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Bab 3 Proses Pemesinan kelompok 3 fakultas teknik
- 1. Proses Pemesinan (Machining) Klasifikasiproses pemesinan Elemen dasar mesin perkakas Elemen dasar proses pemesinan
- 2. Proses Pemesinan (Machining) MaterialRemoval Processes Material Removal Processes common feature is that excess material is removed from a starting workpiece so that the remaining part has the desired shape.
- 3. Proses Pemesinan (Machining) 3Types Machining Processes Cutting (Machining): a sharp cutting tool is used to mechanically remove material to leave the desired part shape. Turning, Milling, Drilling, Shaping/Planing, Boring, Broaching and Sawing Abrasive Processes : the action of hard and abrasive particles is used to mechanically remove material to achieved the desired quality of surface finish of previously processed surfaces. Grinding, Honing, Lapping, Polishing, Buffing and Superfinishing Non-traditional machining processes: Variety of energy forms other than a sharp cutting tool or abrasive particles to remove material. Chemical Milling, Electrochemical Machining, Electrical Discharge Machining
- 4. Cutting (Machining) Cuttingaction in machining involves shear deformation of the work material to form a chip; as the chip is removed , a new surface is exposed.
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- 7. Machining The commonfeature is the use of a cutting tool to form a chip that is removed from a starting workpiece. To perform the operation, relative motion is required between the tool and workpiece. The relative motion is achieved in most machining operations by means of a primary motion (speed motion) and a secondary motion (feed motion) Cutting speed the speed at which the cutting → edge of the tool passes over the surface of the workpiece (menghasilkan permukaan baru). Feed rate a speed at which the cutting tool → penetrates the workpiece.
- 8. Machining The shapeof tools and its penetration into the work surface, combined with the speed and feed motion, produces the desired shape of the resulting workpiece
- 9. Machining There are manykinds of machining operations each of which is capable of generating a certain part geometry and surface texture: Cylindrical or disk-like shape Block-like or plate-like shape part Plane or straight surface
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- 22. Broaching A complete cutis made in one stroke. On the broaching tools each subsequent cutting tooth cuts successively deeper Feed rate : provided by cut per tooth Depth cut : depend on the cut per tooth and the number of teeth on the tool
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- 26. Grinding The feedrate of grinding is referred to as the cross-feed. At which the grinding wheel traverses across the workpiece while the table provides the pass or stroke motion. The cross-feed rate will depend on the wheel shape, size and material and the workpiece material. Typical cross-feeds in the region of 1.0 – 1.5 mm/pass Depth of cut is the distance the grinding wheel projects into the surface of the workpiece
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- 30. Types of Machining Berdasarkan gerak relatif pahat terhadap benda kerja Berdasarkan jenis mesin perkakas yang digunakan Berdasarkan proses terbentuknya permukaan (surface generation) Berdasarkan gerak relatif dan jenis pahat
- 31. Types of Machining Berdasarkangerak relatif pahat pahat terhadap benda kerja: Proses membubut (Turning) Proses menggurdi (Drilling) Proses menyekrap (shaping atau planning) Proses mengefreis (Milling) Proses menggergaji atau memarut (sawing atau broaching) Proses menggerinda rata (Surface grinding) Proses menggerinda silindris (cylindrical grinding)
- 32. Types of Machining Berdasarkanmesin perkakas yang digunakan: Membubut (Turning) Menggurdi (Drilling) Menyekrap (shaping/ planning) Mengefreis (Milling) Menggergaji (Sawing) Mengkoter/memperbesar lubang (Boring) Memarut (Broaching) Menggerinda (Grinding) Mengasah (Honing) Mengasah Halus (Lapping) Mengasah super halus (Super Finishing) Mengkilapkan (Polishing dan Buffing)
- 33. Types of Machining Berdasarkanproses terbentuknya permukaan (surface generation) : Generasi permukaan silindris atau konis Generasi permukaan rata atau lurus dengan atau tanpa putaran benda kerja
- 34. Types of Machining Generasi permukaan silindris • Single point generation • Parallel to the axis of rotation • External: Turning, Threading, Doving • Internal: Boring, Threading, Grooving, Gundrilling • Non-parallel to the axis of rotation • Straight but intersecting: Facing, Surfacing, Taper, Turning, Fly cutting • Complex shapes: Copying, Contour, Forming • Multiple point generation • Two-edge cutting: Drilling, Counter boring, Spot facing • Multi-edge cutting: • Sizeable chips (milling) : Cutter axis perpendicular to generated surface: Face milling • Ground chips (filing, grinding) : Cutter axis parallel to generated surface: Slab milling, cylindrical and peripheral surface grinding Berdasarkan gerak relatif dan jenis pahat:
- 35. Types of Machining Generasi permukaan rata atau lurus dengan atau tanpa putaran benda kerja silindris • Job held cutter reciprocates • Shaping • Broaching • Slotting • Keyseating • Sawing • Tool held, job moves • Planing • Broaching • Job and tool moves • Gear cutting Berdasarkan gerak relatif dan jenis pahat:
- 36. Parameters in Machining Kecepatan potong (cutting speed), Vc ; m/min Kecepatan makan (feed rate), Vf ; mm/min Kedalaman potong (depth of cut), a ; mm Waktu pemotongan (cutting time), tc ; min Kecepatan penghasilan geram (rate of material removal), Z ; cm3 /min 1000 n d Vc n x f Vf f t c V l t v x A Z 5 Parameter yang harus diperhitungkan sebelum sebuah proses pemesinan dapat dilakukan:
- 37. Cutting speedthe speed at which the cutting → edge of the tool passes over the surface of the workpiece (menghasilkan permukaan baru). Feed rate a speed at which the cutting tool → penetrates the workpiece. Depth of cut (there are a number variations definition depending on the specific process) General: the difference between the original surface and that being produced by the cutting tool Turning and boring: the radial distance that cutting edge is set from outer diameter Milling: the distance the tool projects beneath the original surface Parameters in Machining
- 38. Basic Elements ofMachine Tools (Elemen dasar mesin perkakas) Komponen yang selalu ada pada setiap mesin perkakas Rangka mesin Penggerak Peralatan Pemegang benda kerja Pengontrol
- 39. Basic Elements ofMachine Tools (Elemen dasar mesin perkakas) Struktur: Dasar Bangku Kolom Kepala tetap Meja Peluncur silang Bahan: besi cor kelabu baja baja las Rangka Mesin
- 40. Basic Elements ofMachine Tools (Elemen dasar mesin perkakas) Penggerak: Mekanis Listrik Hidrolis Pneumatis
- 41. Basic Elements ofMachine Tools (Elemen dasar mesin perkakas) Peralatan pemegang benda kerja : Pada benda kerja berputar Diantara pusat Mandril Plat Penyetel Pencekam Leher Arbor Peralatan Khusus Pada Benda Kerja Ulang Alik
- 42. Basic Elements ofMachine Tools (Elemen dasar mesin perkakas) Peralatan pemegang benda kerja : Pada benda kerja berputar Pada benda kerja ulang alik Ragum Celah T Pencekam magnet • Magnet tetap • Arus searah
- 43. Basic Elements ofMachine Tools (Elemen dasar mesin perkakas) Metode pengendalian: Dengan tangan Mekanis Hidrolis Gerakan nok (cam) Daur pemilih waktu Pengendali numerik
- 44. Bentuk-bentuk geometri yangumum produk hasil pemotongan Permukaan datar (plane atau flat) Silindris (cylindrical) Konis (conical) Tak beraturan (irregular, curve atau warped)
- 45. Ketelitian mesin-mesin perkakas Ketelitianproduk yang dihasilkan sampai 0.001 inci atau kurang. untuk menghasilkan ketelitian tersebut mesin perkakas harus memenuhi persyaratan sbb antara lain: Fungsional Kekakuan Bentuk Kemudahan dalam pengoperasian Kemudahan pengeluaran serpihan (geram) Keselamatan
- 46. Kekakuan mesin perkakas Kekakuan statis dan kekakuan dinamis untuk: Ketepatan dan ketelitian Kemantapan struktur dari mesin perkakas untuk mencegah getaran. Hal ini untuk mencegah terjadinya penyimpangan geometri dan kualitas dari produk yang diproduksi.