The Fundamentals of a Vertical Machining Center (VMC)

About the Vertical Machining Center

By its name, the Vertical Machining Center (VMC), also known as Milling, is a type of machining center where its three main parts: the Axis, Spindle, and Worktable – are placed vertically. This machine was dubbed as an, “Industrial Workhorse”, due to its ability to deliver outputs that are accurate and in a short period of time.
The VMC is one of the machines that are computer numerically controlled. It performs its operation by placing the material on the worktable while the cylindrical cutters are placed on the spindle axis vertically. It works great with solid materials made of metal such as Steel and Aluminum and shapes it to the required design. The machine performs the following operations to either reshape, carve, drill, chamfer, or engrave the raw material –

• Thread Cutting
• Milling
• Tapping
• Boring
• Drilling

Types of Vertical Machining Center

There are various types of VMC machines and these are classified based on their: Guide Rail, Spindle Speed, Bed Structure, and Column Structure.

Based on Shape of Axis’ Guide Rail – Linear Rail and Hard Rail

• Linear Rail – Ball-bearing guide rail and is known for its sensitive movement and speed.
• Hard Rail – Recommended for heavy cutting and has good ridgity.

Based on the Spindle Speed – High Speed and Low Speed

• High Speed – spindle speed reaches above 18,000 rmp with better processing precision and surface finish.
• Low Speed – spindle speed reaches between 6,000 to 15,000 rmp with high torque and recommended for drilling deep holes and milling.

Based on Bed Structure – C type and Gantry type

Based on the Column Structure – Fixed Column and Moving Column

• Fixed Column – a.k.a. “Table Movement VMC” and 75% of the machine tool manufacturers have this type of machine and this is due to its advantages – it easily manufactures/designs and is cost-efficient.
• Moving Column – a.k.a. “Fixed Worktable VMC” and only 15% of the machine tool manufacturers prefer this type of VMC. Although it can process heavy and large workpieces, the Fixed Column is prevalent since the Moving Column’s headstock vibration of its components are small.

Parts of a VMC Machine

Three Primary Parts – Axis, Spindle, and Worktable

• Axis – A typical VMC would have three axis – X,Y, and Z. This machine’s system is CNC controlled and moves depending on the spindle’s orientation –
  1. X – moves the workpiece, along with the table, from left to right.
  2. Y – moves the table from front to back
  3. Z – moves the spindle up and down
• Spindle – Placed perpendicularly to the worktable and moves on the direction of the Z-axis, this can handle a variety of cutting instruments and perform the preferred cutting procedure.
  1. Worktable – This is where the material will be placed in order to shape the workpiece and can either move from left to right (X axis) or front to back (Y axis).
• Additional Parts of a VMC Machine
  1. Tool Changer – This allows automatic selection of tools depending on the cutting procedure, thus, increasing the machine’s productivity.
  2. Coolant System – It is a type of liquid, water and soluble oil, that keeps important parts and cutting tools lubricated.
  3. Chip Conveyor – Removes chips from the work area without the need to manually perform the task.
  4. Enclosures – Protects the workers and workplace from splatters caused by the machine.
  5. Rotating Tables – Adding 1 or 2 more axes (4 or 5 Axes) will certainly improve the machine’s productivity. Highly recommended for complex projects.
  6. Quick Loading Loaders – Uses automatic part loading systems to increase the machine’s productivity.

Workpieces Produced by VMC Machines

Recognized for its versatility, the VMC machine poses a lot of advantages for the manufacturing industry. It is used to manufacture the following parts that would industries such as:

• Automobile
• Shipping
• Commercial
• Aviation

These parts are mostly rectangular parts. Workpieces that have lots of cavities but with only one hole system.

• Spindle Box
• Diesel Engine Block
• Gear Box
• Gear Pump Shell

Curved and Irregularly-shaped Parts
Most of these parts are produced for the transportation sectors. These are mostly characterized as those that have complicated curves that are difficult to accomplish, especially its accuracy and precision. Examples of these parts are:

• Mold Cavities
• Cams
• Propellers
• Integrated Impellers of Engines

Prototypes
This type of CNC machine is versatile and adaptable. Programs can be easily changed to suit your preference – enter the new program or alter the current program to your preference. If you’re ready to purchase a used CNC machine, make us at S&M Machinery your first call when buying surplus Vertical Machining Centers! S&M Machinery is the leading independent machinery dealer of late-model surplus used CNC industrial machine tools in the United States With over 300 machine tools.