1-End Cutting Angle ( Group: Manufacturing)
The end-cutting-edge-angle is the amount that the end-cutting edge slopes away from the nose of the tool, so that it will clear the finished surface on the workpiece, when cutting with side-cutting edge. The size of this angle is very important, particularly when cutting materials that tend to form a large crater on the face of the tool. This crater will then tend to enlarge toward the end-cutting edge where it will eventually break through and cause the tool to fail.
(Moltrecht K. H., Machine Shop Practice Volume 1, p.182)
The end-cutting-edge-angle is the amount that the end-cutting edge slopes away from the nose of the tool, so that it will clear the finished surface on the workpiece, when cutting with side-cutting edge. The size of this angle is very important, particularly when cutting materials that tend to form a large crater on the face of the tool. This crater will then tend to enlarge toward the end-cutting edge where it will eventually break through and cause the tool to fail.
(Moltrecht K. H., Machine Shop Practice Volume 1, p.182)
New and better explanation
The auxiliary or end cutting-edge angle (γa
or γe ) is provided to clear the cutting edge from the machined
surface and reduce tool chatter. Too large an angle, however, weakens the tool
and affects heat conduction. The principal or side cutting-edge angle (γp
or γs) affects tool life as well as surface finish. With principal
or side cutting-edge angle the tool first contacts the workpiece some distance
away from the tip and also increases the tool length in action during cutting.
The edge, therefore, lasts longer and conductivity also increases. At large
principal cutting edge angles, the force component trying to separate the tool
from the workpiece increases and promotes chatter. Large angle also weakens the
tool. For most machining operations an angle in the range of 5 to 15 degrees
for both cutting edges has been found to be quite satisfactory.
( Lal, G. K.(2003). Cuning-Edge Angles. Introduction To
Machining Science (p.40). )
( Woodson, C.W.( September 1957).LAthe
tools. Popular Mechanics Magazine (p.214).
) –picture from
2-Hydraulic automation (Group: Machine System)
Hydraulic systems have a significant advantage over pneumatic systems in their ability to handle higher loads and torques. Hydraulic oil is also practically incompressible. Hydraulic systems operate at significantly higher pressures ranging from 35 Mpa to 200 or more Mpa. This reduces the size of the actuators. Hydraulic systems require a power pack to supply pressurized oil of adequate quantity. As in pneumatic systems, the actuators are either motors or cylinders. The muscle power of hydraulic systems combined with the flexibility and ease of electrical and electronic control makes electro hydraulic systems an obvious choice even for very demanding applications. Industrial hydraulic systems use a wide variety of components like cylinders, rotary actuators, pumps, valves for the control of flow direction, volume, pressure etc, accumulators, filters and tubing.
( CAD/CAM/CIM, P. Radhakrishnan S. Subramanian V. Raju,p359)
Hydraulic systems have a significant advantage over pneumatic systems in their ability to handle higher loads and torques. Hydraulic oil is also practically incompressible. Hydraulic systems operate at significantly higher pressures ranging from 35 Mpa to 200 or more Mpa. This reduces the size of the actuators. Hydraulic systems require a power pack to supply pressurized oil of adequate quantity. As in pneumatic systems, the actuators are either motors or cylinders. The muscle power of hydraulic systems combined with the flexibility and ease of electrical and electronic control makes electro hydraulic systems an obvious choice even for very demanding applications. Industrial hydraulic systems use a wide variety of components like cylinders, rotary actuators, pumps, valves for the control of flow direction, volume, pressure etc, accumulators, filters and tubing.
( CAD/CAM/CIM, P. Radhakrishnan S. Subramanian V. Raju,p359)
New and better explanation
Basic system
A basic
hydraulic system for a machine tool consists of an (electric) motor driving
apump, which circulates an hydraulic fluid from a reservoir to the various
control valves, and on to cylinder/actuators. An hydraulic power pack is a
convenient source (see chapter on Ring mains and power packs). At least one
filter in the system is essential to maintain the necessary standard of
cleanliness in the hydraulic fluid for the required machine reliability. Piping
and hoses are the links between the components, but by use of carefully
designed manifolds (for the control valves) these may be kept to a minimum.
Another feature which may be necessary to give the maximum accuracy to the
machine operation, is that of maintaining the temperature within a few degrees
of the optimum; this is done by means of an oil cooler such as an air blast
cooler.
Automation
There are various degrees of automation ranging from
semi-automation to a fully programmed system, namely.
i)
Semi-automation - typified by sequential
control where an operator is responsible for start/stop and also inspection and
supervision.
ii)
Automation - typified by sequential control
with 'feedback' where an operator is only necessary for stop/start.
iii)
Full automation - or a programmed sequential
control system using punched tape Or a computer.
iv)
Fully programmed automation - where the
control is fully programmed and is capable of self-analysis, correction. etc.
( Hunt, T. M., Vaughan,
N. D., Warring, R. H. (1996). Basic system- Automation .The hydraulic
handbook (pp. 597,603). )
(Mikell P.Groover, Fundamentals of Modern Manufacturing , materials,processes, and systems third edition page 596-597)
3-Grain Size ( Group:
Material)
The grain size of the abrasive particle is important in determining surface
finish and material removal rate. Small grit sizes produce better finishes,
while larger grain sizes permit larger material removal rates. Thus, a choice
must be made between these two objectives when, selecting abrasive grain size.
The selection of grit size also depends to some extent on the hardness of the
work material. Harder work materials require smaller grain sizes to cut
effectively, while softer materials require larger grit sizes.The grit size is
measured using a screen mesh procedure.In this procedure, smaller grit sizes
have larger numbers and vice versa. Grain sizes used in grinding wheels
typically range between 8 and 250. Grit size 8 is very coarse and size 250 is
very fine. Finer grit sizes are used for lapping and superfinishing.
(Mikell P.Groover, Fundamentals of Modern Manufacturing , materials,processes, and systems third edition page 596-597)
New and better explanation
grain
size. (1) For metals, a measure of the areas or volumes
of grains in a polycrystalline material, usually expressed as an average when
the individual sizes are fairly uniform. In metals containing two or more
phases, grain size refers to that of the matrix unless otherwise specified.
Grain size is reported in terms of number of grains per unit area or volume, in
terms of average diameter, or as a grain-size number derived from area
measurements.
( American Society for Metals
(1993). Grain size. ASM metals reference book (p.43). )
4-Spaghetti Diagram ( Group: Process
Management)
The spaghetti diagram is associated with a processof
designing revised steps to reduce process waste by eliminating unnecessary
transportation of information or materials. Such transporting is called “parts
travel” in industrial engineering because the items are parts that travel on
material handling equipment. Process observation tools such as process maps,
cycle time observation, spaghetti diagrams, and value stream mapping (VSM)
techniques are lean tools used to identify areas of concern and wasted time.
Creating a spaghetti diagram requires the process flow in the facility. The
flow is given in facility routings. The facility routings include a location of
the product defined by an area in the facility and a brief description of what
is being done at that area. When analysis of the spaghetti diagram is being
done you use the total travel distance (TTD). TTD is the distance the parts
travel throughout the facility.
(Introduction to
Engineering Statistics and Lean Sigma, Theodore T. Allen; Page:128)
New
and better explanation
Readers of Mc Family Curcus, comic strip, in which a
boy often runs all over the neighborhood to get to the house next door, will
appreciate the value of the spaghetti diagram. It gets its name from the
drawing of lines to track a process routing through the factory. Like the boy
in the comic strip, parts may travel thousands of feet (or even a few miles)
before they get to the shipping dock.
Heizer and Render quantify the costs that are
associated with the spaghetti diagram as follows. Cost =
is the cost to move a lot or batch between
departments i and j, and Xij represent the number of lots to be
moved.27 It is important, however, to consider the cycle time costs
in addition to the monetary costs of moving the pieces. The unquestioning use
of the preceding metric may, in fact, encourage dysfunctional behavior like
letting the parts wait until they make up a full forklift-load or cartload. For
example, it "costs” twice as much on paper to move two ten-piece lots as
it does to move a twenty-piece lot, and acting on this observation encourages
hatching and queuing as opposed to single-unit flow. ln general, it might be
better to focus on reducing the cost (whether in time, money, or both) of
moving lots to encourage lot splitting or even single-unit flow. The moving
assembly line and the work cell realize this goal by reducing the movement cost
to virtually nothing.
( Levinson, W.A.(2007).
Spaghetti
Diagram. Beyond
the theory of constraints (pp. 97-98). )
5-Fixed
Automation (Group: Production System)
Fixed automation is a system in which the sequence of processing (or assembly) operations is fixed by the equipment configuration. Each operation in the sequence is usually simple, involving perhaps a plain linear or rotational motion or an uncomplicated combination of the two, such as the feeding of a rotating spindle.It is the integration and coordination of many such operations into one piece of equipment that makes the system complex. Typical features of a fixed automation are 1) high initial investment for custom-engineered equipment, 2) high production rates, 3) relative inflexibility of the equipment to accomodate product varicity. The economic justification for fixed automation is found in products that are produceed in very large quantities and high production rates. The high initial cost of equipment can be spread over a very large number of units, thus making the unit cost attractive compared to alternative methods of production. Examples of fixed automation include machining transfer lines and automated assembly machines.
(M.P. Groover, Automation, production systems, and computer-integrated manufacturing, 3rd Edition, p. 10)
Fixed automation is a system in which the sequence of processing (or assembly) operations is fixed by the equipment configuration. Each operation in the sequence is usually simple, involving perhaps a plain linear or rotational motion or an uncomplicated combination of the two, such as the feeding of a rotating spindle.It is the integration and coordination of many such operations into one piece of equipment that makes the system complex. Typical features of a fixed automation are 1) high initial investment for custom-engineered equipment, 2) high production rates, 3) relative inflexibility of the equipment to accomodate product varicity. The economic justification for fixed automation is found in products that are produceed in very large quantities and high production rates. The high initial cost of equipment can be spread over a very large number of units, thus making the unit cost attractive compared to alternative methods of production. Examples of fixed automation include machining transfer lines and automated assembly machines.
(M.P. Groover, Automation, production systems, and computer-integrated manufacturing, 3rd Edition, p. 10)
New
and better explanation
Fixed automation is what Harder was referring to
when he coined the word automation. Fixed automation refers to production
systems in which the sequence of processing or assembly operations is fixed by
the equipment configuration and cannot be readily changed without altering the
equipment. Although each operation in the sequence is usually simple, the
integra-tion and coordination of many simple operations into a single system
makes fixed automation complex. Typical features of fixed automation include
(I) high initial investment for customengineered equipment, (2) high production
rates, (3) application to products in which high quantities are to be produced,
and (4) relative inflexibility in accommodating product changes. Fixed
automation is economically justifiable for products with high demand rates. The
high initial investment in the equipment can be divided over a large number of
units, perhaps millions, thus making the unit cost low compared with alternative
methods of production. Examples of fixed automation include transfer lines for
machining, dial indexing machines, and automated assembly machines. Much of the
technology in fixed automation was developed in the automobile industry; the
transfer line (dating to about 1920) is an example.
( Dorf, R. C., Kusiak,
A. (1994). Fixed automation. Handbook of design, manufacturing, and
automation (p.9). )
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