Beginner’s Guide to CNC Machinery

Horizontal CNC Milling MachineryImagine that you are running a machine tool, be it milling or a lathe, but you are not in direct control. Someone else has the levers, dials and buttons.

All you have to do is simply tell him or her what to do and it is done. This is because this “Operator” is far more adept in running the machine than you are, or any human being for that matter.

This “Operator” here is the Computer in “Computerized Numerical Control”, or as more commonly known, CNC.

At the business end, a CNC milling machine or a CNC lathe is the same as any manual machine. A CNC machine may have bells and whistles added to them, but they both do their job in the same manner.

Most of the tools can be used in either a manual or a CNC machine to do the same job in many cases. The main difference is the computer that controls the CNC machine.

How Does Numerical Control Work?

benchtop cnc milling machine in actionIf you put the drawing of a part that needs to be machined on a piece of graph paper, you can get the coordinates of the points that the cutter or the tool has to move through.

The computer on a CNC machine tool just runs the motors of the machine so that the tool moves through those points. Control by coordinates, i.e., numbers, that’s Numerical Control.

Letting the computer “see” the drawing on the graph and telling it exactly what to do is called Programming. The coordinates themselves have to be put in or perhaps just the drawing needs to be done.

There are codes to tell the CNC machine how to move (on straight line or on arc), how fast to move (feed rates, spindle rpm), when to turn on coolant, when to stop it…the list goes on.

Every action that CNC machinery can take has a code associated with it. There are hundreds of machine manufacturers out there, with hundreds of best ideas how they should work. Luckily, the codes are mostly standardized.

G codeOften, you would hear “G code” programming in CNC discussion. The reason is that this “Standard” list of code has lots of G’s in them.

Like if you want to move the machine to point x, you have to type G1 followed by coordinate of the point. Next code G2, or G02, is for the arc… and the list continues. Also, there are “M” codes which are arguably the second most prominent. These codes can turn on or off the spindle, control coolant and many such functions.

Advantages of CNC machines can be thought of in two opposite extremes. Think of a workshop that makes low volume but highly complex parts, most of them one-of-a-kind.

With manual machines, getting the desired shape out of the machines will be very difficult and time extensive, if not impossible altogether. CNC equipment can machine very complicated sculptured shapes by moving in 3, 4, 5 or more axes at the same time.

On the other end of the spectrum, where you have to make large number of relatively simple parts, manual machines with human operators can produce substantial amount of out-of-spec instances or rejects.

This is mostly because human operator can keep productivity at peak for only a limited time, especially if the work is monotonous.

A computer does not have this limitation. You tell it what to do and it will do it in the morning and the same thing at the end of the day when it churns out 100th or 1000th piece. You can even let it run continuously day and night.

On the downside, CNC is more expensive to buy and maintain. You will also need people with higher skills to program and run them. However, as CNC is now a mature technology, the benefits usually far outweigh these small trade-offs.

CNC Mini Lathes

CNC Desktop LatheComputer numerical control (CNC) mini lathes are essentially a smaller sized version of an industrial CNC lathe. CNC mini lathes are most often used to produce very small parts more economically than on a large lathe or to machine very small parts that cannot be made using a larger CNC lathe.

Many mini lathes are designed to fit on a bench top or desktop and other models are designed to be compact and take up only a small footprint on a shop floor.

Lathes are used to make components like shafts and bushings, parts that are cylindrical in shape. In reality, almost all mechanical and engineering devices utilize parts made on a lathe. Lathes are perfect for those who dabble in robotics, race cars, planes, boats, appliances, jewelry and just about any hobby.

Home professionals and hobbyists that create small objects constitute the primary user group for CNC mini lathes. CNC mini lathes and mini machining centers are also used extensively for engineering education and machining training as well as small manufacturing runs.

These mini CNC lathes are used to turn or spin a metal cylinder at a very high speed while it cuts metal to create a new part. Some CNC mini lathes with advanced programming and machine design can even cut complex curves and shapes like their industrial counterparts. Mini lathes are also useful to cut lightweight materials including wax, and plastics.

CNC Mini lathes have a lot of potential to optimize small batch manufacturing and for prototyping and R & D but most CNC mini lathes still have some shortcomings although the technology has definitely improved. It is always best to check with a qualified machinist or engineer to discuss your specific needs and which type of mini lathe or standard lathe best meets your needs.

What to Look for When You Buy a CNC Mini Lathe

CNC Mini LatheThere are not too many CNC mini lathes on the market. In many cases lathes come prepared to add CNC controls and in other cases individuals will buy the peripheral equipment and turn a manual or automatic mini lathe into a CNC lathe.

If you are thinking about purchasing a CNC mini lathe you should make certain that the CNC mini lathe is capable of delivering the accuracy and precision you need for your application.

CNC mini lathes are generally not able to maintain the high levels of accuracy and precision of standard CNC lathes designed for industrial use. Another thing to consider when buying a mini lathe is the durability of the machine and the parts.

A mini lathe should also have enough mass to remain stable during use. If you need to perform multiple operations you should also investigate the work-holding options available and the ease of operation to change tooling.

SIEG

Shanghai SIEG machinery Co., Ltd was founded in 1988. They manufacture mini lathes and milling centers OEM for many different companies. They may well be the premier manufacturer of mini machine tools for DIY, hobbyists and education and training facilities.

SIEG CNC mini lathes feature high reliability, simple operation, 2 axis step motor, high torque brushless motor, metric MT3 spindle, high strength guideway.? SIEG also sells a variety of optional accessories and cutting tools as well as stands and a cooling system for the lathe.? The CNC mini lathe for DIY and hobbyists comes in two models.

Additional CNC lathe models are available for Education and training? and light industrial applications.

Tormach

Tormach CNC mini lathe

Tormach designs and manufactures a line of personal CNC machine tools specifically for light industrial and home hobby use. Their duality CNC lathe is unique in the world of CNC machines. It offers two operation modes.

Without your Personal CNC mini milling machine it functions identically to traditional manual mini lathes but when it is mounted on to the bed of the Personal CNC 1100 mini milling machine it becomes a small CNC prototyping lathe that costs only a fraction of the cost of a free standing lathe.

In the CNC mode, the duality lathe is mounted to the PCNC 1100. It uses a rigid quick change lathe tool post that is mounted to the spindle cartridge of the PCNC 1100 and CNC lathe software to provide precise motion of the lathe operations on the X and Z axes.

In the CNC mode, the mill table moves the duality mini lathe left and right while the mill spindle head moves up and down so that all conventional CNC lathe operations are available such as turning, cut off, boring, drilling, and threading. No threading gear changes, radius attachments, or taper attachments are required.

Tormach also offers slant bed compact CNC lathes designed for prototyping and specialty manufacturing of turned parts.? It features a cast iron frame, 15” diameter swing over the bed, a 3 HP spindle up to 3500 RPM, a D1-4 Nose with removable 5C taper insert, 25” carriage, rigid tapping capability along with standard conversational control, configurable tooling, optional 8 station turret and full enclosure, work holding and a 12 month factory warranty.

Haas Automation Inc

Haas Automation offers an office lathe that is designed to deliver high performance and reliability to industries that cannot fit a standard CNC lathe into their facility. This compact lathe is designed for high production or rapid prototyping of small, precision parts.

This lathe fits through a standard 36” door and into most freight elevators. It also delivers a higher level of precision and accuracy than generally found in other mini lathes.

New Twin Turret CNC Lathe From Germany

Spinner TTC 300 SMMCY CNC Lathe Specs

Quickly replacing mechanical production turning machines are?CNC lathes. Most notably for turned part production due to their ease of use, efficiency and fine accuracy. German engineering has gone a step further by creating a computer controlled lathe with dual turrets and spindles.

German based company, Whitehouse Machine Tools, recently released a multi axis CNC Lathe with twin opposed spindles. The Spinner TTC 300 SMMCY twin opposed-spindle, twin-turret CNC lathe offers a number of new features which can increase product quality and production speed.

The CNC lathe is available in two models. The first is designed to process 42mm bar stock and the second can process 52mm bar stock.

  • Each turret is equipped with its own tool stations
  • Each tool station can hold 12 cutting tools
  • Uses 6,000 RPM tooling
  • Main spindle rating: Larger model – 6,000rpm / 12KW Smaller model – 5,000rpm / 19KW
  • Sub Spindle rating: 7,000rpm / 8KW for both models
  • Top turret has a Y-axis? of ± 40 mm
  • Cast iron bed
  • Top turret can adjust to 16 tooling positions
  • Maximum turning length: 400mm
  • Maximum turning diameter: 250mm
  • Machine Weight: 3.5 Tons
  • Dual Direct Drive Spindles with built in motors
  • Large preloaded ball screws offer efficient vibration absorption
  • Liquid cooling system built into each turret
  • Turret indexing time: 0.15 seconds
  • CNC System: SIEMENS 840D-SL or FANUC 31i. Both with a 15” LCD screen.

The size and configuration of these machine tools are becoming increasingly popular for milling complex turned parts with tight tolerances.

Advantage Of A Dual Opposed Spindle Lathe

Each spindle has its own built in motor which directly drives it and built in cooling systems which provide compact and efficient cooling of tools and material. The absence of a drive belt or gear chain offer lower vibration during operation, allowing this CNC turning center to produce turned parts with improved machining quality and accuracy.

The dual spindles are positioned opposite one another and the main spindle is positioned higher than the secondary spindle. Both spindles work together to simultaneously machine each part quickly and accurately.

The computer controlled direct drive feature offers increased acceleration and deceleration of each spindle. The result is increased productivity due to minimized part turning down time and a high quality finished product.

The turning machine is capable of making heavy cuts and hard part turning without sacrificing quality or damaging cutting tools. This feature increases productivity even further.

Spinner TTC 300 SMMCY CNC Turning Center Accessories

Optional features for the CNC lathe include a robotic loading and unloading system and a chuck part storage area.

All CNC lathes are designed to produce turned parts quickly, accurately and automatically; most accomplish this with a single turret. The added features of this twin turret, dual spindle turning center allow a single machine to turn parts almost twice as efficiently as single turret CNC lathe machines.