Model locomotives: Made in Germany

Author: Oliver Ehm
Published with kind permission of the company Gebr. Märklin & Cie.

The expert adds that another advantage is that this material is easy to machine, process and coat, and has many excellent properties for model railways. In particular, diecasting is very heavily used in locomotive production – primarily in the structure and chassis sections. »Ninety-eight percent of all diecast parts we process in our models are produced here at our foundry in Göppingen,« Gaißert explains. »We buy in the remaining parts, such as the drives, since their size means that we can't manufacture them ourselves.« Based in the town of Göppingen in south-western Germany, Märklin brings together all of the manufacturing technologies required to build a model railway. These include tool and mold making, diecasting, injection molding, turning, gear manufacturing, electroplating (nickel-plating), coloration, punching at a small facility, assembly and quality assurance. Göppingen also supplies the subsidiary plant in Hungary with parts, which are then colored and assembled on site, Gaißert adds.

A 36-year partnership
In 1984, Märklin acquired its first CHIRON CNC machine – an FZ 16. For the long-established company, this was also its first step towards complete machining in the chassis area of the locomotives. At the time, Märklin's employees in Göppingen still produced the drives themselves, with the processes of chassis and gear machining forming a key production area. Märklin approached CHIRON in the early 1980s because, Gaißert explains, the Tuttlingen-based machine manufacturer was the only supplier which adapted multi-spindle heads and achieved process times which went beyond what the conventional machinery could achieve with respect to cost-effectiveness. »From an economic point of view, we'd never have gone in that direction otherwise,« Gaißert believes. »The CHIRON machines still stand out today thanks to their very short downtimes and, at our company, we're always performing a lot of tool changeovers and machining operations.« While Märklin also considers other manufacturers from time to time, Gaißert states that the downtimes and machine design are exactly what Märklin needs for its applications.

»For many years, it's been obvious that we're very likely keep going with CHIRON machines. We also benefit from the partnership when a new machine series comes out – particularly when the FZ 08 was released and the company representing CHIRON at the time let us observe the machine at another business before it came on the market,« Gaißert sums up. »We then bought a machining center shortly after it was launched.« The managers at Märklin think highly of CHIRON's proactive dedication. »Together with CHIRON, we've adapted our interfaces and equipment as part of a major project. CHIRON was very heavily involved. They even adapted the machine design especially for us,« Gaißert remembers. »What's more, the machines are very reliable, stable and operate with high precision.« There are also pragmatic reasons for Märklin's decision to continue purchasing CHIRON machines.

»There are great advantages to homogeneous machinery. The variety in control systems is manageable, the supply of spare parts is excellent and our employees are included in this approach. They know how CHIRON operates and if there's ever a real issue, their servicing and programming support is outstanding,« Gaißert underlines. »For a competitor to come close to us, they'd need to offer significant advantages.« Märklin tries to avoid having an unchecked variety of machines from different manufacturers. This is because, in terms of organization, it would be difficult to manage heterogeneous manufacturing machinery. Under certain circumstances, you would need to use different tool systems or measuring technology and this would, in turn, drive up costs. Gaißert adds that Märklin also once internally considered the merits of STAMA, another brand in the CHIRON Group, before deciding against it.

This was because, when compared with STAMA's wheel change concept, CHIRON's pivot holder and chain tool change concept offered advantages with respect to interfering contours. Märklin last purchased a machine in 2014. The machining centers have a service life of around 20 years when operated for two shifts, five days a week.

Modernized production
In the meantime, Märklin's main area of production has changed again. The Göppingen-based company currently has a total of six machining centers – three FZ 08 models, two FZ 08 models and one FZ 12 model – primarily for producing the structural and locomotive housing. The business now uses industrial motors for its drives. While these are bought in from elsewhere, they significantly improve the level of detail in the structure and locomotive housing sections. The experts at Märklin say that this results in the constant challenge of finding a middle way between what is possible from a casting perspective or what is only possible with a great deal of effort, and what can subsequently be achieved more cost-effectively using a machining center.

»We're now using a fourth generation of machines from CHIRON. Everything is going very well and our partnership is working perfectly,« Gaißert explains. He particularly emphasizes the quality of support provided for process time generation and feasibility studies, adding that test machining operations are also possible. »Two years ago, we were at CHIRON's premises because we wanted to try something new – we milled a semi-finished product into an undercarriage. We first programmed it here and made various attempts, but we weren't fully satisfied with the outcome,« remembers Sven Dannenmann, Head of Diecasting and Cast Iron Machining at Märklin. »We then approached CHIRON and they redesigned the program and produced samples.« Gaißert adds, »At the time, this production set-up was uncharted territory for us. While we did have a five-axis machine, we only used it for positioning because we needed to make holes at suitable angles. For this project, we wanted to mill a solid block into an undercarriage for the small Z track gage, which was something we'd never tried before.« Dannenmann continues, »If we are working on a new product in-house during the design phase and our experienced on-site specialists are reaching their limits in terms of technical manufacturing, we contact CHIRON and know that we'll be supported by a skilled partner.«

Bernd Hechler, Technical Consultancy/Sales at CHIRON, states »Development is 100% in Märklin's hands; CHIRON is only brought in if it there are applications where our specialists need support.« As one of the greatest challenges for Märklin is making its products as realistic as possible, the departments involved in development and production are included in order to recognize and resolve any problems at an early stage.

Depending on the part interdependencies, Märklin produces between 80 and 200 housings and attachments a day. The runtimes for each part can vary considerably, depending on the parts' complexity due to their features and details. »Sometimes a part like this can take up to four minutes,« Gaißert explains. »But there are also simple workpieces which can be made in 30 seconds.«

Plans for automation
However, Märklin has experienced difficulties when it comes to automating its production facilities. This is primarily because the company machines a wide range parts and therefore the process of automating the machinery is very complex. »There's already automation in the form of a brush robot, which machines many – but not all – of the housings,« says Dannemann, Head of Diecasting and Cast Iron Machining at Märklin. But ideas are being considered for gradually automating production. With the assistance of CHIRON, the experts at Märklin are looking for ways to advance automation in order to further increase the profitability of its business operations.

Gaißert says that Märklin produces a relatively high number of new products every year – like the current »TEE Edelweiss«, a four-carriage train with all of its attachments made from diecast metal. »Model train collectors expect new innovations at regular intervals. They must all pass through production in a timely manner and on schedule,« states Gaißert. »This entails a great deal of effort in preparation, as the partner parts must interact perfectly and we machine a large number of high-precision items.«

On top of this, the company also produces classic locomotives. »We've still got a lot of molds from the 1950s and 1960s which we continue to use in production today,« Dannemann notes. »These locomotives are known as replicas.« When Märklin releases a new locomotive model, it often also offers the old version at the same time so that collectors have the option of purchasing both. »While the interiors are fitted with brand new technology, the design is the same as the old model's and has all of its characteristics – such as fewer details and attachments,« Gaißert explains. »But that's exactly what makes them so charming and appealing to customers and prospective buyers.« However, just because these models do not have a modern design, this does not mean that they are easier to machine. In fact, they are usually more time-consuming because their mold and tools are technically inferior to modern designs and, therefore, a great deal more manual work is required.

In the medium term, Märklin plans to replace its four-axis FZ 08 W with a five-axis machine. This modernization will increase cost-effectiveness because complete machining will lower the costs for equipment and set-up and also reduce the potential for errors. »Our experience with the five-axis FZ 12 has shown us that this is the right way to go,« says Gaißert. »It would mean that we'd no longer be working with a conventional workpiece changer but instead undertaking complete machining with the five-axis machine. This would also increase flexibility in production.« Each new model brings one-time costs for molds, equipment and tools and you therefore need to find where you can make savings in the process. For smaller batch sizes, complete machining is clearly superior to the workpiece changer setting. Should Märklin ultimately decide to invest in this replacement machine, the machining center will almost certainly be purchased from CHIRON once again.

For more information: www.märklin.de