Ahmet Gökay Öztürk 030050143 (4rd week)

Overhead Cost

Overhead cost in present cost accounting practice is the
portion of total cost that cannot be directly traced to particular operations,
products, or projects. Indirect expenses should be allocated, utilized, and
added to the unit cost estimate. The problem with allocating overhead
charges is that these costs often exist even if the product is not produced.
Companies, based on their activities, may adopt different techniques in
measuring the overhead cost. Overhead charges may be determined in
different ways including:

1. Overhead as a ratio of direct labor dollars
2. Overhead as a ratio of direct labor hours
3. Overhead as a ratio of prime cost

The product cost is the summation of the material cost, direct labor plus
overhead cost, and the total tooling cost. The cost of the product can be
obtained by charging the overheads to the operation product cost.

(Emad Abouel Nasr,Ali K. Kamrani, Computer-Based Design and Manufacturing An Information-Based Approach, pg.57)

Fixtures

Fixtures were developed for job, batch and mass productions, which are widely used in manufacturing operation to locate and hold a part firmly in position so that the required manufacturing processes can be carried out according to design specifications. In machining processes, geometric accuracy of a manufactured part mainly depends on the relative position of workpiece to the machining tool. Fixtures are needed to locate the workpiece relative to the machining tool in order to ensure the manufacturing quality. It is clear that the primary requirements for a fixture are to locate and secure the workpiece in a given position and orientation on a worktable of the machine tool. In order to locate a workpiece, locators and supports are usually used in contact with the locating surfaces of the workpiece to restrict it to six degree of freedom, including linear and rotational motions. To secure the workpiece on a fixture, clamps are often utilized to keep a stable location against the machining force.

(Rong Y., Zhu Y., Computer-Aided Fixture Design, pg.1)

Encoders

1. A device that is capable of trans-
lating from one method of expression to
another method of expression. For example,
an encoder might translate a verbal message,
"add the contents of A to the contents of B,"
into a series of binary digits. Contrast with
decoder.
2. A device that transforms a linear or
rotary displacement into a proportional digi-
tal code.
3. A hardware device that converts
analog data into digital representations.

(Paul G. Friedmann,The Automation, Systems, and Instrumentation Dictionary 4th ed. , pg.177)


Spheroidizing

It is lowest temperature range of annealing process in which iron base alloys are heated 20 to 40°C below the lower critical temperature, held therefore a considerable period of time e.g. for 2.5 cm diameter piece the time recommended is four-hours. It is then allowed to cool very slowly at room temperature in the furnace itself. During this process, the cementite of steel which is in the combined form of carbon becomes globular or spheroidal leaving ferrite in matrix, thus imparting softness to steel. After normalizing of steels, the hardness of the order of 229 BHN and as such machining becomes difficult and hence to improve machining, these are spheroidised first and then machined. This treatment is carried out on steels having 0.6 to 1.4% carbon.
(R. SINGH, Introduction to Basic Manufacturing Processes and Workshop Technology, pg.139)