in the kit are now being produced on the Traub TNL lathe.
This involves machining two stub-axles, two crank throws and four slip eccentrics which are among the most complex turned parts manufactured to date.
The 3.2mm diameter by 12.7mm long stub-axles have a 3deg taper on one end to locate the wheel, flats milled at the other end to secure the coupling rod crank and minute 1mm diameter cross hole to lock the crank throw.
The axle is produced in a cycle time of under one minute.
Another 12.7mm diameter by 2mm thick crank involves facing and drilling in both axial and cross attitudes and this too is produced in around a minute cycle time.
The final element of the crankshaft kit is the slip eccentric which has a lobed profile.
All four of these are produced from one 12mm wide block at different angles to each other and created out of 12.7mm diameter bar in just two minutes.
Both ends of each eccentric have a stub-axle which has two, 1mm diameter holes crossed drilled at 90deg to each other.
In all, Slater's can now produce a complete crankshaft kit in just four minutes turning time.
As this is a new venture, initial batch runs have been limited to 100 to test the market.
But as David White explains: "We would never have been in the position to take on this latest project without the machining capability of the Traub." As well as dispensing with the need to subcontract small turning work the components are now produced totally under Slater's control which is proving to be more accurate and cost effective.
The TNL 12/7 has provided other benefits too, as David White concluded: "It has given us far better control over stock, enabled lead times to be reduced and we have the ability to machine parts we would not have entertained before.
As a result, we can enter new markets and our general stock holding requirement has been, and is continuing to be, reduced." While some 25 programs were up and running within six months, this will eventually increase to around 50 as stock levels reduce and the next production development will see Slater's Plastikard both milling and hobbing small gears within the turning cycle on the sliding head lathe.
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