Posted on: June 20, 2018, | By Will, WayKen Project Manager
China has become the world-leading industry in the recent decade. Its production growth is unparalleled and the first compared to any other country in the world. One of the main advantages of Chinese industry is the ability to quickly produce small quantities of parts by using modern CNC machining technologies. China CNC machining has developed far more quickly than ever, let's move on to have a look at how CNC machining unfolds before the world’s eyes.
How It All Started
After World War II and during the Cold War times, the Chinese economy was in disarray. But after a few years after the end of the Cold War, China started to work on its industrial potential. At first, the quality of their products was lower and what they had made were cheaper copies of popular products. This allowed them to flood the international markets with their products and even despite the quality, cheap prices and quantity allowed them to get the required revenue.
Time went by and Chinese quality started growing, as specialists started to get more and more experience. The increase in production quality brought a lot of international customers to China. The country was ideal for manufacturing since labor prices were lower and working efficiency was getting higher very fast. This is when many famous manufacturing giants moved their production to China. Since the costs were much lower, manufacturing things here brought more revenue. This fact made Chinese manufacturing specialists world-class in regards to manufacturing technology.
However, we saw leap development in the application of China CNC machining from then on.
China Machine Shops
After the Cold War and following modern times, the market has drastically changed. Mass production of a single product in millions became obsolete as consumer society became the most popular commerce model in most countries. This brought about creating newer versions of the same product, or just different ones by smaller companies in smaller volumes.
China was one of the first countries to adapt to this situation.
Lots of small efficient machine shops had been created in order to be able to produce small sets of parts really fast. Due to those universal machining shops, Chinese small volume manufacturing industry became one of the most prominent in the world. Despite the shipping costs, designers all over the world order their prototypes done in China because of its speed, efficiency and, most importantly, quality. In CNC machining field, there are including machining techniques for pushing machined parts to rapid and high-precision services.
Why Ordering Prototypes And Small Part Sets In China Is Efficient?
Chinese industry is quite young and thus more suitable to modern needs. There are not that many massive automated clumsy assembly lines and giant factories where you have to move from one place to another in a car, like the ones that exist in Russia or the USA. Those factories are not suited for low volume manufacturing. It is just not profitable for them. However, China has many smaller factories that may not have all the specialized equipment but it is not even needed most of the time. The main advantage here is flexibility.
The flexibility of Chinese factories is achieved by using modern instruments to decrease the lead-time of every part produced. CAM systems are implemented to increase the rate at which manufacturing preparations are carried out, modern measuring and automation systems are installed on the machine tools in order to control part quality right on the spot and CNC operators are trained to meet the demands of any client in regards to surface finish and part precision.
How CNC Machining Costs Achieve in Rapid Services
Machine cost
Machine wear costs account for most of the processing costs. In the CNC machining field, machine purchase costs range from thousands to hundreds of thousands of dollars. And the same piece can be machined by using different types of machines, but the processing costs may vary a lot. This is largely due to differences in machine cost. The accuracy of the part and surface textures produced by different machines can be very different, which is obvious when machining precision parts. As for those products that are very simple in structure and have no requirements for processing machines, there is often no minimum cost and only lower cost.
CNC machines can be divided into milling machine and lathe by processing. According to the number of control axes, it can be divided into three-axis, four-axis, five-axis machining centers. The three-axis is the most cost-effective machining method and is suitable for machining part with simple structure and less detail. Because the three-axis machining can only process one surface once positioned, if the part needs to process multiple surface details, it needs to repositioning, the repositioning times should not be too much, otherwise, the processing cost (clasmping cost, time) will rise. Each time the repositioning will reduce the accuracy of the product.
On the basis of the three-axis, the four-axis or five-axis machine adds a rotatable shaft or a table, so that once clamping can process multiple surfaces, improving the overall machining accuracy of the part, simplifying the process, improving production efficiency, and shortening machining time. However, the cost of using four-axis or five-axis machining will increase much more than the three-axis, and the hourly labor cost is about 30%-100% higher. Therefore, if only from the cost considerations, it is often not preferred to use five-axis machining, and only those parts with complex surfaces and high precision requirements will use five-axis machining.
Processing steps
When manufacturing and processing any piece of part, it involves designing processing route, that is, the machining process. The design of the route generally follows the following three principles:
1. Basic surface priority
When machining parts, it is necessary to select the appropriate surface as the positioning base in order to properly install the part. In the first process, only the blank surface (unprocessed surface) can be used as the positioning base surface. In the subsequent process, in order to improve the processing quality, the processed surface should be used as the positioning base surface. Obviously, when the processing is arranged the precise base surface should be processed by priority. For example, when machining shaft parts it usually take the center hole as the precise base surface. Therefore, when arranging its processing, lathing end surface and drilling center hole should be arranged first.
2. Separate roughing and finishing, roughing should be priority than finishing
When the quality of parts processing is required high, the surface with high precision should be divided into several processing stages. Generally, it can be divided into three stages of roughing, semi-finishing and finishing. Finishing should be carried out at the end. In this way, it is beneficial to ensure the processing quality and facilitate the arrangement of some heat treatment processes.
3. Surface takes priority over hole
For parts such as boxes and brackets structure, it should machining plane surface then holes. This is because the contour of plane surface is flat, and the placement and positioning are stable. By machining the plane surface first, the hole can be machined in a plane position to ensure accuracy.
In summary, the general CNC machining sequence is: first processing precision base surface → roughing main surface (the surface with high precision) → finishing the main surface. The processing of the second surface is suitably interspersed between these stages. When determining the process of machining a part, it is necessary to evaluate the complexity and accuracy requirements of the part firstly. For example, for metal parts, tolerances less than 0.05 mm are regarded as high requirements, and for some special positions, higher accuracy is required, such as within 0.025, which are generally apertures and outer circles. Costs often rise when these high precision requirements arise. Because in addition to CNC machining, it is often necessary to add other fine processes such as grinding machines and reamer to ensure tight tolerance.
Post finishing
In many cases, after parts are machined, the surface will still have some defects. In order to improve the condition and properties of the part surface and optimize the combination with the material to achieve the expected performance requirements, surface treatment is required. Common surface treatment methods, also known as post finishing can be divided into the following:
1. Surface modification technology
Through the physical, chemical and other methods, change the surface morphology, phase composition, microstructure, defect state and stress state of the material surface. The chemical composition of the surface of the material is unchanged. This type of post-treatment mainly includes sandblasting, knurling, brush, and polishing.
2. Surface conversion coating
By chemical method make the additive material is chemically reacted with the substrate to form a conversion film. Such technologies mainly include blackening and phosphating of steel parts and anodizing of aluminum alloys.
3. Surface coating
The additive material is formed into a plating layer or a coating layer on the surface of the substrate by physical or chemical methods. The substrate does not participate in the formation of the coating. Such post finish includes common vacuum plating, plating, printing and painting.
All of these post finish will increase in cost based on the surface size being processed. For some color-related post finish, if you need customize colors, there will always be MOQ requirements and the price is higher than regular color.
CNC Machining In China
One of the most viable options for creating metal prototypes is ordering them to be machined from solid stock. China is a pioneer here. Due to the nature of its industry, CNC machining plays a large role. It allows the creation of a part with almost any complexity with low lead-times due to the fact that the movements of the machine tool are all determined by a CNC program.
Different modern software exists to assist the generation of NC programs. This software is called Computer Aided Manufacturing system. The operator does not have to choose the coordinates for every movement of the tool now. He just has to choose the surfaces he needs on the CAD model of the part. The Computer Aid systems have grown even further, comprising the whole part lifecycle. Such systems are called Product lifecycle management and they are being widely implemented in Chinese manufacturing institution.
The main advantage of such programs is the interoperability of every stage of the part life. From an idea up to utilization. For example, the CAD packet of such a system allows a number of people to change the design of the part simultaneously and the variety of each person will be saved on the server and an optimal one can be chosen among them in real time. Same features exist on every stage. This makes the designing and manufacturing process much more organized as all the changes that had been implemented can be seen by every participant.
Conclusion
Right now, China is the most industrially able country in the world. Its yearly growth is astounding and its low prices put many of its competitors out of business. An abundance of CNC machine shops creates a healthy competition on the Chinese manufacturing market, which promotes growth, lower prices and a constant struggle to get better. A number of reasons make Chinese manufacturing one of the cheapest in the world while keeping the outstanding quality. A large number of small flexible factories are ideal for taking prototyping orders. Their manufacturing cycle is smaller as well as their manageability, lack of bureaucracy and faster responsiveness.
At the present stage, we, WayKen selects a wide variety of materials including production plastics, metals and other composites to cast fast turnaround and high-quality models to customers satisfactory for product materials. And we have a great advantage over CNC machining capabilities aim to produce the finest, highly accurate visual design models, full-functioning engineering prototypes or master patterns. All these we do just to provide manufacturing experience for all customers.
