Machining Flashcards
Describe the fundamental mechanism behind cutting processes, including types of chips produced.
o A tool which is harder than the workpiece contacts the piece removing material in the form of chips. The tool has a relief angle so that it contacts the piece at one point. Either the tool can spin with work fixed(mill), or the work can spin with tool fixed (lathe)
o Continuous chip: gives good surface finish and steady cutting forces, but may be undesirable for automated machinery
o Discontinuous chip: is desirable for chip removal, but cutting forces may fluctuate, affecting surface finish and causing chatter
o Built-up-edge (BUE) chip: generally results in poor surface finish, but a thin stable edge can protect tool surfaces
Identify the purpose of common cutting operations based on a rotating workpiece, including turning, facing, boring, parting, threading, knurling, and reaming
o Turning: reduction of diameter along axis of work, can produce straight, conical, curved or grooved surfaces
o Facing: produces a flat surface at the end of the part and perpendicular to its axis
o Boring: turning on internal surface, used to enlarge a hole or cylindrical cavity
o Parting: (cutting off) used to cut off a section from the end of the part
o Threading: produces internal or external threads along the parts axis
o Knurling: produces a regularly shaped roughness (indentations)on cylindrical surfaces, as in knob or handles
o Reaming: used to make an existing hole dimensionally more accurate than can be achieved by drilling alone
Describe the functionality of basic parts of a lathe with proper terminology, including common cutting tools used on a lathe
o Chuck: holds the workpiece securely to the spindle of the lathe (can be done with collet, faceplate)
o Headstock: is fixed to the bed and houses the motors, pulleys, belts, etc.
o Bed: main body of the lathe, supports all major components
o Tailstock: can slide along the ways and be secured at any position, used to support or align the workpiece, can also be used for drilling, reaming, etc.
o Tool post: used to secure the cutting tool to the lathe, and adjust its position and orientation
o Carriage: slides along the ways is an assembly of the cross-slide, tool post and apron
o Common tools: parting tool, single-point cutting tool (left-hand, right-hand, threading), knurling tool, boring bar, etc.
Quantitatively inter-relate lathe cutting parameters including rotational speed, surface speed, feed, feed rate, time, depth of cut, length of cut, and material removal rate
o rotational speed (N), surface speed(V), feed(f), feed rate(v), time(t), depth of cut(d), length of cut(L), diameter part(D) o t=L/v o d=(D0-D)/2 o v=f*N o V=pi*D*N o MRR=pi/4(D0¬2-D2)*v
Identify the purpose of common machining operations including countersinking, counterboring, reaming, end milling, face milling, peripheral milling, pocket milling, and, broaching
o Countersinking: is a conical hole cut into a manufactured object, or the cutter used to cut such a hole. A common usage is to allow the head of a countersunk bolt or screw
o Counterboring: an refer to a cylindrical flat-bottomed hole, which enlarges another hole, or the tool used to create that feature
o Reaming: is a metalworking tool used to create an accurate sized hole
o End milling: cutter rotates on an axis perpendicular to the workpiece surface the end of the cutter is used
o Face milling: the cutter is mounted on the spindle having its axis of rotation perpendicular to the workpiece surface, usually cutter is applied to the largest face
o Peripheral milling: the axis of the cutter rotation is parallel to the workpiece
o Pocket milling:
o Broaching: a long multiple-tooth cutter is used to machine internal and external surfaces, such as holes of circular, square, or irregular section
Describe the functionality of basic parts of a milling machine with proper terminology, including common cutting tools used on a milling machine
o Worktable: on which the workpiece is clamped using t-slots, table moves longitudinally relative to the saddle
o Saddle: supports the table and can move in the transverse direction
o Knee: supports the saddle and gives the table vertical movement so that the depth of cut can be adjusted, and accommodate various height workpiece
o Base: the bottom most structure of the mill
o Head: contains the spindle and cutter holders, in vertical machines the head may be fixed or can be adjusted vertically
o Column: the vertical structural component of a mill, supports the head
o Tools: end mill, fly cutter, ball-nose cutter, face mill
Explain the effect of cutting parameters and process variables on milling surface quality, including characteristics of conventional milling vs. climb milling
o Conventional milling: The chip thickness starts at zero thickness, and increases up to the maximum. The cut is so light at the beginning that the tool does not cut, but slides across the surface of the material, until sufficient pressure is built up and the tooth suddenly bites and begins to cut (material fed opposite cutter rotation)
o Climb milling: Each tooth engages the material at a definite point, and the width of the cut starts at the maximum and decreases to zero. The chips are disposed behind the cutter, leading to easier swarf removal (material fed in same direction as cutter rotation)
Quantitatively inter-relate milling and drilling parameters including rotation speed, feed, feed rate, surface speed, cut dimensions, time, and material removal rate.
o rotation speed(N), feed(f), feed rate(v), surface speed(V), depth of cut(d), width of cut(w), length of cut(L), number of teeth(n), time(t), cutter diameter(D), and material removal rate (MRR) o f=v/(nN) o V=pi*DN o MRR=dwv o t=L/v
Select proper spindle speed for drilling, turning, and milling based on materials and recommended cutting parameters.
look up
*Propose methods for machining given shapes, with correct reference to machining axes, cutting tools, and capabilities.
look up
