What does the production of Flipper Zero cases look like from the inside

_{Flipper Zero – a project of a pocket multitool for hackers in the Tamagotchi form factor, which we are developing. Previous Posts [1],[2],[3],[4],[5],[6],[7],[8],[9],[10],[11],[12],[13]}

We are now actively setting up the Flipper Zero mass production process in factories. Flipper’s components are manufactured in several factories: body and plastic parts in one factory, electronics in another. Today there is a report from the factory where the building is being made.

There are many ways to make plastic parts, but the only way to mass produce quality parts is by injection molding. At first it may seem like this is a simple process, but in fact it is not. Designing the case and all the rigs is not much easier than designing electronics. Therefore, cheap products are always visible in the low quality of plastic. In this post, we will tell you what the production of a case looks like in a factory.

Casting preparation begins at the design stage

The development of the mold begins with the design of the case, because the casting method imposes many restrictions: the industrial designer must lay the correct angles and surfaces so that the part can be removed from the mold. Any mistake here will lead to the fact that the manufacturer simply cannot produce such a part, and the model will have to be redone.

Openings in the case require special attention: a GPIO comb, a hole for a USB port, etc. To make such blind holes, the body is threaded with needles from the side.

But how, then, to remove the body from the mold, if it is held by needles? To do this, they are made mobile, and the form is poured in several stages:

• The movable part with the needles moves into the mold

• Plastic is poured

• The movable part moves out when the plastic has cooled down a little

• The part is removed by a pusher

Simplified diagram of moving parts in the video:

How are molds arranged

The shaping parts themselves are small in size. Usually these are two metal halves, which close and form a cavity, into which plastic is poured.

The photo shows the intermediate stages of the manufacture of shaping parts. Places that were later modified are marked with a marker. There are 11 plastic parts and 7 molds in Flipper. The photo shows only some of the most recognizable forms.

In addition to the molds themselves, the mold consists of many injection channels, contains electronics for heating, pushers and motors for them, springs, temperature sensors, connectors and much more.

The final size and weight of the mold is so large that it is transported on a trolley. The photo below shows only one mold for the bottom cover. We have six such pieces in total.

3D model of the mold (video)

Inside, the form looks like this. See how many details!

Casting simulation software

It is very important that the plastic in the mold solidifies evenly. If at some points the cooling occurs too abruptly or too slowly, then stains and sinkings will appear on the surface of the part. For this, the mold is heated in different places.

Before the mold is made, its physical model is built, with the help of which the plastic molding is simulated programmatically and its temperatures are calculated at different points.

The animation below shows two options for supplying the injection channels and heating the mold at the end point of casting. After simulating different options, the best shape design is selected.

All important steps are simulated: casting temperatures, filling speed, cooling temperatures, extraction pressure.

Casting start

The plastic injection process does not start overnight. The forms are tested and perfected in several stages. At the first stages, it is checked whether the expected physical model corresponds to reality, and how the plastic flows inside the mold. For this, incomplete parts are specially poured, gradually adding plastic until the form is completely filled.

If at the stage of filling out verification the reality does not meet expectations, the form is sent for revision. At this stage, the final surface coatings are not yet available in the molds.

Each form goes through this testing stage. It is important to understand that the glossy shine on the surface of the case is not the final look. The surface texture is applied to the forms only at the very end.

All parts hang on injection channels, from which they are then broken out. It is important that the place of attachment of the part is as thin as possible and does not leave unnecessary burrs and deformations when breaking off.

Final cover

In all the photos, the plastic parts look glossy and squalid. This is because the final coating has not yet been applied to the mold. To obtain a beautiful matte soft-touch coating, shagreen is etched on the surface of the mold with acid. Only then does the detail acquire a noble matt look. This is done at the last moment, after all the modifications to the forming part.

Defects

As in any production, jambs are found at the first stage. In general, we rate the first castings quite high, no fatal defects were found, and the bulk of the edits were already being made at the time of the article description. The defects listed below will be fixed in the final device.

Color mismatch

The color of the part is achieved by mixing the pigment into a mass of liquid plastic. In addition to the color pigment, there are additives for UV protection. Because of this, it is not so easy to get into the right color. In the photo below it is difficult to see, but in reality the finished button is much darker than the color swatch on the left.

Utyazhiny, stress marks

Due to uneven cooling of the part, minor defects arise: noticeable seams, stress marks. Such defects are corrected by adjusting the heating and plastic supply.

Moving parts can leave a seam. According to our specification, the seam should be less than 0.05mm. To remove the seam, the factory adjusts the seams more precisely and grinds the surfaces.

Covers

The covers turned out to be unrealistically cool: very dense matte silicone, expensive-bahato to the touch, like branded iPhone cases. I did not expect that the first time such cool samples will be. The shape will be slightly altered so that the cover does not protrude in the area of ​​the screen, otherwise everything is fine.

Preparation of packaging and articles

Getting ready for international shipment. Registered official barcodes in GS1… We form customs classifications and other pieces of paper. Food icons on barcodes are our internal designation of regions and device colors to make it easier to visually distinguish.

Our social networks

First of all, I publish all updates on the project to the Telgeram channel. @zhovner_hub