In Focus – Current Topics and Background Information
HELLER CBC (CylinderBoreCoating)
Pole position in innovation with surfaces smooth as glass
Already in 2006, Mercedes-Benz began using the newly developed twin-wire arc spraying technology for the 6.3L V8 AMG engines. In 2011, the process was integrated into series production of the Mercedes V6 engines. Then in 2012, the companies Gebr. Heller Maschinenfabrik GmbH in Nürtingen and Daimler AG decided to industrialise the technology and all steps of the process. Meanwhile, the process Daimler named NANOSLIDE® is not only used in series manufacturing but has also found its way into the F1 champion's extremely successful car, the Mercedes-Benz PU 106A Hybrid.
When evaluating the efficiency of a vehicle, drivers are paying closer attention to fuel consumption now. For a number of reasons, CO2 emissions are becoming more and more important as a factor, since they also form the basis for emission limits and subsidy programmes. As a result, the automotive industry is focusing on weight reduction measures and downsizing. Today, the efficiency of a motor vehicle can be increased in various ways.
The quality of the cylinder surfaces, for example, has a major influence on the consumption of combustion engines. After all, surface hardness, roughness and texture are not only the determining factors for fuel consumption but also the performance characteristics of the engine. Up to 25 percent of fuel energy in the part-load operational range is required to overcome the engine's internal friction.
To reduce frictional losses on cylinder surfaces, Daimler AG developed an innovative thermal spraying technology that received several national and international awards, enabling the coating of cylinder bores of aluminium lightweight crank-cases for car engines using twin-arc spraying. To generate the NANOSLIDE® surface, the molten material is sprayed onto the cylinder wall by means of a gas flow and deposited as a layered, ultrafine to nano-crystalline coating. Subsequently, the NANOSLIDE® coating is smoothed to an extremely high degree in a specially developed mirror honing process, which gives a thickness of only 0.1 to 0.15 millimetres and a surface that is almost like a mirror. The honing process also exposes pores in the material, which are able to retain oil and help optimise lubrication of the piston assembly. All in all, the process enables to reduce mechanical friction loss by up to 50 percent whilst providing extremely high wear resistance.
Although the coating process is considered extremely cost-effective and technologically superior, quality-determining parameters such as current, voltage, wire feed and process gas flow need to be carefully adjusted and matched to the coating procedure.
Working together on the industrialisation of the process
In 2012, Gebr. Heller Maschinenfabrik GmbH in Nürtingen and Daimler AG established a successful cooperation for the further industrialisation of the process. The goal for HELLER was to industrialise all steps of the process and to develop it into a dependable application for the global markets under the name of HELLER CBC (CylinderBoreCoating) based on a global network of systems and services for the complete process chain of crankcase manufacturing.
In the same year, HELLER gave the go-ahead with the official opening of the HELLER CBC TechnologyCenter at the company's headquarters in Nürtingen during the Automotive Dialog 2012 and started with the coating of customer-specific prototypes. Initially, the process was used for exclusive small-batch series. With the entry into mid-sized batch production, a viable alternative to existing liner technology was born. The production rules and criteria for the automotive industry had been fulfilled and thus the preconditions for high-volume production.
To implement this next step, market-oriented solutions in terms of system supply and services were required. In 2013, Mercedes-Benz introduced NANOSLIDE® to the US market for the turbocharged V6 spark-ignition engines in the context of the BlueEFFICIENCY technologies. NANOSLIDE® helps to reduce engine weight by several kilogrammes and reduces fuel consumption by up to three percent by eliminating the need for thick grey cast iron liners used in the predecessor engine.
Meanwhile the technology is also used for the latest generation of 4-cylinder and 8-cylinder engines of Mercedes-AMG. In 2013, HELLER commissioned enhanced manufacturing systems and integrated the process, including the process steps for pre- and finish-machining, into the process chain of engine production, whilst ensuring the necessary high degree of process quality and dependability.
Awards in the most important categories
In 2013, HELLER and Daimler received the German Innovation Award for Climate and Environment in the category “Process Innovations for Climate Protection”. In 2014, NANOSLIDE® received an award from US trade journal R&D Magazine, the so-called Oscar of Invention, naming it one of the most important high-tech products. Today, the two partners see this as another award for a technology that has also had a share in winning the first F1 Constructor's Championship and the Drivers' Championship in 2014. NANOSLIDE® also realises its full potential in the V6 turbo engine of the current world champion's car, the Mercedes-Benz PU 106A Hybrid.
The NANOSLIDE® process
By means of twin-wire arc spraying technology the cylinder surfaces in the aluminium crankcases are coated with an extremely thin layer based on an iron-carbon alloy. The result is a very wear-resistant nano to ultrafine material structure with micropores, ensuring lubrication during operation. As a result, heavy grey cast iron liners in the aluminium crankcases that can be several millimetres thick are eliminated. The result is a surface as smooth as glass, providing up to 50 percent less friction between piston, piston rings and cylinder surface and a weight reduction of several kilogrammes. Meanwhile, the process incorporates numerous inventions and ideas and is protected by more than 90 patent families and more than 40 patents.
SMARTER PRODUCTION – Multitasking for all needs
Shortening the process chain with the ›smart technology mix‹ from HELLER can create enormous application-specific potential. In this interview, Managing Director Christian Pfleiderer talks about maximising customer value through optimal ›Lifetime Productivity‹ of HELLER machines.
The HELLER machine range comprises 4-axis and 5-axis machining centres, as well as mill/turning centres. How do multitasking machines provide the various technologies for complete machining?
CP: All the standard models in the HELLER machine range are already equipped for numerous standard technologies and processes. And the machines are designed to allow other technologies to be integrated without major additional effort. HELLER divides the technologies into two categories.
First the primary technologies, which are within the mainstream. All models enable milling, boring and tapping and, with the C series mill/turning centres, also turning. Then there are non-mainstream technologies, such as reaming, deep-hole drilling, facing and interpolation turning, which are likewise part of the standard module, as well as special technologies, including shaping, gear cutting, honing and grinding, which are tailored specifically to the customer’s needs. As a preferred solution provider, HELLER wants to offer the optimal process every time. This is based on the recognised strengths of HELLER’s universal machines - productivity, stability, reliability, availability and precision.
If the customer or the application requires additional technologies to be integrated, HELLER can achieve this, following a detailed examination of technical feasibility, flexibly, swiftly and without any overengineering - even at a later time. The focus is always on per-piece costs, machining quality and process reliability.
Which aspects do customers consider important for the integration of other processes, and what is the usual procedure at HELLER for communicating with customers?
CP: Basically, there are two different scenarios: first, the customer already has one or more HELLER products and is confronted with various requirements. This can happen as part of the continuous improvement process, where process chains and throughput times have to be shortened. Or the customer has received a major order, the per-piece costs of which could be reduced by integrating another process. Or it can be about replacing machines with other technologies, and the idea of cost-effectively integrating processes on the HELLER machine instead of buying a new one. These are just a few of the situations we encounter.
Application engineering then reviews the viability of retrospective process integration, allowing for the fact that the customer is meant to be familiar with this technology already. Secondly, the customer presents us with a specific application, where integration of a non-mainstream technology appears to make sense in terms of both quality and per-piece costs.
Whichever scenario, HELLER has a wealth of application engineering experience for providing the customer with an optimal machine and process solution, also in the form of a multitasking concept. HELLER deliberately speaks of a ›smart technology mix‹. For a complete machining operation, the customer pays only for what is actually required. As a result, a very efficient and direct return on the additional investment can be achieved.
In addition to pure machine implementation, which services does HELLER offer for multitasking?
CP: Generally speaking: when a HELLER machine is shipped to the customer, the control software required for efficient programming and production is integrated onboard. In some cases, this includes cycles developed by HELLER for grinding complex contours such as control curves, for example. With the C series mill/turning centres, HELLER has implemented not only all cycles for turning, but also a proprietary balancing cycle for reliable workpiece clamping into the control’s user interface. Then there is the comprehensive range of aftersales services which permits universal machines to be retrofitted at a later time. The best example here is the HELLER out-facing head system, which allows the customer to apply more efficient machining strategies for producing complex contours.
How important is the ability to retrofit technologies with respect to cost efficiency and the acceptance of multitasking as a means for complete machining?
CP: This aspect is very important for the customer as part of an investment decision made for a particular situation and no less important for HELLER in terms of a certain technological uniqueness. HELLER purposely makes the ›Lifetime Productivity‹ of its machines a subject of discussion.
For two reasons: many customers certify HELLER machines as providing longer productivity than the competition. This requires in turn that HELLER remains a partner to its customers over the machine’s entire service life, so that the machine can be modified to suit changed framework conditions. The numerous optimisation and upgrade packages available constitute an essential element of the HELLER philosophy.
HELLER expands 5-axis C series
Milling and turning in a single setup with workpiece weights of up to 4,000kg is anything but standard. For performing multitasking processes on large workpieces HELLER has now expanded its 5-axis C series, integrating HELLER DNA such as high chip removal rate and reliability.
HELLER takes a methodical approach to ambitious development targets, implementing them based on its wealth of experience. This also applies when entering larger workpiece dimensions with combined milling and turning in a single setup. The goal was to design C series machining centres providing two fully fledged manufacturing processes and delivering new dimensions of performance for reliable multitasking application 24 hours per day and 7 days a week.
The results obtained are unique:
- Model CP 8000, providing a work envelope of 1,250x1,200x1,400mm, enables turning of workpiece diameters up to 1,250mm with pallet loads up to 2,000kg.
- The new model CP 10000 with a work area of 1,600x1,400x1,600mm even enables pallet loads of 4,000kg and workpiece diameters of 1,400mm.
- The extremely high power and torque provided by the swivel head unit in combination with the rotary torque table with up to 5,000Nm torque is just as impressive.
Optimal integration of Combined Processing
The unique qualities are based on two elementary development aspects:
- HELLER spares no effort to gear machine technology towards process stability. After all, the integrated power and torque must allow to produce chips at high process dependability.
- Additionally HELLER is one of only a few manufacturers providing the expertise to perform state-of-the-art structural dynamic testing and simulations in the early stages of development in order to establish a machine's stability in milling or turning ahead of prototyping.
The customer will benefit from the direct added value provided by a HELLER mill-turning centre of this size, enabling complete machining of his workpieces on a single machine and eliminating the previous need for re-clamping or use of another machine type.
Machining in a single setup enabled by the 5-axis kinematics with turning capability on top minimise re-clamping errors and increase component quality, resulting in reduced handling requirements and lower per-piece costs.
HELLER is offering 5-axis machining in combination with horizontal, vertical and tilted turning for increasingly smaller batch sizes and a wide variety of parts on machines with or without pallet changer.
HELLER focal topics
- Complete machining: Machine tools are required to produce components at competitive per-piece costs. Machines for complete machining make a signicant contribution towards reducing setting times, cycle times and the effort required for part handling and measuring.These tools also increase the achievable levels of accuracy.
- Multi-tasking: HELLER is following the trend towards hybrid machine design in a cost-effective manner based on flexible standard products and tried and proven modules. HELLER sees multi-tasking as a combination between standard machine and process and know-how of control technology. One example is the C series enabling to combine
turning and 5-axis milling processes.
- Automation and availability: Every customer strives to achieve maximum availability of their machines ›around the clock‹ wherever possible. This is where HELLER’s automation expertise comes in. The technical possibilities offered by HELLER range from simple pallet changers, linear or rotary pallet magazines through to flexible loading robots or the combination with rack-type systems for tools. In the case of production plants that use multiple machine tools within one process chain, the range spans from simple interlinkage by means of conveyor and gripper to flexible solutions with central workpiece handling system through to the cycled transfer line.
- Technology: Modern multi-tasking in the machine tool sector is based on technological expertise. A standard machining centre complemented by technological and process know-how becomes a powerful tool for efficient complete machining. HELLER is a comprehensive solution provider.
- Applications engineering: Increasingly smaller batch sizes, short lead times and more complex components mean that the production process has to be continuously optimised and rationalised. HELLER takes a clear stance in this respect: machining centres not only need to meet current demands, they must prove to be efficient and productive throughout their entire service life. HELLER possesses the applications engineering expertise required to combine milling with turning, grinding, punching, honing and gearing technologies.
- Visionary process design: Production challenges that can be solved only by exceeding standards call for collaboration with the customer. HELLER possesses comprehensive process and technological expertise and a broad portfolio of solutions and experience. Highly productive yet universal machining centres carrying the HELLER genes – ›productivity, stability and precision‹ – form the basis of visionary expansions. HELLER refers to this as a ›smart mix of technologies‹.