Unibody, translated as Chinese, means: one-piece molding; integration; one-piece molding fuselage. The understanding of this process is explained on Baidu Encyclopedia as: a machining technology that extruds aluminum alloy into plates and then forms it through CNC machine tools. This is mainly for a piece of metal material (especially aluminum alloy) through cnc processing out of the integrated structural characteristics of the part. Such a part, with integral characteristics, acts as both the most of the appearance of a product and the frame for the fixation of the internal parts.
My understanding is that not only for metal parts, but also for other materials, such as plastics, through the uni moulding process, can be manufactured integrated shell parts, such shell parts such as according to the traditional injection molding process can not be molded normally, need to be split by multiple parts and finally assembled into a whole. However, if the one-piece injection molding process is used, a very simple appearance form can be obtained, while the number of parts is reduced, reducing the seam between the two parts.
Therefore, the unibody integrated molding process is roughly divided into:
1. Metal unit
2. Plastic unit
3. Ceramic unibody
Among them, the metal unibody is the most widely used, so if not specifically indicated, unibody generally refers to the metal unibody, the development of unibody technology is still due to Apple, it is his first application of this integrated fuselage molding technology in consumer electronics, after a large number of praise, other companies have followed up, metal integrated shell mobile phone became the common point of each mobile phone at that time.
Because the aluminum alloy has good machining properties, and can get a variety of different colors of beautiful appearance after anodizing coloring, the aluminum alloy anodized unibody integrated molding body has become the main tone of Apple's full range of product design at that time, and it is still used today.
However, the first application of this all-in-one body forming technology to consumer electronics was not an iPhone, but a MacBook Air, a laptop thin enough to fit in a file bag.
2008 MacBook Air Launch
Macbook Air's display and main body are designed with a unibody one-piece molding body, and most of the parts are screwed to the integrated aluminum alloy body with high precision, which has the advantage of doing so, as Apple's former chief design officer Jonathan Ive (Jony Ive) said: "When you face different parts, in addition to the increase in size and weight, it also increases the potential error rate." And this major breakthrough is that we replace all those parts with only one part, that is, the unit. ”
Jonathan Ive: An introduction to the design of the unibody one-piece molding
The smart phone body uses aluminum alloy anodized unibody integrated molding body, which is from 2012 Apple released the iPhone 5, of course, the iPhone 5 is (half) unibody aluminum alloy body, not all unibody aluminum alloy body, because in order to avoid the signal being shielded by metal layers, iPhone 5 and the back 5s will be the upper and lower two sections of hollowing out behind the fuselage, replaced by a glass cover, forming a three-stage structure.
By the time of the iPhone 6, Apple removed the glass cover on the back of the iPhone 5, and the phone had two large components left from the appearance: the screen and the fuselage. In the field of mobile phones, this is a real all-metal body in a certain sense.
Of course, due to the consideration of the antenna signal, Apple had to inlay four plastic strips through nano injection molding on the back cover of the aluminum alloy fuselage, although the tactile processing has been very perfect and tends to be integrated, and there is almost no gap and segment difference between metal and plastic, but the impact of these "white bands" on vision is even worse than the three-stage structure of the original iPhone 5 and 5s "metal + glass", so that it was spat on a lot as soon as it was released.
At that time, people would complain less about the silver version of the iPhone 6, because the sky line color of this style would be closer to the original color of the back cover, and would not be as obviously abrupt as gold and rose gold.
As for why not make the color of the plastic sky line close to the fuselage?
First of all, the plastics that can be used in nano injection molding generally have pps, pbt, pa6, pa66, ppa, etc. These kinds of engineering plastics, the colorability of engineering plastics is not good, it is difficult to make bright colors, and the adhesion of spraying is not strong.
There may also be a point based on industrial design considerations, because metal and plastic are two different materials, it is very difficult to make the color and texture exactly the same, of course, it is possible to be almost close, but at that time Apple's decision-making is estimated not to allow this similar effect to be presented, since it is due to technical limitations that it cannot be done for the time being, then simply make a clear demarcation, clearly tell you that the white plastic tape is a sky line. For example, in the early iPhone 3G and the previous generation of iPhone 5 and 5s, the two adjacent parts of different materials are very different in color to clearly distinguish.
However, this is only a compromise that has to be made in the pursuit of all-metal integration, although the integration has been achieved on the physical level, but visually, for consumers is still divided, Apple can not be unaware of the aesthetic needs of consumers, may also think so, this practice is just a compromise strategy at that time, not worthy of praise and admiration, should be in a better direction to work hard, to pursue. Therefore, when it comes to the iPhone 7, on the basis of the number of internal antennas is not reduced, the number of white belt lines is less than that of the previous generation, leaving only two upper and lower corners, so that the effect will look much more comfortable than the previous generation.
At the same time, it is also trying in other directions, such as the following black and bright black models, as well as the red models behind, which have taken another step in the pursuit of integration.
All-metal body mobile phones have the need to solve the problem of antenna signal overflow, the industry usually has the following ways:
1. Full cnc+nmt+anodizing (antenna vaginal discharge design)
Typical representatives are iPhone 6 to iPhone 8 series mobile phones, the general process is: first of all, an aluminum alloy block cnc processing out of the overall structural parts, and cut out the antenna slot, and then through nano injection molding to fill the plastic into the corresponding antenna slot, so that metal and plastic are connected together, and finally through sandblasting, anodizing, coloring and other treatment.
2. Forging + cnc + nmt + anodizing (three-stage design)
Typical representative of oppo r7, its antenna processing is somewhat similar to the treatment of iPhone 5, using a three-stage structure on the back, oppo r7 upper and lower antenna cover is made of ordinary plastic, the color of the plastic can be similar to the fuselage, fixed to the fuselage by double-sided adhesive. Compared with the iPhone 5, the early stage through forging to obtain a thicker structural parts coarse, the purpose of this is to reduce the cnc processing time, thereby reducing costs, while the metal material used for aluminum alloy that can be anodized, the later can be made into an integrated appearance with metallic texture, but even if the upper and lower plastic parts try to reduce the visual difference by spraying and painting treatment, the color difference problem is definitely there, and finally causes certain damage to the integrity in the visual effect.
3. Die casting + cnc + nmt + spray paint (overall spray paint design)
Typical representative of the charm blue metal, this way is more cost-saving than forging, because after the aluminum alloy die-casting molding, most of the structure on the mobile phone body has basically been made in this step, such as the injection molding area of the antenna slot, and the follow-up only has some areas with high precision requirements for local CNC.
Then the upper and lower antenna slots are nano-injection molded, as shown in the upper and lower white areas.
Finally spray paint, because the fuselage is made of die-cast aluminum alloy, high silicon content, not suitable for anodizing, charm blue metal using the overall spray metal paint treatment (that is, in the paint will add pearlescent powder or aluminum powder), and finally can achieve a variety of colors of the integrated fuselage.
Charm blue this overall spray paint treatment, both to ensure the integration of the metal body, but does not affect the antenna signal, to achieve visual effects and touch of the double excellent, is worthy of appreciation, although the spray painting process makes the fuselage is not as obvious as the pure metal texture of anodizing, but can well hide the antenna injection molding, to avoid visual abruptness. In this kind of thousand yuan machine, both the cost and the appearance of the process are taken into account, and I personally think it is also a good choice.
Here you may have a question: since the final is to carry out the overall painting, what is the difference with the direct plastic body?
A: There may not be much difference between vision and texture, and the reason for the use of an integrated metal fuselage is mainly to ensure that the strength of the mobile phone body is sufficient while achieving a light and thin fuselage, which is one of the reasons why everyone used a metal integrated fuselage at that time.
But this way has a risk point, that is, in the appearance of the very similar to the full metal, in fact not all, and Meizu in the marketing hype of the all-metal selling point, even the mobile phone name with metal meaning (metal), when there is no problem, consumers may default, but once there is a quality problem, such as the following, consumers may feel that it is not an all-metal body, or even a plastic body, but through the spray painting method disguised as an all-metal body, if this problem spreads, The impact on brands is enormous.
Back to the introduction of Apple's mobile phone, with the introduction of wireless charging, the use of all-metal integrated structure on the mobile phone can no longer meet the needs of the time, so the iPhone 8 series has also become the last version of Apple's all-metal integrated iPhone, and the subsequent iPhone 4 has returned to the similar "metal frame + glass back cover" form in the iPhone 4 era.
However, in other categories of products, it has also been designed based on the concept of unibody integrated fuselage,
For example, imac:
For example, airpods max:
For example mac mini:
There are many more, which will not be introduced here.
Summary: Apple has insisted on using the metal unibody process on many of its products for many years, which shows that the metal unibody process has irreplaceable advantages:
1. Improve the integrity of the appearance, simple and beautiful
The most intuitive advantage of unibody is to improve the integrity of the product appearance, reduce unnecessary details, make the product look and feel more neat and beautiful, and enhance the product style.
2. Reduce parts, screws and assembly processes
The structural rigidity and plasticity of the metal workpiece itself greatly reduce the design of reinforcement ribs and bones, as well as the assembly processes such as inlaying, welding and pasting, and optimize a large number of workstations and circulation links.
3, there is no seam, parting line, no need to draft angle
The inevitable assembly clearance of injection molded parts, the clamping of the mold and the draft bevel seriously reduce the aesthetics and design reduction of the product, and unibody can avoid such problems very well.
5. Avoid common appearance defects of the mold
In addition to the design, there are technical defects in the injection molding process, such as shrinkage, gas patterns, flow marks, weld marks, etc.
6. The design freedom is higher, which can break through the appearance limitations of the injection molding process
Due to getting rid of some of the limitations of the mold, you can break through in the shape or try more variations and styles. In particular, multi-axis multi-head equipment is gradually popularized, and cnc's modeling ability in most scenes can even be comparable to 3D printing.
7, is conducive to recycling, in line with environmental protection requirements
Because the use of parts and joining processes is reduced, the unibody fuselage contains as little material as possible, which is more conducive to the separation and recycling of waste. At the same time, it also reduces the use and emission of toxic and harmful substances, and has excellent environmental protection attributes
At the same time, the metal univer process also has drawbacks: the high cost
1, CNC processing on the equipment accuracy requirements are extremely high, processing man-hours than injection stamping and other processes are much longer, the early stage needs a relatively high equipment investment, only the formation of large-scale mass production can share the cost, so the general small company or processing plant is not able to purchase a large number of equipment, only large factories can afford to play.
2, similar to other reduced material processes, the full cnc consumes more materials, so the cost of materials is also higher than other molding processes (die casting, stamping, etc.), fortunately cnc waste can be recycled.
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