Practical 3D Printing: Finishing The Part
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Finishing The Part
05.50
| 00:00 | Depending on the part and its application, some prints will be ready to use straight out of the printer, while others will require post-processors which might be completed either by the manufacturer, ourselves or some other party. |
| 00:12 | We'll continue with our Merge Collector worked example to show some of the common actions here, picking up immediately after the part was finished printing. |
| 00:20 | At this stage, the manufacturer will de -powder the part and the print bed, collecting what they can to recycle with a powder recovery system. |
| 00:29 | The part then needs to be cut off the build platform as they're welded together while fusing the first layer. |
| 00:34 | This is usually done with a wire cutter. |
| 00:37 | The supports are also broken off, which can sometimes be done by hand, or with hand tools like pliers, or even with basic power tools. |
| 00:45 | Following this, the manufacturer will complete any surface finishing processes based on our requirements from the previous module. |
| 00:52 | In almost all cases, the parts will be sandblasted, which smooths the surface to a consistent, grainy, matte finish. |
| 00:59 | And helps remove any remaining powder. |
| 01:01 | In our example, we requested a satin glossy finish, which is achieved through additional blasting with glass beads. |
| 01:08 | But there are other options like polishing via tumbling techniques, or manual operations. |
| 01:14 | These were all the options available in this case, however there are of course plenty of other techniques for finishing metal parts. |
| 01:21 | For example, the extensive list of coatings for functional purposes, like corrosion resistance, or simply aesthetics. |
| 01:30 | Electroplating, Cerakote, and powder coating are a few worth mentioning, asides from the myriad of different paints. |
| 01:37 | For our merged collector, stainless steel naturally has good corrosion resistance, so doesn't require any surface finishes for an exhaust application. |
| 01:45 | However, in the interest of longevity and heat insulation, we could turn to certain forms of ceramic coatings. |
| 01:51 | Again, there's an endless list here, and that's not the focus of this course, so let's move on. |
| 01:57 | Essentially, any other process that could be applied to a billet or cast part of that particular metal can be used on 3D printed parts. |
| 02:06 | It's typical for 3D printed metal parts to require some form of machining to tidy up functional features with critical dimensions. |
| 02:14 | Ceiling flanges, like those on exhaust or intake manifolds, to the cylinder head are good examples of this. |
| 02:20 | If the part can't be fixed in a mill and machined perfectly flat, it is possible to get good results on a billet. |
| 02:27 | However, extreme care must be taken here to apply even pressure to the part. |
| 02:32 | Otherwise, it's very easy to add a taper to the flange, in which case the part could be ruined. |
| 02:38 | The V-band flange on our merged collector is another example of a feature that could be machined to ensure good fitment of the mating surfaces. |
| 02:47 | On this note, let's quickly review the condition of our finished printed part and discuss some necessary actions. |
| 02:53 | On receiving the part, we measured the V -band flange to find it was dimensionally accurate and mated nicely with the other side of the flange. |
| 03:01 | Recalling that we chose the satin glossy finish when ordering the part through Craft Cloud, the extra glass bead blasting step resulted in a relatively smooth surface finish that should allow for adequate sealing, at least in this naturally aspirated application that also uses slip joints anyway. |
| 03:19 | Speaking of which, the slip joints, while being relatively accurate, did benefit from a light polish using a flap wheel, for a more consistent surface finish and better slip fit for the primary tubes. |
| 03:30 | At this point in the course, you're probably expecting us to cover threaded features, and these are no exception to machining finishes. |
| 03:37 | While we can print threads directly, they should also be chased with a tap to tidy up the critical surfaces. |
| 03:43 | Of course, drilling and tapping threads manually is also an option. |
| 03:47 | Finally, we need to discuss welding, a common process for metal fabrication. |
| 03:52 | Most metals will print for automotive applications, like aluminium, stainless steel, titanium, and inconel, can be welded with mostly the same set of considerations as the more traditional forms for these materials. |
| 04:05 | Let's say, for example, we were welding a V-band flange onto our printed merge collector, to ensure the fit and finish of the critical surfaces was ideal. |
| 04:14 | TIG welding is the go-to here, and with any case, if we want a good result, then thorough cleaning and preparation of the welded area will set us up for success. |
| 04:23 | We'd also use a back purging technique on a part with internal structure like this, to ensure shielding gas reaches the backside of the weld for full penetration and a smooth internal surface that won't disturb airflow or form a weak area. |
| 04:37 | One last note before we move on. |
| 04:40 | If this was a merge collector for a turbo application, it would be extremely important to ensure that there's no powder remaining in the part, as this could cause serious damage to the turbo. |
| 04:50 | And with that, let's summarise this module. |
| 04:52 | Most typical finishing touches that can be applied, to a metal part, can be used on our SLM 3D prints. |
| 04:59 | Some of these may be done by the manufacturer, or we can do them ourselves, or they might be other services offered by another party. |
| 05:07 | After the initial depowdering process and cutting the part from the build platform, the manufacturer will usually sandblast the part, resulting in a grainy, matte finish. |
| 05:17 | This can be followed by more media blasting, tumbling or polishing, depending on how smooth of a surface finish we're after. |
| 05:24 | Coatings can also be applied for functional or aesthetic purposes. |
| 05:29 | Passers, it's common for critical surfaces to be machined to more precise tolerances, and this could be anything from using a mill for sealing flanges, to chasing a thread with a tap. |
| 05:40 | It's also common to tig weld the parts, and proper preparation and setup is extremely important. |
