Metin Atmaca 030080007 5th week definitions

1. Induction Heating (Manufacturing Process):

Previous Definition:

 Induction heating for forging is now fairly common, particularly for repetitive forging operations. Temperature control for induction heating must be taken seriously, given the rapid heating rates possible with this system. It should be remembered that the temperature of the billet is related directly to its initial temperature and the electrical power input to the induction coil. Commonly, the induction heater is set up the use a specific wattage for a given billet size and weight,based on the billet being at ambient temperature at the outset. The controls downstream of the induction coil can detect a billet temperature outside of the required range and eject the billet from the line. the billet is allowed to cool and is fed back into the system. If the billet is still warm when it enters the coil again, the exit temperature will be higher than intended and the risk of burning is increased. In induction heating lines, optical pyrometer systems are generally used and these must be kept clean and maintained.

( Steel forging: design, production, selection, testing, and application - Edward G. Nisbett - page76 )

New Definition (Better):

Electric furnaces for industrial process heating may use resistance or induction heating. Theoretically, if there is no gas or air exhaust, electric heating has no flue gas loss, but the user must recognize that the higher cost of electricity as a fuel is the result of the flue gas loss from the boiler furnace at the power plant that generated the electricity.

In induction heating, a current passes through a coil that surrounds the piece to be heated. The electric current frequency to be used depends on the mass of the piece being heated. The induction coil (or induction heads for specific load shapes) must be water cooled to protect them from overheating themselves. Although induction heating usually uses less electricity than resistance heating, some of that gain may be lost due to the cost of the cooling water and the heat that it carries down the drain.

Induction heating is easily adapted to heating only localized areas of each piece and to mass-production methods. Similar application of modern production design techniques with rapid impingement heating using gas flames has been very successful in hardening of gear teeth, heating of flat springs for vehicles, and a few other high production applications.

(W. Trinks, Industrial Furnaces, p.16)

2. Flexible Automation (Automation):

Previous Definition:

 
Flexible automation or programmable automation includes:
> Computer- aided design (CAD) - engineering analysis and simulation and computer- aided design and drafting(CADD)
> Computer -aided manufacturing (CAM) consisting of computer numerically controlled (CNC) machine tool, direct numerical control (DNC) machine tool, flexible manufacturing systems (FSM), automated material handlingsystem (AMH) and robotics.
> Computer -aided techniques for management consisting of management information systems (MIS), computer -aided planning (CAP), computer-aided process planning (CAPP),
These tools are used to help design products, manufacture precision products on the factory floor and assist in management of many shop floor ar plant operations. When systems for design, manufacturing and management are used together in a coordinated system, the result is computer -integrated manufacturing (CIM), a new strategy. ( Robotics Technology and Flex - Deb - page 282 )

New Definition (Better):

Flexible automation is an extension of programmable automation. A flexible automated system is capable of producing a variety of parts (or products) with virtually no time lost for changeovers from one part style to the next. There is no lost production time while reprogramming the system and altering the physical setup (tooting, fixtures, machine settings). Consequently, the system can produce various combinations and schedules of parts or products instead of requiring that they be made in batches.

What makes flexible automation possible is that the differences between parts processed by the system arc not significant. It is a case of soft variety, so that the amount of changeover required between styles is minimal. The features of flexible automation can be summarilized as follows:

• high investment for a custom-engineered system

• continuous production of variable mixtures of products

• medium production rate,

• flexibility to deal with product design variations

(Mikell P. Groover, Automation, Production Systems and CIM, p.11)

3. Inspection and Testing (Quality Control):

Previous Definition (Better):

 Inspection is normally used to examine whether a product conforms to the design standards specified for it. For a mechanical components, this would be probably concerned with the dimensionsi surface texture and tolerances specified for the part. Non-confirming goods result in scrap, rework and the loss of customer goodwill. The common situation that warrant inspection are :
>Incoming materials (raw materials, standard items, subcontracted parts )
>Stage inspection during manufacturing (e.g., when the parts are moved from one production section to another)
>At the completion of processing of the parts
>Before shipping the final assembled product to the customer
Whereas inspection is a regular activity in production, testing is a significant stage of work in product development to prove the capability of the product. Testing is normally associated with the functionalaspect of item, and is often directed at the final product rather than its components. Testing consist of the appraisal of the performance of the final product under actual or simulated conditions. If the product successfully passed the tests, it is deemed suitable for use. Testing ascertains the quality of performance of product.

(CAD/CAM/CIM - P.Radhakrishnan - page 493 )

New Definition:

Inspection and test are quality control activities. The purpose of inspection is to determine whether the manufactured product meets the established design standards and specifications. For example, inspection examines whether the actual dimensions of a mechanical part are within the tolerances indicated on the engineering drawing for the part. Testing is generally concerned with the functional specifications of the final product rather than with the Individual parts that go into the product. For example, final testing of the product ensures that it functions and operates in the manner specified by the product designer.

(Mikell P. Groover, Automation, Production Systems and CIM, p.34)

4. Injection Molding Cycle (Manufacturing Process):

Previous Definition:

The injection molding cycle is controlled by very precise timers.These time controllers are either of analog or digital design and are used to control the machine's operations precisely to within fractions of seconds.Most timers are digital, as they can be set more precisely.
The three phases of cycle time control are injection time,cooling time and ejection time.Because precise control of the molding cycle and part quality go hand in hand, select the most accurate timers for repeatable control of each cycle.Profitability is also closely tied to the molding cycle.Piece-part price is based on the overall cycle time required to make a part, and a molder wants to produce the parts in minimum cycle that ensures part quality and positive return for labor.


(Total quality process control for injection molding 2nd edition, M.Joseph Gordon, p.295)

New Definition (Better):

The sequence of events during the injection molding of a plastic part is called the injection molding cycle. The cycle begins when the mold closes, followed by the injection of the polymer into the mold cavity. Once the cavity is filled, a holding pressure is maintained to compensate for material shrinkage. In the next step, the screw turns, feeding the next shot to the front of the screw. This causes the screw to retract as the next shot is prepared. Once the part is sufficiently cool, the mold opens and the part is ejected.

Total cycle time can be calculated using

t_cycle = t_closing + t_cooling + t_ejection

(Osswald, T.A., Turng, L., Gramann, P., Injection Molding Handbook, p. 13)

5. House of Quality (Quality Management):

Previous Definition:

The term House of Quality is a diagram which is a part of Quality Function Deployment that is defined as ‘a system for translating consumer requirements into appropriate company requirements at each stage from research and development to engineering and manufacturing to marketing/sales and distribution’ by The American Supplier Institute.

(House of Quality in a Minute, Christian N. Madu, p.1)

New Definition (Better):

The “house of quality” is the framework of the approach to design management known as quality function deployment (QFD).

The House of Quality provides an organization with the means for inter-departmental or inter-functional planning and communications, starting with the so-called customer attributes (CAs). These are phrases customers use to describe product, process, and service characteristics.

Figure 3.2 shows the essential components of the quality table or HOQ diagram. The construction begins with the customer requirements, which are determined through the “voice of customer”- the marketing and market research activities. These are entered into the blocks to the left of the central relationship matrix. Understanding and prioritizing the customer requirements by the QFD team may require the use of competitive and compliant analysis, focus groups, and the analysis of market potential.

Once the customer requirements have been determined and entered into table, the importance of each is rated and rankings are added.

Each customer requirement should then be examined in terms of customer rating; a group of customers may be asked how they perceive the performance of the organization’s product of service versus those of competitors’. These results are placed to the right of the central matrix. Hence the customer requirements’ importance rankings and competition ratings appear from left to right across the house.

(Oakland, J.S. Total Quality Management, pp. 49-50)