User Review: EOSINT M280 Developer Kit

The EOSINT Mxxx are the fastest-selling Selective Laser Melting (SLM) production and R&D machines on the AM market for metal applications (10 EOSINT M400 sales forecast for 2015 in Asia alone). Following the EOSINT M280 hardware user review, this post assesses the processing parameters and software control available in the optional ‘development kit’. This package is in essence a licence to freely use numerous laser processing parameters. It gives you open access to the actual “EOS Default” set of parameters.

When acquiring an EOSINT M280, standard processing parameters are supplied with the hardware. Actual values, such as laser power, scanning speed, etc are invisible to the operator, and this has several advantages:

• It removes the risk to accidentally change the parameters;
• It is a press-and-go user-friendly machine;
• You can leave the cold, hard parameters development to the EOS engineers in Finland and get on with building (and selling) components and growing your business. 

Do you need the developer kit?

Before digging right in, let’s consider whether you need this add-on:

You will not need the developer kit if:

• you’re only interested in making non critical components, 
• you plan to outsource your parameters development,
• you’re happy to rely on EOS as a single powder supplier and use their processing parameters, 
• post-treatment techniques are integrated in your work flow anyway. In other words, you plan to finish the component with let’s say a 5-axis mechanical process, and/or have the (financial or practical) means to carry out and incorporate heat treatments.

You might need the developer kit if:

• you want to buy powder from different suppliers,
• you want to produce powder yourself, or work with unusual or exotic powders,
• you are interested in specific powder composition, stringent density, metallurgy or mechanical properties (isotropy),
• you want to minimise post-processing costs, for instance surface processing or HIPing,
• you want to carry out your own process development,
• you want to investigate fundamental mechanisms such as laser/powder interaction, grain growth control, mechanical properties, etc…

EOS Standard parameters

Using “EOS standard” parameters for nickel- or aluminium-based alloys usually results in densities >98/99%, anisotropic mechanical properties, internal stress and typical surface roughness in the range of 10-50um. Of intermediate speed, they tend to show adequate build stability for sturdy, straight-forward designs exhibiting few overhands and walls thickness>3/5mm. Generally, standard parameters are a trade off between 1) slower high-performance parameters, focused on high quality metallurgical and mechanical properties and surface roughness, and 2) adequately-named “fast build” parameters, used for rapid prototyping, design feasibility studies or non-critical components manufacture.

For “high-risk” designs, difficulties may arise from lack of build stability and poor surface roughness in the down-facing areas. Components built using these parameters would typically require post-treatment. In other words, by relying on “EOS standard” parameters, you’ll be saving (time and) money on parameters development and actual AM process (ie machine time), but, if you’re serious about component quality, you’ll most likely be spending it on post-processing techniques.

Besides, EOS “Standard parameters” are only suited for the EOS powders. If you choose this option, it might be useful, as reference and for traceability, to ask for actual density, SR, mechanical properties, etc values. Make sure to clarify whether they guaranty reliability of these parameters in time.

Parameters development and process engineering

For a specific material setting, the EOSINT M280 optional process developer kit will give you full reign to choose your exposure strategies and complete access to numerous laser processing parameters such as laser power and scanning speed. Selecting exposure strategies consists in choosing, for instance, the scanning pattern, whether or not you need pre-scanning (heating) or contour scans, etc. Up to you to vary the combinations! As such, the EOSINT M280 is one of the most flexible machines on the market with parameters specifically addressable to tailor SR, density, etc Financially, this flexibility will set you back another 10K€.

However, parameters such as layer thickness, processing atmosphere (nitrogen or argon), oxygen purity and build platform temperature are “locked” and restricted to a given material setting. For instance, 30um is the nominal layer thickness accessible in the aluminium settings. For the nickel settings, the layer thickness is fixed at 40um. To change these basic variables, you’ll have to – wait for it – upgrade to (buy!) different material settings…. For teams interested in hard parameters development, this remains a frustrating point for the EOSINT M280. However, in a new PSW software version coming up with the EOS M290 and EOS M400, these parameters will be readily accessible. Before you ask: no, it seems this new software will not be retrofitted on the EOS M280… Note that for the processing atmosphere, you can bypass this by “tricking” the machine and feeding it whatever gas you want. As for the built-in nitrogen processor (meant to save you money on bottle/cylinder gas), its purity (set and locked to 1%/1.2%) is currently too low to achieve high quality components.

Unlike the “locked-in” route, this open-access option offers more flexibility, especially given that no commercially available powder is specifically designed for SLM but derived from casting applications. Indeed, metallurgy and mechanical properties of SLM component are still being investigated for a range of powders.

The downside of this flexibility is complexity due to the large number of parameters combination possible: process development is time consuming and demands that you master the machine controls and understand how to address the variables and how they interplay with one other.

Still, given the large number of exposures and processing parameters available, the PSW control software remains very reliable and fairly user-friendly. The only hiccups noticeable are caused by the build-time calculator and can be easily by-passed while EOS is fixing the issue. The last, more annoying point is that currently, exposure files can’t be read after upgrade of the PSW version. New PSW upgrades occurs every 18months in average. EOS engineers are working on a fix.

All in all, the Developer Kit is a remarkable flexible tool for SLM parameters development of a given material. Regrettably (for process engineers), this comes as an add-on with no straight-forward access to some of the most basic parameters (layer thickness, etc). Thankfully, this will be corrected in the PSW software provided with M290 and M400, offering full open access. Let’s hope EOS will change their mind and agree to retrofit this new software on the M270 and M280!