Getting our hands dirty with 3D Printing

Over the last 10 years, Stratasys Strategic Consulting have spent a lot of time developing software to analyse the cost of 3D printing. Labour is still a big element of the cost of 3D Printing and so to refine our cost models further, we sent our Senior Consultant, Loic Le Merlus to the Stratasys EMEA demo centre in Baden Baden to spend a week capturing data about the work activities with the 3D printing process chain. Over the next few weeks he will discuss what considerations are important when analysing the cost of labour in 3D Printing.

Lot of people still see 3D printing as a totally automated process which doesn’t involve much labour. However, following my week in Baden Baden, witnessing the production activities, I was reminded a lot of traditional manufacturing factories. Similar to traditional manufacturing, additive manufacturing follows a process flow of different operations in order to produce finished end products. The first blog in this series is about preparing builds – in other words, everything that happens before you even walk to the machine.

Baden-Baden Benchmark and demo center
Figure 1: Baden-Baden Benchmark and demo center

Understanding the design requirements

Before being able to start printing a lot of preparation needs to be done. In 3D printing, everything starts with a STL file. But having the file is not enough, it is important to understand what the part is for and what are the design constraints – this determines how the part should be built. Sometimes it is necessary for the production engineer to ask more information in order to do a correct assessment. It can happen that the file needs to be fixed, in that case specialist software is used for fixing or, if the file quality is irreparable, a new file is asked for. These steps can take between 5 minutes, if there is no problem, to a few days if there is a need to go back and forth to have details about the part.

Planning for the perfect print

Once a suitable file has been obtained, the engineer has to prepare the build. For PolyJet technology you generally only need to choose the orientation and the material which takes less than 10 minutes usually. If the part needs a lot of different colour, it can be a bit trickier and would take 10 to 20 minutes to prepare. In the Objet Studio you can go through each slice to check if there is a problem but this can take a long time to compute – usually just a couple of critical slices are checked.

For FDM technology there is a lot more user input required. The support structure can be specified, as well as the toolpath. The toolpath and infill can be totally different for different layers, allowing you to print challenging geometry. Working through the slices and tailoring the parameters can be a time consuming task, taking anything from 10 minutes to few hours for very complicated parts.

At this stage it is important for the engineer to consider the impact of the machine’s print process on the output part. For instance, if you want to print an injection mould using PolyJet you have to think of which direction the flow of plastic will go in the mould and orient your print in the right direction to maximise the flow.

Operator preparing build on a PolyJet
Figure 2: Operator preparing build on a PolyJet

How’s this going to change in the future?

3D Printing is still a very labour intensive and time consuming process – not everyone appreciates all the activities that a process engineer needs to undertake to have a successful print. We are increasingly seeing software that will make this step automatic, using algorithms to select the most appropriate technology and material for the print based on the requirements of the part. This will help to reduce the time to prepare a print.

Selecting the right parameters is probably the most complicated part and the one which requires the most experience. It is essential to know all the details about what the part is used for and the constraints of each 3D Printer. It is something that you can only learn with time and experience making the application engineer a very valuable resource in the 3D printing process. Over time, we will see software brought to market that will have all that knowledge incorporated to enable a perfect print every time. Interesting developments in this space include incorporating Finite Element Analysis (FEA) or simulation to find the best parameters for printing that particular part. The problem at the moment is that 3D printing processes are so complex that computing simulations a takes almost as long as printing the part. As the software develops, however, this is likely to become more commonplace.