In this video we look at the basics of machining. Depending on the cutting material and the material to be machined, a compromise must always be found between the smallest possible wedge angle while still ensuring that the cutting edge is sufficiently stable. When machining, the cutting surface must not touch the cutting surface of the workpiece. This is why it is also referred to as the clearance surface. If the clearance surface and the cutting surface touched, enormous frictional forces would arise. This is why a clearance angle must always be present. With soft workpieces, the clearance angle is somewhat larger than with harder materials due to the greater elastic deformation. The area over which the chip is removed is called the chip surface. The angle between the chip surface and the perpendicular to the cutting surface is called the chip angle and influences chip formation. With large chip angles, favorable machining conditions result and the chip is not deflected as much and long chips are usually formed. Such flowing chips are undesirable because they can get caught in the machine and damage the workpiece and endanger work safety. Flowing chips can be avoided by using a smaller rake angle, where the chips are deflected more strongly. This causes the chips to break off more quickly and creates tear chips. However, due to the strong deflection and the relatively low cutting forces, relatively high cutting forces are required. The sum of the clearance angle, wedge angle and rake angle is always 90°. Depending on the size of the wedge angle, the rake surface can also protrude beyond the perpendicular to the cutting surface and the rake angle becomes negative! This is then referred to as scraping. Negative rake angles and thus large wedge angles are used when machining very hard workpieces. Positive rake angles, on the other hand, have a cutting effect. This is used when machining softer materials. The machining process is characterized by three movements: the cutting movement, the feed movement and the infeed movement. Milling, drilling and turning are circular cutting movements. While the tool performs the circular movement when milling and drilling, the workpiece performs the circular movement when turning. The infeed indicates the amount in millimeters by which the tool moves through the workpiece once (cutting depth). When it comes to the feed movement, a distinction is made between feed and feed rate. The feed is the amount in millimeters by which the tool moves forward in the workpiece during a single rotation. The feed rate, on the other hand, indicates the speed in millimeters per minute at which the tool moves forward in the material. When machining, and especially when milling and turning, a distinction can be made between so-called roughing and finishing. Roughing is about high machining performance, while finishing is about high surface quality, dimensional stability and shape accuracy! 00:00 Cutting with geometrically defined cutting edges 00:37 From cutting to chipping 00:59 Clearance and clearance angle 01:49 Chipping surface and chipping angle 02:16 Flowing chips and tearing chips 03:27 From chipping to shaving 04:04 Cutting movement when turning, milling and drilling 04:51 Cutting speed, rpm and diameter 06:54 Calculating rpm 07:54 Tool life 08:19 Infeed and feed when turning 09:54 Infeed and feed when drilling 10:38 Infeed and feed when milling 11:08 Feed per tooth 11:42 Roughing and finishing