The effectiveness of any training program should be evaluated periodically. During this evaluation, the progress made by individual toward skill development should be observed. Periodic reviews of the skills, training system, training process, and the curriculum are essential ingredients for continious improvement. For this purpose, a worker-skill inventory form can be used. This form provides the information regarding additional skills needed by each worker and also the total additional skills for all the workers with respect to maintaining a particular equipment. The data obtained before the onset of a training program may be compared with the data collected after completion of the program.
(Planning and control of maintenance systems: modeling and analysis, s. Duffuaa, A. Raouf, p.290 )
Evaluating Effectiveness (new-better) (elaborate method)
Evaluating the effectiveness of training is not always a simple task; thus,
oflen it is overlooked or ignored because the organization does not know
how to perform the evaluation. There are several ways to evaluate this effec-
tiveness, ranging from simple to elaborate methods. A few of the simpler
methods are discussed below.
A common approach utilize
s pretests and posttests. Thisway, you know
how much subject knowledge the employee possessed coming into the training
and how much the employee gained during the training. With a little preplan-
ning, this method is simple to initiate and meets the standard’s requirements.
Another common approach is to evaluate the training obtained during
the employee's performance review. Did the training help the employee to
improve job performance? This method should work—although the result
may have been due to multiple factors, not just the training.
Another method sometimes used is to evaluate the organization or
department's overall performance. Did the training provided improve the
performance? 'l‘his method is the least direct. but is helpful in looking at the
big picture.
I recommend utilizing a combination of all three methods listed above
to get the best evaluation of training. Training is normally a costly invest-
ment and should be monitored to ensure that the organization is getting its
money's worth. I worked with a very large company that required each
employee to obtain a significant amount of training hours each year.
Accomplishment of this task was linked to the company’s bonus program;
however, the subject of the training did not matter. We commended the com-
pany for enriching its employees’ lives, but suggested that at least some of
the training be directly linked to the job so the organization would benefit as
well as the individual. Evaluating training effectiveness should be a very
helpful tool for the organization to leam which training helps them improve.
(The Process Approach Audit Checklist For Manufacturing, Karen Welch, 2004, page: 18,19)
2) Pulse Counter (old)
Pulse counters can be used for both counting and measurement applications.A typical counting application might add up the number of packages moving past photoelectric sensor along a conveyor in a distribution center.A typical measurement application might indicate the rotational speed of a shaft.One possible method to accomplish the measurement is to connect to shaft to an optical encoder, which generates a certain number of electrical pulses for each rotation.To determine rotational speed ,the pulse counter measures the number of pulses received during a certain time period and divides this by the time period and by the number of pulses in each revolution of the encoder.
(Automation, production systems, and computer integrated manufacturing, 3rd edition,Mikell P. Groover,p.135)
Pulse Counter (new-better) (counter)
A counter, divider or divide-by-n counter is a circuit composed of multiple flip-flops that
stores pulses and produces an output pulse after a specified number (n) of input pulses have
occurred. In a counter consisting of flip-flops connected in series, when the first stage chang-
es state it affects the second stage and so on. Each input pulse toggles the counter circuit to
the next state. The outputs front all of the flip-flops can form a composite output that forms a
hinary number representing the total pulse count.
A ripple, ripple-carry or asynchronous counter passes the count from stage to stage; each
stage is clocked by the preceding stage so that the change in the circuit‘s state "ripples"
through the stages. In a synchronotrs counter. each stage is controlled by at common clock so
that the outputs of all stages change at the same time.
Most counters have the ability to clear the count to 0. Some counters can also be preset
to a desired count. Some counters may count up (increment) and some countdown (decre-
tnent). Upldown counter lCs are available. able to count in either direction. depending on the
status of a control input.
Internally, a decade counter IC has I0 distinct output states. Some counters have a sepa-
rate output pin for each of these I0 states. while others have only one output connected to the
last hit of the counter. The last llip-llop stage produces one output pulse for every I0 input
pulses.
Counter or divider circuits tind application in various forms. Common uses for these cir-
cuits in Amateur Radio include marker generators and frequency counters.
(The ARRL Extra Class License Manual: For Ham Radio, Ward Silver, 2008, page: 5-26)
3) Stress Corrosion Cracking: (old)
Stress corrosion is an interaction of sustained tension stress and corrosive attack causing cracking that can result in premature brittle failure of a ductile material. Before stress corrosion can occur, there must be the proper combination of a chemical environment and metallurgical condition of the material. Failures of this type have been identified with certain alloy systems of practically all menas, and in most instances the failures have been shown to be associated with electrochemical activity. In aluminum alloys, stress corrosion can be promoted by a film of moisture on the surface of metal exposed to the atmosphere or by contaminants such as chlorides. Only a prolonged surface tension stress will cause SCC, and sustained compression stresses actually prevent it. The tensile stress required to cause SCC are small, usually below the macroscopic yield stress. These stresses can be externally applied, but rsidual stresses often cause SCC failures. Susceptically to SCC limits the static strength of a material in certain applications just as fatigue cracking does in others. Both types of failure are caused by tension stress, but there the similarity ends. While fatigue failures occur under dynamic loads, stress-corrosion failures occur under dynamic loads, stress-corrosion failures are caused only by sustained static tension loads. An important difference with aluminum alloys is that stress-corrosion cracks are predominantly intergranular, most fatigue cracks are transgranular. It should be noted,however, that transgranular SCC has been observed for a few alloys under highly specific environmental conditions.
(Joseph R. Davis, Corrosion of aluminum and aluminum alloys, p.99)
Stress corrosion is an interaction of sustained tension stress and corrosive attack causing cracking that can result in premature brittle failure of a ductile material. Before stress corrosion can occur, there must be the proper combination of a chemical environment and metallurgical condition of the material. Failures of this type have been identified with certain alloy systems of practically all menas, and in most instances the failures have been shown to be associated with electrochemical activity. In aluminum alloys, stress corrosion can be promoted by a film of moisture on the surface of metal exposed to the atmosphere or by contaminants such as chlorides. Only a prolonged surface tension stress will cause SCC, and sustained compression stresses actually prevent it. The tensile stress required to cause SCC are small, usually below the macroscopic yield stress. These stresses can be externally applied, but rsidual stresses often cause SCC failures. Susceptically to SCC limits the static strength of a material in certain applications just as fatigue cracking does in others. Both types of failure are caused by tension stress, but there the similarity ends. While fatigue failures occur under dynamic loads, stress-corrosion failures occur under dynamic loads, stress-corrosion failures are caused only by sustained static tension loads. An important difference with aluminum alloys is that stress-corrosion cracks are predominantly intergranular, most fatigue cracks are transgranular. It should be noted,however, that transgranular SCC has been observed for a few alloys under highly specific environmental conditions.
(Joseph R. Davis, Corrosion of aluminum and aluminum alloys, p.99)
Stress Corrosion Cracking (new-better) (failure mode)
Stress corrosion cracking is a complex phenomenon driven by the synergistic interaction of mechanical,
electrochemical and metallurgical factors. Both BWR and PWR components can suffer from SCC, which may have transgranular (through the grains) or intergranular (along the grain boundaries) morphology.
Sometimes the modes are mixed or the mode switches from one to the other. IGSCC and TGSCC can occur in
the same alloy, depending on the environment, the microstructure, or the stress/strain state. SCC usually propagates perpendicular to the principal tensile stress. Cracks can also vary in the degree of branching.
All SCC has a brittle-like appearance, since cracks propagate with little or no macroscopic plastic
deformation. An alloy affected by SCC does not usually display abnormal mechanical properties (yield strength and tensile strength) although this may be observed in certain classes of alloys; such as precipitation hardened stainless steels or as a result of irradiation damage. Many alloys are susceptible to SCC in at least one environment.
However, SCC does not occur in all environments, nor does an environment that induces SCC in one alloy
necessarily induce SCC in another alloy.
SCC is usually divided into an initiation and a propagation phase. The initiation time can vary significantly and
can be up to several decades. The propagation phase is often divided into two parts, a ‘slow’ propagation phase and a ‘fast’ propagation phase of which the latter is usually characterized by crack tip stress intensities, KI
, exceeding a characteristic apparent threshold value in pre-cracked fracture mechanics type specimens known as KIscc.
Perhaps the most critical factor concerning SCC is that three preconditions are necessary and must be present
simultaneously. The elimination of any one of these factors or the reduction of one of these three factors below
some threshold level can, in principle, prevent SCC. The three necessary preconditions are:
— A susceptible material;
— A tensile stress component;
— An aqueous environment.
Figure 2.1 illustrates the critical factors for stress corrosion cracking.
(STRESS CORROSION CRACKING IN LIGHT WATER REACTORS: GOOD PRACTICES AND LESSONS LEARNED, IAEA NUCLEAR ENERGY SERIES, 2011, page:3)
4) Tape Forming (old)
5) CIRCULAR SAWING (old)
Circular sawing uses a rotating saw blade to provide a continuous motion of the tool to past to work.Circular sawing is often used to cut long bars ,tubes and similar shapes to specified length.The cutting action is similar to a slot milling operation, except that the saw blade is thinner and contains many more cutting teeth than a slot milling cutter.Circular sawing machines have powered spindles to rotate the saw blade and a feeding mechanism to drive the rotating blade into work.
(Fundamentals of modern manufacturing,materials,processes and systems,3rd edition, Mikell P.Groover, p.536) 01.01
Circular Sawing (new-better) (manufacturing method)
Sawing brittle materials, such as stone, concrete, ceramics, etc., by means of a diamond-
impregnated saw consists in wearing away its mineral constituents by passing
rigid grits over the machined surface. The diamond crystals, acting as cutting edges,
are firmly held in a matrix, which wears progressively exposing fresh particles while
those protruding sufficiently to cut are subjected to mechanical degradation to be
finally dislodged.
In order to attain the economically best sawing conditions, an ideal balance
between the tool life and cutting rate has to be achieved. The harder the workpiece
to be cut, the stronger the diamond type to be selected is a general rule while the
matrix has to erode at a rate compatible with the diamond breakdown. An incorrect
choice of the matrix and/or the diamond type, size and concentration yields a tool
that wears away excessively or refuses to cut altogether.
Regardless of the choice of diamond and matrix, there are other factors, which
have a strong effect on the sawblade performance. The most important are:
* segment, or cutting rim, manufacturing method and parameters ,
* workpiece properties ,
* sawing conditions ,
* cooling efficiency ,
* quality of the segment-to-metal core joint ,
* metal core design and tensioning ,
* machine condition and operator's skills .
Obviously, all the above-mentioned items are closely interrelated and therefore
each of them may prove critical and must not be neglected.
With circular sawing, the blade rotates in a constant direction at high peripheral
speeds of typically 25-65 m/s. This leads to the development of a tail of matrix
behind each individual diamond particle, as shown in Fig. 2.1, which acts as a support
during cutting.
To provide enough space for chip removal, parameters characterising the sawing
operation have to be considered in conjunction with the composition of the cutting
rim so not to thicken the slurry excessively, thus avoiding harsh wear conditions for
the matrix. The direction of sawing, whether upwards or downwards, may also
affect the tool behaviour and justify a modification to the sawblade specification.
Its effect is two-fold. First, the relative orientation of the resultant cutting force
and the support frame is different in down- and up-cutting as shown in Fig. 2.2.
(Powder Metallurgy Diamond Tools, Janusz Konstanty, 2005, page: 22,23)
Tape formingis used to make thin
ceramic parts like alumina substrates for integrated circuit chips and
special capacitor. A thin layer of slip is laid on a flat carrier which
can be a paper sheet or polymer film. A doctor blade controls the slip
thickness, resulting in a tape that can be stamped into small shapes.
These can be stacked or coiled for subsequent sintering.
(Ohring M., Engineering Materials Science, Part I, pg.420, Kayra Ermutlu)
Tape Forming (Casting) (new-better)
Tape casting is widely used in the industry for making large
thin sheets of ceramic materials for the fabrication of ceramic
substrates, multilayer products, piezoactuators, sensors, etc.
(Hotza and Greil, 1995; Bitterlich et al., 2002). Typically, during
tape casting, slip consisting of the ceramic powder dispersed
in a solvent, with the addition of dispersants, binder and plasticizer,
is cast onto a moving or stationary substrate. The cast
is then dried, if necessary laminated, and finally sintered to
obtain a flat ceramic sheet. As a ceramic forming method by
tape casting has great advantages in producing of thin sheets
relatively large area, with uniform and high-unfired densities
(Albano and Garrido, 2005).
thin sheets of ceramic materials for the fabrication of ceramic
substrates, multilayer products, piezoactuators, sensors, etc.
(Hotza and Greil, 1995; Bitterlich et al., 2002). Typically, during
tape casting, slip consisting of the ceramic powder dispersed
in a solvent, with the addition of dispersants, binder and plasticizer,
is cast onto a moving or stationary substrate. The cast
is then dried, if necessary laminated, and finally sintered to
obtain a flat ceramic sheet. As a ceramic forming method by
tape casting has great advantages in producing of thin sheets
relatively large area, with uniform and high-unfired densities
(Albano and Garrido, 2005).
(Journal of Materials Processing Technology 198, Emel Ozel, Semra Kurama, 2008, page: 68)
5) CIRCULAR SAWING (old)
Circular sawing uses a rotating saw blade to provide a continuous motion of the tool to past to work.Circular sawing is often used to cut long bars ,tubes and similar shapes to specified length.The cutting action is similar to a slot milling operation, except that the saw blade is thinner and contains many more cutting teeth than a slot milling cutter.Circular sawing machines have powered spindles to rotate the saw blade and a feeding mechanism to drive the rotating blade into work.
(Fundamentals of modern manufacturing,materials,processes and systems,3rd edition, Mikell P.Groover, p.536) 01.01
Circular Sawing (new-better) (manufacturing method)
Sawing brittle materials, such as stone, concrete, ceramics, etc., by means of a diamond-
impregnated saw consists in wearing away its mineral constituents by passing
rigid grits over the machined surface. The diamond crystals, acting as cutting edges,
are firmly held in a matrix, which wears progressively exposing fresh particles while
those protruding sufficiently to cut are subjected to mechanical degradation to be
finally dislodged.
In order to attain the economically best sawing conditions, an ideal balance
between the tool life and cutting rate has to be achieved. The harder the workpiece
to be cut, the stronger the diamond type to be selected is a general rule while the
matrix has to erode at a rate compatible with the diamond breakdown. An incorrect
choice of the matrix and/or the diamond type, size and concentration yields a tool
that wears away excessively or refuses to cut altogether.
Regardless of the choice of diamond and matrix, there are other factors, which
have a strong effect on the sawblade performance. The most important are:
* segment, or cutting rim, manufacturing method and parameters ,
* workpiece properties ,
* sawing conditions ,
* cooling efficiency ,
* quality of the segment-to-metal core joint ,
* metal core design and tensioning ,
* machine condition and operator's skills .
Obviously, all the above-mentioned items are closely interrelated and therefore
each of them may prove critical and must not be neglected.
With circular sawing, the blade rotates in a constant direction at high peripheral
speeds of typically 25-65 m/s. This leads to the development of a tail of matrix
behind each individual diamond particle, as shown in Fig. 2.1, which acts as a support
during cutting.
To provide enough space for chip removal, parameters characterising the sawing
operation have to be considered in conjunction with the composition of the cutting
rim so not to thicken the slurry excessively, thus avoiding harsh wear conditions for
the matrix. The direction of sawing, whether upwards or downwards, may also
affect the tool behaviour and justify a modification to the sawblade specification.
Its effect is two-fold. First, the relative orientation of the resultant cutting force
and the support frame is different in down- and up-cutting as shown in Fig. 2.2.
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