INDUSTRIAL
TRAINING REPORT
Training
Taken at:
LAKSHMI
MACHINE WORKS Ltd, COIMBATORE
&
SIMTA Ltd,
COIMBATORE
SUBMITTED
BY
SATHYA PRAKASH.G
2K2-177
DEPARTMENT OF MECHANICAL ENGINEERING
NATIONAL INSTITUTE OF TECHNOLOGY
KURUKSHETRA
FOUNDARY SHOP
SIMTA
FOUNDRY DIVISON:
SIMTA Foundry Division has adequate and advanced infrastructure. The shop floors are fully equipped with most modern manufacturing facilities. With a workface of around 250, the company can produce 350 tonnes of castings every month. Their in-house casting operations cover all phases of cast manufacturing from development & pouring to fettling & testing. Their direct handling of casting operations result in improved product quality and smooth production flow that minimizes the delivery time.
SIMTA Foundry Division consists of following shops: -
· Melting Shop
· Moulding Shop
· Fettling Shop and
· Pattern Shop.
FOUNDRY OPERATIONS:
Metal units ranging in complexity from pipefittings to engine blocks are often produced by pouring molten metals into sand moulds. This process is called CASTING. MOLDERS prepare the moulds into which metal is transferred.
When hollow castings are desired, COREMAKERS form cores, which are placed
inside moulds before the metal is poured. PATTERNMAKERS fabricate the
metal or wood shapes that give moulds and cores the proper shape. Now, we see these operations separately in detail: -
PATTERN MAKING:
Pattern making is the first step in which
you make a pattern that is an exact replica of the exterior of the casting you
want to make, with dimensional allowances included for shrinkage of the metal
upon cooling and any finishing that might be necessary. If the casting is to be
hollow, other patterns, called "cores", are also made and used to
create these cavities in the finished product.
Most patterns are usually made of wood,
metal, or plaster; however, other materials or combinations of materials are
used if there are specific properties required of the pattern. The number of
castings that are to be made from the mould, and the specifications required of
the finished casting, are two of the criteria that determine which material is
selected for the creation of the pattern. Since the patterns are used over and
over again they must hold up to fairly rough handling.
MOULDING
SHOP:
The moulding shop in the SIMTA Foundry Division, consists of the following machines,
· Sand mullers
· Core sand mixers
· Moulding machines
· Pneumatic sand rammers
· Sieve analysis/ permeability tester
· Mould/core hardness tester
The principal material used in the foundry shop for moulding is the sand. This is because it possesses the properties vital for foundry purposes. The following are the principal ingredients of the moulding sand.
· Silica and Grains.
· Clay
· Moisture and
· Miscellaneous Materials
Sand Muller Specifications:
Sand muller - 500 kgs.
Maintenance schedule – weekly.
Moulding sand Preparation:
The following procedure is adopted in the preparation of moulding sand in SIMTA Foundry Division.
1.Clean the sand muller and Switch on the machine.
2.Mix the black sand and the river sand and put them in to the muller.
3.Mix the pentonite powder upto 8-10% to the sand mixture.
4.In the dry state, mix the constituents up to a minute.
5.To this mixture add water upto 3-4%
6.Now, Shake the mixture upto3-4 minutes.
7.After mixing, take down the mixture and preserve a small amount of sand for sand testing.
The above method is followed while in the production of the moulding sand.
Moulding Sand Testing:
In progressive foundries like our SIMTA Foundry Division, it is recognized that the foundry sand deserves as much attention as the casting metal. The foundry sand may account for one-third of the cost of the finished casting. In modern mass production of sand castings, the moulding sand, which constitutes the chief moulding material, is therefore, required to be tested periodically in order that control of its composition and properties may be maintained. Test may be either chemical or mechanical. Chemical tests are used only to determine the undesirable elements in the sand, and in most cases mechanical tests are employed.
The essential mechanical tests include fineness, moisture content, clay content, permeability, strength in compression and mould hardness. Some of the tests that are performed here are,
· GRAIN FINENESS TEST
· TEST FOR MOISTURE CONTENT
Grain Fineness Test:
Grain size of sand is designated by a number called “grain fineness number” that indicates the average size as well as the proportions of smaller and larger grains in the mixture. A give grain fineness number corresponds to a standard sieve of 280 mm diameter, which has the identical number of meshes in it. The test of fineness is conducted by screening sand grains by means of a set of standard sieves that are graded and numbered according to the fineness of their mesh.
Test for moisture content:
This test is performed by drying 50 gms of the moist sand to constant weight between 105 degrees and 110 degrees in a uniformly heated oven, cooling to room temperature in a desiccator and then weighing the dry sample. The difference between the moist and dry weights of the sample in grams divided by 50 gm gives the percentage of moisture content in the given sand. For this an instrument called moisture teller is widely used in here.
The instrument blows hot air through the moist sand in a pan, the bottom of which is made of 500-mesh metal screen. The sand sample is spread over the pan in a thin layer, and hot air is blown for a period of approximately three minutes through a 50 gm sample. The moisture is effectively removed and precision balance determines the loss in weight of sample.