Issue Dec 16
Metallic additive manufacturing processes are already being used in a range of industries including aerospace, medical and defense, but manufacturers are still learning its capabilities and limitations. If nurtured correctly, however, it has the potential to become a truly transformative method, offering unrivalled design freedom to manufacturers and the ability to manufacture components previously thought beyond reach.
Why Additive Manufacturing?
Additive manufacturing is radically transforming how manufacturers make products. In the future, it’s easy to imagine many of the machine tools currently utilized on the factory floor becoming redundant, required only for final finishing.
There are a number of clear commercial benefits to the additive process, which uses 3-D design data to build up a component in layers, rather than a subtractive process such as milling. The freedom of design offered is a clear benefit, as is the opportunity to produce complex shapes or internal structures that would be impossible to create using traditional machining methods. This means it will be much easier for manufacturers to produce highly customized parts quickly and profitably and to do so in a materially efficient way. Scrap rates for parts produced this way are usually below five percent, compared to scrap rates of more than 90 percent for many complex milled parts. In today’s economic climate of rising costs and scare raw materials, this represents a significant advantage.
Additive manufacturing is a complex process and cannot simply be referred to as 3-D printing. Despite its inherent flexibility and ability to make changes relatively quickly, production time can be challenging with complex parts taking anywhere from four to 16 hours to produce.
These parts are, contrary to understanding, not finished. Most of the parts still require heat treatment and subsequent machining in order to achieve the desired surface finish and dimensional requirements for the final part. This will still need to be clamped in a CNC machining center, and manufacturers will still need location surfaces that allow for that.
Take-up is also being hampered by a severe lack of industry guidance, standardization and best practice methodology. There is no piece of software or programming explaining how best to design and engineer a part additively. With that said, there are efforts from all involved to push the boundaries. Powder manufacturers are looking at ways to improve powder quality, CAD/CAM producers are developing new models specifically for additive manufacturing, and production managers and machinists are learning more about how they will handle additive manufacturing within their specific application, from preparing the machine to managing the powder.
Need to Standardize
In moving towards additive manufacturing, there is a need for greater industry standardization. Currently, machine tool manufacturers have total control, they determine the particle size for the powder, the laser deposition, the power of the laser and the process the machine uses. This means that individual machines have their own set of operational standards.
In an effort to combat this, there are already many organizations working on standards for additive manufacturing in an effort to bring consistency to the process, in the form of standardized particle size, energy for deposition of the laser and the way the machine tools operate.
This will be critical to the uptake of additive manufacturing and there are activities supporting this around the world. For example, the EU project Support Action for Standardization in Additive manufacturing (SASAM), which is driving the growth of additive manufacturing to become a feasible and efficient process “by integrating and coordinating Standardization activities for Europe by creating and supporting a standardization organization in the field of AM.”
Metal additive manufacturing is undergoing a period of rapid development. In the last few years, there has been far greater commitment to and excitement about the benefits of this transformative process. Further steps towards standardization will play a key part in wider implementation, but changing the attitude of the engineering community towards additive manufacturing will also be fundamental to achieving further progress. We need to think differently about additive manufacturing. As the current generation of engineers struggles to grasp the capability of such a revolutionary technology, there is a need to open minds and embrace new thinking.
Alongside this shift in attitude, we need to promote the learning of the next generation of engineers, ensuring they are exposed to additive manufacturing so that it becomes as natural to them as subtractive machining is to us. They will be the ones to create new dimensional designs and think laterally about the opportunities of this groundbreaking technology.
Building additive parts takes a “thinking outside the box” mentality as the building process differs greatly from traditional subtractive manufacturing. As it is an additive, rather than subtractive method, not only do you design the build for the final geometry/part but you design the build with the building process in consideration too.
For example, when building overhangs or angled geometry, there needs to be support structures added to the geometry due to melt pool distortion. Programming parts or geometry in a CAD/CAM takes practice and skill as the programmer essentially creates the opposite of a traditional tool path.
Traditional machining requires a certain set of parameters such as feeds and speeds to achieve good quality parts within tolerance. Additive manufacturing also requires parameters that need to be precisely fixed, to achieve parts within tolerance. Most commonly, these parameters have to do with power settings to the laser, feed of powder, amount of powder, speed of laser/orifice in traverse movements, and amount of inert atmosphere protecting the process.
While still in its infancy, the benefits of metallic additive manufacturing are beginning to be understood and as its processes spread beyond the defense, aerospace and medical sectors into new industries, a new era of modern machining is emerging.
Sven Thiesen is Chief Operating Officer of OPTIS, a joint venture that brings together the deep machining expertise, analytic tools and process improvements of TechSolve with the heritage and global commercial reach of Castrol, to deliver transformative efficiency to the manufacturing industry in North America and beyond. With the ability to mimic customer equipment and validate process solutions using its unique instrumented machining lab, OPTIS thinks like the machine. OPTIS experts deliver tangible benefits that go to the bottom line, accelerating clients’ efficiency programs, solving manufacturing problems and reducing part costs.