The sum of evolution and coexistence

AM was originally developed in the mid-1980s and is today categorised in seven different standardised AM technologies, of which some can be used for metals. Specialist companies started to use metal AM by laser sintering processes over twenty years ago.

Since then, the technology has seen significant progress in terms of both powder-bed fusion systems (in which layers of component material are melted) and direct energy deposition (also known as blown powder or powder-fed or metal powder deposition) alternatives that build up a part through the deposition of thin layers of material.

In support of this evolution the types of materials available for use in AM also continues to grow. Now atomised metal powder options encompass low alloy steels, tool steels, stainless steels and duplex steels, cobalt alloys, nickel alloys, aluminium alloys and titanium alloys.

In reality, we can expect the gradual evolution of manufacturing processes, with the productivity and cost-efficiency of conventional machining solutions being augmented by AM techniques where they can be shown to add value in the end-to-end process. Indeed, we’re already seeing the emergence of hybrid CNC machines that allow additive processes to be combined with machining processes or in which interchangeable machine heads allow the rapid changeover from AM to metal cutting.

Subtractive and attractive

What’s more, the option to use additive or subtractive techniques is much less of an ‘either or’ scenario than you might expect. For example, even when the decision is made to manufacture a part using AM, it can still be more cost-effective or necessary to perform finishing using conventional metalcutting techniques. In order to obtain required tolerance and to meet surface finishing demands, conventional metalcutting techniques might be preferable than trying to print to very high tolerances. AM technologies are part of a production flow and post processes and machining are required if high tolerances are needed. In these cases, parts can actually benefit from being printed oversized to give better cutting conditions for the subtractive (machining) operation to deliver the final design demanded by the target application.

Hybrid solutions will also be applicable to the manufacture of hollow components. In this case, it’s possible to envisage a scenario where component manufacture would begin and end with an AM process, but in between there would be the need for conventional machining. The part can then be manufactured in one piece and assembly avoided.

Even where a manufacturer continues to use conventional machining techniques there will be a chance they can benefit from AM if this is the way that their cutting tools have been produced. Whilst creating tools using AM techniques remains commercially prohibitive in the vast majority of cases, there are certain areas where it can bring productivity improvements. One of the benefits of a printed tool, for instance, is lower weight – due to a lattice structured design – which will give a lower susceptibility to the vibration that can impact productivity and quality when machining components with long overhangs.

What is clear is that machine builders, tool suppliers, manufacturers and a variety of other related parties are all increasing their investment in R&D into new AM processes. Sandvik Coromant is no exception - the organisation saw the official inauguration of a new AM research facility in Sweden earlier this year.

This facility, which has access to advanced powder solutions from Sandvik Materials Technology’s Sandvik Osprey, builds on work that Sandvik Coromant has been doing since 2013. Key aims are to investigate how new AM solutions can address customer requirements; to identify how hybrid machining/AM techniques can add value to the end-to-end manufacturing process; and to look at those areas that will benefit from the capability to create machine tools using 3D processes.

www.sandvik.coromant.com