How to design a housing for a device. Complete Guide

This is what cold casting looks like in a silicone mold (the mold itself is pictured on the right). Silicone equipment is cheaper than metal, but is only suitable for a couple of dozen cycles, then the mold can be thrown away

Every engineer and technologist knows that a project never goes 100% according to plan. Even if you foresee possible risks, at some point you still have to act according to real circumstances, and not according to plan. Especially if you are doing something for the first time, working with a contractor from a different cultural environment, who is thousands of kilometers away. With experience, unplanned situations become much smaller.

For seven years on Habré, we have talked about all the stages of creating new devices for the electronics market: from the idea to the launch of mass production. This time we will focus on the development and production of cases in China, noting the pitfalls that may await you on the way to a new product.

How to design a case - work diagram

You can almost certainly design the case for your device yourself.
The main thing is to have a good understanding of the entire cycle, from idea to production. Corpus development is a process divided into several mandatory stages. I won’t even discuss this: it has been tested many times. Even if you are not going to get involved with “big” production (for example, if you plan to make a device only for yourself), it would still be better for you to follow the correct sequence of steps.

And for those who doubt their abilities, I’ll say right away - you’ll definitely be able to figure it all out: software has stepped far forward, and now you don’t need to spend several years to put the first prototype of the case on your desk.

Here is the scheme we will follow:

Step-by-step scheme for developing the device housing

Task

I have a test in my work that allows us to weed out would-be innovators-compilers.
I ask you to send a description of their idea with formal (numerical) characteristics. For example, the idea is such and such, the device should function this way and this way, the cost is approximately this. If the product is a pure compiler (we’ll attach Wi-Fi + a cloud service with a blockchain to a teapot), then there is (as a rule) no description and there won’t be: the person is most likely lazy, he needs to be listened to, and the task described in his words. But the problem here is not even laziness, but an unwillingness to think about the key characteristics of the product, which are directly related to the complexity of the future product. It’s not for me to explain to you that at least the functionality, battery life, cost (and sales) directly affect the “hardware” component of the future device.

That is why we need to formulate everything we want to implement and describe it in a document. Even if it is clear that it will still change 30 times, yes. Therefore, we move on to paragraph 1.1.

1.1. Formulate your wishes

Let's start with 5 main questions:

1. Why do you need the case - what will you do with it?
   Will you use it at home, create a prototype for an investor, or sell the device? The answer to this question will immediately tell you at what stage of readiness the housing needs to be designed. After all, there are technologies that forgive mistakes during development (for example, 3D printing), and there are those that can ruin the project (molds, more on that later).
2. What is the planned circulation of your device in the first year?
   I understand that often there may not be a clear answer to this question, but at least take a guess. One device? Tens, hundreds or thousands?

   The choice of production technology depends on the answer, which, in turn, greatly affects the project budget. More on this in the post on how to evaluate a hull. And here are examples of prices for the production of cases with different sizes and circulations, and manufactured using various technologies.

3. How important is design to a case?
   We all love beautiful and comfortable things. But is design really that important when starting a project? More details about this in this post.
4. Under what conditions will the instrument or device operate?
   In regular ones, at room temperature? What if it’s snowing outside?

   A video of the same thing, but of better quality, is available on the Technotron NPP channel.

5. Who are your competitors?
   If you answered this question that there are no competitors, then something is wrong here: you are either too lazy to look, or, in principle, incorrectly assess the real need of your client and how your product solves it (I touch on the topic a little here: formlab.ru /konkurent). The answers to all these questions will form the basis of the technical specifications.

1.2. Set the cost bar and circulation

A very important point.
At first, few people think about the maximum cost of a product. The faster it is understood (at least at the filling + body level), the sooner the project will be completed, and the less wandering and iterations there will be. If there is no data at all, you can look at your competitors. We take a weighted average direct competitor, look at the selling price of its product, and divide it into three parts: cost + marketing + margin.

This is the cost level that we will have to navigate. And I would like to emphasize that it doesn’t matter how accurate this estimate is, the main thing is the order of costs for one product, which will then have an impact on everything: what circulation is best to plan, what components to use and how large the start-up costs will be.

Note to the owner: even if you produce a product in a smaller quantity than your competitors, you will not be able to get a price lower than theirs. Those start-up costs that they have been covering for several years now are just ahead of you.

1.3. Fill out the terms of reference

All the information that we collected above must be included in the terms of reference. Its form depends only on you - write as you see fit. Or download our template (free.formlab.ru/tz.zip) with instructions for filling it out; there are even a couple of “live” examples in the archive (formlab.ru/tz).

What methods of making metal cases are most in demand today?

1. Laser cutting.

Laser cutting of metal is the latest technology for cutting sheet metal. This method has several advantages over traditional methods:

• with laser cutting there is no mechanical impact on the material being processed;
• a laser beam cuts almost any material, no matter what thermophysical properties it has;
• The positioning accuracy of the laser head is approximately 0.08 mm, due to which the accuracy of the relative position of the workpiece elements is quite high;
• laser cutting can be used on easily deformable and non-rigid parts;
• The diameter of the laser beam is about 0.25 mm, which makes it possible to create holes with a diameter of 0.5 mm.
• high power of laser radiation determines high productivity of the laser cutting process;
• Using the capabilities of laser cutting, you can cut almost any sheet material along a complex contour.

Laser cutting of metal means a high speed process, impeccable quality and an affordable price in any application. Also, laser cutting does not involve high financial costs: no matter how many parts there are, the price for them practically does not change.

Lasers can be used to cut steel, aluminum and other materials. The laser machine is the initial stage of case production. The production of other types of metal products most often also begins with laser cutting. It begins with the production of metal cases, cases for electronic equipment, custom-made metal products in the form of sheet blanks and other metal flat parts of any complexity and any geometry. Metal products made using laser cutting do not require post-processing, and the production of sheet metal enclosures is simplified.

2. Flexible.

Bending of industrial products is performed on high-precision hydraulic bending machines. These machines bend metal and metal workpieces up to 2.5 m long and 0.3 to 8 mm thick. Bending can also be performed with installed hardware and threaded bolts. This allows for a more technologically advanced approach to the production cycle for manufacturing cabinet products.

Often, the manufacture of housings for metal devices involves the presence of welded or otherwise secured fasteners - studs, threaded bolts, threaded rivets and bushings.

All these fasteners are installed in instrument housings in various ways. This:

• condenser welding of hardware;
• pressing of bonks, bushings and studs;
• installation of blind rivets and threaded bushings.

3. Welding.

Sometimes it is necessary to carry out welding work to secure the bent body. Welding is carried out in the following ways:

• semi-automatic welding in a carbon dioxide environment;
• argon-arc welding of aluminum alloys with alternating current and stainless steel with direct current;
• resistance welding.

Welding connects products of different thicknesses made from different metals:

• welding of metal with a thickness of 0.5 to 10 mm;
• welding stainless steel with a thickness of 0.5 to 6 mm;
• welding of aluminum with a thickness of 0.5 to 6 mm.

Welded metal cases or stainless steel welds are cleaned and, if necessary, ground or subjected to other types of metalworking before applying paint.

Design

Another question I often ask when talking to clients is: “How important is design to you?” The total majority answers that it is important and this is understandable (and where is it not?), but it is better to ask an additional question: “Do you have competitors? Do they invest in the design of their products?” And the answers to these questions will give a clearer and more in-depth idea of ​​how much design is needed to sell a product. I have already touched on this topic on Habré.

2.1. Sketch an idea

Sketching (aka hand sketches) allows you to imagine what the future building will look like.
Now you will say: why is this necessary? Still, it will be clear. Not entirely true.

Experience shows that project visualization is important because we all see the same things differently. If you need other developers to see the future body of the device the same way you do, draw it as best you can.

Be sure to draw the body of the future device - how it turns out.
You don’t need to be an artist here. You can just start sketching one element, and it immediately becomes clear whether you’re going in that direction or not:

Sketch

You can sketch it on a napkin or A4 sheet; on the way home on the subway, in a cafe, on your knee, anywhere. Again, quality doesn't matter.

2.2. Draw a sketch

Hand drawing is good for only one thing - speed.
But often what is drawn in the picture (if you are not a professional designer) is not realizable in practice. Therefore, you need to “ground” your idea, bringing it closer to reality, starting with the dimensions and ending with the detailing of the elements. It’s better to take a screenshot of an image of your electronic board and try to sketch on top of the resulting picture how you see the case. Here, quality is also not very important: the main thing is that the person to whom you demonstrate it imagines what exactly you wanted to show, and that they are understood correctly:

• proportions;
• what parts the body will consist of;
• where the controls and displays of the device are located;
• materials from which the parts are made.

It makes sense to check the result on someone who is doing the project with you. For example, show the drawing to a programmer sitting at the next table and ask him how he understood the idea (if he understood it at all).

Detailed rendering

If a colleague, after looking at the drawing, starts asking about problems (“The board won’t fit here, but how are you going to get the cable through here?”), that’s great. This means that, most likely, the form factor and proportions of the case are correct, it accepted your idea.

Well, then the developers just need to start agreeing on the details and “embroider” the problem areas of the future product with additional explanatory drawings.

2.3 Develop a 3D model

If you have even a little knowledge of CAD, skip this step. If not, then there is only one piece of advice: start using CAD (but not AutoCAD - that’s not it).
Below is my own list of the required software - with links to the official websites of the developers. At the model development stage, you can use the simplest and even free programs. After all, the task of this stage is relatively simple - just imagine the future building in real dimensions and proportions.

3D model

I strongly recommend that you design the design directly in engineering software (from the list below) - save yourself a lot of nerves and a bucket of blood. No polygonal 3ds Max or analogues. As a last resort, you can use surface modelers (Rhino, Alias ​​studio), and then in capable hands.

2.4. Visualization

This point could be skipped altogether - visualization (rendering a model with photorealistic materials), in my observation, disappears from projects in its pure form.
This happens because the result (pretty pictures) has lost its significance for the actual product development process. It is needed only for advertising departments - so that managers can show pictures to investors, partners and management. But if you still have to show your project to someone, then the visualizers built into CAD will be more than enough. If not, it’s easier to turn to freelancers and entrust this task to them - there is a lot of software that makes beautiful pictures literally on the fly (google keyshot

, For example).

On renderings it makes sense to show the degree of glossiness (matteness) of the surface and color:

The handle of the device is made of matte plastic

Case design development

Industrial designers and designers believe that the design of the case is the main component of a new device, because it is precisely because of it that gadgets are bought.
I saw it, I wanted it, I bought it, I used it. Of course, the engineers and programmers who work on the product's functionality might argue with this. In the process of developing the design and construction of the case, many restrictions are taken into account at once:

• customer wishes;
• purpose of the product;
• area and conditions of application;
• ease of use;
• consumer requests.

At the start, designers work through many options, usually at least 5-7 different directions, from which they select 2-3 of the most interesting ones to demonstrate to the customer or project working group.
As a customer, you may have many ideas that you want to implement in your product, but they cannot always be combined due to technical production limitations or aesthetic contradictions. Experienced designers take into account that discussing and finalizing various cabinet solutions will take about half the time of the entire project. Negotiations, calls, correspondence - personal, together with the designer, with the project manager. Coordination is sometimes more difficult than the design development process itself, but this is a normal part of the project. You need to be prepared for this.

iPhone sketches. Authors: Jonathan Ive and the Apple design team. Date unknown

In parallel (necessarily in parallel!), a designer is involved in the development of the design. It brings the designer's flight of thought down to the real requirements of production technologies. If you leave the designer to his own devices, the development time may be delayed: the design has been developed, agreed upon, re-agreed, super, but it is no longer possible to produce the product by casting in a mold without significant adjustments to the appearance. And you have to start the process again.

Engineering

In which program is it better to design a case
? Great, the appearance is approximately defined, now let's get down to engineering the future case and start working on its design. Here you will have to master a new program - a computer-aided design system or CAD (CAD).

There are several dozen such programs, all different and intended for different audiences and solving different problems. Therefore, I have compiled a list of those that suit most.

I would like to note right away that you need to look for free versions yourself, but they are freely available, they just have restrictions or are intended for non-commercial use.

This is a list of CAD systems that I have come across myself, but there are a great many of them - for every taste, task and budget. Those who want more CAD software are welcome to Wikipedia.

If you have enough qualifications to design electronics, then I recommend immediately looking at Compass, Solidworks or Inventor: these are easy-to-learn programs, there are a lot of materials and videos on working with them online, and they themselves have everything for development and production; in short, they can make projects based on any production technology. They are also almost omnivorous in terms of formats. I myself have used SolidWorks for many years and have only seen problems when using complex surfaces.

3.1. Layout of elements

Now you need to model your board or main components in 3D.
We will continue to build our building around this model. Try to measure all the details more accurately, it is better not to use the “by eye” principle - it is ideal to use a model from the manufacturer of the components and the board itself and check everything “hands” on “live” parts - with a caliper. There is no need to be afraid of making a mistake - there is always the opportunity to roll back and correct some size.

3.2. Engineering modeling

We build a housing around the board, starting from the main primitives and the largest sizes and gradually detailing it.

You need to follow a few basic rules:

• there should be no intersecting parts;
• you need to imagine how the body should be assembled, and all the parts should mate with each other;
• we must strive for equal thickness: all walls of the case should be approximately the same thickness, for example, 1.5 mm:

You can read more about designing a plastic case here → formlab.ru/kak_razrabotat_korpus_iz_plastika.

3.3. Development of production technology

“Am I planning to mass-produce my product or am I making it just for myself?”
At this stage of developing the corpus, it is very important to answer this question as honestly as possible. If you don’t plan, then immediately move to the next stage of the development process. If there is a “series” in the plans, then you need to decide how many copies the product will be produced.

And here - in detail about the circulation and its calculation.

Now let's limit our wishes to a couple of dozen buildings.
This circulation is ideally suited to the technology of polyurethane casting into silicone molds (parts are made from a material that is identical to conventional plastic). But first, let's make our product more technologically advanced. We need the body to be able to be removed from the silicone mold (equipment), which means that all the walls of the mold should be at a slight inclination(s), literally 3° vertically:

Giving technological slopes to the ribs

Test passed - surfaces turn green

I repeat again - there is no need to be afraid of making mistakes. The development cycle is designed in such a way that all errors appear and can be corrected.

Hull design development

Let's assume that we went the right way and immediately after agreeing on the design we started 3D modeling of the product and its components.
A designer, or several designers, depending on the complexity and composition of the product, using various CAD systems, bring the designer’s sketches to life. In the process of developing computer models of the case and more detailed study of every detail, the need for minor design adjustments may appear (and appears!). Designers provide for casting slopes, ensure uniform wall thickness and correct corner design. We have already talked about these subtleties in an article about injection molding.

A good designer will also coordinate all these changes for manufacturability with the customer so that there are no misunderstandings during acceptance.

iPhone 5 drawings, image from Apple Inc.

When developing a housing, it is important not to skip the stage of computer modeling of physical processes to check the reliability and defects of the casting.

Then, having 3D models and product drawings in hand, you can send them to potential contractors in our beloved China to estimate the cost of production. After thinking a little, adding their margin, they happily send offers, often differing significantly. This happens because there is a difference between contractor and contractor, and some really make high-quality things at a high price, while others make not very high-quality things, but also at a high price.

Typical demo stand with product samples at a Chinese plastic housing manufacturing plant

How to make a choice? Rely on your own and others’ experience of working with contractors, analyzing previous proposals for similar or analogous products, comparing production times.

When the housing manufacturer has been selected, a supply contract can be signed. At the same stage, you can estimate the cost of manufacturing a prototype housing.

Design documentation

Examples of design documentation here → formlab.ru/cad.

A package of design documentation is, in fact, a single package of files that should describe your case and all its components in as much detail as possible for production.
Inside there will be (in addition to the three-dimensional models from the previous section) detailed and assembly drawings, specifications (a list of parts with their parameters), a document on the cost of production according to this documentation. All drawings are made, as a rule, in the same CAD in which you developed the models, but I still recommend passing them on to specialists with relevant experience for preparation: you can get seriously burned if you do not notice an error in the design or do not provide the necessary information on the drawing.

4.1. Detailed and assembly drawings

I have heard more than once that drawings are being used less and less in design work. But this is not entirely true - nothing can replace a drawing. The thing is that the drawing describes what cannot be described in the model: tolerances, production accuracy, materials, methods of pairing dependent parts and much more - according to the standards of design documentation. If not according to standards, then different enterprises will have different interpretations of documentation, which means the number of problems during production can increase many times over.

4.2. Specifications

Also an important component of the design documentation package. This is a description of all parts, quantity, material from which the case is made, price (if the component is purchased) and any other important information - all in the form of a single plate, which is filled out at the very end of development and complements the package with drawings and model.

4.3. Cost estimation

It’s a commercial proposal, it’s a quotation, it’s an offer:

And if there is a red seal, then it’s generally good:

Prototyping: production of a prototype housing

Before making an expensive prototype, we need to make 1-2-3 models of the product to make sure that we really get what we wanted. There are different ways to make a body model - it can be grown or milled; most often, FDM-growing is used as the best option in terms of cost, time and result.

A CNC milling machine cuts a prototype body from caprolon, which is also known as polyamide 6

Only after receiving the model, holding it in your hands, touching it, dropping it, and pressing physical buttons, you can understand the correctness of the chosen design. Why are the second or third iterations needed, you ask? Because often the first grown model, and sometimes the second, requires some adjustment based on the results of live testing.

The housing prototype, manufactured using the milling method on a CNC machine, is practically indistinguishable from a serial product obtained in industrial production. That is, you will be holding a sample in your hands, ready to show to potential buyers, management or investors.

Gantry CNC milling machine for fast and precise processing of parts in one of the factories in China

This is what the cutter looks like in the machine with the doors open. They are closed during operation to prevent aluminum shavings from flying into your eyes and onto the floor.

Prototype

In fact, our body has been developed, but it is still a picture on the monitor, a 3D model.
Experience shows that any 3D model has a number of shortcomings that are simply impossible to calculate in a virtual development environment. To identify and eliminate problems, you need a physical model - a prototype of the case. Let's take care of them. To do this, you need to export your model from the source program into a universal format, such as .stl, and send it to a company that does 3D printing. There are a lot of them, the search will help you (and I wouldn’t chase the lowest price tag - it doesn’t end well).

The first question from such a printing company will be: “What technology do you want to use to print your case?”

Case prototype
The question is reasonable: there are already several dozen technologies, and each of them has its own pros and cons. So let's decide: what do we want from the prototype?

• Of course, assemble the device and see what it will look like - i.e. close the issue of collection. At the same time, check whether the device looks as expected.
• I would like to test the device in real life, carry it in my pocket, put it outside in the snow, or dip it in a real puddle to check the tightness.
• Show it to an investor, client, at an exhibition - solve marketing issues, business problems, etc.

Unfortunately, the first generation prototype will not be able to solve all these problems at the same time. On it you can only check the assembly and conditionally evaluate the appearance. “Conditionally” - because the printed model of the case will be far from the real one, mass-produced. But for now this is not necessary.

5.1. Prototype production

For a first-generation prototype (or mock-up), it is better to choose the cheapest technology - plastic filament printing
, or
FDM
. In short, the body will be printed from plastic thread layer by layer from bottom to top, something like this:

Printers that print with plastic filament or FDM technology are now everywhere. All this is inexpensive (a couple of thousand rubles per case, prices hereinafter are relative).

Sometimes it is even advisable to buy a printer and make layouts immediately during development, but this only saves time.

If funds allow, then it is better to order higher-quality printing using SLA or SLS technologies (here the cost will be from 10 thousand rubles). I have already reported on Habré about how to choose the right production technology for a case. And in order not to get up twice, here is my video about “When and why is 3D printing useless?”

Milling of plastic and metal

— the required body or part is milled from a plastic blank, which differs little from the serial product. Such a building will cost from 30 thousand rubles.

Silicone casting

- generally a good option (and the only one if you require a sealed housing or “rubber”, i.e. flexible parts). Such a building will already cost from 50 thousand rubles.

5.2. Assembly and testing

Based on the results of prototyping, you will immediately see where there are problems in the design and design of the case.
Therefore, the next step will be to return to the previous stage and make changes to the model. And so - several times, depending on your accuracy and experience. Experts make do with a couple of generations of prototypes and move on; beginners need more - sometimes even up to dozens. Why is prototyping important? The more prototypes are made, the more problems will be identified, which means the final product will be as thoughtful as possible.

Tests: the device in the housing we developed lay in a bucket of water for a day and then continued to work

5.3. Editing models and documentation

Nobody even thinks about this point at the start, and it’s impossible to avoid changes: always (not even like that - absolutely for all projects) after the testing stage (layout, prototyping), errors are identified that need to be corrected in the model and documentation. And then again and again. Corrections should continue until the team runs out of budget or until it feels like the model is completely polished, the prototype is perfect, and we need to move on to mass production.

Electronics housing production in China

4.1. Selection of materials and contract for the manufacture of equipment

To produce the housing, equipment, tooling, materials and workers are required.
The contractor has the equipment, because we chose it based on the technical requirements of our production. But the materials for the production of body parts need to be decided in advance, even before the production of the equipment, because each material has its own casting and performance characteristics; volumetric shrinkage during cooling is especially important for polymers. And initially, the mold must be designed for a certain range of materials in order to match the final dimensions of the cast part to your drawing/model. So, the design, construct and prototypes have been agreed upon, and we can begin production of the product. It all starts with the development and production of equipment, that is, molds for plastic, injection molds for aluminum, dies for steel parts. These processes are quite lengthy and expensive, and they begin with the approval and signing of an agreement for the manufacture of equipment and mass production.

Mold assembly and maintenance area, unused equipment is prepared for preservation

A contract for the manufacture of equipment or for serial production of products is prepared very carefully, usually in Russian and English. The comrades from China sign the agreement instantly, probably only looking at the amount and terms. But if, in the event of any incidents, you demand compensation for a low-quality product, and you are refused due to the lack of close ties or weak prospects for further cooperation, then you can safely forget about both the contract and compensation. Suing a party located on the other side of the Earth is extremely unprofitable if you do not have million-dollar projects...

Therefore, both mature companies and startups without their own production do not always turn to Chinese manufacturing plants directly, but work with them through contract manufacturers, who themselves choose a contractor from a list of trusted partners and take care of all organizational issues, including quality control and all related There are risks with this.

It is also worth considering that at the stage of design and manufacture of tooling, it may again be necessary to adjust the design and design of the body to ensure manufacturability of the part.

Workshop for the production of molds at one of the factories in China. On the left is an area with equipment, on the right is CNC metalworking machines

If you work directly with a manufacturing plant, you need to regularly inquire about the status of the tooling production process: is everything going according to schedule, are there any problems in production, will we be able to meet the deadline. Not all Chinese manufacturers carefully monitor production deadlines and immediately inform customers about delays and failures. If you don’t check them yourself, there is a risk of receiving a “bu hao isy” response from your contractors at the required time instead of the result, i.e. “Sorry,” well, it happened, such circumstances, we couldn’t do anything, that’s how the stars aligned...

4.2. Obtaining industrial samples of the case and approval of the Golden Sample

After the design and manufacture of the equipment, the most exciting process begins - obtaining the first industrial samples and getting closer to the cherished goal - holding your serial product in trembling hands.
Usually a suitable sample is not obtained the first time. Often, modifications to certain elements and surfaces are required to ensure that the housing fully matches the desired look and feel.

Injection molding machines for the production of plastic products using injection molding. Finished products move down a green conveyor belt

Since China is far away, to optimize overall costs, the first samples are evaluated using numerous detailed photographs and videos. This is quite enough for a preliminary assessment of quality. We point out the shortcomings to our Chinese comrades, discuss them and find the optimal way to solve them.

The shortcomings are corrected (under constant supervision), and we get the second iteration of the sample. With careful study of the first sample and the right steps to improve it, the second iteration usually fully matches the desired result. Again we evaluate the case using photos and videos. If all is well, we order delivery of 3-5 samples for visual and tactile evaluation.

After 4-5 days and customs clearance, we receive the first long-awaited production samples of the case. We touch, feel, iron, drown (subject to water resistance requirements), freeze, analyze, evaluate and again look for ways to improve it further to achieve the ideal result.

If any comments appear, we adjust the equipment again and make repeat samples. If everything suits you, you can safely demonstrate it to the customer, investor or potential users. The closer the product is to the final stage of the project, the more expensive, time-consuming and painful it will be to make changes to the design and construction. However, it is possible.

This is what molded buttons look like for various electronics housings. The casting channels are then broken off, and the joints are ground

After all the above iterations, you can go on a business trip to a contractor in China. This usually takes several days, excluding travel time. At the manufacturing plant, it is necessary to completely simulate the process of mass production of the housing (i.e., work on a small batch) in order to debug all stages, obtain and finally approve a serial sample, the so-called Golden Sample, and equipment for its production.

4.3. Serial production of housings

The actual production of the treasured cases for a new electronic device occurs practically without your participation.
Chinese contractors, according to the deadlines specified in the contract, and only after prepayment, manufacture product components and, if necessary, organize assembly. It is imperative, as in the case of tooling, that it is necessary to periodically monitor the production process and its schedule. You also need to determine the frequency of quality control of the cases and agree on sending information about the progress of the production process. For example, up to 100% of products can be subject to appearance control (especially if castings are removed from the mold manually). We check compliance with the specified dimensions every 200 mold cycles. Test for water resistance of the assembled product - every 1000 products, and so on.

Quality check at a Chinese plastic products factory

Our experience shows that Chinese contractors have their own specifics of working with photo and video reports. The photos sent are almost always not of very good quality, although technically now in any more or less decent phone the camera allows you to take excellent photos and videos. Only after several repeated requests for photos and videos can we finally examine in detail any defects or inconsistencies. The calculation is simple: since you didn’t see the defect, it’s your problem, we sent you everything, you looked at everything, agreed, what do you want now? So don't hesitate to request as many good quality photos and videos as possible.

Test batch

A test batch differs from a serial batch, firstly, in its circulation: as a rule, this is only a few products. Secondly, another, less widespread technology. And that’s exactly why each copy from the test batch is “golden”. Habré even suggested the term golden sample - it fully reflects the essence. Let's figure out how to organize all this.

6.1. Production

Any production begins with preparation for it. Let's see how this is done (don't forget that our conditional circulation is two dozen cases). As a production technology, we will take polyurethane casting into a silicone mold.

Search for production

Searching for production is no different from choosing any other contractor.
With the exception of the budget, a large plant is absolutely not interested in dealing with a small order. In this case, you need to either be persistent or immediately weed out those who do not make contact. The algorithm is as follows: we are looking for enterprises that use the technology that we need in production, we attach our model in the universal .step (or .iges) format to the application, we write a letter to the factory, where we indicate the circulation, requirements (color, case rigidity, availability inscriptions) and send it to everyone we found. We are waiting for responses. The productions that respond to your letter will definitely ask you clarifying questions. Answer them in detail.

For those who are lazy to look for housing manufacturers on their own, we have created the “Customer” website - zakaz.ist/plast.

Another recommendation is not to pay attention to the geography of the enterprise: there is no point in choosing “closer”. This certainly won’t give you real control over the production process, but it will definitely increase the price. China here is a completely different story, about which volumes could be written.

Production of molds

As I wrote earlier, we will now limit ourselves to a simple example - casting polyurethane into silicone molds.
Other technologies are more complex. When the contract is concluded and the advance portion is paid, the plant begins to produce molds for production. Since we agreed that we need dozens of cases, this means that the mold will be made of silicone, and before that they will make a master model of our case. There are a lot of videos with this process (search for the keyword “casting in silicone molds”) on the Internet, and below is a photo of the mold itself:

They begin to produce test cases of cases using such equipment - to understand how satisfied you are with the resulting case. If you are not satisfied, then you need to make changes either to the case model, and then start the entire development process over again, or limit yourself to a “cosmetic” alteration. The number of changes and the extent of changes is difficult to guess; guarantees are also impossible to achieve; you just need to use common sense and discuss changes with plant specialists.

6.2. Feedback from users

And this is exactly what the test batch is made for - users will tell you things that you won’t be able to figure out on your own.
Conventionally, we assume that the device will be used like this, but for a real user the scenario will turn out completely different; and what kind - you may not even know about it. For clarity, here is an example. A couple of years after the product went into production, it turned out that users were forced to regularly open the device’s case. And the design of the fasteners and latches was made taking into account the opposite scenario - hang it and forget it. And if a test batch had been made and decisions had been made with an eye to testing not only the prototype, but also this batch, then the problem would not have come to light at all. But there was no test batch, and users are still breaking the case (more details - formlab.ru/alarm_system_pritok).

You definitely need to not only listen to what they say (because everyone lies and doesn’t say anything), but also try to understand what they are silent about (for example, a lot becomes clear by examining the samples, if you see chips on the case, scratches from a screwdriver, pinched screws, etc. .d.) All this gives a ton of information that will tell about installation and ergonomic problems much better than the user himself - he may not say anything, because he will consider that this is not important for the project: so, nonsense, think about it, it was a little inconvenient crawl with a screwdriver or for a long time I couldn’t get into the screw head because it was hard to see.

Everything collected in this way, including even seemingly small things, must be carefully collected into a single document, the importance of each identified problem or issue must be determined, and the necessary changes must be made to the documentation and models.

6.3. Editing models and documentation

Everything is simple here - adequate production will definitely let you know about errors in your model, which will need to be corrected in accordance with the recommendation given by this production.
However, if they write to you that the model is “low-tech”, but do not specify why, be sure to ask directly what exactly you don’t like. Or contact a third-party designer to check the model and eliminate any shortcomings.

Before choosing a technology, you can still make mistakes - there is an opportunity to return to previous stages, correct, change or test something. But from this point it will become more difficult and much more expensive to win back.

One of the most common problems, for example, when the prototyping stage was not completed (here: formlab.ru/12mln-v-minus is the story of how people burned 12 million rubles in this manner) or at the stage of equipment production, what equipment was not taken into account - minor changes at the time. The latch doesn’t work as long as it should, something crunches during assembly, or the seam between the body parts is uneven - it’s crazy how expensive it will be to fix all this in production, it’s better to go back a step and double-check.

However, if you have worked well with errors in the previous stages, then there will be no problems with production.

And, of course, a lot depends on the technology you chose for the production of your case: each has a different cost, approach and features.

Delivery of a batch of electronics cases and customs clearance

To deliver finished products, you can use several types of transport, which differ in cost and delivery time: air, railway, sea and road transport.
You can also use combined options. Each type of transport has its own advantages and disadvantages that determine the possibilities of its use. Air transport is the most expensive type of delivery, but at the same time the fastest. The simplest items - samples - are usually sent by express delivery services. This takes on average 3-5 days excluding customs clearance.

When sending larger shipments, it is necessary to especially carefully consider the feasibility of sending by plane, this is the most expensive delivery method. Yes, it takes no more than 4-5 days, but the cost is several times higher than delivery by rail or sea. Customs clearance of cargo involves customs clearance and payment of customs duties. The provision of such services is carried out by a customs representative or a customs broker. This is an agent who has the right to carry out any customs clearance operations on behalf and in the interests of the customer.

To begin the procedure, it is necessary to submit to the customs service all documents confirming the origin of the cargo, its characteristics and value.
Such documents include (list of 12 items):

1. Agreement (contract) of international purchase and sale.
2. Specifications for the agreement (contract).
3. Registration of the transaction with the bank if the contract amount exceeds 3 million rubles. at the exchange rate of the Central Bank of the Russian Federation on the date of signing the agreement. Registration with the bank takes 2-3 days.
4. Invoice or proforma invoice.
5. Packing list.
6. Transport document: for sea delivery - bill of lading, for road delivery - CMR, for air delivery - air waybill, for courier delivery - express waybill, for railway delivery - railway waybill);
7. Permits and/or licenses for the import of goods restricted for movement across the customs border (if required).
8. Documents certifying the compliance of goods with the requirements of technical regulatory legal acts - in relation to goods for which a “certificate of conformity” is required.
9. Certificate of origin of goods in form “A”, ST-1, general or other form provided by law.
10. Documents confirming payment of customs duties.
11. Contract and invoice from the transport expedition.
12. Documents allowing the identification of goods - a description of the goods indicating the contract or commercial name of the goods with an indication of its characteristics sufficient for identification in accordance with the Commodity Nomenclature of Foreign Economic Activity.

Customs clearance usually takes 1-2 days unless additional customs checks (tariff and non-tariff) are carried out. After customs release of goods, they can move freely throughout the EEC.

Mass production

7.1. Production

This is roughly what the development and launch into production of a simple plastic case in a small edition looks like.

Is it difficult? No. You just need to move - step by step - and not force the process.

I am sure that you have or still have questions about the article. I will be happy to supplement it with anything that is interesting or seems important to you.

What metals are housings for various instruments and devices made from?

In electronic equipment, metal cases are used as shells for devices for various purposes. The manufacture of metal cases for radio equipment can be made of any shape, and the materials used in the work process are highly durable and reliable.

Metal cases are used for the manufacture of objects such as:

• payment terminals;
• vending machines;
• electrical panels;
• retail store equipment;
• other instruments and apparatus.