Alpay Teoman YILDIZ 030050014 - 12th Week

Countersinking:

Countersinking is the shaping of a hole or depression to conform to the shape and thickness of a flat or oval screwhead; it is done with a cone-shaped cutter called a countersink. The angle at which the depression is cut is standard, being controlled by the countersink, which in turn is made to conform with the angle of the underside of the screwhead. The purpose of countersinking is to permit the head of a flathead screw to set flush with or slightly below the surface of the wood. A hole that is to receive a flathead or ovalhead screw is first bored, then it is countersunk on the surface which the screw enters. The depth to which a hole is countersunk will depend on the thickness of the screwhesd. This thickness is measured from the point where the body of the screw ends and the head starts, to the widest part of the head.

Fundamentals of shopwork, p. 169

Impact Extrusion:

Impact extrusion is one of the cold fonning processes used for large-sized productions. A lubricated volume-controlled slag is placed in a die cavity and struck by a punch, forcing the metal to flow back around the punch, through the opening between the punch and die. The thickness of the extruded tubular section is a function of the clearance between the punch and the die cavity. The most common impact extrusion techniques are forward extrusions and backward extrusions. However creative design can enable both of the techniques to be used simultaneously in combination to minimize production costs, as many designs include both types of extrusion. The process is usually performed on a high-speed mechanical press. Although the process is performed cold. considerable heating results from the high-speed deformation. lmpact extrusion is restricted to softer metals such as lead, tin, aluminum, and copper. Products made by this process include toothpaste tubes and battery cases. As indicated by these examples, very thin walls are possible with impact-extruded parts.

Boljanovic V., Metal Shaping Processes, p.182

Climb Milling:

ln climb milling, the chip thickness is thin when the cutting flute leaves the contour, eliminating tool pressure at the contour. ln this mode, the tool has the tendancy to push down the part toward the table, and for that reason, climb milling is also known as down milling. This method is preferred for CNC contour milling.

Smid P., CNC Control Setup for Miling and Turning: Mastering CNC Control Systems, p.112

Gang Drilling Machine:

The machine has a long common base and table. Four to six drills heads are mounted on the table. Each head has its own driving motor so that the speeds and feeds of individual units can be controlled independently. Gang drilling machines are used in production line where a series of operations like drilling, reaming and tapping are performed on a single job, in a succestive manner, each spindle performing one particular operation only.

Ramanath V, Kesavan R, Manufacturing Technology - II, section 5.2.5