303 Каталог INGERSOLL 2011 Режущий инструмент и инструментальная оснастка Стр.305

Каталог INGERSOLL 2011 Инструмент и оснастка Стр. 305 0303 Lab2u

MILLING APPLICATION & SELECTION Fig. 4 Lead Angles Effective lead angles. Cutter lead angles also affect performance. A 45 lead tool reduces chip thickness about 30 percent as compared to a 0 lead tool (Fig. 4). This allows you to maintain a given chip load at a higher feed rate increasing the metal removal rate. A proper lead angle allows a cutter to enter and exit the cut more smoothly minimizing shock to the cutting edges. Workpiece edge breakout a common problem when machining cast iron can be significantly reduced or eliminated by use of increased lead angle. The lead angle allows the cutting edge to exit the workpiece gradually. This reduces radial pressure and minimizes breakout. Remember that increasing the lead angle to reduce radial pressure does increase axial pressure. This can cause deflection of the machined surface when the workpiece has a thin cross-section. Choosing cutter density. The cutter density must allow chips to form properly and clear the cut. Inadequate chip space can cause chips to plug the gullet breaking the cutting edge and possibly damaging the workpiece. However the cutter must have sufficient density to keep at least one insert in the cut at all times. Failure to do this could cause severe pounding which can lead to chipped cutting edges a damaged cutter and excess wear to the machine (Fig. 5). Coarse pitch tools with 1 to 1-1 2 inserts per inch of diameter allow for greater chip gullet space. These tools are recommended for soft materials that produce continuous chips and in wide cuts with a long insert engagement. It is desirable to have at least one insert in contact with the workpiece at all times. Fine pitch tools though primarily for cast iron are also good for shallow or narrow cuts in high-temperature alloys where light chip loads are taken. Small chips require less gullet allowing more inserts per inch. Although selecting a face mill can be a complicated and somewhat subjective process these guidelines can give you a good starting point. By using and expanding on these principles you will be able to select a face mill for any operation in your plant. Fig. 5 Coarse Pitch Medium Pitch 1 to 1-1 2 inserts per inch of dia. 2 to 3-1 2 inserts per inch of dia. Cutter Density Fine Pitch 4 or more inserts per inch of dia. 305