How to choose the right turning insertIssuing time:2024-04-07 10:02 There are many parameters to consider when selecting a turning insert. Carefully select the insert geometry, insert grade, insert shape (tip angle), insert size, tip radius and lead angle (lead angle) to achieve good chip control and machining performance. Choose insert geometry based on the selected operation (e.g. finishing) Choose the largest possible tip angle on the insert for strength and economy Choose insert size based on depth of cut Choose the largest possible tip radius for insert strength If there is a tendency to vibrate, choose a smaller tip radius l = cutting edge length (insert size) RE = Tool nose radius Nose angle Turning insert geometryTurning geometries can be divided into three basic types, optimized for finishing, semi-finishing and roughing. This diagram shows the working area of each geometry, based on acceptable chip breaking, in relation to feed and depth of cut. roughingHigh cutting depth and feed rate combinations. Operations requiring maximum edge security. ModerateMedium to light roughing. Wide range of depth of cut and feed rate combinations. finishingOperations with small cutting depths and low feed rates. Operations requiring low cutting forces. Turning wiper geometryUse wiper inserts to improve surface finish with standard cutting data or to maintain surface finish at significantly increased feed rates. -WMX wiper geometry is preferred and a good starting point for most applications. When conditions change, there is always an effective alternative. Choose a positive wiper geometry to reduce forces and maintain productivity when vibration is a problem. Choose wiper geometry as follows: -WL: Improves chip control when moving to lower f n / a p. -WF: Improves chip control at lower f n / a p. Also reduces cutting forces when vibration occurs. -WMX: Always preferred in a wide range of chip applications. Provides maximum productivity, versatility and best results. -WR: When a stronger edge line is required, for example, for interrupted cuts. Turning insert materialThe choice of insert grade is mainly based on: Component material (ISO P, M, K, N, S, H) Type of method (finishing, semi-finishing, roughing) Processing conditions (good, normal, difficult) Insert geometry and insert grade complement each other. For example, the toughness of the grade can compensate for the lack of strength in the insert geometry. Turning insert shapeThe blade shape should be selected based on the accessibility of the cutting edge angle required by the tool. The largest possible nose angle should be selected to provide blade strength and reliability. However, this must be balanced with the variation in the cuts that need to be performed. Large nose angles are strong but require more machine power and have a higher tendency to vibrate. Small nose angles are weaker and have less cutting edge engagement, both of which make them more sensitive to the effects of heat. Cutting edge strength (larger nose angle) Stronger cutting edge Higher feed rates Increased cutting forces Increased vibrations Less tendency to vibrate (smaller nose angle) Increased accessibility Less vibrations Lower cutting forces Weaker cutting edge Turning insert sizeSelect the insert size based on the application requirements and the space available for the cutting tool in the application. The larger the insert size, the better the stability. For heavy-duty machining, insert sizes above IC 25 mm (1 inch) are usually used. Once completed, the size can be reduced in many cases. How to choose blade size
Turning insert nose radiusNose radius RE is a critical factor in turning operations. Inserts are available in a variety of nose radius sizes. The selection depends on depth of cut and feed, and affects surface finish, chip breaking and insert strength. Cutting depth and cutting forceThe relationship between nose radius and depth of cut affects vibration tendency. As depth of cut increases, the radial forces pushing the insert away from the cutting surface become more axial. It is preferred that axial forces be greater than radial forces. High radial forces negatively affect the cutting action, resulting in vibration and poor surface finish. As a general rule of thumb, select a nose radius that is equal to or less than the depth of cut. Direct or reverse turning insert stylesNegative blades have an angle of 90° (0° clearance angle), while positive blades have an angle less than 90° (e.g. 7° clearance angle). The illustration of a negative blade shows how the blade is assembled and angled in the holder. Listed below are some characteristics of the two blade types: Forward turning inserts
Clearance Angle Negative turning inserts
Clearance Angle Turn entry angleThe lead angle KAPR (or lead angle, PISR) is the angle between the cutting edge and the feed direction. Selecting the correct lead angle/lead angle is very important for a successful turning operation. The lead angle/lead angle affects: Chip formation Direction of cutting forces Length of cutting edge during cutting Large entering angle (small entering angle)
Small entering angle (large lead angle)
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