Melkan Çelik-503041311-3rd week unanswered words

Indirect Labor-Accounting

Previous definition: These cost are generated in servicing of the total manufactoring operation, consisting of such activities as supervision, repair, maintenance, quality control, engineering, research, and sale it also includes the cost of office staff. Because they do not contribute directly to the production of finished parts, or they are not chargeable to a specific product, these costs are referred as overhead and are charged proportionally to products. the personnel involved in these activities are categorized as nonproductive labor.

(Serope Kalpakjian, Steven R. Schimidt, MANUFACTORING ENGINEERING AND TECHNOLOGY, 5th Edition, page 1264) 

New-better:

Direct labor hours is time spent by individuals who work specifically on manufacturing a product or performing a service. In contrast, indirect labor hours is the time spent by individuals involved in supervising or supporting the process of manufacturing a product or performing a service. For example, in a car manufacturing plant, direct labor is defined as those individuals who directly work on car products (i.e., phsycially use the production equipment to make cars). Indirect labor in a car manufacturing plant would involve line supervisors, machine maintenance staff, plant security personel, etc.

(Encyclopedia of production and manufacturing management-Paul M. Swamidass-p.159)

Vibratory Agitation-Production equipment

Previous definition: Research on vibratory agitation has been carried out using a commercial vibromixer with a motor operating at 50Hz. Both flat and perforated discs were employed; the latter are preferable so that the disc does not operate as an hydraulic piston which uses large amounts of energy to produce little mass agitation.

Various types of agitation patterns were studied. Vibrational agitation is reproducible and is controllable by the input voltage or power to the motor of vibromixer. The use of Reynolds number to characterize the agitation was proposed where Re = 2fad/v; a is amplitude, if is the frequency, d the diameter of the disc and v is the solution viscosity. A transformation from laminar to turbulent conditions occured at a Reynolds number of approximately 2500. This mode of agitation has also been used for the study of deposition of composite coatings.

(Nickel and Chromium Plating, J.K.Dennis, T.E.Such, Page 429)

New-better:

The mixing studies demonstrated that vibratory agitation produced strong vertical fluid motion, good bulk circulation and dispersion in the liquid. The effects of stroke frequency, n;

amplitude, a; blade width, w; blade clearance, c; and liquid depth, h, on mixing time, θ are the variables.

Vibratory agitation is capable of producing mixing and solid suspension in a slab tank. Of

the geometries studies, the single flat blade configuration with a minimum off-bottom clearance and a w/T (T:Tank width) of 0.75 was considered to be the most effective for mixing and solid suspension requirements in a slab tank.

Vibratory mixing in a slab tank is very similar to rotary mixing. The homogenization number, H_o, the number of revolutions or strokes require to.obtain complete mixing, is constant for a given geometry with the stroke amplitude included in the geometry specification. The type of bulk motion induces by a vibratory agitator is very effective in the production of a homogeneous slurry. Particles are pulled off the tank bottom, drawn into the bulk circulation, and dispersed throughout the tank. The general solid suspension behavior in vibratory mixing is also very similar to rotary mixing.

(Making and Suspension Capabilities Of Vibratory Agitators In a Slab Tank-C. J. Ramsey, E.A. Kyser, and G. B. Tatterson-pg.17)

Assembly planning-Product design

Previous definition: Since most manufacturing products are composed of assemblies of individual components, assembling these components is a key point in manufacturing products. In light of this fact, it is odd that assembly and assembly planning receive far less research attention than individual component manufacturing. Assembly planning can be roughly divided into three phases:

1. Selection of assembly method: identifying the one most suitable method for the product while accounting for the type of assembly system to be used;

2. Assembly sequence planning: generating a sequence of assembly operations (placing each component in its final position in the assembly) to be used to implement an assembly task in a given assembly system;

3. Assembly operations planning: emphasizing the details of individual assembly steps, such as access directions, mating movements, and application of fasteners.

 (Nasr E.A., Computer-Based Design and Manufacturing, p. 76).

New-better:

In the digital factory assembly planning is supported by collision examinations, ergonomic simulation, process planning, scheduling and material flow simulation. The aim is to support the assembly planning tasks more strongly and to automate routine activities. The assembly planning is based on the bill of materials by which assembly surface matrix, the directed and undirected assembly surface graph as well as the assembly priority graph can be created. These planning tasks are based on the final three-dimensional model. That means, planning tasks have to be integrated earlier in the product development process to evaluate the product model in early design phases with regard to the possibility to assemble the product or to initiate design changes in order to avoid cost-intensive assembly processes. So, standarts have to be worked out that allow such analysis without generating additional work for the different departments that are involved in the product development process. Ensuring an improved sequence of operations in assembly planning based on basic design information, new strategies fort he data transmission have to be installed to solve the interaction tasks realising a stronger connection and a beter transparency along the whole product development process.

Therefore milestones along the development process have to be defined in order to generate a frictionless data exchange between the departments that optimise the sequence and parallelisation of operations.

Normally the design department supplies the assembly planning with the finished three-dimensional model and the bill of materials. Then the assembly department has the task to assemble the product and to transform the design-oriented bill of material into a production-oriented manufacturing bill of material.

(Precision assembly technologies for mini and micro products- Svetan Ratchev-pg.121-122)

Production Rate-Accounting

Previous definition: A major factor in manufactoring process section is the production rate. This is defined as a number of pieces to be produced per unit of time (such as hour, per day, or per year). Recall this project such as die casting , powder metallurji, deep drawing, wire drawing, adn roll forming are production rate operations. 

(Serope Kalpakjian, Steven R. Schimidt, MANUFACTORING ENGINEERING AND TECHNOLOGY, 5th Edition, page 1256) 

New-better:

The theoretical production rate of a system, or machine cycle,refers to pieces produced per unit of time when a machine or system is running with no interruptions or delays. This rate is typically constrained by the physics of the processes and the robustness of the machines. The actual production rate of a system is called the process or system yield, which is the number of acceptable pieces produced per unit of time, incorporating both delays, occuring regularly during production and unpredicted interruptions, such as machine breakdowns. The efficiency of the overall process, as far as production rate is concerned, is the ratio of process yield as a percent of machine cycle.

(Manufacturing systems: theory and practice-George Chryssolouris-pg.16)

Life cycle assesment (LCA)-Quality Control

Previous definition: According to the ISO 14000 standard life cycle assesment is defined as a systematicset of procedures for compiling and examining the inputs and outputs of materials and energy and the associated enviromental impacts or burdens directly attributable to the functioning of a product, process, or service system throughout its entire life cycle.

(Kalpakjian S., Schmid S.R., Manufacturing engineering and technology, 1245)

New-better:

Although many definitions exist, LCA essentially comprises a systematic evaluation of environmental impacts arising from the provision of a product or service. The original International Organization for Standardization (ISO) definition provides some indication, although it is self-referencing: “compilation and evaluation of the inputs and outputs and the potential environmental impacts of a product system throughout its life cycle”. Generic LCA method requires that all the main inputs to the processes that provide the service are taken into account, as well as the processes and materials that feed into those processes, and so on back “up” the supply chains of the various materials in the product to the raw resource inputs. These raw inputs are invariably energy-based-the coal mine or oil well- rather than simply raw materials. For example, making bricks may require brick clay and an extraction quarry, but this process operates with fossil fuel-powered machinery. Hence, although bricks are made from quarried clay and other materials, at the end of this process is the oil well or coal mine required to drive the steel mill to maket he machinery used in clay extraction.

International standards asist in the specification, definition, method and protocols associated with undertaking, reviewing and reporting LCA studies. ISO 14040 describes the principles and framework for life cycle assessment. The original standard (produced in 1997) was updated in 2006 (ISO 2006a). This “core” standard includes guidance on defining the goal and scope of an LCA study, development of the life cycle inventory, the life cycle impact assessment, and interpretation (Fig. 1.1).

(Life cycle assessment: principles, practice, and prospects- Ralph Horne,Karli Verghese,Tim Grant-pg.2-3)