CNC Machining Centers

What is a machining center?

A machining center is a type of CNC machine tool. Those without a tool magazine are CNC milling machines, while those with a tool magazine are called machining centers, also known as CNC machining centers. The processing center (Computerized Numerical Control Machine), or CNC, is a highly efficient automated machine tool for processing complex-shaped workpieces, composed of mechanical equipment and numerical control systems.

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Top 3 Types of Machining Centers

CNC machining centers are essential tools in modern manufacturing, utilizing computer numerical control (CNC) technology to achieve efficient and precise machining processes. Within the realm of CNC machining centers, there are three common types, including Horizontal Machining Center (HMC), Vertical Machining Center (VMC), and Universal Machining Center (UMC).

Horizontal Machining Center (HMC)

Horizontal Machining Center (HMC) features a horizontal spindle orientation, with the workpiece mounted on a horizontal table. The cutting tool moves along the X, Y, and Z axes. HMCs are renowned for their capability to handle heavy cutting tasks, efficient chip evacuation, and suitability for large workpieces. They find wide application in industries such as aerospace, automotive, and heavy machinery.

Vertical Machining Center (VMC)

Vertical Machining Center (VMC) has a vertically oriented spindle. The cutting tool moves along the X, Y, and Z axes, while the workpiece is secured on a vertically movable table. VMCs are versatile machines widely used for milling, drilling, tapping, and complex contouring of small to medium-sized workpieces. They are commonly employed in mold-making, general machining, and prototype production industries.

Universal Machining Center (UMC)

Universal Machining Center (UMC) is a flexible, multi-purpose machine that combines the characteristics of both HMC and VMC. UMC has a swiveling head or a rotating spindle, allowing it to perform both horizontal and vertical machining operations. This type of machining center offers the flexibility to choose the most suitable spindle orientation based on the machining requirements of the workpiece. UMCs are particularly suitable for manufacturing scenarios that require handling diverse machining tasks and workpiece orientations.

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Structure and Components of Machining Center

Base Components

The foundation of a machining center consists of the bed, columns, and worktable, among others. These components primarily bear the static and cutting loads generated during machining. Consequently, they must possess sufficient rigidity. These larger parts can be made of cast iron or steel structures assembled by welding. They represent the largest and heaviest elements in the machining center. AKIRA-SEIKI employs high-grade Meehanite castings for stability after undergoing heat treatment.

Spindle Components

The spindle assembly comprises the spindle box, spindle motor, spindle, and spindle bearings. The start, stop, and speed variation of the spindle are all controlled by the CNC system. The cutting tools mounted on the spindle participate in the cutting motion, making the spindle the power output component for cutting operations. It is a critical part of the machining center, determining its processing precision and stability.

CNC System

The CNC part of the machining center consists of the CNC unit, programmable logic controller (PLC), servo drive devices, and the operator panel.

Automatic Tool Changer System

This system includes the tool magazine, mechanical arm, and driving mechanisms. When a tool change is required, the CNC system issues commands, and the mechanical arm (or other means) retrieves the tool from the magazine and inserts it into the spindle hole. This system addresses the automatic storage, selection, handling, and exchanging of tools between consecutive machining processes after a workpiece is clamped for multiple operations. The tool magazine can have different capacities, ranging from a few to several hundred tool positions. The structure of the tool arm varies depending on the relative position and structure of the tool magazine and spindle, such as single-arm or double-arm configurations. Some machining centers achieve tool changes directly through the movement of the spindle box or tool magazine.

Auxiliary Devices

These include lubrication, cooling, chip evacuation, protection, hydraulic, pneumatic, and detection systems, among others. Although these devices do not directly participate in the cutting motion, they play a crucial role in ensuring the machining efficiency, precision, and reliability of the machining center. As such, they are indispensable components of the machining center.

Automatic Pallet Changer (APC) System

Some machining centers use multiple automatic exchange worktables to achieve further unmanned operation or reduce non-machining time. One workpiece is mounted on a worktable for processing, while another worktable can load or unload other parts. When the processing of one workpiece on a worktable is completed, the system automatically exchanges the worktable for processing a new part. This approach reduces auxiliary time and improves machining efficiency. For more CNC knowledge, search for the public account “CNC Programming Teaching” on WeChat to receive free tutorials.

Significant 4 Advantages of Machining Center

High Production Efficiency

Machining centers offer high production efficiency by eliminating tasks like marking lines and intermediate inspections. Moreover, their automatic tool-changing function often eliminates the need for complex fixtures, reducing the relative complexity and tediousness of tasks such as part installation, adjustment, and multiple tool changes. Machining centers can choose the optimal process route and cutting parameters, effectively reducing auxiliary time during machining and thus improving production efficiency.

High Machining Accuracy and Stable Quality

The automatic tool-changing function of machining centers significantly reduces the number of workpiece clamping operations, lowering or eliminating positioning errors caused by multiple clamping. This, in turn, enhances machining accuracy. When precise positioning is required for various parts of a component, the automatic tool-changing function of machining centers conveniently and effectively reduces errors in positioning and tool alignment. It can complete the machining of different parts in a single clamping and aligning process, ensuring the precision requirements for each machining section.

Strong Adaptability and Flexibility

Machining centers can easily perform various processes on box-type components, such as drilling, reaming, tapping, boring, thread milling, face milling, and slotting. Hence, they can handle parts with complex contour shapes or difficult-to-control dimensions, such as fan blades, automobile engine housings, and more. Machining centers are also capable of processing complex curved parts and intricate three-dimensional surfaces.

Enhanced Cost-effectiveness

A single machining center combines the functionalities of milling machines, drilling machines, and tapping machines, reducing the number of machine tools needed in a company. With one operator being able to handle multiple machining centers simultaneously, the requirement for operating personnel decreases, leading to a corresponding reduction in labor costs. Moreover, possessing CNC machining centers showcases a company’s capability and can attract increased business volume, ultimately enhancing cost-effectiveness.

Top 5 Applications of Machining Center

Box-type Components

Box-type components generally refer to parts with one or more hole systems, internal cavities, and certain proportions in length, width, and height.

Complex Surfaces

Complex surfaces are difficult or even impossible to be machined using conventional machining methods.

Irregular-shaped Components

Irregular-shaped components have irregular outer shapes and often require multi-station mixed machining with point, line, and surface processes, such as forks.

Disk, Sleeve, and Plate Components

These components come with keyways, radial holes, or distributed hole systems on the end faces, as well as curved surfaces, such as flanged sleeves, shaft components with keyways or square heads, and plate components with numerous hole processes, like various motor covers. For components with distributed hole systems and curved surfaces on end faces, a vertical machining center is recommended, while components with radial holes can be processed using a horizontal machining center.

Parts with Periodic Production

When machining parts using a machining center, the required time mainly includes the base time and setup time, where setup time occupies a significant proportion. Activities like process preparation, programming, and first-piece trial cutting take a long time. By using a machining center, these preparatory activities can be stored for future repeated use. This way, when machining the same part in the future, these setup times can be saved, significantly reducing the production cycle.

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