WorkNC CADCAM software has made it possible for German boat builder and composite mold manufacturer Knierim Yachtbau GmbH and its subsidiary, Knierim Tooling GmbH, to machine structures up to 30m long, in-house. Located on the Knierim dockyard on the Kiel Canal, its facility covers 20,000 m2 and has been building luxury boats and racing yachts for over 40 years. Gunnar Knierim became the second generation in his family to run the boatyard in 2000, and was joined by Steffen Müller, entrepreneur and expert in boat building, in 2002. Both men know how to maximize hull performance, being part of the winning German team for the 1993 Admirals Cup.
According to Steffen Müller, experience, advanced plastic materials, and a precise hull mold are essential elements for success in the high technology yachts it builds. To achieve this, the company uses a multilayer construction of glass or carbon fiber composites. "To build the mold we start with a substructure in balsa wood or polystyrene; we then apply a fiber-reinforced epoxy resin, before finally machining to the finished shape. Previously we subcontracted the machining phase, which resulted in extra cost and time delays. To overcome these limitations we invested in a 5-axis CMS portal machining center, capable of cutting parts up to 32m long, in 2004".
As well as producing hull molds for its own yachts, Knierim Tooling now produces molds for deck furniture, radar masts and wind turbine blades, amply justifying its investment in machinery. Initially, lack of in house experience in CNC machining led the company to work with an external partner to run the CMS machine. However, this cooperation soon ran into problems so it decided to invest in a CAD/CAM system so that it could carry out the programming itself.
Steffen Müller explains, "We get CAD data for the products we manufacture, so we wanted software which would allow us to build the appropriate substructure and mold, and machine it, all within one system." WorkNC was recommended to them as highly reliable and trouble free, and in the demonstration Sescoi generated a boat deck mold to provide a realistic example of the software's capabilities. In particular, Sescoi showed how the software could cope with large volumes of CAD data, typical of Knierim Tooling's products, and WorkNC's methodology for collision avoidance. Steffen Müller adds, "WorkNC looked ideal for our business, its ability to easily create reliable programs was the deciding factor for the one-off parts we make." He continued, "Although we had no experience in programming, we were able to generate safe and reliable cutterpaths after just a few hours training. We even created 5-axis toolpaths for some of our complex components."
Knierim Tooling has now invested in two more CMS machines, one 34m long and the second 6m long, for smaller parts, together with an extra WorkNC license. Lars Berner manages WorkNC and design and build projects within the company. "WorkNC provides us with a complete solution from CAD data manipulation to machining and lay-up." He describes the process for manufacturing a mold for a wind turbine blade. These can be up to 70m long. "From the imported CAD data we divide the blade into 30m segments and extract the geometry for the substructure, enabling us to machine the mold borders and the steel and wood ribbed supporting framework. Plywood is then added to support the first layer of laminate, followed by a layer of balsa wood which is machined to the undersize net shape of the blade. A second layer of laminate is added and fused to the first to produce a vacuum sealed plug. Fiber reinforced epoxy resin is then extruded onto the plug using the CMS machine. Once it has hardened, the plug is rough and finish machined to a tolerance of 0.1 mm and finally, hand finished ready to produce the mold. We program all the machining and resin extrusion in WorkNC using 5-axis toolpaths. These are just as easy as 3-axis paths to create, enabling us to produce the CNC programs with virtually one click."
Knierim Tooling can now produce the program for a wind turbine blade in just a few hours. Lars Berner says, "We use a large proportion of the CAD and CAM functions available in WorkNC to manipulate the design data and machine both holes and complex elements of the job. I have never known a software package that is as easy to use, and which gives us safe, collision free toolpaths as quickly as WorkNC."
WorkNC was used by Knierim to produce the hull and deck molds for the "PlanetSolar catamaran", which is powered exclusively by 536 m2 of solar panels. The goal of the PlanetSolar team is to be the first to circumnavigate the globe in a solar powered boat, and to demonstrate the potential for renewable energies. PlanetSolar left Monaco at the end of September 2010, and its progress can be followed online - www.planetsolar.org. Steffen Müller is proud that Knierim could contribute to the project, "We were involved in the development to help the team meet the requirements for a light and efficient boat structure, yet take into account the floor space required for the photovoltaic panels and the weight of the battery packs."
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