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Intelligent solutions for increasing productivity Print E-mail
Written by Arjun   
Tuesday, 16 October 2007

Final technical report on the EMO Hannover 2007

Introduction
The economic upturn in the recent past has been given a further boost thanks to the performance and innovation capability of the German machine tool construction industry. This has been reflected in full order books for component, machine tool and software manufacturers. Growing demands from customers have led to the increased requirement for more efficient machine tools and the latest manufacturing methods and technologies. In the following, it will be illustrated in an exemplary fashion just how this was reflected for various sectors at the EMO Hannover 2007.

Machine tools and tools have stood out on account of their high degree of development and with particular reference to high-performance, high-speed and dry machining. An increasing number of machine tool and component manufacturers are considering operating in a manner that conserves resources and also relates costs to the life cycle of their products (TCO - Total Cost of Ownership) as early as at the construction stage.

The requirement for software products is likewise increasing and these will enable manufacturing processes to be designed and verified in optimised form. This way, the hourly-rate for machines will be drastically reduced and collisions will be practically excluded. Even smaller companies will be able to employ these solutions in a productive manner.

Machining centres
The trend in past years towards the integration of various manufacturing technologies into fewer and fewer machines continued unmistakably in the envisaged machining centres. The productivity of the anticipated new developments was largely able to be increased to a considerable extent.

With lowering of production costs in mind and that above all in respect of Europe's industries, even already well-known solutions for deployment in manufacturing have been refined. For example, a major manufacturer of machining centres revealed improvements to a manufacturing process as a result of integrating handling robots for the flexible fitting out of machining centres.

Integrated manufacturing technologies are being complemented by higher and higher degrees of automation. For example, with the aid of powerful interfaces in machine's control systems process-integrated metering has become possible. This offers several advantages. For one thing, products can be automatically checked for their correct position before machining and the NC code can be automatically adjusted accordingly. However, for many products a high-precision measuring represents overkill; process-integrated measurement on the other hand is quite sufficient for checking purposes. In addition, error-prone re-chucking procedures can be cut down.

A pivotal topic, particularly in machining centres for all-purpose use, is the reduction of non-productive time. Since these machine tools were conceived for milling the most varied of products, a low hourly rate per machine can often not be guaranteed by expensive and optimised process design. Non-productive time typically involves feed motions, tool change times or loading times that can take up a significant proportion of machining time. Another manufacturer of machining centres, known for its low non-productive times, conceived a new compact high-performance centre that achieves a tool change cycle time of merely 1.7 seconds.

The low tool change times are achieved by means of a cage changer with a tool-holding feature. A 180° turn of the pallet requires a mere 1.9 seconds; powerful drives permit a fast rate of up to 75 m/min. In order that the rapid positioning movements of individual components can be undertaken without sacrificing accuracy, the machine's structure was designed with the aid of FEM simulations. This permits processes that are sturdy, vibration deadening and thermally stable.

Drilling, milling and turning machines
Trends towards automation and complete machining at milling machining centres are in terms of turning machines indeed comparable; nevertheless, in terms of technology they are implemented quite differently. Whilst drilling and milling machines generally employ only one spindle, turning machines are developed to use several driven spindles. The productivity of these multi-spindle automatic lathes achieves four times that for single-spindle automatic lathes.

At the EMO Hannover 2007, a specialist for multi-spindle machines revealed his new development with its 50 movable shafts. Using this, even demanding contour passes can be machined in the shortest possible time. However, in order to be actually able to use the time and productivity, a production engineer has to coordinate the great number of shafts when designing production-optimised processes. Here, a computer-supported manufacturing design is an obligatory prerequisite. For this, the company's developers have suitable software available for production planning. This development will increase in years to come: Software support during more and more complex developments in machining planning is now mainly employed for avoiding collisions. In the future and due to the constantly growing demands with regard to automation, machining integration, quality and economic viability, software tools will be required that will support the planning and machining process in a machine tool environment and only then enable an economically-viable operation.

As a consequence of increasing raw material costs, exhibitors at the EMO Hannover 2007 increasingly presented components or even machine tools that had been specifically constructed or optimised with regard to minimum costs during their period of use in accordance with TCO (Total Cost of Ownership). Maintenance and repair costs within the machine time for a machine tool can easily exceed the acquisition price for these. The in the main higher one-off investment costs will be paid off after a short time if components are selected in a purposeful manner.

Grinders
In years past, machine tool manufacturers focussed on optimising the actual machining process, i.e. on reducing the peak times. Here though, there are no more great leaps forward in terms of development to be expected, unless there is significant progress on the part of component manufacturers. In order to minimize this dependency and achieve a competitive edge, a few machine tool manufacturers have developed methods for specifically minimizing non-productive time.

For example, a grinder manufacturer has implemented the objectives mentioned in his new CNC grinding centre. With the integration of a grinding disk changer and a pick-up loading unit in the working area, a high degree of automation was achieved, raised both productivity and repeat accuracy.

A particularly efficient solution for reducing non-productive time was introduced by a well-known grinding technology company at the EMO Hannover 2007. Nozzle elements for injection pumps, used by the motor vehicle manufacturers, are being produced on their new grinding machine. The machine has been so constructed that the required cooling jet does not just fulfil its actual function but is also used for transporting the workpieces. In this way, the time taken for changing workpieces was able to be reduced by over 50 per cent to 0.9 seconds. Since the grinding process for these nozzle elements only takes a few seconds, by means of this interesting solution, the whole machining process duration was considerably reduced.

Metal forming machines and sheet metal machining centres
For metal forming machines and sheet metal machining centres too, a trend towards shortening non-productive time in manufacturing was revealed at this year's EMO Hannover 2007. Technical challenges arising in the course of this were solved by exhibitors in very different ways. A further and very important topic for manufacturers and users of metal forming machines and sheet metal machining centres is the reduction of manufacturing costs. In order to meet both requirements, manufacturers showed the results of their optimisation attempts and of their machines that had been improved in terms of construction details.

In sheet metal machining, the requirement for laser welding equipment is increasing, since particularly for increasingly employed tailored blanks and tailored profile sections it is accuracy that is of prime interest to users. In previous years, great progress had been made here and these tasks had in the meantime been converted into standard procedures in the machining units. In order now to reduce the costs for laser machining, machining centres will now become more compact and flexible. Over and above this, they will be offered with integrated automation, e.g. a directly linked loading and unloading unit. This way, a hitherto employed pallet changer will become superfluous. This will reduce the footprint, which in turn will be able to be used to best advantage for tasks to be carried out.

The operating speed for the latest laser machining devices is limited by the mass of the workpiece to be moved. Here, the so-called flying optic (laser head) is the optimisation device, which is moved using highly dynamic motion sequences at speeds of up to 200 metres/min and acceleration of up to 20 m/s2. In order to achieve this mass reduction by lighter and more stable structures, various types of lightweight construction are employed in these machines.

In forging work, developments for applying very high pressure forces were exhibited. By means of these, near net shape forgings are made, such as aluminium wheel rims for cars and, using fewer process stages, finished parts or components are manufactured for onward transmission and further treatment.

The trend towards automation is also a hot topic in forging. Since automation is important for the forging process in terms of cost reduction, positioning and therefore component accuracy, plus increasing of cycle times, a fully automatic drop forging system was presented. Two robots hold the workpiece to be formed during the whole of the two-stage process. The innovation consists of a claw-feed system on the manipulators that is suitable for rough forging work, absorbs the robot's acceleration forces, releases specific "hanging" components and guarantees safe and precise positioning.

Cold massive forming was likewise exhibited at the trade fair and focussed on shorter processing times. This way, high-tensile materials can be rolled, using optimised thread rolling machines, economically and with maximum precision, even for minimum runs. Along with thread making, gear cogs, worm gears and other profile sections are also cold-rolled.

At the EMO Hannover 2007, a machine concept was presented, with which, for example, complete gear cogs can be completed in a mere 46 seconds.

Gear cutting machines
Manufacturers of gear cutting machines have to optimise production processes just like those for other machine tools, as well as designing them to be more efficient and economical.

A solution to this that offered several advantages was presented at the trade fair. The vertical high-performance hob-milling machine processes workpieces dry. The advantage of vertical processing consists of the fact that components can be formed more quickly due to chips falling downwards and being removed immediately from the working area by means of a magnetic belt and that the high potential for extremely powerful dry cutting tools can be further exploited. Accordingly, there no longer has to be so much emphasis on the disposal of chips any more, as there was for horizontal versions. A further advantage is dry machining, which guarantees homogeneous and direct utilization of waste material generated, by means of which an active contribution is made to disposal and direct recycling.

Sawing and cutting-off machines
Classic cutting-off methods, such as plasma cutting and sawing, were strongly represented in detailed form at the EMO Hannover 2007. Here too, high machining speeds and a raising of achievable precision were the centre of attention.

For manufacturers of plasma cutting installations, cost reduction is a significant sales argument in the competition with laser cutting equipment. Inasmuch as the demand for accurate cutting is somewhat less, it is the first choice. At the EMO Hannover 2007, detailed solutions were also revealed, by means of which sheet metal of up to 35 mm thickness can be cut. A machine was presented that has a plasma cutting head with no rotational limit and that automatically regulates the angle of inclination for its cutting head. By means of this, preset contours can be cut very quickly and with little travel of the whole bogie. In addition, these installations nowadays offer several machining functions, such as a 6-position drilling and thread-cutting head with an automatic tool changing system. This way, the total machining time is reduced.

For saws, development is likewise heading towards raising their machining speeds and availability. However, here the topic of noise emission has to be taken up. A the EMO Hannover 2007, a fully clad band saw was presented for the first time, which, along with enclosed drives for reducing noise pollution at the workplace, also has improved operability and more simplified accessibility. With its modern CNC control system, plus integrated servo feeding of the saw blade, process stability for this classic cutting-off machine can once again be increased. The shortening of machining time is achieved by coupling of drilling units and partial integration of alignment technology.

The trend towards increasing effectiveness and productivity was taken up at the EMO by an optimised combined laser / punching machine. It deals with machining tasks that are becoming more complex. Contours such as round or right-angled holes are created using a lift through the punching unit and likewise for threads or other deformations. If the cuts for inner and/or outer contours need to be carried out in a more sophisticated manner, they can be laser-cut with smooth edges and no burrs.

Laser and water jet cutting methods are in the meantime covering more and more cutting-off applications. If highly accurate and neat cuts are required and possibly the cutting of differing materials (plastics, aluminium, steel, etc.), water jet cutting installations are employed. Here an absolutely new departure was presented, which, by means of a water pressure of up to 6,000 bars - depending on the material to be cut, can achieve big material thicknesses or faster cutting speeds. Once again, this makes a contribution to reducing production times.

Precision Tools
The employment of novel and difficult to machine materials, such as titanium and its alloys, in the aerospace industry, plus the machining of composite materials in the automotive industry spur on development in tool making and confront industry with new challenges. Precision tool manufacturers presented at the EMO Hannover 2007 new products and machining methods for these. In addition, new generations of tools for existing products were presented, which with regard to process stability and wear resistance had in part been considerably improved.

The increasing demand for ceramic cutting materials can be seen as a fundamental trend in precision tool manufacturing. The manufacturing process for these tools that has only been employed for a few years has been newly conceived on the basis of current research findings. By using these, cutting templates can be manufactured, the productive employment of which was previously not possible. This material can only maximize tools' serviceable life in combination with the best possible cutting template.

In tool making too, the requirement for additional services related to core products is reflected in different service bids and increasing turnover in this sector. In accordance with market requirements, precision tool manufacturers introduced modular-constructed service packages at the EMO Hannover 2007. In the past it could be observed that the main focus of bidding had shifted away from individual tools right up to an overall concept. By means of new services, customers can benefit from professional process knowledge in addition to the knowledge contained in the tools. Whether choosing tools, assembling accessories, designing parameters or processes and repair work: services on offer can be put together in a modular and customer-specific form to create service packages.

Automation, components and accessories
In control system technology, innovations are undertaken less at the user interface but much more in the substructure. For example, a well-known manufacturer of control and metering systems considered how his components would in future communicate exclusively in digital form via Ethernet and in real time. This raised the speed of information exchange and was to contribute to the integration of new components into the control system.

At the front end too, impressive progress can be seen. Control system manufacturers themselves, as well as machine tool manufacturers, introduced ready-for-use and productive solutions for virtual control systems, which thus far had only been exhibited as development versions. In connection with the kinematic model for a machine tool, new areas of deployment can be exploited. For example, exact images of real machine control systems and including an operator's panel can be employed on the screen of a standard PC for training purposes. In this manner, all procedural movements can be tested at no risk and the behaviour of the machine and its kinematics can be easily learned.

Component manufacturers are being motivated by their customers' requirements to tackle trends such as energy saving in their workplaces. At the EMO Hannover 2007, an epicyclical gearbox was included for machine tools, by means of which it is possible to decouple the planet-wheel stage in its 1:1 ratio. As a result, in direct drive the heat loss can be reduced and the cooling expense as well.

Other matters
Quality assurance was represented at the EMO Hannover 2007 by various innovations. To achieve higher metering performance in the shortest possible time by means of more compact metering systems was the main focus for exhibitors in this specialised field. For example, a very user-friendly designed gear-tooth measuring system shortens the measuring times by having an automated sensor changer carry out differing metering tasks on one component and this very quickly.

A further highlight of this year's trade fair was a 5-axis measuring system that was pre-announced at the last EMO in 2005 and is now ready for mass production. It can measure so-called blisks (bladed disks) from aircraft engines in about 4.5 minutes. That equates to a shortening of the measurement time for previous systems by 922 per cent or 41.5 minutes.

The world's smallest switching measurement system with radio transmission proved that even in a difficult measuring environment cable-free working is possible by means of a programmable remote control. This system will work for several hours independently and can boast a transmission range of some 15 metres. In order to be employed internationally, the radio measuring system is designed to use a frequency of 2.4 ghz.

A completely novel measuring system, presented at this year's EMO, fulfils the wish for even more precise and more regular quality control of hitherto non-ascertainable very fine tubes and wires (e.g. drills for dental practices).

Customer desires for different machining technologies within one machine or for covering a big range of workpiece geometries are important topics in specialised mechanical engineering. For example, here a so-called round phased machine tool for turning and finishing work can be a real alternative to CNC multiple spindle machines. This round phased machine can work rod thicknesses of up to 80 mm (100 mm option available). Apart from this, the installation can also machine the reverse of the workpiece in very little time.

One manufacturer of eroding machines is very proud of his particularly precise results in tool and mould construction. In order to satisfy the highest demands, not just the machines but also their machine control systems were developed in-house. To date, a highlight in this class was a hitherto unique cavity-sinking EDM machine. It combines features that in the world of mould making hitherto counted as a contradiction in terms; it provides efficiency and is accurate to a few thousandths of a millimetre whilst maintaining maximum repetitive accuracy; for this it represents a traverse path of 700 x 500 x 500 mm. By using this, very big workpieces can be machined. The multifunctional employment of this machine for small and big parts covers a wide usage spectrum for electrodes and workpieces.

The trends and new developments in past years with regard to integrative manufacturing simulation and virtual production planning have ripened into fully operational products. The CAM products and NC simulations solutions presented at the EMO Hannover 2007 will help the manufacturing planner to improve and verify the manufacturing process with regard to selected criteria like manufacturing time or surface quality. In addition, well thought out and intelligent manufacturing strategies for typical form elements will be developed and implemented into new software versions. Planning and manufacturing are often not the responsibility of one and the same person. All the more so, present-day processes require checking to see whether planned tool routes can be carried out free from collisions. It can be carried out by the manufacturing planner with the aid of NC simulation products in a virtual environment. The price for this solution will be rapidly recouped by the lower hourly rate for machines, as well as by the avoidance of collisions. Technical performance data for machines and tools can likewise be included in planning and thus, for example, the in-feed will be adapted to erosion conditions. The until now manual and imprecise delivery by means of a hand wheel and the machine's operator belongs to the past for automated and reproducible processes.

Chinese exhibitors
For the first time, the People's Republic of China with its 86 exhibitors ranks amongst the top five exhibiting nations at the EMO Hannover. Its automotive exhibitors are the biggest customers. In future, the aeronautical industry will be increasing in interest. In 2006, a total of some 80,000 CNC machine tools were produced and sold. (EMO daily 4 MM dated 20 September 2007).

Summary
Past years' trends have continued since the EMO Hannover 2005. During this time many systems and particularly software products have been further developed from the experimental stage to productive deployment to customers. The inclusion of costs during the period of usage in the investment decision and the growing environmental consciousness have caused manufacturers of machine tools and tools to be faced with new challenges. In this context, exhibitors at the EMO Hannover 2007 presented increased suggestions for solutions. The increasing of productivity and the flexibility of new machines remain the driving force for German and European economic growth.

Authors:
Dipl.-Ing. Patryk Hoppe, Institute for Manufacturing Technology and Machine Tools, Leibniz University, Hannover
Dipl.-Ing. Marcus Kamp, Institute for Metal-Forming and Metal-Forming Machines, Leibniz University, Hannover
 
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