The Tools For Numerical Control
The selection Of the proper cutting tools for each operation on machining center is essential to producing an accurate part. Generally there is not enough thought and planning going into the selection Of cutting tools for each particular job.The NC programmer must have a thorough knowledge of cutting tools and their applications in order to properly program any part.
Machining centers use a variety Of cutting tools to perform various machining operations. These tools may be conventional high-speed steel, cemented carbide inserts, CBN (cubic boron nitride) inserts, or polycrystalline diamond insert tools. Some Of the tools used are end mills, drills, taps, reamers, boring tools, etc.
Studies show that machining center time consists of 20 percent milling, 10 percent boring, and 70 percent hole-making in an average machine cycle. On conventional milling machines, the Cutting tool cuts approximately 20 percent of the time, while on machining centers the cutting time can be as high as 75 percent. The end result is that there is a larger consumption of disposable tools due to decreased tool life through increased tool usage.
End Mills End mills and shell end mills are widely used in machining centers. They are capable of Performing a variety of machining operations such as face, pocket, and contour milling,spotfacing. counterboring, and roughing and finishing Of holes using circular interpolation.
Conventional as well as special drills are used to produce holes. Always Choose the shortest drill that will produce a hole of the required depth. As drill diameter and length increase, so does the error in hole size and location, Stub drills are recommended for drilling on machining centers.
Center drills are used to provide an accurate hole location for the drill which is to follow. The disadvantage of using center drills is that the small pilot drill call break easily unless Care is used. An alternative to the center drill is the spotting tool, which has a 900 included angle and is widely used for spotting hole locations.
Machine taps are designed to withstand the torque required to thread a hole and Clear the chips out of the hole. Tapping is one of the most difficult machining operations to perform because of the following factors:
• Inadequate chip clearance
• Inadequate supply of cutting fluid
• Coarse and fine threads in various materials
• Speed and feed of threading operations being governed by the lead of the thread
• Depth of thread required
Reamers are available in a variety of designs and sizes. A reamer is a rotary end cutting tool used to accurately size and produce a good surface finish in a hole which has been previously drilled or bored.
Boring is the operation of enlarging a previously drilled, bored. or cored hole to an accurate size and location with a desired
surface finish. This operation is generally performed with a single-point boring tool. When a boring bar is selected, the length
and diameter should be carefully considered: as the ratio between length and diameter increases, the rigidity of the boring bar decreases. For example, a boring bar with a I : I length-to-diameter ratio is 64 times more rigid than one with 4 : I ratio.
Deshengrui Machinery is a professional CNC manufacturing and sheet metal fabrication company, including CNC machining services, CNC turning service, CNC milling services, CNC drilling services, laser cutting services, stamping services, die casting service, iron casting service and steel forging service.