Sinter /// concept
Executive Summary
The combined solutions proposed revolve around 2 core innovations. They are based on what we see being developed in laboratories around the world at the moment, and that is 3d printing of sintered metal powder. This is already applied in fields such as aeronautics, medicine, prosthetics and the car industry mainly for small high resistance components. 1.The first solution is taking inspiration from natural formations such as bone, in order to make structures lighter and stronger. 2. The second solution consists in the mixing different powders and creating objects with varying physical properties along their volume straight from the 3d printer. For reference the main material put forth in this presentation will be Aluminum PM, but many other materials are also of interest. Weight Reduction Methodology The project looks at the current state of the art and projects it 20 years ahead. The main areas improved are material solutions and structural ideas pushing for a new way of thinking and its potential to bring forth future engineering opportunities. The innovation spans over 2 main areas: body in white with exterior panels, and power train; even glass is not excluded. These 2 areas make up more than 50 percent of a vehicles total weight. The project aims to improve that by 40 to 50% equating in a 25% or 500 kg weight decrease to a 2000kg modern luxury sedan, or 35% of a 1300kg modern sports car. http://www.renishaw.com/en/first-‐metal-‐3d-‐printed-‐bicycle-‐frame-‐manufactured-‐by-‐renishaw-‐for-‐empire-‐cycles-‐-‐24154
Studying living organisms tissue and physical and geometrical structural element arrangements will bring great benefits to the way we create cars in the future. Innovation The ideas for weight reduction consist in elaborate methods of using 3d printed sintered metal alloy powders. First of all we have to imagine that 3d printers will get bigger and more complex in the coming years. This will pave the way for many more applications with larger scope. In the next 10 years we will probably see the first 3d printed metal car space frame. In the next 20 years we will see the first 3d printed functional power train, most likely for a high-‐end sports car. The ideas proposed here would come after the first metal chassis and even power train have been printed and look to build upon that and evolve the concept even further. Imagine a car frame built from one single piece. It will not need any rivets, bolts, glue, welding and joints. It will look like something from a science fiction illustration, like something biological grown in a laboratory. This reality is closer than most people expect. This is the concept put forth: A structure with double the rigidity and half the weight of today's most advanced car frames. This frame is made out of aluminum, steel, and soft materials all in 1 piece.
It is achieved through the use of a large and slightly more complex printer that the ones we have today. The method for achieving this consists in adding different powders within the same printing batch and combining those in key areas of the same final object. The next 2 images are used to explain the concept: Here, ceramic can gradually turn into metal in the same way that bones turn into tendons and then into muscle. Tendons grow gradually out of bones and their density, chemical properties and elasticity change gradually. This can be achieved and mimicked through 3d printing of multiple materials and porosities. Using these types of methods, consistent weight reduction is obtained through multiple key steps: 1. Elimination of joints and weak areas. 3d printing gets rid of all that and offers much greater adaptability and fine-‐tuning of key areas. 2. Single piece construction of vehicle frame, with inclusion of fixings and additional parts. Big 3d printer needed. 3. Single piece construction of structural body elements -‐ example -‐ longitudinal door impact beams and door exterior panel can be made in one piece. This will allow much more freedom in material choices with a net gain in strength and weight saving. 4. The creation of structural elements with varying density for maximum lightness and support in strategic areas. Ex: Soft elastic engine mount heads growing straight from the chassis and CV boots integrated within drive axle. 5. Complete integration of wiring and electronic canals through the structural beams for excellent optimization of weight distribution. This can be called liquid packaging. 6. If need be integration of optional auxiliary fuel cells or liquid fuel storage within the car's structural beams for optimal weight distribution. This is also a form of liquid packaging. Finally through this type of technology man made engineering solutions can be as optimized as the ones that have evolved in nature over many eons.
Bill of Materials The main material used is aluminum Powder. Theoretically it would weigh in at around 420kg between exterior panels, space frame and drive train with a 1.4-‐liter turbo engine. This will be enough to build the aluminum space frame, engine mounts, safety beams and exterior panels of a 5 seat modern sedan. These assumptions are made based on previous 3d printed metals with outstanding lightness compared to their traditional counterparts. For example a seat post bracket for a bicycle created in 2014 is 44% lighter than aluminium alloy version. Even more for a commercial plane's door hinges. http://www.renishaw.com/en/first-‐metal-‐3d-‐printed-‐bicycle-‐frame-‐manufactured-‐by-‐renishaw-‐for-‐empire-‐cycles-‐-‐24154 http://www.3ders.org/articles/20140818-‐ge-‐reveals-‐breakthrough-‐in-‐3d-‐printing-‐super-‐light-‐weight-‐metal-‐blades-‐for-‐jet-‐engine.html
The current price for 15um aluminum PM is 29$ per kg (source Alibaba.com). This means 12.180$ in raw material cost for most metallic parts in the car. Material properties and advantages of existing alumiunium powders chart Required Manufacturing Processes The NEW manufacturing solution that the project is putting forward is the mixing of different powders for the printing of the same part. This will allow different mechanical properties on one end of the part compared to the other end. A must is to look at this as a transition between bone and soft tissue. This in some cases is done gradually without the 2 areas being disjointed. One can almost go, as far as to think that door hinge will be an integral part of the door panel. This potential solution needs careful research and the mixing of powders in the machine needs to be done automatically with a precision of microns. This will allow the final part to have well-‐controlled resistance and lightness properties. A laser with temperature modulation is needed. It will pulsate multiple times on the same point, because different materials have different ‘melting’ points. This will allow the materials to intertwine. Also a powder spray nozzle can be used to create structural strands within an object made from a different material. It will spray a different strand of powder on each layer as explained in the proposed process image.
Proposed process: However, most of the manufacturing solutions involved largely exist. An important step is general scaling of metal powder production around the world, which will come naturally in the coming years driving the price down. The second natural leap is creating bigger and more capable 3d printers with multiple, more powerful and greener lasers that can print a full size sedan space frame in one go and in a very short time. 3d printers with multiple powder reservoirs will be needed, as they should be able to precisely combine 2 or more different powders in certain quantities and areas in order to obtain final products with varying densities and compositions. Image example:
Image with the purpose of illustrating the concept explained above. Layers are added micron my micron with different rations of quantities of 2 mixed powders. Different and new alloys can be created straight from the printer. The end result would be something like selective heat treating or tempering different areas of an object, but on a much bigger scale of alteration. It can be called a dynamic material matrix composite, and the paper is not aware of the existence of such materials at present in the world. The innovation consists in creating one piece chassis and vehicle panels as well as fixings integrated in the chassis with different densities and material properties where needed. Earth's oldest rocks sometimes form basic random metal matrixes (as shown underneath). With 3d printing we can theoretically control the matrixes to a micron level and create new composite structures fitted to specific physical requirements. Passenger Safety Passenger active safety will be greatly improved by modeling optimized reinforcements around stress areas. Internal bone like structures with varying densities will greatly help absorb impact energy and materials more advanced than metal foam will act like cushions that will “potentially make 40 mph crashes feel like 10mph“. Just like metal foam absorption properties, it will be similar for 3d printed objects with internal bone and crumple structures and varying material densities and strengths. The paper cannot quantify these improvements with exactness at present time, although the values will probably be higher than current production standards. Innovative/Safety Component “According to the Encyclopedia Britannica, compact bone specimens have been found to have tensile strength around 20,000 psi (pounds per square inch). "Mild" steel such as AISI 1020 Hot Rolled, on the other hand, has a tensile strength of 70,000 psi, and alloy steels that are heat-‐treated can have tensile strengths of over 200,000 psi, ten times stronger than bone. However, steel is about 4.5 times heavier than bone, so bone is actually stronger than mild steel on a per-‐weight basis”. This is because of bones intelligent internal structural management and chemical composition. Using similar structures made out of aluminum or other elements will bring forth incremental crash safety and impact absorption levels. The dynamic material composed could also help take in greater forces.
Potential Challenges 1. A challenge to overcome in some cases is that the materials used need to have similar dilatation characteristics. Extensive research focused on solutions depending on case is needed. 2. Car manufactures will have to invest heavily in 3d printing tech in the coming years and decades if they want to stay competitive and meet consumption standards. http://3dprinting.com/3dprinters/daimler-‐invests-‐in-‐large-‐scale-‐3d-‐printer-‐for-‐metal-‐printing/ 3. “ To date, the 3D printing revolution has focused on the use of plastics. Until now 3D printing with metal has been prohibitively expensive because of the cost of titanium powders which currently sell for $200-‐$400 per kilogram. But we are seeing a gradual decrease in prices for metal sintered powders. “ 4. Demand for aluminum is high and that will keep prices up for the time being. 5. Possible economic downturns and low investment in innovation and technology scaling. 6. Initial production and investment costs and technology adoption. A proposed solution that will help push this technology is collaborating with motorsport organizations that can implement this in their vehicles, such as Formula1 cars. This is a great publicity and awareness solution for further implementation of high-‐end technologies into the future main stream.