Manifolds are certainly quite complex components, especially for larger hydraulic applications. To achieve the right actuators, the right hydraulic pressure at the right time with the right speed, an extensive system of bores and valves is needed. Traditionally, manifolds including bores are produced on a CNC machine. But can it be done differently? With 3D metal printing perhaps?
By Marjolein de Wit - Blok
(Original article, in Dutch, appeared in Constructeur magazine and can be read online.)
Paro Software hosts a round table discussion
During a mini-symposium of the Vereniging Hydrauliek Platform (VPH) last summer, two presentations showed that 3D printing is also a product technique with possibilities in this area (tinyurl.com/yhpqo37f in Dutch). Whether those possibilities are sufficient for large-scale application in the short term is another story. That is why a 'round table' with Marc Paro of Paro Software, Adri Overbeeke from Hydrauvision and Job van Berkel from Mazak about the different perspectives.
Hydrauvision is a specialized company in hydraulic drive technology and was Adri Overbeeke was one of the speakers at the VPH symposium. The company was one of the participants in the European CompoLight project that ran from November 2008 to October 2011 (tinyurl.com/ygnkkmks). Among other things, the project investigated the 3D metal printing of manifolds and revealed various interesting features. That starts with the original goal of 3D printing: rapid prototyping - just as quickly produce a plastic model that can then at least be tested for functionality. With manifolds, the use of plastic limits the possibilities of putting the model at full pressure, but the correct course of the various corridors in the block can be checked.
Never say never
Yet it is not a production technique that Marc Paro, director of PARO Software, will embrace in a short time. PARO specializes in the engineering of manifolds. This starts with drawing up a hydraulic diagram that is then converted into a 3D model that forms the basis for the final CNC program. Due to the partly automatic conversion from scheme to model, the chance of errors in the final production drawing is minimized. An important advantage in view of the production time that can be several hours with a complex manifold. First-time-right production is more than desirable.
Marc Paro: "I never rule out anything. The example of Steve Ballmer is too familiar for that. The then CEO of Microsoft laughed the balls off his pants in an interview:" There is no chance that the iPhone will even get a significant market share. No chance. "Where many people felt that a phone without a physical keyboard would really not win, the current time is learning differently. So let me not be the one who calls that 3D printing will not work turn into."
Crux of the matter
But he does not think that the benefits of 3D printing are sufficiently distinctive for the production of manifolds. Certainly not when it comes to the lead time. "Designing a hydraulic diagram, converting this into a model and then a program - these are all processes that remain. Whether you make a program for your CNC machine or your 3D printer. 3D production also provides in the production itself I do not think it is time-saving, and even if that is the case, I do not think that this is significant, certainly not in view of the fact that manifolds are often produced in smaller numbers, even regularly as single pieces, so that the law of large numbers does not apply here. "
Job van Berkel, general director of Yamazaki Mazak Europe adds: "In that regard, we are currently working on parts of the total process where greater time savings can be achieved. The attention for us as a machine supplier is currently focused on post-processing. So a fast and error-free conversion of a CAM file to a final CNC program. This would allow you to reduce one of the most time-consuming parts of conventional machining, and that's the crux of the matter. "
Adri Overbeeke who was involved with the CompoLight on behalf of Hydrauvison: "The results of this research are now ten years old and therefore no longer up to date with regard to the feasible lead times. I think you can assume that printing itself is now faster. So on the basis of the research I cannot give any concrete figures, but there are other advantages that can be distilled from the research that are specifically related to the way in which a product is built up from layers. In particular, free design is a property that can bring benefits in design. "
For manifolds, a free design means that the engineer is no longer bound by the limitations of traditional machining. For example, the fact that a drill can only drill straight holes. Adri Overbeeke: "Quite the contrary. With a design for additive manufacturing you can optimally design the corridors, for example avoiding all (right) angles, which in turn contributes to an optimal flow and minimal pressure drop. There are also no openings that are unavoidable during applying drilling operations and having to seal them with caps later on, and the freeform design can prevent you from having to come up with complex solutions when two channels intersect at the same point, which is one of the problems we had in a trial design at the time solved by designing the channels in such a way that they could walk past each other without crossing one and the same cross section. "
Thousands of cavities
Marc Paro agrees with this characteristic advantage: "Quite clearly. The only thing is that the benefits are large enough to invest in AM, and that tipping point has not yet been reached in my opinion." Job van Berkel: "At the moment, for example, a great deal of knowledge is available about the optimum production of manifolds through machining and about the materials. For example, we know that a five-axis CNC machine with a large tool magazine is capable of maneuvering to produce blocks with hundreds to thousands of cavities, because make no mistake, that is the number that a complex manifold is about. "
Design for functionality and - as Job indicated - a hassle-free conversion to a CNC program. If and when you were to switch to AM, you would have to be able to derive a great deal of benefits to justify the accompanying costs, and time needed to build up knowledge and experience in working with this new production technique to make the investment feasible. "
Marc Paro continues to philosophize. "If we would eventually continue with AM, I would believe in the possibilities of Big Data. If you were to store all the designs you make in a database, then you would be able to rely more and more on existing designs, which shortens the engineering time. If you then come to a final design in a quick way and the time required to arrive at a 3D print file is limited, then you can take steps in terms of lead time, I think, but unfortunately that database does not yet exist and I understand that in principle, the necessary time must also be reserved for the step from design to program for a 3D printer. "
Weight that tips the scale
A second important advantage that emerged from Adri Overbeeke's research is the possibility of drastically reducing the weight of a manifold with AM. "After all, an essential difference between AM and machining is the fact that material is removed during machining while AM is used precisely to add material. Preferably as little as possible in connection with the production time. Sufficient material to be able to absorb all expected forces but not more The end result is a weight saving that - on the basis of simulations in the study - can go up to 80%, which are percentages that put weight in the scales, in applications where weight plays a role, for example in the air and space travel, this can be a distinctive advantage. "
When lead time is secondary
The final conclusion within the group is that AM only becomes interesting for hydraulic manifolds when the specific advantages such as free and compact design and weight saving outweigh leadtime. In any case, the benefits are not to shorten the lead time. Adri Overbeeke: "In principle, the turnaround time is determined by the material you choose - that is, plastic or metal - and the volume that you have to print. This means that the size of the manifold is really crucial for the speed of production - which plays a slightly less important role in machining. This means that for smaller products the tipping point may be reached earlier, but especially in the case of manifolds where a design is required that cannot be achieved with machining.
"Another advantage could be that you could print your manifold via AM anywhere in the world, which can make a difference in the event of an emergency. You simply send the file to a location in the neighborhood where it is subsequently delivered on site. Of course, such a machine must be available, but unlike machining, I think that less knowledge is needed to ultimately produce the product, for example, steering a CNC program does not automatically lead to the desired end result because the knowledge and skills of the on-site operator. "
Time is not yet ripe
Marc Paro: "I think we can further conclude that the technology is suitable in principle, but perhaps the time is not yet ripe for real applications. Again because the market for hydraulic manifolds is relatively small and the batch sizes are limited. In addition, I think there more knowledge and experience must also be built up about the reliability of the quality with which you produce. I can imagine that it will be commonplace in ten to twenty years' time, but I don't think you should be concerned as a 'block factory'. "