Gordon Styles in Star Rapid’s factory.
Gordon Styles in Star Rapid’s factory.
While 2016 prompted a more widespread use of 3D metal printing, this year we can expect to see varied applications of this process as it comes to the forefront of manufacturing for production. According to SmarTech Publishing, annual shipments of metal additive manufacturing systems will grow between 20 and 25 percent in 2017. We will also see a rise in using 3D printing for conformal cooling cores in toolmaking and new post-processing techniques for plastic and metal parts.
The 3D Metal Printing Design Learning Curve
3D metal printing is unlike 3D plastic printing so the industry is experiencing a learning curve when it comes to designing for this process. 3D metal printing requires the ongoing education of designers on how to design parts to avoid excessive support structures. There are two factors hindering the adoption of 3D metal printing: topological optimisation and part weight/volume reduction.
Topological optimisation improves material layout within a given design space, but with metal parts, this presents a challenge. Manufacturers have to EDM wire the build off the plate, with all the supports still attached to the part, and then spend hours using robust engineering tools to remove each support, one at a time. Go through this process a few times and you are desperate for parts that can be oriented where only one or a few supports are required. That’s why there are key rules that designers must abide by to help reduce costs associated with support removal. These include: overhangs need to be less than 0.5mm; all downward facing structures must be designed so that they can be built on at least a 45-degree angle from horizontal; horizontal holes cannot be less than 0.5 mm and holes greater than 10 mm need supports.
Weight/volume reduction will also drive adoption of 3D metal printing. To do this, one must consider making hollow or highly-optimised and organic designs. Programs such as Altair’s OptiStruct, AutoDesk’s Within or Dreamcatcher are helping designers create extremely organic and highly evolved structures that optimise the weight to performance ratio dramatically.
Rapid Tooling through 3D Printing Going Mainstream
3D printing of tooling in both metals and polymers is simpler and creates fewer barriers to adoption. The use of 3D printing for conformal cooling cores (CCC) in toolmaking can improve the accuracy and aesthetics of the resulting injection moulding. First, it allows the tool to be cycled between hot and cold for each moulding right at the surface of the core or cavity. The capillary cooling channels are very close to the surface of the core or cavity and therefore the entire mold does not have to be cycled. Having a hotter mould surface during injection allows the melt to flow further, have fewer gates, and/or reduces the effects of weld-marks. It also reduces the effect of sink marks and improves the quality of textures on the part. Secondly, you can improve cycle time by being able to remove the energy from the part much faster since efficient cooling is so close to the surface of the tool face. This can reduce cycle times by as much as one-third of the regular time.
Post Processing of 3D Parts
For plastic and metal, post processing improves the quality of parts and ensures that they meet the design specifications. PVD coatings and vacuum metallisation creates stunning finishes for plastics and metals including gloss parts, various colours, and textures. One post-processing method that is truly cutting-edge is the texturing of 3D printed parts directly by Mold-Tech. Manufacturers can have any pattern from their library or a special design directly onto the prototype part. Although this texture can be applied directly to the model, it is common that the plastic or metal part is first sanded or painted to improve the quality of the texture or pattern applied.
These three trends present an exciting future for the additive manufacturing industry so we’ll just have to wait and watch.
More detailed information about the benefits of 3D printing and the capabilities can be found here.