Friday, February 22, 2013

Open Manufacturing: Laser Engraving and Logos

When you have a hammer, everything is a nail; when you have a laser cutter, everything needs to be engraved.

We have been engraving the backside of our plates with a QR Code and part number, so to improve readability and aesthetics we have been exploring ways to paint the plates.There are two points to cover 
  1. Method of Application
  2. Paint used in Application.
The painting methodology was tested in two manners. The first, application of paint over the transfer tape. The tape was removed immediately, in one test, and after the paint had dried in another. Neither made a noticeable impact so long as the paint was able to dry undisturbed.

This picture, however, illustrates a flaw in the application using this method:
Paint applied and transfer tape removed after drying
The smudging and distortion of is caused by excessive application of paint. This should be kept in mind for manual use as well as future process automation. When done correctly, the end result so resemble this plate:

Successful Application
It also turns out that as long as the applier takes great care, similar results can be achieved without the use of transfer tape. One simply fills the engraved sections with paint and removes excess from the surface with a cloth moistened with acetone or paint thinner. The results of which are seen below.

Successful Application without Transfer Tape

However, looking at this image, one could say that the green isn't sufficient as some MDF can be seen through it. Perhaps we should look into using something as a base paint and then adding a coat of the intended color, much like priming a wall. Well we did test that and the results were not satisfactory.

Painted with White base layer and Green top coat
Resulted in a mess. This method was not successful in multiple attempts and shelved for later. It is a suspicion that this idea may work better depending on the type of paint used in the application. The necessity for something providing a similar hardness as enamel is understood, but perhaps their are paints available tailored to these types of jobs or more MDF friendly and so forth. We have yet to test this factor.  What we do know is that moderate application of paint and time to dry undisturbed are key to producing a quality fill. Perhaps a better way to mitigate the MDF coverage problem is to increase the depth of the engraving. It so happens that we tested this idea and with levels of success as well.

Why not do the same thing for the topside of the TurtleBot's top plate? Engraved text and images can replace stickers as means of identification and aesthetics.

This is a sticker that we currently have in use:

Companies have logos. Most agree, putting your logo on a product amounts to free advertising. Advertising is so pervasive in our culture products look strange without them. So far, the TurtleBot has only been branded with a simple stickers.  We have been looking at sticker manufacturers that could produce die cut stickers with fine line and details.

While the sticker is of good build quality, it does not entirely meet desired specifications. We wanted a sticker that felt like part of the product; cosmetically, we wanted to achieve finer line width on the lettering and "power heart."

Overall, this idea means we now have a cost effective means of producing high quality labels and logos for prototypes and low volume production runs. In the future, we would like to explore efficient methods of multiple color applications in addition to expanding application methods themselves such as spray painting. Part of that process includes finding solutions for achieving a satisfactory fill.


Anonymous said...

That's pretty neat. What I'm actually wondering is: How do you paint the turtlebot plates? The finish looks really nice.

I Heart Robotics said...

The black surface is laminated on.
Talk to your local suppliers about what types of laminated MDF they offer.