INDUSTRIAL TRAINING REPORT

Training Taken at:

ARUNA MACHINE TOOLS Ltd,

MADURAI

SUBMITTED BY

S.KRISHNA KUMAR

2K2-156

DEPARTMENT OF MECHANICAL ENGINEERING

NATIONAL INSTITUTE OF TECHNOLOGY

KURUKSHETRA

ARUNA MACHINE TOOLS:

Company Profile:

Evolution

Aruna Alloy Steels formerly known as, Aruna Machine Tools was founded in 1961 and is one of the leading manufacturers of steel castings based in south India. Aruna Machine tools has got its Foundry Unit I in Industrial Estate, Madurai, Tamilnadu. I undertook my industrial training in this foundry unit for 21 days (3 weeks).

Founder

Established by Sri AR.Sevugan Chettiar, a first generation successful Industrialist, the humble beginning has now blossomed into a prestigious industrial family with an annual turnover of INR 600 millions and the family is making considerable contribution to the economy through its varied industrial activities such as steel foundry, spinning and garments.

Features

AASPL has got the capacity to produce castings conforming to international Specifications in carbon, alloy & stainless steel grades. The continuous up-gradation of the production system ensures high quality, competitive pricing & speedy delivery. The company widens its product range constantly and thereby offers a more convenient product sourcing to its customers.

AASPL has the Quality Assurance System, which ensures that Quality is maintained consistently at all operating stages and the end products meet the customer requirements. Testing &inspection facilities include physical, chemical, visual & non-destructive testing.

AASPL, which is manned by qualified and experienced professionals, is confident of upholding and enhancing its reputation and reliability in all endeavors.

Product Manufactured:

The products produced by the Aruna Machine Tools have got various application in various industries especially in the valve industry and their foundries are equipped with flexible production system, which enable to meet the varied industry requirements.

The company’s main product line is for valve industry and it has a rich industry in supplying castings for rich performance valves. It offers bodies, bonnets, yokes and wedges for gate, globe, check, and ball, butterfly and plug valves with maximum pressure rating of 5000 PSI. and bore diameter up to 30 inches.

To fit the rapidly changing needs of the customers, the company is working continuously and thereby expands their product line. Aruna Machine Tools has got the infra structure to produce both valve castings and engineering castings including bodies, bonnets, wedges and yokes. The various valves produced here are as follows:

· Gate Valve

· Globe Valve

· Check Valve

· Ball Valve

· Butterfly Valve

· Plug Valve and

· Control Valve

Product Specifications:

ASTM A216

Grades : WCB - WSB(NACE) – WCC

ASTM A217

Grades : WC1 WC6 WC9 C5 C12 C12A CA15

ASTM A351

Grades : CF3 CF3M CF8 CF8M CF8C CD4MCU CN7M HK40

ASTM A352

Grades : LCB LCC CA6NM

ASTM A487

Grades: 4Q 60K

ASTM A744

Grades: CF8

ASTM A747

Grades: CB7Cu-1

Integrated Production:

Aruna has two steel foundries with adequate and advanced infrastructure. The shop floors are fully equipped with most modern manufacturing facilities and can produce castings to a maximum weight of 1250 kgs.

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.

The electronic data processing system at their foundries controls every activity of the organization order processing, delivery, and production status and inventory management throughout the company’s operations. This advanced management information system enables them to keep track on every single casting they make and thereby provide the customer with accurate and reliable feedback.

Aruna Machine Tools consists of following shops….

· Melting Shop

· Moulding Shop

· Fettling Shop and

· Pattern Shop.

Now, we will the training procedure taken in all the above stated shops separately.

Pattern Shop:

Pattern is the principal tool during the casting process. It may be defined as a model of anything, so constructed that it may be used for forming an impression called mould in damp sand or other suitable material. When this mould is filled with molten metal and the metal is allowed to solidify, if forms a reproduction of the pattern and is known as the casting. The process of making a pattern is known as pattern making. Let’s discuss about the selection of material used in the pattern making. The selection of pattern material depends primarily on the following factors.

1.Service requirements, e.g. quantity, quality and intricacy of casting i.e., minimum thickness desired, degree of accuracy and finish required.

2.Type of production of casting and the type of moulding process.

3.Possibility of design changes.

4.Number of castings to be produced, i.e., possibility of repeat orders.

To be good of its kind, pattern material should be:

1.easily worked, shaped and joined;

2.light in weight;

3.strong, hard and durable, so that it may be resistant to wear and abrasion, to corrosion, and to chemical action;

4.dimensionally stable in all situation;

5.easily available at low cost;

6.repairable and reused;

7.able to take good surface finish;

Types of the Patterns:

The type of pattern selected for a particular casting will depend upon several conditions. Among these one is the anticipated ease or difficulty of the moulding operation to come. Others are whether a small or large number of castings is wanted, the type of moulding process and other factors, which may enter the situation because of characteristics peculiar to the casting. Several of the more commonly used types of pattern are listed and described below:

1.Single-piece pattern

2.Split pattern

3.Match plate pattern

4.Cope and drag pattern

5.Gated pattern

6.Loose-piece pattern

7.Sweep pattern

8.Skeleton pattern

9.Segmental pattern

10. Shell pattern and

11. Boxed-up pattern.

Colour coding for pattern and core boxes:

All surfaces of a wooden pattern are coated with shellac to keep out moisture and important parts of a pattern and core-box are coloured for identification of their different parts. A widely accepted colour code for general use is give below,

1. Surfaces to be left unfinished are to be painted black.

2. Surfaces to be machined are to be painted red.

3. Seats for loose-pieces are to be marked by red stripes and a yellow background.

4. Core prints are to be painted yellow.

5. Stop-offs are to be marked by diagonal black stripes on yellow base.

A team of 15 workers is working in this unit on a daily wages basis. The average time taken for preparing, checking and painting a pattern is around 1 hour. After the checking of the pattern, it is kept in a corner of the shop.

Moulding Shop:

The moulding shop in the foundry unit I of the Aruna Machine Tools, 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 moulding sand for Aruna Machining Tools comes from the nearby village Chathirapatti that is located 15 km north of madurai. Also annually, moulding sand is also brought and piled up in large amount from Avadi and Veeriyambakam. 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.

Identification number 31211.

Maintenance schedule – weekly.

Moulding sand Preparation:

The following the procedure adopted in the preparation of moulding sand in Aruna Machine Tools.

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 Aruna Machine Tools, 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 a 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.

Mould core assembly:

The following procedure is followed during the assemble of mould and core here in the Aruna Machine Tools.

1.Check whether mould particle lining is uniform.

2.Use the 2PG torch to heat the mould and the core uniformly.

3.Place the core above the mould. Use, if necessary, the shape plate to fix the core according to the method card.

4.Once again, using the LPG torch hear the mould and the core uniformly.

5.Check the core assembly.

6.Place the core assembly in the places of location guides.

7.Clean the mould vent, riser, runner, sprew and ingate using the compressor air.

8.Coat the mould with core past/chalk powder.

9.Use the crane to join top mould with bottom mould.

10. Cover the boring cup, which covers metal sprew through which the molten metal would be poured in, using the CO2 powder sand.

11. Place thick iron bar besides the boring cup, if necessary.

Lets move on to the melting shop.

Melting Shop:

The melting shop consists of the following,

Ø 2000 kg / 800 kg induction melting furnace

Ø Bottom & tea spout ladles

Ø Laddle preheaters and

Ø Immersion pyrometers.

Melting details on 5-7-2004:

Furnace switch on: 12.20 hrs

Running heat number: B 8941

Running heat grade: WCB

Tapping expected at: 13.45 hrs

Tapping temperature: 1635 degrees

Next heat grade: WOB

Melting Procedure:

1.First of all, weigh the scraf according to the guidance of the supervisor.

2.Visually inspect eh empty furnace.

3.If there are no deformities in the furnace lining, put 150 kg of the scraf iron pieces in the bottom of the furnace.

4.Switch on the furnace.

5.After the melting of the charge put also the remaining charge into the furnace and melt down each of the charges.

6.After the charge melts down fully, remove the slag present using the slag spoon.

7.Put the weighed alloy particles into the molten metal and then mix them thoroughly.

8.Using a sample spoon, take out a sample of molten metal and test it chemically.

9.Submit the sample to the lab.

10. After getting the lab results, mix the alloy materials into both.

11. Increase the alloy bath temperature up to the desired level.

12. By placing a aluminum piece at the tip of the NS rod and soak it into the furnace again and again.

13. When the super wiser orders, tilt the furnace to a side and take the molten metal bath into lable place in the crane operator.

14. As according to the order of the superwiser, put the de-oxidizing particles into the ladle.

Metal Pouring:

The molten metal taken in the ladle is poured into the mould cavity by means of the following procedure.

1.First of all, check the pouring temperature before pouring.

2.Remove the slay in the latile.

3.Pour the molten metal exactly in the down sprew.

4.Remove the escaping gases using the fire flames.

5.The number of castings inside which the molten metal was poured, should be noted down in the ‘poring log’ (GR-PR:12)

6.We have to place the number tag above the vent sprew after the metal is poured in.

7.If we find any mistakes, then we should report to the section head.

Liquid metal temperatures:

Data sheet:

Description

Tapping Temperature in degrees

Pouring Temperature in degrees

· ASTM A216 Gr.WCB

· ASTM A217 Gr.WC6, EN16

· DINEN 10213-2:1.0625

· ASTM A217 Gr.WC9

· ASTM A217 Gr.C5/CA15

· ASTM A351 Gr.CF3

· DINEN 10213-4:1.4308,1.4408,1.4309

1610-1650

1620-1660

1630-1660

1580-1610

1570-1625

1570-1615

1580-1620

1540-1580

Cleaning of the casting(Fettling):

After the molten metal has been poured into the mould, it is permitted to cool and solidify. When the casting has solidified, it is removed from the sand in the moulding box. This operation is called shake out. This shake-out can be effected either manually or mechanically, but generally mechanical sharke-outs are used for large-scale work here.

Castings, when taken out of the mould, are not in the same condition in which they are desired since they have sprue, risers, gates etc. attached to them. Besides, they are not completely free of sand particles. This operation of cutting off the unwanted parts, cleaning and finishing the casting is known as fettling. This includes…

v 4MT/3MT/1.5MT automatic temperature controlled heat treatment furnaces with water quenching facilities.

v 1000 kgs/ 500 kgs hook hanger automatic shot blasting machines.

v Pickling/passivation facilities

v Electrically operated high speed grinders

v Welding rectifiers.

This process consists of the following steps.

1.Removal of cores from the castings.

2.Removal of gates, risers, runners, etc. from the castings.

3.Removal of fins, and other unwanted projections from the castings.

4.Removal of adhering sand and oxide scale from the surface of the castings (surface cleaning)

5.Repairing castings to fill up blowholes, straightening the warped or deformed castings.

Casting material identification:

The casting materials are identified with help of the respective colours given to them. The various colours used are while+blue, black, white+green, and Green+blue for WC6, WC 9, LCB and LCC respectively.

Defects in the castings:

Sand castings particularly are subject to certain defects, which in a well designed casting, are controllable by proper foundry technique, but are not wholly preventable. However the common types of defects found in the castings, their causes and remedies are explained here under:

Shifts:

This is an external defect in a casting caused due to core misplacement or mis machining of top and bottom parts of the casting usually at a parting line. Mis-alignment of flasks is another likely cause of shift. The defect can be prevented by ensuring proper alignment of the pattern or die part, moulding boxes, correct mounting of the patterns on pattern plates and checking the flasks, locating pins, etc. before use.

Warpage:

Warpage is unintentional and undesirable deformation in a casting that occurs during or after solidification. Due to different rates of solidification in different sections of a castings, stresses are set up in adjoining walls resulting in warpage in these areas. Large and flat sections or intersecting sections such as ribs are particularly prone to warpage. The remedy is to produce large areas with wavy, corrugated construction, or add sufficient ribs or rib-like shapes, to provide equal cooling rates in all areas. A proper casting design can go a long way in reducing the warpage of the casting.

Fin:

A thin projection of metal not intended as a part of the casting is called the fin. Fins usually occur at the parting of the mould or core sections. Moulds and cores incorrectly assembled with cause fins. Insufficient weighting of the moulds, or improper clamping of flasks may again produce the fin.

Blow Holes:

Blow Holes are smooth, round holes appearing in the form of a cluster of a large number of small holes below the surface of a casting. These are entrapped bubbles of gases with smooth walls. Blow Holes are caused by excessive moisture in the sand, or when permeability of sand is low, sand grains are too fine, sand is rammed too hard or when venting is insufficient. To prevent blow holes, the moisture content in sand must be well adjusted, sand of proper grain size should be used, ramming should not be too hard, and venting should be adequate.

Sand Holes:

Sand holes are found on external surface or inside the casting. They are caused by loose sand washing into the mould cavity and fusing into the interior of the casting or rapid pouring of the molten metal. Proper cleaning of the mould and careful pouring of the molten metal prevent sand holes.

Pin holes:

Pinholes are numerous small holes, usually less than 2mm, visible on the surface of the casting cleaned by shot blasting. They are caused by sand with high moisture content, absorption of hydrogen or carbon monoxide gas or when steel is poured from wet ladles or is not sufficiently gasified. Using good melting and fluxing practices, by reducing the moisture content of moulding sand and increasing its permeability, and by promoting a rapid rate of solidification can minimize the defect.

Hot Tears:

They are internal or external cracks having ragged edges occurring immediately after the metal has solidified. Hot tears may be produced if the casting is poorly designed and abrupt sectional changes take place, no proper fillets and corner radii are provided, and chills are wrongly placed. Incorrect pouring temperatures and improper placement of gates and risers and hard ramming can also create hot tears. Improved design, proper directional solidification, even rate of cooling, correct pouring temperatures, and control of mould hardness eliminate hot tears.

Cold Shut and Misrun:

A cold shut is an external defect formed due to imperfect fusion of two steams of metal in the mould cavity or unequal sections of pattern assembled together. The defect may appear like a crack or seam with rounded edges. A misrun casting is one, which lacks completeness due to the failure of the metal to fill the mould cavity. The reasons for cold shut or misrun may be too thin sections and wall thicknesses, improper gating system, damaged patterns, slow and intermittent pouring, poor fluidity of metal caused by low pouring temperature, improper alloy composition, etc. Use of hotter metal, frequent inspection and replacement of patterns and core boxes and proper design of the casting keeping in mind the fundamental principles of gating and risering are some of the steps that may be used to eliminate cold shut and misrun.

Inspection and Quality Control:

Inspection is an act of checking the acceptability of a casting. After the castings have been cleaned, they are inspected to check if they will perform specified functions during service. It broadly covers large number of methods and techniques used to check the quality of castings. These methods, explained used to check the quality of casings. These methods explained used to check the quality of castings. These methods, may be classified into five basic categories. It deals with the whole system of production and the methods employed to establish and achieve an economic production and desired quality and standard. An efficient quality control, therefore, simplifies the task of meeting specifications and can reduce the amount of inspection needed. Quality control using statistical techniques known as statistical quality control (S. Q. C) has several applications in the foundry in all stages of its working.

The production system of the Aruna Machine Tools is principally quality oriented and they have carefully integrated an elaborate quality assurance system in all their functions.

Their quality assurance activities include verification of purchased products , verification of verification of products at in-process and final stages , calibration of monitoring & measuring equipments , handling of non conformances , corrective & preventive actions and document control.

They have developed both grade wise & customer specific quality plans with reference to relevant inspection plans and this ensures that our quality assurance system covers all phases of production from incoming material inspection to final inspection.

Their quality management system has been certified by RWTUV of Germany as being in conformance with ISO 9001 requirements.

The mechanical and chemical laboratories are fully equipped with advanced devices, which include , impact testing , hardness testing , UTM and optical emission spectrometer.

Our in-house non-destructive testing facility has qualified and experienced personnel and the tests are carried out in accordance with relevant industry procedures.

All inspection , measuring and test equipments are calibrated periodically to ensure the accuracy and precision required .

Throughout their foundry operations we implement the most stringent test and inspection procedures to ensure that the products meet the requisite global standards such as ASTM & DIN.

Their products are subject to all applicable tests at final stage to ensure the reliability of our products performance under extreme operating conditions.

The following testing are done here, in order to check the quality of the castings…

Physical Testing:

ü Universal Testing Machine

ü Hardness Testing Machine and

ü Impact Testing Machine

Chemical Testing:

ü Optical Emission Spectrometer

ü Carbon and Sulphur determination equipment

Non-Destructive:

ü Radiographic Testing

ü Magnetic particles testing

ü Ultrasonic testing

ü Dye Penetrant testing

Inspection:

ü Visual Inspection.

ü Dimensional inspection

Internal audit check:

ü Pattern equipments castings

Certifications attained by the Aruna Machine Tools Ltd:

q ISO 9001-2000 by RWTUV

q WO\TRD100 Approval

q Lloyd’s Register Approval and

q Central Boiler Board Government of India Approval

Conclusion:

The training which I undertook in the Aruna Machine Tools, eventually ended as a successful industrial training for me. I came across various instruments, methods and terms used in the modern foundry and it helped me to understand the manufacturing sciences easily.