Каталог Dormer Pramet фрезерование 2021 - 2022 - страница 781

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9 TYPES OF WEAR ON MILLING INSERTS INSERT FRACTURE ↓ (H) grain has a great influence. (MT)CVD + PVD coating recommended. PVD f ↓ Very important to reduce cutting force. v ↑↓ It is about swarf control and vibration. ap ↓ Reduces the force load. ↓ Use less positive cutting geometry. It has no influence. Use better working conditions (ae/DC). POOR SURFACE QUALITY Description and cause: Corrective measures: Numerous causes depending on the workpiece material, cutting • Use a finishing insert, or an insert with finishing segment conditons (feed rate and cutting speed), the condition of the cutting • Use an insert with suitable cutting geometry edge, the extent and type of wear, and the condition and rigidity of themachine – tool – workpiece assembly.•Reduce the feed rate • Incorrect tool chosen • Adjust (usually increase) the cutting speed • Incorrect chip thickness • Use coolant or lubrication (MQL) • Incorrect cutting speed • Eliminate vibrations • Coolant is needed • Use a tool with which the position of the individual inserts can beadjusted more accurately • High feed rate • Change the chip thickness (modify the machining conditions) VIBRATIONS Description and cause: Corrective measures: This is a very common problem, which is mainly caused by an • Check the stability of the workpiece fixing unbalanced workpiece or tool, unstable fixing of the machined part and • Check the stability of the tool fixing high cutting forces. • Reduce the cutting depth • Low rigidity of machine-tool-workpiece assembly • Use a tool with smaller overhang • Excessive chip depth (both axial and radial) • Modify the cutting speed • Run-out – poor workpiece or tool balance • Reduce the chip thickness • Large tool overhang (change the cutting or machining conditions) • Choose a suitable cutting geometry and tool material to minimize the cutting process force balance (as sharp and as positive as possible), i.e. use a tool with a lower cutting resistance • When milling, use a tool with a smaller setting angle 780