Inventory is a physical
stock of items that a business or production enterprise keeps in hand
for smooth functioning. Inventory control is a concept in which
material with apposite quantity and quality is made available
whenever required with due regard to economy in storage and ordering
costs and working capital. Inventory control helps to ensure goods
requirement in reserve format at the lowest possible ultimate cost.
Improper inventory control leads to heavy loss. The most important
functions of inventory control are to run the stores effectively, to
ensure timely availability of material and avoid build-up of stock
levels, technical responsibility for the state of material, stock
control system, maintenance of materials, supply etc. and avoiding
improper handling. The tools to control inventory are maximum
stores, minimum stores, standard order, re-ordering point and
procurement time. A good inventory control allows an organization to
make purchases in economic lots, maintain continuity of operations,
avoid small time consuming orders and assured prompt delivery of
finished goods.
VTU TECHNICAL SEMINAR TOPICS
Monday, February 17, 2014
Classification of rivers
The two main types of
rivers are rivers in hills and rivers in flood plains. Rivers in
hills start from the mountains and flow through the hilly regions
before reaching plains. Rivers in hills are of two types. They are
incised river stage (rocky stage) and boulder river stage.
Degradation process is responsible for flow channel in Rocky stage
types. In Boulder river stage, river flows through wide shallow beds
and interlaced channels and develops a straighter course. Rivers in
flood plains or alluvial plains are of four types. They are
aggrading, degrading, stable and deltaic. A silting river which forms
a slope is known as aggrading river. In a degrading river, the river
bed gets sourced constantly. In a stable type river, it is very
difficult to find any significant changes in alignment, slope and
regime. A deltaic river gets divided into branches before joining the
sea. Based on flood hydrographs, there are two categories of rivers.
They are flashy rivers and virgin rivers. Sudden flood rise and flood
fall results in a flashy river. If the river water dries completely
before it joins another river or sea is known as Virgin River.
Wednesday, December 25, 2013
Metallic and non-metallic coatings
Metallic and non-metallic
coatings are used for corrosion protection in metals. The major types of
metallic coatings are hot dipping, spraying, electroplating and diffusion
coating. In hot dipping, the metal part which is to be protected against
corrosion is dipped in a molten bath of the coat metal. In spraying method, the
coat is melted into small drops of liquid and propelled by a blast of air on to
the metal surface. Aluminium coatings are obtained by hot dipping or spraying. In
electroplating method, the metal part which is to be coated is made cathode and
immersed in an electrolytic bath with the electrolyte containing the ions of
the coating material. Nickel coating and tin coating are usually done by
employing electroplating technique. In diffusion coating, the diffusion of the
coat metal into the part through the surface is achieved at an elevated
temperature. Metal coating can be classified according to their electrochemical
behavior into two-noble coatings and sacrificial coatings. The coat is noble
with respect to the underlying metal in noble coatings. The underlying metal is
protected by the sacrificial action of the coating in sacrificial coatings. Zinc
coatings on iron are sacrificial. There are two categories in nonmetallic
coatings- organic and inorganic. Organic coatings refer mainly to paints
applied to metals. Paints are normally mixture of particles of a pigment in a
continuous organic medium. Examples of pigments are red lead and zinc chromate.
Examples of inorganic nonmetallic coatings are enamel and porcelain.
Bearing alloys
A stationary bearing
should possess least friction between the bearing and the rotating part for
better result. The wear of the contacting metals is made as low as possible and
made strong enough to withstand pressures that arise from small misalignments. For
preventing seizures, stationary bearing melting point should be low. To make
friction and wear low, a thin film of lubricating oil is introduced between
bearing and the rotating part. Soft and low melting alloys are preferred to
deal with pressure and melting related issues. Normally a soft matrix bearing
alloy in which hard particles are incorporated is a preferred choice. Babbits
or white metals are used for this purpose. Normally babbits are either
lead-based or tin-based alloys. Addition of small amount of arsenic increases
the pressure withstanding power of alloys. Bronze bearings are normal choice
when we have to deal with high bearing loads. Some other commonly used bearings
are aluminium based and silver based.
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