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- Quality in metal AM
Quality in metal AM with respect to the AM machine is discussed in this chapter. The chapter is a summary of the full document which can be found HERE. The main content focusses on the differences between EBM and SLM technology. Furthermore, powder source, build platform, recoating/whiper mechanisms are discussed and a procedure for control of the machine is given.
Keywords: SLM vs EBM, power source, build platform, recoater mechanisms.
Additive Manufacturing includes a range of production technologies, which are differentiated by four main characteristics (table 1), namely;
- Material - feedstock
- Material - Deposition Method
- Energy Source
In this chapter the machines used for two powder-bed fusion technologies are discussed; Selective Laser Melting (SLM) and Electron Beam Melting (EBM). Although SLM is a trademark term for SLM solutions, we use the term as generic for all Leaser Beam Melting (LBM) technologies.
- SLM & EBM Hardware Review
- Power source
- Build platform
- Recoating/Wiper mechanisms
- Procedure for control of the machine
- Further reading
1. SLM & EBM Hardware Review
Next to the full 'Machine' document, we adress the following sources as providing information on SLM & EBM technology:
An thourough comparison of SLM vs EBM has been made by Rachel Park and can be found HERE.
2. Power source
Recent development in laser services has assisted AM hardware to improve the speed and feature resolution. SLM systems used for metal parts have a laser as the power source; this can be up to 1KW however it is more common to be between 200-500W. The high powered lasers help to increase the deposition rate of SLM process. There are several SLM equipment OEM’s in the market and only one EBM equipment provider which is made by Swedish company ArcamAB, the electron beam gun can generate up to 3000W power.
SLM Solutions Germany implemented a multi-laser with multi-scanning mechanisms in their hardware SLM280HL and SLM500HL to improve the productivity of the SLM process to build rate of 70 cm^3/hr. These systems have the ability to work with 2 lasers (400W each) & 2 scanners Or 4 lasers & 4 scanners combinations.
3. Build platform
AM technology providers are also striving to produce systems with increased platform size. The drive for this increase is to allow larger parts to be manufactured using this technology, particularly in the Automotive and Aerospace industries.
4. Recoating/Wiper mechanisms
Recent developments in recoating mechanisms have also assisted in the increase the productivity of the SLM process. The ability to deposit powder in both directions has helped to improve the auxiliary
time per layer.
The EBM process also benefits from a bi-directional recoating system; this is done by having two hoppers on each side of its power source which allows powder delivery in both ways.
5. Procedure for control of the machine
This procedure is extensively discussed in the 'Machine' document and concerns supervision of several machine components and main elements which are necessary to be revised after a build.