A

SUMMER TRAINING REPORT

ON

FOUNDARY MANUFACTURING ASSEMBLY

OF

HMT MACHINE TOOLS LTD, AJMER (RAJ.)

GOVT. ENGINEERING COLLEGE, BHARATPUR(AN AUTONOMOUS INSTITUTE OF GOVT. OF RAJASTHAN)

BACHELOR OF TECHNOLOGY

MACHANICAL ENGINEERING

2015-2016 Submitted By:- Submitted To:-

PUKHRAJ MALI Er. RAHUL SHRIVASTAV

12EELME035 HEAD OF DEPARTMENT

YEAR - 4thYear (VII SEM.) MECHANICAL ENGINEERING

MECHANICAL ENGINEERING

MECHANICAL ENGINEERING DEPARTMENT GOVERNMENT ENGINEERING COLLEGE, BHARATPUR (AFFILIATED BY RAJASTHAN TECHNICAL UNIVERSITY)

GOVT. ENGINEERING COLLEGE BHARATPUR

(AN AUTONOMOUS INSTITUTION OF GOVT OF RAJASTHAN)

DEPARTMENT OF MECHANICAL ENGINEERING

SESSION: 2015-16

CertificateThis is to certify that _____PUKHRAJ MALI______ of B-Tech IV year

ROLL NO. ___12EELMEO35_ Branch Mechanical Engineering has

Successfully Submitted Summer training Report.

HEAD MECHANICAL ENGINEERING

DEPARTMENT

ACKNOWLEDGEMENT I would like to thank the entire HMT limited who has provided me this nine weeks training. I am thankful to the HRD officer of training centre who organized my training schedule and also the DGM’s and AGM’s of various shop departments who have provided me the various knowledge about their respective shops.

I also thanks to the workers of their respective departments, who were always ready to clarify our doubts and helped us to increase our knowledge by illustrating us to the finer points.

I wish to express my deep gratitude to all the concerned persons, whose co-operation and co-ordination have given me the success to complete my training in organization.

I hope that my report will reflect our technical knowledge and innovativeness, which we gained at HMT MACHINE TOOL LTD,Ajmer.

PUKHRAJ MALI

Mechanical Engineering

Roll No. 12EELME035

PREFACEIndustrial training is part and parcel of every technical course and

gives a face or form to all the theoretical knowledge we gain in our classroom. We get to have a virtual experience of the processes, methods, objects and phenomenon which used to be just an imaginary picture in our minds. It also gives an exposure to the environment of the industries and workshops which are virtual components of our professional life. We too were provided with this opportunity this summer.

We are thankful to our college administration that handed this invaluable chance to us and at the same time we pay our regards to the administration of HMT Ajmer (Machine Tools Division) that proved to be a great supporting force for the fulfillment of the purpose. The officials and the workers of the firm provided us with the best of their attention and share ample of knowledge of their concerned field with us.

CHENA RAM

MECHANICAL ENGINEERING

12EELME010

Index1. Chapter-1

1.1Introduction – Fulcrum of Indian Industrial Development

1.2 HMT at A Glance

1.3 HMT Machine Tools Division, Ajmer

2. Chapter-2

2.1 Different Department Of HMT

3. Chapter-3

3.1 Foundry Department

(A) Pattern Shop

3.1.1 Pattern Making

3.1.2 Sand Mould and Core Making

(B) Melting Department

3.1.3 Metal Melting

3.1.4 Casting and Separation

3.1.5 Removal of Runner and Riser

3.1.6 Finishing

3.1.7 Sand Recovery and Reclamation

4. Chapter-4

4.2 Manufacturing department

4.2.1 MMS (Medium Machine Shop)

4.2.1.1 Milling Machine (H & V-milling)

4.2.1.2 Lathe Machine (Centre & Turret)

4.2.1.3 Boring Machine

4.2.1.4 Radial Drilling Machine

4.2.1.5 Surface and Cylindrical Machine

4.2.1.6 Honing Machine

4.2.1.7 Shaper Machine

4.2.2 ROUNDS SHOP

4.2.2.1 Internal Grinding Machine

4.2.2.2 Surface Grinding Machine

4.2.2.3 Rotary Grinding Machine

4.2.2.4 Cylindrical Grinding Machine

4.2.2.5 Slotter

4.2.2.6 Gearing

4.2.3 HDMS (HEAVY DUTIES MACHINE SHOP)

4.2.3.1 Planning

4.2.3.1.1 Double Housing Planer

4.2.3.1.2 Open Slide Planer

4.2.3.1.3 Plano Milling Machine

4.2.3.2 Boring

4.2.4 TOOLS ROOM

4.2.4.1Veriner Caliper

4.2.4.2 Micrometer

4.2.4.3 Dial Indicator

5. Chapter-5

5.3 Assembly Department

5.3.1 GPM Section

5.3.2 CNC Section

5.3.2.1 Assembly

5.3.2.2 Machine Description

5.3.2.2.1 Bed Type Machine Configuration

5.3.2.2.2 Linear Motion with Guide Ways

5.3.2.2.3 Open Package Design

5.3.2.2.4 Long Nose Quill Type Spindle

5.3.2.2.5 Spindle Cooling

5.3.2.2.6 Step-less AC Spindle Motor

5.3.2.2.7 Electronic Orientation

5.3.2.2.8 AC Servomotor

5.3.2.2.9 Lubrication

5.3.2.2.10 Automatic Chip Collection

5.3.2.2.11 Guide Protection

5.3.2.2.12 Automatic Tool Changer

5.3.2.2.13 Numerical Head Counter Balance

5.3.2.2.14 Machining Features

6. Chapter-6

6.1 Bibliography

Chapter-1

INTRODUTION

Fulcrum of Indian Industrial Development:

When India achieved independence in 1947, there was hardly any industrial base in the country. Right form the prior H.M.T. has played an important role in providing the much needed industrial base as well as a launching pad for the growth & development of the country.

HMT was conceived by the Government of India in 1949, and was incorporated in 1953, with the objective of producing a limited range of machine tools, required for building an industrial edifice for the country.

HMT Limited was established in 1953 in technical collaboration with M/s Orleikon of Switzerland. Over the years, new products have been added to its manufacturing range. It has technical collaboration with over 30 leading International Engineering Companies for manufacture of various products HMT’s diversified product range includes Machine Tools, Watches, Tractors, Printing Machine Press, Di-Casting and Plastic Injection, Moulding Machines, Food Processing Machinery, CNC Systems, Bal Screws etc.

This Unit was established as Machine Tool Corporation of India limited in January 1964 keeping in view the Government Policy of differing new industries in under developed areas of the country and achieving self reliance in production of Grinding Machine Tools which were imported.

This Unit was started 1970-71 with a production of Rs. 8.64 Lack faces with difficulty in procurement of quality Machine Tool Casings a captive Foundry Plant was installed in 193 with a capital of about Rs.2 Crore.

This Unit was subsequently merged with HMT Ltd. On 1st April 1975 as sixth Machine Tool Plant with this merger; the Unit got backup support of HMT. The basic plant was established with the collaboration of the Czechoslovakian firms, M/s Skoda Export, Praha and German firm WMW, then in East Germany.

HMT’s commitment to the development of the machine tools technology is clearly reflected in the fact that HMT has as many as seven exclusive machine tool units, spread across the country. Each superbly equipped to meet the most challenging demand for machine tools. These units are in Ajmer, Banglore, Pinjore, Kalamassery, and Hyderabad are all ISO 9000 certified.

Today HMT is well positioned at the fore front of the precision engineering field. Its manufacturing plants employ highly skilled workforces strongly supported by R&D. Today over 780000 machine tools manufactured by HMT are in used in India and elsewhere.

In tune with changing business environment, HMT limited restructured into holding company tractors as its core business and the following subsidiaries:

HMT Machine Tools Limited, HMT Watch Limited, HMT Bearings Limited, HMT Chinar Watches Limited, HMT (International) Limited, Praga Machine Tools Limited.

1.1 HMT AT A GLANCE

Date of Registration 11-01-1967

Commencement of Production 1970-71

Merger with HMT 1-04-1975

Capital Employed (as on 1.4.2007) 201 Lacs.

Land Area –Total 178 Acres

Plant Foundry 62 Acres

Township 116 Acres

Covered Area (Plant) 31848 Sq. Mtrs.

No. of Quarters 136

Power Required 4.00 Lacs Units/Month

No. of Employees (as on 01.04.2011) 381

No. of Machines 250

ISO-9001 Certified 1994

factory campus 166 acres : for township 136 quarters : for housing its employees]

Cost of Machines working in the unit 6 Lacs up to 1 CR.60 Lacs

No. Of machine shops 180

Working shifts 4 [‘A’ shift - (6.00am to 2.00pm) ‘B’ shift - (2.00pm to 10.00pm) ‘C’ shift - (10.00pm to 8.00am)

HMT, MACHINE TOOLS DIVISION, AJMER

Profile of the Unit

Name of the Company HMT MACHINE TOOLS LIMITED

Name of the Unit Machine Tools Division

Location Ajmer, Rajasthan

Major Products:

Wide range of CNC Conventional, General Purpose & Special Purpose Grinding Machines (Cylindrical, Centreless, Internal, Crankshaft, Double Disc, Duplex, Horizontal & Vertical, Tool & Cutter) CNC Turning Centres PUSHKAR CNC Training Lathes & Machining Centres Reconditioning & Refurbishing

Major Manufacturing Facilities:

Machine Shop equipped with Machining Centres, CNC Turning Centres, Jig Boring Machine, Honing Machine, Superfinishing Machines Measuring Centre Materials Testing Laboratory CAD Centre Foundry.

Working Hours (General Shift) : 0830 Hrs. to 1630 Hrs.

Weekly Holiday: Sunday

Chapter-2

DIFFERENT DEPARTMENTS OF HMT, AJMER

Foundry

Manufacturing

Assembly

Maintenance

Inspection

Chapter-3

MMS

ROUNDS

HDMS

TOOLS ROOM

K130

GCL

GDS

GTC

ELECTRICAL ASSEMBLY

3.1. Foundry Department Headed by AGM Foundry. This department is administratively under HMT Ajmer, but functionally under executive director.

HMT’s foundry shop comprises of two units:

One is the captive foundry, meant for the small production of casting having weight upto 4 tonnes. The capacity of this foundry is 1000 MT per annum.

And the other is meant for mass production of comparatively smaller tractor and machine components. The capacity of this foundry is 2000 MT per annum.

(A) PATTERN SHOP

3.1.1 Pattern making

In casting, a pattern is a replica of the object to be cast, used to prepare the cavity into which molten material will be poured during the casting process.

Patterns used in sand casting may be made of wood, metal, plastics or other materials. Patterns are made to exacting standards of construction, so that they can last for a reasonable length of time, according to the quality grade of the pattern being built, and so that they will repeatably provide a dimensionally acceptable casting.

Patterns provide the exterior (mould) or interior (core)shape of the finished casting and are produced in wood,metal or resin for use in sand mould and core making. Patterns are usually made in two halves.

Fig. Pattern of motorcycle-yolk

3.1.2. Sand mould and core making

In HMT due to complex structure of components (such as gear box) are produced with the help of master pattern. Here core is first made with the help of master pattern after which the core is allowed to be baked.

Sand casting is the most common production technique, especially for ferrous castings. Sand is mixed with clay and water or with chemical binders and then packed or rammed around the pattern to form a mould half. The two halves are joined together to make the mould - a rigid cavity that provides the required shape for the casting.

The core is made with the help of sand such as

Rigid coated sand in shell core machining. Air setting sand or no bake sand. Green sand.

Here the gear box is made with no bake/air setting sand which is prepared by mixing different constituents.

Here the prepared core (made from master pattern) is allowed to solidify.

Smaller core is baked with the help of shell core machine, which has a box containing rigid coated sand. When allowed to operate the front assembly rotates and the box moves upward from which the sand falls in the die (die used according to shape of core required) here die can be changed.

Now the core is put in cope, drag and the molten metal is poured after which pattern can be easily obtained.

Fettling:

Fettling is the process by which the pattern obtained is given the desired finish by various processes. Before fettling, the casting obtained is subjected to removal of projections, chips, core, runner, riser etc. by the following processes:

Decoring Chipping Shot blasting (for heavy pattern) Wheel abrasion (for small pattern)

Decoring:

Decoring is the process of removing the fused sand.

Chipping:

Chipping is the process of removing the runner, riser etc.

Shot Blasting & Wheel Abrasion:

Shot blasting or wheel abrasion is used for removing the sand particles by the usage of air.

After this fettling is done by the following process:

Pneumatic gun- to remove corner sand. Angle grinder- to give corner finish. Die grinder- to give finish to inner portion. Pedestal grinder-to give surface finish.

While making casting for gears, surface finish is not required because gear has to be cut on it with the help of milling machine after which it is grinded.

Priming & Painting:

After clean and fettling, the casting is subjected to priming and painting to prevent corrosion.

(B) Melting Department3.1.3 Metal melting

The process of melting in HMT is carried out in induction furnaces at a temperature of about 1400°-1450° C.

Process:At first the induction furnaces are coated with fine cement clay. Now metal scrap is inserted in the furnace and slag coagulant is added to it. The requisite amount of coke is added to it. The current is supplied to copper coils provided in the furnace which induce current in the metal scrap and the scrap gets heated up, when the melting temperature is reached the molten metal is collected in ladles and taken to the pouring zone. When this process is being carried out the copper coils are regularly cooled with coolant (water) so that the coils do’not melt due to the high temperature generated in the coils.

The foundary of HMT has three furnaces, two, each having capacity of 3MT and one of 1.5MT. The two types of induction furnaces are:-

Main frequency Induction Furnace(50Hz) Medium frequency Induction Furnace(250Hz)

Melting of metal ion medium frequency furnaces are faster than the main frequency furnaces. Molten metal is prepared in a variety of furnaces, the choice of which is determined by the quality, quantity and throughput required.

Electric induction furnaces are the most common type used for batch melting of ferrous, copper and super alloys. This method involves the

use of an electrical current surrounding a crucible that holds the metal charge. Furnace sizes range from < 100 kg up to 15 tonnes. For production of super alloys and titanium, melting may be undertaken in a vacuum chamber to prevent oxidation .

Fig. Electrical furnace

3.1.4 Casting and separation

Molten metal is poured into moulds using various types of ladles, or in high volume production, automated pouring furnaces. Metal is poured into the “runner” (a channel into the mould cavity) until the runner bush is full. The “riser” provides an additional reservoir of feed metal to counteract the shrinkage that occurs as the casting begins to cool.

When the metal has cooled sufficiently for the casting to hold its shape, it is separated from the mould by mechanical or manual methods. Where sand moulds are used, the process is often referred to as shakeout or knockout, and large amounts of dust may be generated.

3.1.5 Removal of runners and risers

A riser, also known as a feeder, is a reservoir built into a metal casting mold to prevent cavities due to shrinkage. Most metals are less dense as a liquid than as a solid so castings shrink upon cooling, which can leave a void at the last point to solidify.

Risers prevent this by providing molten metal to the casting as it solidifies, so that the cavity forms in the riser and not the casting. Risers are not effective on materials that have a large freezing range, because directional solidification is not possible.

They are also not needed for casting processes that utilized pressure to fill the mold cavity. A feeder operated by a treadle is called an underfeeder.

After casting, these extraneous pieces of metal are rem oved and often collected for re- melting. In ferrous castings and larger non-ferrous castings, they may be removed by knocking off, sawing or cutting using

an arc air or oxy-propane torch. In die-castings, they are often snapped off manually.

3.1.6 Finishing

A range of finishing processes is usually undertaken. These include:

♦ cleaning to remove residual sand, oxides and surface scale, often by shot or tumble blasting;

♦ heat treatment, including annealing, tempering, normalising and quenching (in water or oil) to enhance mechanical properties;

♦ removal of excess metal or surface blemishes, (e.g., flash resulting from incomplete mould closure or burrs left from riser cut-off), by grinding, sawing or arc air (oxy-propane cutting);

♦ rectification of defects by welding;

♦ machining;

♦ non destructive testing to check for defects;

♦ priming, painting or application of a rust preventative coating.

3.1.7 Sand recovery and reclamation

The industry recycles a large proportion of mould and core making sand internally for re-use. This involves processing to remove tramp metal and returns the sand to a condition that enables it to beused again for mould or core production .

Chapter-4

4.2. Manufacturing Department Headed by AGM (manufacturing). HMT Ajmer’s manufacturing environment is highly advanced; this department also looks after utilizing only the latest production techniques in all phases of manufacturing maintenance.

MACHINE FEATURES

Bed made of high tensile strength cast iron, heavily ribbed for better vibration damping and shock absorption.

Precision, widely placed V & flat guideways for table with continuous automatic lubrication. Turcite lining for G17.

Grinding wheel head spindle runs in a high precision hydrodynamic bearing.

Higher powered wheel head for production model for high rate of stock removal.

Spindle is nitrided and super finished for reliability and life. Precision, V & Flat guideways with turcite for infeed slide for

better damping & higher repeatability. Automatic infeed at table reversal for traverse grinding operation. Auto plunge grinding cycle consisting of rapid approach, coarse

feed, fine feed, spark out and rapid retraction. Single piece robust construction with long guided sleeve for better

rigidity of tailstock. Independent drive for internal grinding attachment. Single push button control cycle.

4.2.1 MMS (Medium Machine Shop)In HMT, Ajmer; It is the medium machine shop which gives the shape to the castings which come from the foundry after being painted rough. In this section various operations are performed for making small parts of machines by the help of lathe (V-Turret & Centre lathe), milling, drilling, boring and surface grinding machines. In it first of all the jobs are marked, checked so that machining time is saved if the casting size is oversized.

There are many types of machines are available for performing operation like as cutting, drilling, milling, grinding etc. Each machine is used for different operation purpose.

The main machines in shop are:

Milling (H & V-milling) Machine Lathe (Centre & V-Turret) Machine Vertical Boring Machine Radial Drilling Machine Surface & Cylindrical Grinding Machine Honing Machine Shaper Machine

4.2.1.1 Milling Machine (H & V-milling)

Milling is the machining process of using rotary cutters to remove material from a workpiece advancing (or feeding) in a direction at an angle with the axis of the tool.

It covers a wide variety of different operations and machines, on scales from small individual parts to large, heavy-duty gang milling operations.

It is one of the most commonly used processes in industry and machine shops today for machining parts to precise sizes and shapes.

V-Milling Machine

Fig. V-milling Machine

Vertical milling machine. 1: milling cutter 2: spindle 3: top slide or overarm 4: column 5: table 6: Y-axis slide 7: knee 8: base

In the vertical mill the spindle axis is vertically oriented. Milling cutters are held in the spindle and rotate on its axis. The spindle can generally be extended (or the table can be raised/lowered, giving the same effect), allowing plunge cuts and drilling.

H-Milling Machine

A horizontal mill has the same sort but the cutters are mounted on a horizontal arbor ( Arbor milling) across the table.

Many horizontal mills also feature a built-in rotary table that allows milling at various angles; this feature is called a universal table.

4.2.1.2 Lathe Machine (Centre & V-Turret)

A lathe is a machine that shapes pieces of material. Usually the material being molded is wood or metal, and is referred to as the "work." The most common lathes are centre lathe.

The sits between two parts of the lathe called the headsock and the tailsock. The two parts hold the work in place and spin it quickly. When using centre lathes the pieces are shaped by tools with a single point cutting tools, while lathes that shape other materials, such as metal, have tool attached to an adjustable carriage that holds the cutting tools in contact with the spinning metal.

Main operation perform on Lathe machine are:

Turning Taper turning Threading (External & Internal) Boring Grooving Drilling Facing Knurling Taping (internal thread cutting) etc.

Turret Lathe

It allow multiple cutting operations to be performed, each with a different cutting tool in easy, rapid succession, with no need for the operator to perform setup tasks in between, such as installing or uninstalling tools, nor to control the toolpath. The latter is due to the toolpath's being controlled by the machine, either in jig-like fashion, via the mechanical limits placed on it by the turret's slide and stops, or via electronically-directed servomechanisms for computer numerical control lathes.

4.2.1.3 Boring Machine

Boring is the operation of enlarging an already drilled hole. The holes are pre-drilled as in casting only.

Machining time in boring:-

Machining time is the time required to complete the work place in a request period of time.

Time required = Length of cut/(RPM × feed per meter)

Machines installed

Horizontal Boring Machine Vertical Boring Machine Jig Boring Machine

Horizontal Boring Machine

In the horizontal boring machine, operations are performed on those large components which cannot be rotated. The spindle and the boring bar are horizontal.

It has mechanical system and fixture is attached with table. The work table can be transverse along and across the machine bed.

Vertical Boring Machine

The spindle is vertical and bores vertical holes in the spindle. The size of the machine is determined by maximum length of the job which can be machined on it. The machine can also be used as a drilling machine.

Jig Boring Machine

Jig boring machine is used to accurately enlarge existing holes and make their diameters highly accurate. Jig boring can also maintain high accuracy between multiple holes and surfaces.

Tolerances can be held readily within ±0.002mm. The machine can also do accurate milling, reaming, drilling and facing,

In general, the vertical jig boring machine employs a precision vertical tools spindle and coordinate work table with a great accuracy. The position measuring system consists of accurate lead screw with micrometer and an optical scale along with a vernier.

The machine are of rail type i.e. they are constructed with a cross rail that is supported and adjusted vertically on two columns. The cross rail serves to carry vertical spindle in its housing along the transverse axis.

4.2.1.4 Radial Drilling Machine

A radial drilling machine or radial arm press is a geared drill head that is mounted on an arm assembly that can be moved around to the extent of its arm reach. The most important components are the arm, column, and the drill head. The drill head of the radial drilling machine can be moved, adjusted in height, and rotated.

Aside from its compact design, the radial drill press is capable of positioning its drill head to the work piece through this radial arm mechanism.

Salient Features :

» Massive and rigid construction.

» Ergonomically grouped controls for operating convenience.

» Light centering of spindle.

» Precise depth release.

» Electrohydraulic clamping provided for drill head, arm & sleeve.

» Shock-free engagement of taps through clutch and spindle reverse for withdrawals.

» Machine with drilling capacity 80 mm / 100 mm also available.

Fig. Radial Drilling Machine

Specifications :

    RM 62 RM 63 RM 65

 

Drilling CapacityIn Steel

In Cast Iron

mm

mm

50

60

50

60

50

60

dia 100(At 60 rpm

with0.5 mm/rev.

dia.125(at 60 rpm with 0.62 mm/rev)

Drilling depth Mm 325 325 325

Tapping In Steel In Cast Iron

M56x2.5 or BSW 1-3/4

M70 or BSW 2-1/2"

dia. 80 dia. 100

BoringIn SteelIn Cast Iron

dia. 250 dia. 300

Spindle speeds Rpm 12:40-1800 32:10-1545

Spindle feeds no:mm/rev 6:0.125-1.25 18:0.075-4

Max. drilling radius

Mm 1500 1790 2350  

Main motor Kw 3.6 / 4.5 20

4.2.1.5 Surface And Cylinder Grinding Machine

Grinding Machines are also regarded as machine tools. A distinguishing feature of grinding machines is the rotating abrasive tool. Grinding machine is employed to obtain high accuracy along with very high class of surface finish on the workpiece.

However, advent of new generation of grinding wheelsand grinding machines, characterised by their rigidity, power and speed enables one to go for high efficiency deep grinding (often called as abrasive milling) of not only hardened material but also ductile materials.

Conventional grinding machines can be broadly classified as: (a) Surface grinding machine (b) Cylindrical grinding machine (c) Internal grinding machine (d) Tool and cutter grinding machine

Fig. Cylindrical Grinding Machine

4.2.1.6 Honing Machine

Honing is an abrasive machining process that produces a precision surface on a metal workpiece by scrubbing an abrasive stone against it along a controlled path.

Honing is primarily used to improve the geometric form of a surface, but may also improve the surface texture.

Typical applications are the finishing of cylinders for internal combustion engines, air bearing spindles and gears.

There are many types of hones but all consist of one or more abrasive stones that are held under pressure against the surface they are working on.

4.2.1.7 Shaper Machine

A shaping machine is used to machine surfaces. It can cut curves, angles and many other shapes. It is a popular machine in a workshop because its movement is very simple although it can produce a variety of work.

The tool feed handle can be turned to slowly feed the cutting tool into the material as the 'ram' moves forwards and backwards. The strong machine vice holds the material securely.

A small vice would not be suitable as the work could quite easily be pulled out of position and be damaged. The vice rests on a steel table which can be adjusted so that it ca be moved up and down and then locked in position. Pulling back on the clutch handle starts the 'ram' moving forwards and backwards.

4.2.2 ROUNDS SHOP

This section concerned with the round job construction and working. The section involves operation like grinding, slotting, drilling etc.

Following are the lists of machines and operations concerned with them:-

4.2.2.1 Internal Grinding Machines

Concerned with grinding of inner surface of job.

4.2.2.2 Surface Grinding Machines

Concerned with outer surface of job. It uses magnetic chuck and shows only horizontal motion of the table at the bed.

4.2.2.3 Rotary Grinding Machines

Concerned with horizontal as well as rotational movement of the table. It also uses magnetic chuck.

4.2.2.4 Cylindrical Grinding Machine

This is used to grind cylindrical jobs with the motion of grinder itself. This job is held in the jaw chuck.

4.2.2.5 Slotter

This machine is concerned with slot cutting. It uses carbide tip and shows vertical motion of the tool for slot cutting.

The other machines concerned with this section are lathes, drilling machines etc.

4.2.2.6 Gearing

Gear is used for power transmission of different parts of machines. This section is concerned with teeth cutting. Proper indexing is maintained in the process with fixtures on the machines concerned. There are four types of gears used in manufactured here:-

1. Spur gear2. Worm gear3. Helical gear 4. Bevel gear

The various machines involved are:-

Milling Machine

Generally used for manufacturing of spur gears. Cutters of prescribed sizes are used.

Gear Hobbing Machines

Gear hobbing machine is used for manufacture of worm gear. It uses hydraulic action.

Broaching Machine

Broaching machine is used to put splines in gear.

Gear Teeth Grinding Machines

It is used for grinding the teeth of the gears. In this machine gear teeth are grinded by a worm type grinding wheel. Here the tooth profile are checked with a machine called gear tooth profile tester.

4.2.3 HDMS (HEAVY DUTIES MACHINE SHOP)

It is the shop which gives the shape to the largest castings which come from the foundary after being painted rough. In this section various operations are performed by the help of planers, boring and planning-boring machines.

In this section, first of all the jobs are checked for the castings to be over-size or undersize. If they are undersize, they are sent to scrap. If they are oversize, they are marked and sent for machining.

Different types of operations are done by using different machines including various measuring devices.

This section also includes in itself a high technology section in which advanced machines are placed to machine crucial parts generally guide ways etc. It accommodates a tool preset device which is used to set the tool of all machines and CNC machines. It is used to measure the length and diameter of the tool with the help of leases.

This section is generally divided into two sections:

Planning Boring

4.2.3.1 Planning

This section consists essentially of planers mounted on one side of the section. In this section the job planning is one of the basic operations done for machining process. It is primarily intended for machining large flat surfaces.

Machines Installed

Double Housing Planer Open Side Planer Plano Milling Machining

Horizontal Turning Centre

4.2.3.1.1 Double Housing Planer

This is the heavy type of planer and is used for heavy cuts by double cutters. Its length is 3000mm. It consists of two columns, one on each side of bed. The cross rail is fitted between the two housings which can accommodate one or two heads, according to the specifications.

4.2.3.1.2 Open Side Planer

This type of planer consists of a single column situated vertically on one side of the bed and other side is left open without any column.

The cross-rail is wholly supported on the single column. Only one tool head can be located on it as there is only one column.

4.2.3.1.3 Plano Milling Machine

This is similar to a double housing planer but the tool can be milling tool. One of the machines is TNC (three axis turning centre) in which only one axis can be moved at a time. Thus round jobs cannot b machined here.

Another machine is CNC in which two axis can be moved simultaneously to machine round job. The length of the bed is 2800mm.

4.2.3.2 Boring

This is already discussing in MMS section.

4.2.4 TOOLS ROOM

This department keeps various kinds of tools which are useful during manufacturing of heavy pats. Most of the tools are measuring devices such as vernier caliper, micrometer etc.

4.2.4.1 Vernier Caliper

A vernier caliper is a device used to measure the distance between two symmetrically opposing sides.

The tips of the caliper are adjusted to fit across the points to be measured, the caliper is then removed and the distance read by measuring between the tops with a measuring tool, such as a ruler. Vernier calipers can measure internal dimensions (using the uppermost jaws in the picture), external dimensions using the pictured lowered jaws and depending on the manufacturer, depth measurements by the use of a probe that is attached to the movable head and slides along the center of the body. This probe is slender and can get into deep grooves that may prove difficult for other measuring tools.

The vernier scale may include both metric and inch measurements on the upper and lower part of the scale.

Vernier calipers commonly used in industry to provide a precision to a hundredth of a millimeter (10 micrometers), or one thousandth of an inch.

Parts of Vernier caliper

Outside Jaws: used to measure external diameter or width of an object

Inside Jaws: used to measure internal diameter of an object Depth Probe: used to measure depth of an object or an hole Main Scale: gives measurements of up to one decimal place (in

cm) Main Scale: gives measurements in fraction (in inch) Vernier gives measurements up to two decimal places (in cm) Vernier gives measurements in fraction (in inch) Retainer: Used to block movable part to allow the easy

transferring a measurement.

4.2.4.2 Micrometer

A micrometer sometimes known as a “Micrometer Screw Gauge”, is a device used widely in mechanical engineering and machining as well as most mechanical trades for precision measurement, along with other metrological instruments such as dial calipers and vernier calipers. Micrometers are often, but not always, in the form of calipers.

Types of Micrometer:

Outside Micrometer (aka micrometer caliper), typically used to measure wires, spheres, shafts and blocks.

Inside Micrometer, used to measure the diameter of holes. Depth Micrometer, measures depths of slot and steps. Bore Micrometer, typically a three-anvil head on a micrometer

base used to accurately measure inside diameters. Tube Micrometer, used to measure the thickness of tubes.

4.2.4.3 Dial Indicator

Dial indicators, also known as dial gauge and probe indicators, are instruments used to accurately measure small linear distances, and are frequently used in industrial and mechanical processes. They are named as so because the measurement results are displayed in a magnified way by means of a dial.

Dial Indicator may be used to check the variation in tolerance during the inspection process of a machined part, measure the deflection of a beam or ring under laboratory conditions, as well as many other situations where a small measurement needs to be registered or indicated. Dial indicators typically measure ranges from 0.25mm to 300mm (0.015in to 12.0in), with graduations of 0.001mm to 0.01mm (metric) or 0.00005in to 0.001in (empirical).

Chapter-5

5.3. Assembly department

5.3.1 GPM Section

GPM stands for general purpose machines. These are generally manually worked machines involving no computerized or numerical control. These machines are semiautomatic in nature and some of its operation like table movement, job movement, tool movement etc. can be carried out either automatically or even manually.

These are operated by concerned operations only. The concept of modern days machines originated from GPMs itself.

These are the simplest form of the metal working machines.

Main machine in this section are:

K130 GCL (Centre-less Grinding) GDS (Double Surface Grinding) GTC (Tool Cutter Grinding)

5.3.2 CNC SECTION

Introduction

We know that GPMs are semi-automatic machines. They require an operator for each work piece loaded on machine and in a limited period. Mass production is not possible in these machines. Moreover complex shaped jobs require high precision. They need for flexible automation has always been felt. And this is an era of machine tool automation. So, flexible automation is implemented in machine tools in the form of NC and CNC (Computerized Numerical Control) technology . Today HMT is producing a lot of CNC variants of conventional machine tools with the specialized functions and mostly CNC products.

CNC machines are part of the field named mechatronics. This field is the combination of electronics and mechanical engineering fields. When they work in combination they are termed as above. A single CNC machine can perform variety of machining operations in a sequential order (based upon the programme). For example drilling , tapping , slotting, milling, etc. operator is used only for clamping and declamping purpose ( after feeding the programme ). These machines ensure repeatability of the dimensions (precision). Accuracy of these machines is in microns.

A CNC machine may be of three dimensional coordinate system with XYZ axis. Rest two are available on machines whose table can rotate and tilt. These are 4th and 5th axis. The axis of the spindle is termed as Z axis. The axis which crosses Z axis perpendicularly is X axis and the other mutually perpendicular axis is Y axis. CNC machines differ in orientation of the main spindle. If spindle is horizontal it is termed as HMC (horizontal machining centre) and if the spindle is vertical it is termed as VMC (vertical machining centre). Model number of machine depends upon capacity of machine. Capacity means traverse length along various axis or maximum size of the pallet. Thus a VTC 1000 designates a CNC machines whose spindle is vertical with pallet size or traverse length of 1000mm.

5.3.2.1 Assembly

Main parts of the CNC machine are:-

1. Bed

2. Column

3. Saddle

4. Table

5. Pallet chaner (optional)

6. Magazine

7. AC servo motors

8. Tool changer arm

9. Head

10. Main spindle

The different processes of assembly are:-

1. Procurement of various parts.

2. Bed is leveled.

3. Column is fixed on bed.

4. Ball screws and drive motors are installed.

5. Alignment of column w.r.t. bed.

6. Fixing table on saddle.

7. Installing ball screws and drive motor.

8. Alignment of saddle w.r.t. column.

9. Fixing table on saddle.

10. Laser test:- In this test the laser beam is thrown on the pairs of

prism one attached to the table and other on the spindle of the machine and reflected back through the same part and data is collected on the computer and thus can be corrected.

11. Tool magazine is assembled and attached to the machine.

12. The oiling system is attached to the machine as separate apparatus and solves the purpose of lubrication .

13. All electrical and electronics appliances are installed.

14. The body of the machine is and rest of the accessories are attached to it.

15. Final inspection is done.

5.3.2.2 Machine Description

Salient features of CNC machines are as follows:-

5. 3.2.2.1 Bed type machine configuration

Bed type construction with longitudinal and cross movement to work table and vertical movement to head , provides stable cutting condition and maximum rigidity. Box type construction of bed and column with properly ribbed reinforcement minimizes torsion and flexural deflection.

5.3.2.2.2 Linear motion with guide ways

Preloaded anti - friction linear motion type. Guide ways in the entire three provide clearance free guidance for slides during cutting. Their use significantly reduces the coefficient of friction and eliminates stick slip and thermal generation during high speed positioning. In addition they offer high positioning and outstanding contouring capability.

5.3.2.2.3 One package design

One package design i.e. integral mechanical- electrical construction with CNC unit mounted on machine guarding, substantially cuts down floor space requirements. This enhances productivity per unit area and assures easy machine movement when production line is changed.

5.3.2.2.4 Long nose quill type spindle

Cylindrically shaped head end and prevents any interference with the work complicated shape. This configuration also eliminates interference even with large steep work. Machining of deep holes in the work are also possible with full power and without compromising tool rigidity.

5.3.2.2.5 Spindle cooling( for machine with spindle speed of 6000 rpm)

Circulation of cooled oil through the oil jacket around the main spindle bearing, maintains precision even in long and continuous runs.

5.3.2.2.6 Stepless AC spindle motor

AC spindle motor eliminates the troublesome brush inspections and replacements required in case of DC motors. Another advantage of DC motor is that it reduces electricaly consumption.

5.3.2.2.7 Electronic spindle orientation

The spindle motor has build in encoder for position feedback of the spindle. Spindle orientation stops spindle in a particular position. This helps in retracting bars without damaging bores in boring operations and counter-boring/Facing. Automatic tool change is also achieved through the features.

5.3.2.2.8 AC servomotors

All the three axes are driven through AC servomotors. Their use provides a higher rapid rate of revolution with minimum maintenance. They also provide high acceleration and deceleration property and subsequently increase the machining efficiency.

5.3.2.2.9 Lubrication

Automatic lubrication is provided for minimal operator attention. Main spindle bearing and all axes drive bearing are fitted with synthetic grease, requiring no attention for long periods . All axes ball screws and linear re-circulating bearings are also lubricated.

5.3.2.2.10 Automatic chip collection

Flushing coolant with discharge of 100lpm is used for automatic flushing of chips and is collected in tray at rear of machine. Wide channels with sufficient scope are provided in both sides of bed for easy disposal of chips at rear of machine.

5.3.2.2.11 Guide protection

Guide ways protection with telescopic cover protects guide ways against external damages and chips.

5.3.2.2.12 Automatic Tool Changer(ATC)

Machine is equipped with a suitable number of tool station/pocket (mainly12,30,60,120) . Using cam the automatic tool changer changes a tool accurately and swiftly.

3.2.2.13 Numeric head counter balance

It offsets the natural weight of spindle head and guarantees consistent cutting,high speed and highly accurate positioning. It eliminates head falling.

5.3.2.2.14 Machining Features

1. External coolant on spindle:- External coolant facilities the machining of steel/aluminium. It also helps in taking away chips from machining zone with its large flow.

2. Mist coolant:- Machining of light metals is faciliated with mist coolant. Mist coolant takes away heat from work zone, with change of state. It does not require any return path.

3. Chip conveyor:- It takes away large volume of chips produced out of the machine continuously with its independent drive.

4. Refrigeration type of spindle coolant:- Coolant of cooled oil with heat exchanger(refrigeration type), through spindle jacket provides higher spindle stability which results in improved working accuracy.

5. Spindle mounted probe:- Spindle mounted probe with auto measuring cycle and datum cycle makes fixture/job setting simple.

6. Higher speed spindle upto 8000 rpm :- It facilitates machining of light metals with latest tool technology.

7. Pallet changer:- This part is concerned with handling of additional table on which the next job can be mounted for machining meanwhile machining of the current job is going on which considerably reduces the mounting time.

Chapter-6

6.1 Bibliography

1. www.hmtmachinetools.com 2. www.hmtmachinetools.com\Ajmer-comlex 3. www.google.com 4. www.hi.wikipedia.org