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What Is a CNC Machine?

So…What Is a CNC Machine Anyway?

Are you interested in manufacturing and considering the purchase of a CNC machine? Want to learn more about how CNC machines work to see if one might be right for your idea? Then you’ve come to the right place!

At CNCMachines.net, we are experts in CNC machinery. We buy and sell used CNC’s from many manufacturers, refurbish CNC’s and advise experienced and novice manufacturers on the best types of CNC machines for their applications. Manufacturing is a challenging but rewarding industry. You may be here because you have a great idea for a product and you need to know enough to find someone who can make it for you, or you may be considering making your product yourself. You’ll be glad to know that CNC machines are designed for use by anyone willing to learn.

The Basics of CNC Machining

CNC stands for Computer Numeric Control and represents the way that the machine tools are programmed to make parts. Long before the computer, metal workers designed lathes and other machine tools that were operated by a series of gears. Ever since there’s been electricity and basic motors, machine tools have been used to remove metal to create parts. CNC machining today is known as “subtractive” manufacturing. The parts you make begin with a piece of material which is cut with a tool that removes material until you get to the shape of the part you want. For companies who do prototype parts only, they likely have CNC machines as well as 3D printers which can do “additive” manufacturing. Some of the latest technology combines both additive and subtractive capabilities within one piece of equipment. Even with the innovations in 3D printing, CNC machines are still preferred for many applications because a part machined from metal, for example, has better strength and higher precision that is possible in 3D printing.

CNC machines basically operate with a workpiece held in one place and a tool that moves to the workpiece (or workpiece that moves to the tool). Either the tool or workpiece move so that the cutting tool cuts the metal to the desired shape. The workpiece and/or the tool are programmed to move in space along various axes. CNC machines may have automatic tool changers that allow for many types of tools to be loaded in the machine that multiple operations can be programmed in, allowing the machine to make parts with multiple features. Some tool holders are stationary, and others allow for “live tooling” where the specific tool can rotate separately from other parts of the CNC machine.

Standard nomenclature for CNC machining refers to the direction of motion that a workpiece can be machined from. X, Y and Z are linear axes with the Z-axis aligned with the spindle of the machine which holds the workpiece.  A, B and C are rotary axes around X, Y and Z respectively. U, V and W may be used to refer to parallel linear axes along X, Y and Z. CNC machines of today have the possibility of movement from many directions. Generally, the more axes, the expertise it takes to run the CNC machine and the more expensive the machine.

The Goal of CNC Machining

The goal of CNC machining is to make parts from raw material as inexpensively as possible. When it comes to CNC machining, time is money. The goal of CNC’s is to make parts as quickly as possible without having to do secondary operations to make your final part. If someone has to deburr, drill holes add taps or do anything after the part come out of the machine, the expense per part goes up drastically. The beauty of CNC machines is in the options available. Today even the most complex parts can be programmed to drop off the right kind of CNC machines all done.

CNC Machine Types

CNC’s come in a wide range of types for different applications. When deciding on the type of CNC machine you need, there are many factors to consider. Some parts are best machined on lathes, which turn material and apply the tool for a “round” basic shape. Other parts can be milled from a block of material into just about any shape. CNC milling machines are often designated by the general direction the cutting tool approaches the material – whether vertically or horizontally.

The Most Popular Types of CNC Machines

CNC Lathes vs. CNC Mills

CNC Lathes

When you hear about CNC turning, CNC turning centers or CNC lathes, you know that this equipment does machining on with a workpiece held in a collet on a spindle that rotates. Usually, the raw material is a round bar stock, but it could be other shapes. When you are thinking about a new product you want to make, if it’s basically cylindrical, it will likely go on a CNC lathe or turning center. Every CNC machine that turns parts will have a maximum outer diameter chuck dimension. This is the biggest size bar that can be held by the machine. Of course, your part has to have a maximum finished outer diameter lower than that. If you plan to make thousands of your parts at a time, you’ll be interested in bar feeders and the maximum colleted size the machine can handle. This is the largest size that can have material bar-fed into the machine so that it can continuously make parts rather than having someone feed the machine one workpiece at a time.

CNC Mills

If the part is going to be made from a block of material that fits best within a square or rectangular shape, then it will likely be a fit for a CNC milling machine. CNC machines that mill material come in two basic configurations, vertical and horizontal. Vertical milling machines have milling tools that are in an up and down configuration. The milling tool comes down and meets the material that sits on a table. For less expensive milling machines, the table is stationary and for more complex parts, that table can move. Horizontal milling machines have milling tools that are oriented horizontally, with the workpiece affected to a vertical surface. These are often used to machine forged materials that could be in any shape but is rough.

Choosing between a Used Vertical Machining Centers and a Used Horizontal Machining Centers

Vertical Machining Centers

Vertical milling CNC machines are more common than horizontal milling machines in part because of their lower cost and ease of use. With vertical milling machines, you can see more of what you’re doing than with 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 or one-off needs. Vertical machining centers also require less floor-space than a horizontal machining centers.

Vertical milling machines are usually for smaller parts. 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 with 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 benefits of Vertical Machining Centers include:

  • You can see what you’re doing. (Horizontal milling machines generally have a blocked view.)
  • VMC’s are less expensive than HMC’s.
  • Vertical Machining Centers tend to be easier to program than horizontal milling machines
  • Vertical milling machines tend to be smaller

Horizontal Machining Centers

Even though from the list above, a VMC may seem to be the answer, it’s not that simple. One horizontal milling machine can be as productive as three vertical milling machines. The spindle utilization on an HMC can be as high as 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

Selecting a Used CNC Lathe for your application:

CNC lathes have many options to optimize them for production of different kinds of parts. For example, you’ll need to consider:

  • Bar capacity (maximum OD that can be bar-fed into the machine)
  • Max part length
  • Tooling capacity – How many tools can it handle? (Based on the complexity of parts you want to machine.)
  • The number of “Live” tool positions (Do you need milling of features in addition to turning?)
  • Sub Spindle capabilities (Does the back-end of the part need features added?)
  • Mist collectors (How clean do you want your shop?)
  • Attachments for long tooling (How long is the maximum tooling length you need?)
  • Collection trays (How long will the machine be unattended? How big are your parts?)
  • Tooling such as collets, guide bushings (ask what tooling comes with the machine)
  • CNC control type (Fanuc is common)
  • Tooling options (Any special tooling that comes with the machine?)
  • Feed rates (Machining soft materials? May want faster feed rates.)
  • Bar feeders (This may come with a used CNC Swiss lathe or may need to be purchased separately. The length bar feeder determines the length bars you will buy, the space needed and the scrap rates you will have.)

How to Get the Most Value from a Partnership with Us

Let us get to know you so that we can provide you with the best possible service. We want to be your partner both for selling and buying used CNC equipment.  The better we understand your business, the better we can provide you with solutions. Buying and selling CNC’s is a critical part of your business, and your most likely to get great deals when you have a partner you can trust.

When you call or email us, details that help us help you include answers to the following questions:

    • What is your primary industry?
    • What kinds of materials do your currently machine?
    • What type of parts (size, kinds) do you currently make?
    • How many, what kinds and brands of CNC machines do you have?
    • Are you satisfied with the CNC machine brands that you currently have?
    • If you could afford anything, what types of CNC machines would you like to have?
    • What kinds of parts do you think your company will be making in 3 years?
    • Why are you considering selling or buying used CNC machines?
    • What is your budget for buying CNC machines this year? (If any.)

Who We Are: CNC Machines LLC, DBA: CNCMachines.Net

CNC Machines LLC was founded in 2014 for Curt Doherty. Curt has been helping manufacturers since 2006 with equipment needs. He founded his company based on his desire to help small to mid-size American manufacturers buy and sell used CNC equipment, so they can be globally competitive. Curt is passionate about building a company with a positive culture for the very best customer experience. American manufacturers are making a difference by making things, and they need affordable equipment.

Contact one of our used CNC machine experts today to get started. Our phone number is 844.262.6789 or contact us online by filling out a quick form. We are located in Florida and our office hours are Monday-Friday 8 AM – 5 PM EST.

5 Fun Facts About CNC Machines

Here are 5 fun facts about CNC Machines to help you learn more about Modern Manufacturing.

  1. A CNC machine is a computer controlled machine that can cut, bend or shape material in the manufacturing process.
  2. The term “CNC” is an abbreviation for Computer Numeric Control.
  3. Computer Numerical Control operates tools paths to produce 3D part.
  4. Most CNC machines today are automated and can finish a product in one operation.
  5. The most common CNC machines are machining centers and turning centers.

Top 10 Most Popular CNC Machine Brands

  1. Haas CNC Machine
  2. Mazak CNC Machine
  3. Doosan CNC Machine
  4. DMG Mori Seiki CNC Machine
  5. Okuma CNC Machine
  6. Fadal CNC Machine
  7. Samsung CNC Machine
  8. Milltronics CNC
  9. OKK CNC Machine
  10. Makino CNC Machine

Still want to know more about CNC machines and what jobs they are capable of performing? Check out the article on ShopBot to learn more about all the different types of CNC machines and how they are continuing to reshape the landscape of the manufacturing industry.

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