How to choose vertical machining centers？

Machining center For ANTISHICNC, the definition is very simple: a vertical machining center is a vertical CNC milling machine with a tool magazine. The vertical machining center is a machine tool with simple machinery and complex electrical appliances, as well as a machine tool with simple structure and complex use.

Why is the vertical machining center simple in structure? Because the components of the vertical machining center are highly integrated and highly standardized, they can be divided into eight parts: CNC system, electrical appliances, bed, spindle, tool magazine, guide rail, lead screw, and sheet metal after disassembly. These eight parts are specialized manufacturer’s production. There are professional opto-mechanical manufacturers, in addition to producing opto-mechanical machines, guide rails, lead screws, spindles, etc. can also be pre-assembled according to the requirements of the machine tool factory. Manufacturing of machining centers.

The manufacturing threshold of domestic vertical machining centers is very low, and even three million funds are capable of manufacturing machining centers. In Taizhou, Wenzhou and other places in Zhejiang, there is even an industry of OEM machine tools, that is, the user of the machine tool has to buy the components of the vertical machining center, and the assembly company comes to assemble the whole machine. The fee is very low, but the quality is also very low.

1.CNC System of Vertical Machining Center

Selection method: Siemens 840D or Fanuc 31i is recommended for the five-axis vertical machining center system. The five-axis of Huazhong and Guangshu are suitable for teaching; for the three-axis four-axis vertical machining center for high-speed and high-precision machining, Fanuc is recommended. 18i and Mitsubishi M700; Among the three-axis vertical machining centers for general applications, Fanuc 0i MD-A is suitable for mold processing, Fanuc 0i MD-B is suitable for product processing, Fanuc 0i Mate-MD is an economical system, and Mitsubishi M70-A is used for Mold machine, Mitsubishi M70-B is suitable for product machine. It is generally believed that Fanuc is easier to control and has higher stability, and Mitsubishi of the same grade is more powerful; in occasions with low requirements and budget constraints, domestic CNC systems can also show their talents. Yes, in all fairness, in recent years, the domestic machining center system has developed rapidly, and it is their progress that has forced the price of foreign CNC system brands to drop sharply; Taiwan’s Baoyuan and Xindai are mainly used in the engraving and milling machine industry, in the vertical machining center. There are certain applications.

2. Electrical System of Vertical Machining Center
Among the electrical systems of vertical machining centers, GE in the United States, Schneider in France, and Omron in Japan occupy the mainstream position. Among the low-end models, there are also domestic Chint and domestic Delixi. With the maturity of spindle servo technology and the reduction of price, frequency converters have gradually withdrawn from the field of vertical machining centers because they cannot solve the problem of rigid tapping.

Selection method: The matching between electrical components is very important. The degree of coordination and fitness of electrical performance determines the stability of the electrical system. Not all components of the same brand can solve the compatibility problem. The quality of compatibility requires precise calculation, experience and technical accumulation.

3. Lubrication System of Vertical Machining Center
Good lubrication is a necessary condition to ensure smooth mechanical movement of vertical machining centers. All parts that have contact movement need to be lubricated. Without the lubrication system of the machine tool, the life and accuracy of the machine tool will be greatly affected. Careful observation of the oil lubrication system of the machine tool is a required course before purchasing a vertical machining center.

Selection method: The bearing seat, nut seat, guide rail, and ball screw of the screw must have oil paths to reach them. At the same time, it is necessary to consider whether the oil path layout is reasonable and whether the maintenance and replacement are convenient. The oil circuit wiring is chaotic, the oil pipes and other pipelines are mixed and interfered, and the machine tools that lack lubrication of the main moving parts cannot be purchased.

4. Vertical Machining Center Bed (Including Guide Rails)
Selection method: hard rail for mold machine, linear rail for product machine, this is the industry-recognized selection method.
The bed body of vertical machining center can be divided into single column type (C type) and double column type (gantry type). The single-column vertical machining center has a C-shaped structure from the side. This structure is only suitable for vertical machining centers with a Y-axis less than 1200mm. If the value is greater than this value, the spindle head will be overhanging too long, resulting in insufficient rigidity of the spindle head. , there will be chattering phenomenon during processing, so it is rare to see a vertical machining center with a large Y-direction stroke. The gantry type has better rigidity, and the Y-direction travel is not limited. It is generally used in large vertical machining centers and high-speed engraving and milling machines. This article only talks about single-column vertical machining centers.

The bed body of vertical machining center is divided into fixed column type and movable column type according to whether the column moves. The conventional vertical machining center is a fixed-column type, that is, the column is fixed, and the movement of the X-axis and Y-axis of the worktable, plus the movement of the Z-axis of the spindle on the column, constitutes the entire movement. The movable column type vertical machining center is that the worktable is fixed, and the three-way movement of the X axis, the Y axis and the Z axis is realized by the column. The influence of movement is generally used in the case of double worktables or additional rotary exchange worktables. The CNC exchangeable workbench can be selected from Taiwan’s Tanxing and domestically produced Yantai Global.

Rectangular guides (ie hard guides) are generally used for heavy cutting, and linear guides (ie, linear guides) are generally used for high-speed feed. In order to increase the support rigidity of the machine tool, some vertical machining centers adopt the structure of four or even six guide rails.

ANTISHICNC believes that machine tool factories can buy various functional parts, but the machine body should be produced by itself. First, the quality of the machine tool can be controlled. Second, if a machining center can be built with a few screwdrivers and wrenches, this Does the industry still have value?

5. Screw of Vertical Machining Center
The advent of linear motors made ball screws awkward. The characteristics of linear motor drive are fast speed, high efficiency and good rigidity. The existing problems are high price, high heat generation, and slightly poor transmission stability. Therefore, the traditional ball screw in conventional CNC machine tools is still the mainstream. However, with the gradual maturity of linear motor technology and the gradual reduction of prices, it is foreseeable that the application of ball screws in CNC machine tools will gradually decrease. The market is very cruel. Those who should withdraw from the historical stage will inevitably withdraw, and the fittest will survive.

The pitch of the ball screw directly determines the feed speed of the machine tool. Large pitch corresponds to high speed, but accuracy is sacrificed, and there are gains and losses. God is fair. Blindly emphasizing high feed speed, high rotation speed, and high precision has no practical significance. Buying a machine tool is to use it, not as a vase. It is the best that is applicable.

There are two ways to install the ball screw on the vertical machining center: one is to fix one end and one end to move. The ball screw is pre-stretched at the moving end to eliminate the axial clearance of the ball screw and avoid the occurrence of temperature rise. This is the most common installation method; the other is fixed at both ends, which is suitable for high-speed and high-precision machine tools. It is difficult to install and debug, but it can solve the problem that pre-stretching affects the bearing life.

The structure of the ball screw nut seat also has a great influence on the rigidity of the machine tool. The overall nut seat is difficult to manufacture and has good rigidity, but the entire workbench needs to be replaced after damage.

6.Spindle of Vertical Machining Center

Spindle is the most critical functional component of a vertical machining center. It is basically provided by professional spindle manufacturers. There are very few machine tool factories capable of producing spindles by themselves. The technical content of the machine tool spindle is very high. If there is no special ability, professional things should be left to professional manufacturers.
The main shaft is generally divided into four categories according to the transmission structure.

Gear drive spindle: high rigidity, suitable for heavy cutting occasions, the speed is generally less than 6000 rpm.

Synchronous belt rotating main shaft: simple structure, easy to manufacture, strong buffer capacity, overload sliding protection can effectively protect the main shaft. It is one of the mainstream vertical machining center spindle structures. The speed is generally 6000-12000 rpm.

Directly connected spindle: The servo motor directly drives the spindle through the coupling, with large torque and low energy consumption, which is also the mainstream vertical machining center structure. The speed is generally 8000-15000 rpm.

Electric spindle: also called spindle unit, Taiwan is called internal expansion spindle. That is, the motor is built into the main shaft, and the motor and the main shaft are combined into one, shortening the length of the main transmission chain to zero. The speed is generally 18000-40000 rpm. The speed of electric spindles using magnetic bearings and aerostatic bearings abroad can even be as high as 100,000 rpm.

7. Tool Magazine of Vertical Machining Center
The most common tool magazines for vertical machining centers are bucket hat-type tool magazines and manipulator tool magazines, which have been introduced in detail in previous articles, so I won’t talk about them here.

8. Sheet Metal of Vertical Machining Center
Sheet metal and paint are the clothes of the machine tool. The grade of the machine tool can be distinguished from the appearance. Domestic machines are almost always printed in the same mold, and they are the same; imported brands basically have their own unique appearance logos. In addition, the sheet metal thickness of imported machines is generally more than 2mm, which is thick and stable, and there are few domestic machines whose sheet metal thickness can reach 1.5mm.
The airtightness of the sheet metal of the vertical machining center is particularly important. Water leakage and oil leakage will cause difficulties in workshop management and may even lead to safety accidents. Poor dustproofing will directly affect the electrical life. Who would hope that the machine tool they buy is a three-leak product that leaks water, oil, and electricity?

Selection method: The thickness of the sheet metal should be more than 1mm, the seam gap should be small and uniform, and the paint should be thick and flat. The door should be tight, and there should be a buffer when pushing and pulling, and the electric cabinet door will automatically cut off when it is opened.

9. Control of Vertical Machining Center
In fact, a large part of the control is related to the numerical control system. Excellent machine tool factories have the ability to carry out secondary development of the numerical control system, and even allow the operator to automatically generate a program by filling in the form and inputting parameters, truly realizing programming-free control. . In addition, the position of the control box, the rotation method, the position and opening and closing method of the sliding door, the placement of tools and tools, etc., all need to be designed from the perspective of the operating mechanic, and such a design will bring humanized control.
Selection method: Priority is given to the machine tool that can realize programming-free control. In addition, please actually operate the machine tool to see if the structural components of the machine tool will interfere with the processing. Excellent machine tools will make people use them with ease.

10. Optional accessories of Vertical Machining Center
Many users ignore the optional accessories, in fact, reasonable optional accessories can make the machine even more powerful. CNC turntables, oil coolers, chip conveyors, oil mist separators, high-precision universal fixtures, in-machine measuring devices, etc., are indispensable killers in many processing situations.
Selection method of CNC turntable: CNC turntable is a necessary component for vertical machining center to realize four-axis machining. If three-axis vertical machining center is equipped with CNC tilting turntable, five-axis machining can be realized. Of course, four-axis and five-axis machining also requires CNC System support. You can choose Taiwan Tanxing, Taiwan Tanjia, and Yantai Universal.
Oil cooler selection method: Oil cooler is mainly used for spindle cooling, which is very important for spindle stability under high-speed machining. The main brands are: Dongguan Shengguang, Shanghai Yihua, Shanghai Zheyue and so on.
Chip conveyor: The chip conveyor is widely used with the sharp rise in labor costs. Before 2005, the chips were basically cleaned manually, and now the chip conveyor has become the basic configuration of most vertical machining centers. There are two types of chip conveyors: screw type and chain plate type. The screw type has strong chip cleaning ability, and the chain plate type is suitable for long-distance chip removal. There are many brands of chip conveyors.
Oil mist separator: Also known as oil mist collector, it is a device that solves the oil mist, water mist and dust generated by machine tools, and plays a role in protecting the health of workers and prolonging the life of machine tools. For factories with small space and poor ventilation, it is recommended to install an oil mist separator. Common brands are: Wuxi Bodi, Shanghai Zhaohe, Shaoxing Ruixin, etc.
High-precision universal fixtures: The precision loss caused by the repeated clamping of workpieces must be compensated by high-precision fixtures. Sweden’s 3R and Switzerland’s EROWA are top high-precision fixtures. Taiwan Jingzhan and Baodingyang are also good choices.
In-machine measuring device: The in-machine measuring device is the best way to solve the online precision measurement, which can reduce the time loss caused by downtime measurement and avoid errors caused by loading and unloading measurement. Leading in-machine measurement manufacturers include Renishaw from the UK, Marposs from Italy, Tosei from Japan, and Sanmenxia Zhongyuan, a Sino-Japanese joint venture.
The harsh operating environment of machine tools has led to the saying: there is no machine tool that does not fail in the world, only machine tools with a low failure rate. Therefore, after buying a machine tool, you also need good operating habits and normal routine maintenance to ensure the normal operation of the machine tool. Good parts are not necessarily a good machine tool. It is only by looking at the essence of the phenomenon that the machine tool is selected. It’s really hard work; you can’t just buy a machine tool for fame, there may also be gold buried in the sand waiting for you to discover.
ANTISHICNC’s leading products include CNC machining centers, five-axis machining centers, CNC machining centers, vertical machining centers, turning centers and other general-purpose machine tools. Welcome to consult!