The most common type of machining used for chip removal is CNC subtractive metal machining. CNC (Computer Numerical Control) machines have electronic controls that make axis and spindle movements using digitized data. The digitized data is commonly generated using a CAD (Computer Aided Design) program, which makes a part drawing. The CAD-generated drawing is processed through a CAM (Computer Aided Machining) program. The CAM program produces a G & M code formatted program.
The G & M codes provide machine instruction that controls and monitors the machines’ axis movement, spindle speeds, and feed rates. The generated programs can be edited and modified to maximize machining efficiencies and stored for later use.
CNC technology can be applied to many different types of machines. Some of the most common machine types are:
- CNC Lathes
- CNC Lathes w/Milling
- CNC Swiss Type
- CNC Milling Machines (vertical and horizontal)
- CNC Laser Machines.
- CNC Electrical Discharge Machines (EDM)
Why CNC Subtractive Metal Machining Is So Popular?
There are many reasons that CNC subtractive metal machines have become the machining standard.
Machine builders have made many advancements in machine and control technology. The primary design and engineering focus have been accuracy, repeatability, flexibility, and efficiency.
Accuracy – Many factors influence machine accuracy (mechanical design, weight, materials used in the construction, motors, encoders, controllers, etc.). Today’s machines incorporate all those factors in producing more accurate CNC machines. The main spindle motors are quieter, smoother, and robust. The servo motors that drive the axis movements are very accurate. Coupled with software from the machine controller, they can receive and execute actions down to .0000001” increments.
Repeatability – Being able to reproduce accurate parts, especially in a production environment, requires constant management of the machining process. CNC machines can monitor and compensate for machine speed, feeds, horsepower, part measurement, and cutting tool wear, all in real time. All this control lends itself to consistent, repeatable production components.
Flexibility – Much manufacturing has shifted from large batch production to shorter production modules. There are many reasons for this shift, but two primary drivers are:
- Minimizing inventory cost. Producing parts in large volumes and slowly bleeding off the inventory as needed requires holding large amounts of inventory, which ties up monies. The cost of carrying extensive inventories is prohibitive.
- Semi-customization. Customers want to customize their orders to fit their timeframe and needs better. This requires manufacturers to be more versatile and flexible in their production methods.
CNC machines are designed with greater flexibility in mind. The ease of setup helps reduce lead times and is more responsive to customer needs.
Efficiency – To remain competitive, everything that a manufacturer provides is designed around efficiency. When metal removal is required to produce manufactured components, CNC machines are ideal. Some functions that can be incorporated into the CNC machines are:
- Programming – usually offline does not impact spindle utilization
- Cutting tools are easily and quickly loaded into the machines
- CNC w/ Automatic Tool Changer (ATC) gives added flexibility (shorten changeover)
- The machine feeds & speeds are easily adjusted to accommodate different raw materials and maximize tool-life
- Machine offsets for size adjustment and compensation are fast
- Work-holding changeout can be accomplished quickly
- In-process gauging can be incorporated (shortening the quality process)
- Multiple simultaneous axis moves are achievable (depending on machine configuration)
- Tool costs are lower (minimum use of special form tools)
- CNC machine controllers can output quality and production results
- All aspects of the machining can be monitored in real-time
- Machine and production reports can be generated for internal or customer use
Tool & Tool Types – CNC machines are designed for almost all tool types and shapes. One of the advantages of using CNC is that you do not have to use special-form tools in most instances. The CNC machine has multiple axis (depending on machine configuration) movement, and complex shapes can be generated using the axis movement of the machine with standard tool configurations.
Future of CNC Machines
The marketplace for CNC machines is ever changing. The introduction of new products, the speed they are developed and brought to market places, a premium on flexible equipment that can produce quality components in a timely manner. This type of manufacturing is ideally suited for CNC machines. Thanks to continuous improvement by builders of CNC equipment their machines are adapting to new and challenging applications. They are evolving and expanding (automation, in-process gaging, additive machining, etc.) to meet the needs of new markets. CNC machines are the present and the future.
If you would like further information or want to discuss your CNC machining needs with Intrex Aerospace, please click here.