Application-oriented laser melting at LPT
Mould inserts with close-contour cooling and a hybrid build style
Schleiz, 18.10.2010: Cores, cavities and moulds require constant care and maintenance to remain fully operational and productive. Mould makers and plastics processors are increasingly opting for flexible and technically accomplished service providers. We went to LPT to find out more information and spoke to the founder and senior partner Erwin Gottschall about laser welding, laser melting and laser engraving for German mould-making and tool-making.
Erwin Gottschall founded LPT in Paderborn in 1995 to provide working resources in metal, aluminium and special materials. It very quickly became apparent that mould-makers are shirking welding, but like to make use of this as a service. In addition, Gottschall recognised the significance of laser technology at a very early stage and relied on the fact that the mould-maker generally does not wish to apply the process of generative laser melting itself. Firstly this is because the technology requires specific knowledge and secondly also because capacitively it cannot always be used in an economically viable way by the mould-makers. LPT filled this gap in the market. 12 branch offices and a technical facility for metal laser melting in Schleiz now bear testament to the level of acceptance the LPT Group enjoys within the sector. Depending on the particular LPT site, components weighing up to 5,000 kg can be processed. Over 2000 customers place their trust in the technical possibilities offered by LPT. Expertise which Erwin Gottschall justifies by offering a customer-focussed consulting service: “For certain applications, we recommend that the customer uses conventional technology if this is more efficient. If our welding technology offers advantages, then we offer them. When it comes to close-contour cooling, we familiarise the customers with the artistic possibilities that LaserCUSING offers in collaboration with Concept Laser. The aim is to offer a method which is as effective as it is economical. A sensible product then.” According to what Gottschall says, LPT differs from the competition because of the technology-independent advice and execution it is able to offer.
Strategic partnership and joined-up thinking
At our appointment, we also met Lutz Frötzschner, head of the LaserCUSING division in Schleiz. The LPT team offers comprehensive advice to customers. Erwin Gottschall brings his experience from many years spent working in plastics processing and he knows what should happen in the cavity. Lutz Frötzschner is in direct contact with the customer and he looks after all aspects of component design, construction, welding technology and LaserCUSING right through to working out the close-contour cooling. The strategic partnership with Concept Laser plays a pivotal role for the service provided at LPT.
LPT was one of the first companies back in 2004 to invest in a Concept Laser M3 linear machine for manufacturing large laser melted components and small batches. Over the course of recent years, the metal laser melting technology has made enormous development strides in terms of laser power, pace of construction and component quality. To ensure that the company could continue to remain competitive in the area of generative metal laser melting in the future, in 2010 LPT invested in an M1 cusing machine which is very much state of the art. The equipment at the technical facility in Schleiz was completed with the addition of a QM Powder module. The automatic sieving station continuously safeguards the powder quality and thus the component quality too. Lutz Frötzschner cites the motivation as being to ensure the component properties which are required in mould-making and tool-making in the areas of density and surface quality. According to him, the Schleiz site is thus ideally equipped to cater for all of its customers’ requirements.
Training efforts to provide the best solution
When it comes to boosting performance and exploiting the options available, the training measures of Concept Laser are very important for keeping LPT in good shape. In the case of complex cooling-channel designs, Concept Laser provides support with its constructive experience from its own mould-making. For instance, LPT utilises the CAD training course “Conformal Cooling” for the purpose of applying the cooling-channel design of Hofmann in Lichtenfels. Suppliers and users also maintain close contact in respect of maintenance concepts on the LaserCUSING machines. Further developments, retrofitting options and software updates complete the concept behind such a partnership.
Possibilities of hybrid technology
The formative residual geometry including the remaining cooling-channel design can be “fused” onto a prefabricated basic body, with predrilled feed and drain holes for the cooling, by means of LaserCUSING. This procedure is patented by Concept Laser. According to LPT, this mixed type of construction has already proven to be the fastest and most economical method in many cases.
Close-contour cooling concepts
According to Gottschall, a very important aspect is the principle of close-contour cooling from Concept Laser which begins 2 to 3 mm below the mould contour. There are a very wide range of forms for the cooling-channel design. The most proven and most frequently used cooling-channel variants are surface cooling and parallel cooling. Whereas close-contour cooling with one channel may be sufficient for normal parts, close-contour parallel cooling with several short cooling circuits may improve the quality and cycle element in the case of sophisticated injection-moulded parts. With parallel cooling, more coolant is delivered to the cavity or surface of the moulded part than is the case through a long cooling channel. For with a long cooling channel the cooling effect diminishes continuously as the distance increases. Furthermore, with parallel cooling each cooling loop is supplied with fresh cooling medium, which leads to optimum cooling. The result is thus dynamic and even cooling. “The use of the respective technology depends on the geometry of the component. We have to assess this on a constructive basis,” says Erwin Gottschall. He estimates that the potential for improvement here is as much as 50%. The injection process is shortened as a result and the component is thus much faster in cycle. In addition, warping in the polymer reduces as a result of these methods. The parallel and surface cooling is a patent which has been granted to Werkzeugbau Siegfried Hofmann GmbH. LPT GmbH automatically receives a licence to make use of the patent with the purchase of the LaserCUSING technology.
Editorial team: LPT got to grips with the laser at a very early stage. Many processors and mould-makers are only finding out more about the subject today. Why is this?
Gottschall: Those people who are involved with moulds, whether it be in construction or in operation, conventionally think of steel emerging from the block. The idea of constructing a part generatively does not conform to traditional thinking.
Editorial team: But there are plenty of companies offering laser technology systems. Why is this taking so long to get into people’s minds?
Gottschall: Look: The laser was a fundamental development for which applications were then sought. However, companies that offer and continue to develop lasers are not always familiar with their specific applications. For example, let us take the area of mould-based plastics processing as an established and above all competing technology. It very quickly became apparent to me that the Hofmann Group in Lichtenfels approached the issue of metal laser melting in an astonishingly practical way with its experience of mould-making.
Editorial team: What do you see as the special aspects here?
Gottschall: I think that Hofmann gears its laser technology heavily around the practical requirements which emerge. On the one hand, LaserCUSING claims to be very robust and reproducible. On the other, the aim is to deliver the desire for a quality-controlled manufacturing process. By integrating the individual QM modules in the area of powder, melt pool, laser, process gas and documentation, the workers from Lichtenfels have already made a very good start. But what particularly persuaded me were the practical training measures. And not least the application of and training in the patented close-contour surface or parallel cooling by Werkzeugbau Siegfried Hofmann. This practical relevance can effectively only arise directly in mould-making. We as a partner are very happy to be able to tap into this wealth of experience.
Editorial team: Why is a generative process in mould-making so important for you?
Gottschall: First of all, it is the speed with which the customer wishes to or has to carry out adjustments or maintenance tasks. There is hardly any slack in the system nowadays. Everything is done just-in-time – not just in plastics processing but also in mould technology. So we have to supply products incredibly quickly, which is a traditional strength of generative laser melting. The other point relates to the nature of the plastic process. With LaserCUSING, it is possible to generate close-contour cooling channels with a geometry and cavity proximity which it is not always possible to produce with conventional metal-processing techniques. The effect emerging from this is that a well-cooled part helps first of all to reduce the cycle time and secondly tends to mean better unit cost calculations.
Editorial team: Where do you see future developments taking place with your applications?
Gottschall: The market still needs to learn how to fully exhaust the possibilities which are already available today. As we practise things, the laser is a universal tool for welding, generative component construction, that is to say melting of metal powders, and engraving. In relation to the mould technology, I see one good opportunity as being the laser hardening of specific areas in the cavity in order to cope better with complex geometries produced using abrasive materials. Another opportunity would be laser-based, extensive coating in the sense of surface hardening of the cavity. This may make sense for heavily filled polymeric materials and above all high-temperature processes such as with thermosetting plastics or rubber. The hybrid build style of LaserCUSING is particularly interesting. The formative residual geometry including the remaining cooling-channel geometry can be “fused” onto a prefabricated basic body, with predrilled feed and drain holes for the cooling, by means of LaserCUSING. This hybrid build style, which has been patented by Concept Laser, is practical and economical in terms of speed and cost. Ultimately, I expect to see gradual improvements to speed, quality and quality assurance from the manufacturers. Essentially, you can also send parts by e-mail with this technology: At a point A in the world, you enter construction data for LaserCUSING, send this information via a data line to point B where the LaserCUSING machine is located and “print” out the part. Customer proximity, location independence and production-on-demand will attain a very different significance in production in the future.
Editorial team: Thank you for the interview.
Print approved – ask for copy
Caption 0 (lead picture): Injection-moulded-part-enabled design of the parallel and surface cooling in a mould insert, manufactured using the LaserCUSING process
Caption 1: An automatic sieving station from Concept Laser enables the powder quality and thus the component properties which are required in mould-making and tool-making in the areas of density and surface quality to be safeguarded.
Caption 2: Lutz Frötzschner “The more effective manufacturing of close-contour cooling – optionally using hybrid technology with LaserCUSING – can improve the productive capacity and added value delivered by the plastics processor in a sustained way.”
Caption 3: LaserCUSING with the M1 cusing
Caption 4: Flexible laser melting as a service for mould-making and tool-making: Technical facility of LPT in Schleiz with an M3 linear and an M1 cusing from Concept Laser
Caption 5: Mould insert with parallel cooling
Caption 6: Generative component with surface cooling
The LaserCUSING® process, a metal laser melting process, is used to produce metallic components which can be subjected to mechanical and thermal loading with high precision. Depending on the application, the materials used are high-grade and tool steels, aluminium or titanium alloys, nickel-based superalloys, cobalt-chromium alloys and in future precious metals such as gold and silver will also be used.
Description of the process
LaserCUSING®involves fine metallic powder being locally fused by a fibre laser. Following cooling, the material solidifies. The contour of the component is produced by directing the laser beam using a mirror deflecting unit (scanner). The component is built up layer by layer (with a layer thickness of 20 – 50 μm) by lowering the bottom of the installation space, applying more powder and fusing again. The special feature about the machines from Concept Laser is stochastic navigation of the slice segments (also referred to as “islands”) which are processed successively. The patented process ensures a significant reduction in stresses within the component. For single-part fabrication, a maximum installation space of 300 mm x 350 mm x 300 mm is available.
CONCEPT LASER GmbH is a company belonging to the Hofmann Innovation Group in Lichtenfels (Germany). Since the year 2000, the company has been regarded as a pioneer in the field of generative metal laser fusing technology. With the LaserCUSING® process, the company is involved in all different sectors of industry.
The term LaserCUSING®, made up of the letter C from CONCEPT LASER and the word FUSING (complete melting), describes the technology used: the fusion process generates components layer by layer using 3D CAD data.
The generative process allows complex component geometries to be produced without the use of any tools right through to complex structural geometries which are very difficult to produce, if they can be produced at all, using conventional techniques.
The LaserCUSING® process allows the fabrication of both mould inserts with close-contour cooling and direct components for the medical, dental, automotive and aerospace sectors. Both prototypes and mass-produced parts are manufactured.
Standard machines and customer-specific machine concepts for the LaserCUSING® of metals are on offer. Full service as an option at Concept Laser means that customers can purchase machines for their own independent LaserCUSING® application, or access services and development expertise (prototypes and small batches) directly.
The laser processing machines from Concept Laser process powder materials from high-grade and tool steels, reactive aluminium or titanium alloys, nickel-based superalloys, cobalt-chromium alloys and in future will also process precious metals such as gold and silver.
LaserCUSING® opens up new perspectives in terms of quality, reproducibility, economic viability and speed for more efficient product development in sectors such as:
– Medical and dental technology
– Aerospace industry
– Tool making
– Automotive/motor racing
– Mechanical engineering
The machines make it possible to shorten development times and reduce development costs considerably. The key benefits of LaserCUSING® include greater freedom of geometry, coupled with much greater flexibility in terms of product development. Another central advantage of the process is the opportunity to produce components without the use of tools and the obviation of the machine programming associated with this.
The high quality standards, many years of experience and references of Concept Laser are synonymous with process-reliable and cost-effective solutions which demonstrate their efficiency in everyday production. Thanks to ongoing further development, the unit costs of the generative process are constantly being reduced.
In 2008, Hofmann Innovation Group GmbH generated sales of EUR 55 million with 480 employees.