How we make the Flipper Zero case flawless
Flipper Zero – a project of a pocket multitool for hackers in the Tamagotchi form factor, which we are developing. Previous Posts ,,,,,,,,,,,,,,
All parts of Flipper Zero are made in cool factories (our factory casts casings for Hewlett Packard printers), it is impossible to start production of such a complex device on the fly, without a stage of debugging the production line.
In this article, I’ll show you how we fix casting defects in the first batch of Flipper Zero injection molded housings.
Casting debug stages
Any new body made by injection molding goes through several stages of debugging – called T0 (Testing 0), T1 (Testing 1), etc. Each subsequent stage corrects the design of the parts, the mold, and the casting process itself.
In the first two steps, parts are intentionally fabricated without the final texture applied to the surface so that major changes can be made. In these first stages, shape defects are clearly visible.
Texture and colors
In the later stages of debugging, we finally applied shagreen texture, giving the body a beautiful and expensive look. Goodbye to cheap gloss! We also chose the colors more accurately, now the buttons are juicy orange.
All plastic in Flipper’s body is mass-colored. That is, the paint is inside the material itself throughout the depth and does not rub off.
In order for the surfaces of the parts to acquire the shagreen texture, the corresponding areas of the molds are etched with acid.
Defects around the joystick
In the early stages of production, prior to surface treatment, the button area developed burrs, dents and butt seams due to the merging of two streams of plastic during injection.
After debugging the mold, adjusting the injection flow and applying the texture, we got rid of these defects, and now the surface in the area of the buttons looks nice and smooth.
Wavy lines on the screen cover
The first versions of the screen lid cover had blurring and wavy lines due to the injection stream. These unusual waves are only visible from a certain angle.
Wave creation is caused by sub-optimal injection temperature and pressure settings of the casting machine. After adjusting the equipment, the waviness disappeared and the lid became crystal clear.
Clearance between body halves
The ejector pins that eject the part from the mold after casting protruded too much, resulting in a gap near the GPIO holes.
After resizing the ejector pins, the protrusion has been removed and the halves now fit snugly.
Holes and markings for iButton
The iButton contact holes were covered with excess plastic due to a suboptimal injection process. After adjusting the injection process, the problem was resolved, now all the holes strictly correspond to the design drawings.
The 1-wire pin markings have been updated to match the latest PCB revision.
The slot under the IrDA window
Due to the strong pressure on the infrared port window during the welding process, a 0.35 mm thick gap was formed under it.
To fix this error, we offset the weld point and added guide ribs. Now the IR window is located exactly in the center, and unnecessary gaps do not form around it
Case next to SD-card
The top cover on the side of the SD card had some typical defects caused by suboptimal design of the moving parts of the mold. After modifying these details and applying texture to the surface, all stress marks and butt seams will disappear.
Burrs on the connecting sleeves
In the early stages after injection molding, there was excess plastic (burrs) on most of the coupling sleeves, which prevented proper assembly. This was caused by the incorrect position of the special pins that are inserted into the mold to form the bushings.
These pins are intentionally removable and are not an integral part of the main mold due to their relatively short service life. After fixing the position of the pins, the burrs disappeared.
Laser engraving on black body
In the first black samples, the lettering on the case looked much worse than in the white samples. This was due to incorrect laser settings. Now two separate preset profiles are used for different body colors, and the engraving is neat and readable.
Logo color on black cases
The logo on previous black cases was poorly applied. After calibrating the ink color and print density, the logo became bright and contrasting.
Pre-order Flipper Zero
Our top priority is orders from Kickstarterso our backers get Flippers first.
If you missed the Kickstarter campaign, you can pre-order now and get Flipper in the fall as soon as the second batch is ready. Pre-orders help us calculate production and logistics.