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Design for Manufacturability

To make complex shapes in 3D often requires a 5-spindle machine. That means that the spindle with the milling head can not only move in the X, Y- and Z-axis, but can also tilt in two additional axes. This increases flexibility and one can define more advanced milling paths, which follow complex curves in three dimensions. However, defining complex paths is something that is difficult to do manually because normal interpolations between two points are no longer enough. Moreover, as the complexity increases, it also becomes more difficult to take all limiting conditions into account, and the risk of collisions or other errors increase. TopSolid 7’s sophisticated CAM solution addresses both challenges because the conversion of a design in a NC program for the machine takes place automatically, considering the cababilities and limitations of that specific machine. Because the feasibility of each design can be verified by TopSolid, the designer’s freedom increases. With a high-performance CAM system, one needs, at least in theory, less machine experience, because a lot of knowledge about tooling has been integrated in the software.

A convinced CAD/CAM user is Ben Van Hool, founder of the company Zeydon in Arendonk. The company started at the end of 2004 with designing and building a series of luxurious yachts.

Integrated CAD/CAM

Ben Van Hool is a grandson of the well-known bus builder Van Hool. When founding the company Zeydon, there was an additional motive which would play a crucial role: the company wanted to excel in technology, in working with advanced means and tools from the outset. It is often said in Holland that anyone who wants to produce in our country has to specialize in high-quality products, and this reasoning was followed in the case of Zeydon. The 18-meter-long yacht combines luxury and sport and is full of high-quality materials and technologies. Also, the boat design is of the highest quality. The boat was designed in cooperation with the company Designworks USA, a subsidiary company of BMW. This cooperation may be seen from the boat design, because the typical shapes of cars can also be recognized in the hull of the boat. Yet the design is functional to start with, because the outside shape determines also how the ship looks at the inside.

They selected TopSolid as their CAD/CAM solution – a package with which one may design 3D objects and surfaces. In addition to supplying the CAD/CAM package 3D Ultra Surfaces, a TopSolid reseller in Belgium, took care of a post-processor which was specifically written for Zeydon’s Thermwood machine. The reseller also provided a 3D model of the machine, to be able to do a simulation in the software showing the way the production will elapse on the machine. This is an efficient way to check in advance that no collisions or other errors will occur.

All Parts Start at the Processing Center

The Thermwood machine is a 5-spindle processing center with a processing surface of 1.5 by 3 meters, with a Z-axis of 1 meter. The machine plays a crucial role in the company, because all shapes of the boat are Thermwoodbrought to life with it. The machine was used to produce the first scale models in the design phase. Also, the model that was used in the tank test, to test the hydro-dynamical behavior of the boat, comes from the machine. But it also serves to make the molds with which the hull, the deck and numerous other parts of the boat are produced. These parts are made of a composite material from fiber glass, epoxy and foam, with here and there reinforcements from carbon fiber, which is shaped by vacuum injection. This means that the material is applied to the mold in dry form. After this the material is covered with foil and a vacuum is created at which resin in injected. The advantage of this technology is a big flexibility in creating shapes and weight saving, because the portion of fiber in the final material may amount to 60 percent, while this is limited to 40 percent with hard laminating. Hard laminating is applied with hatches and the like, where one plasters a shape onto a mold, and places it on the processing center afterwards, to get the desired shape with high accuracy.

The molds for the hull and deck have been made at the processing center in pieces and joined together afterwards. The machine first makes a positive shape, on which the actual mold is made. Besides that, there are 60 additional molds for hatches and interior parts. Metal parts are outsourced but are also made in accordance with designs from Zeydon. The CAD/CAM package offers also advantages here, because one can do the preliminary work of the supplier by oneself and thus have maximum control over the quality of the final result. With this the design is crucial because it is one of the points at which the luxurious yacht may distinguish itself on the market. The hydro-dynamic part of the boat was designed by a ship architect, but all parts above the water line and the interior are decisive for the style and prestige of the boat. The flexible way in which design and production have been integrated means that one can go very far in terms of design.

One can develop elegant solutions for every detail, like the connections for fuel and fresh water, at which these elements are integrated into hatches or sinkings. Because of the CAM package and the 5-spindle milling machine, these elements are included in the molds almost automatically. The machine operator shall only put on a block and press on start.

The TopSolid allow you to enter all production parameters in the design phase, so that the processing into a NC program is carried out fast and efficiently.

In Production After Just a Few Weeks 

The value of working with CAD/CAM can clearly be seen by the fact that Ben Van Hool did not have any experience with machining techniques when he set up his company. He saw the machine, which is a wood working machine– many shapes for the molds are made in MDF – at an exhibition in Paris. Within a few weeks after delivery the first shapes were produced on the machine. For that one needs a good post processor, written for this specific machine. The CAM package calculates the necessary ISO curves based on a design. It is the post processor which converts these into an NC code for the machine, considering the precise possibilities and limitations of the machine. Since the company is the first Belgian user of this American machine, the choice was made to have their own post processor developed by 3D Ultra Surfaces. Then it was quite simple to convert designs from the drawing packages to the machine. Also, specific tasks from the machining technology, like tool management, elapse quite smoothly with this software. For 5 spindle tooling mostly, round cutters are used. When these have been sharpened and the diameter is not exactly in accordance with the original, it suffices to enter the new dimensions into the software and run the CAM program again. Then a new NC program is generated, with new milling paths, adjusted to the “new” tool. This way the link between design and result is always maintained, also under changing circumstances. A next task for the software is managing the bill of material (BOM), so that one can also import the relevant data from all bought parts and may have a complete overview in the software of all components and the relevant parameters.