CNC Mill Machines
Buying a CNC Mill
Milling machines are still one of the most common ways to manufacture metals. Manual mills or also known as Knee mills can cut through metal but require a lot of manual labor and time, CNC machine mills which are computer controlled can help speed up the process and atuomate milling production at scale. Industries that commonly use these types of computer controlled mills include motorsports, avaition, and even auerospace companies like Space X. When choosing the right CNC Mill for your production there are many mjor types of milling machines to choose from but the top 3 general mills to consider are the Vertical machining centers, Horizontal machining centers and other mills that have more universal applications like the 5 Axis CNC mills.
Vertical Machining Centers
Vertical mills are more common than horizontal milling machines in part because of their cost and ease of use. With vertical milling machines, you can see more of what youre doing compared to a horizontal milling machine. They tend to be less complicated to program and offer more flexibility, so they are better if you have unorthodox pieces of one-off needs. Another advantage is that they require less floor-space than an HMC. Vertical milling machines are usually for smaller parts and the super-size parts are made on horizontal machining centers. Because of the ever-increasing complexity and features being added to both kinds of machines, both kinds may be referred to as machining centers.
Most CNC milling machines have the ability to move the spindle along the Z-axis which allows for freedom to engrave and make much more complex parts. When a fifth axis is added, making the machine a 5-Axis machine, the B axis controls the tilt of the tool to make extremely complicated geometries. Most selections for CNC milling machines begin with the size parts you plan to machine.
Some of the benefit of Vertical Machining Centers include:
- You can see what youre doing. (Horizontal milling machines generally have a blocked view.)
- VMCs are less expensive than HMCs.
- Vertical Machining Centers tend to be easier to program than horizontal milling machines
- Vertical milling machines tend to be smaller
Horizontal Machining Centers
a VMC may seem to be the answer, its not as simple due to the complexities needed for diffrent industries. One horizontal milling machine can be as productive as three vertical milling machines. The spindle utilization on an HMC is 85% compared to a typical 25% for a VMC. The Horizontal machining center uses better chip evacuation methods when compared to vertical mills, which means less re-cutting and longer tool life. The surface finish from a horizontal mill machine is often better too.
These machines are very sturdy and built to withstand vibrations, so the work environment is quieter, and the machine tends to last longer. Many owners believe that the additional initial investment in an HMC well-worth it since parts are less costly coming off the machine. Depending on the project, it might make sense to buy an inexpensive used HMC and use it exclusively for production. There is software available to help you program and run it to its full capacity.
Benefits of used horizontal machining centers include:
- Higher production rate
- Quieter running
- Better surface finishes
- Better chip management
- Better spindle utilization (more efficient)
- Fewer operators (but they need to be well-trained)
- Pallet change options available for automated loading/unloading
If you have access to the talent to run a horizontal machining center and associated programs (like CAD/CAM), consistent mid-to-high runs of parts and the capital to invest, a horizontal milling machine may be the best choice for you. However, if you are just getting started with machining, have many varied jobs for a wide range of parts and tend to make smaller parts youll probably want to select a used vertical milling machine.
5-Axis CNC Mills: Comparing Vertical Machining Centers and Horizontal Machining Centers
For complex geometries that are high-volume and require precision as well as great flexibility, you may want to consider a 5-axis machining center. 5 axis mills have up to 95% spindle utilization and run overnight and weekend unattended, putting money directly in your pocket. Different HMCs are designed for various size parts and types of materials. 5-axis VMCs reduce cycle times and add to the complexity of parts that can be produced. As with the HMCs some are designed for tougher materials than others. The VMCs tend to be for smaller parts as compared with the HMC.
15 Check Points - How To Buy A Used CNC Mill:
- Inspect for damage and worn components.
- Call the CNC mill manufacturer to see if they still support parts and service.
- Research the brand and model online and with other CNC mill owners think about the brand and support.
- Call the local distributor and talk with sales and service about support.
- Look up independent CNC service techs to get their opinion if the machine breaks or needs work.
- Search online similar year makes and models to see price points.
- Get the hours of operation.
- See if any maintenance records can be found or major repair work. Repair work isnt a bad thing, in many cases it will help you know what been replaced, what hasnt and if it was done right.
- Find out the types of material and industries it made parts for in the past.
- Ask the owner why hes selling the machine.
- Find out what process controller is on the machine. For older machines, the processor may have been upgraded.
- Consider tool-access, how long will it take to switch out tools?
- Review chip & coolant management options. Does it have thru spindle coolant?
- Consider the ergonomics of the machine
- Find out the electrical requirements for install
For machines that are similar compare:
- Horsepower of spindle drive motor
- Rapid traverse rates
- Max cutting feed rates
- Tool-change time (chip to chip)
- Maximum spindle-speeds
- Spindle speeds
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