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DESIGN AND FABRICATION OF MULTI-POINT DRILLING FIXTURE A PROJECT REPORT Submitted byD.SHRI BALAJI K.S.SHYAM SUNDAR 31108114087 31108114088
In partial fulfilment for the award of the degree Of
BACHELOR OF ENGINEERINGIN
MECHANICAL ENGINEERINGKCG COLLEGE OF TECHNOLOGY, KARAPAKKAM
ANNA UNIVERSITY: CHENNAI 600 025APRIL 2011
ANNA UNIVERSITY: CHENNAI 600 025
Certified that this project report DESIGN AND FABRICATION OF MULTI-POINT DRILLING FIXTUREis the bonafide work of D.SHRIBALAJI ,K.S.SHYAM SUNDAR and VIJETA BASUMATARY who carried out the project work under my supervision.
SIGNATURE Prof. G.MAIKANDANHEAD OF THE DEPARTMEN Professor, Dept. of Mechanical Engineering K.C.G. College of Technology Karapakkam, Chennai-600097.
PROJECT GUIDELecturer, Dept. of Mechanical Engineering K.C.G. College of Technology Karapakkam, Chennai-600097.
We would like to express our sincere and heartfelt gratitude to our guide Mr.A.Venkatesan , Lecturer, Department of Mechanical Engineering , KCG college of technology, for being patience and valuable guidance.
We are very thankful to our head of the mechanical department Prof G.Maikandan for donating his valuable information for the out coming of this project.
We would also like to thank Dr.V.Edwin geo Senior Lecturer & S.Senthil raja Senior Lecturer for giving high co-ordination and
encouragement throughout this project and also spending all precious time for us.
With deep feeling of indebtedness we owe many special and heartful thanks to all staff members for their complete co-operation, help and suggestion.
DESIGN AND FABRICATION OF MULTI-POINT DRILLING FIXTURE
ABSTRACTOur project is based on the need for the work holding devices. This design and fabrication which will enable the operation of drilling easier. Our project is mainly composed of design and fabrication of the SPRING INDEXING MECHANISM which cover the absolute design to the specified dimensions of the work piece. This drilling fixture is economical means to produce OUR PROJECT HAVE THE FOLLOWING OBJECTIVES 1. To make multiple holes on the work-piece . 2. Fixture is a source which holds the job strong and firm. 3. It eliminates the need for marking on the job. 4. These are light weight these can be used either by fastening them with the table or holding them in hands. 5. Even an unskilled technician can use them. 6. With these features, we sincerely hope that our project serve as a valuable project. We welcome the correction, comments based on our project.
LIST OF TABLES
LIST OF FIGURES
INTRODUCTION1.1 1.2 1.3 General Definitions Difference And fixtures 1.4 1.5 1.6 Advantages Essential features General rules for designing of Jigs 1.7 Factors to be considered for Design of jigs 1.8 1.9 Tolerance and fits Material for bushes 9 14 15 15 16 17 7 4 5 between jigs 3 1 2
1.10 Types of bushes 1.11 Elements of jigs 1.12 Types of jigs
22.1 2.2 2.3
DESIGN CALCULATIONSSelection of bush Supporting blocks Design of Angle plate jig 18 19 19
FABRICATIONMachining operations Further operations
OF ANGLE PLATE JIG22 25
COST ESTIMATION4.1 Material cost 4.2 Machining cost 4.3 Over heads 4.4 Total cost 27 27 27 26
DRAWINGS5.1 Assembled drawings 5.2 Part drawings 29 30 37
LIST OF TABLES
Table 1 Table 2 Table 3 Table 4
Difference between jigs and fixture Bill of materials Material cost Machining cost
3 20 31 32
LIST OF FIGURESNO. DESCRIPTION PAGE NO.
Fig 1 Fig 2 Fig 3
Top, front and side views of the fixture Cut section of the fixture Part drawings
34 35 36
INTRODUCTION 1.1.GENERAL Drilling jigs are used to machine holes in mechanical products. To obtain positional accuracy of the holes, hardened drill bushes or jig bushes are used to locate and guide the drill, reamers etc., in relation to the work piece. These guide bushes are not essential but these prove to be economical and technically desirable as will be discussed ahead. The portion of the jig into which the hardened bushes are fitted is called bushes. Drilling jigs are either clamped to the work piece in which holes are to drill on the work piece is housed and clamped in the jig body. If more than one hole is to be drilled, the drill jig made to slide on the table of the drilling machine. Such a drill jig is moved by hand into the position under the drill so that the drill readily enters the bush. During the drilling operation, the jig is held by hand. If the drill size is large enough to produce high torque, either stops should be provided or the drill jig clamped to the table on the drilling machine. Drilling jigs makes feasible the drilling of holes at higher speeds, with greater accuracy and with less skilled workers than is possible when the holes are laid out and drilled by hand. Also, they produced interchangeable parts, because
each parts drilled in a drilling jigs should have the same hole pattern as every other part.
1.2.1 FIXTURES: A fixture is a work holding device, which only holds and positioned the work, but does not itself guide, locate or positioning the cutting tool. The setting of the tool is done by machine adjustment and a setting block or by using slip gauges. A fixture is bolted or clamped to the machine table. It is usually heavy in construction.
1.2.2 JIGS: A jig may be defined as a device which hold and positions the work, locate or and guides the cutting tool relative to the work piece and usually is not fixed to the machine table. It is usually lighter in construction. Jigs are designed to hold, support and locate the work piece to ensure that each part is machine within the specified tolerance. Jigs are usually fitted with hardened steel bushes for other cutting tools.
1.3. THE DIFFERENCE BETWEEN FIXTURES & JIGS Table 1 FIXTURES It is a work holding device that holds supports and locates the work piece and does not guides the tool for specific operation JIGS It is a work holding device that holds, supports , locates the work piece and guides cutting tool for a specific operation.
The fixture should be securely clamped to the table of the machine upon which the work is done.
Jigs are not clamped to the drill press table unless large diameter to be drilled and there is a necessary to bring one each bush directly under drill.
Fixtures are special tools used particularly in machine, planner, shapers and slotting machine. Gauge blocks may be provided for effective
The jigs are the special tools particularly in drilling, reaming, tapping and boring operation. Gauge blocks are not necessary.
1.4 ADVANTAGES OF FIXTURES PRODUCTIVITY A fixture increases the productivity by eliminating the individual marking, positioning and frequent checking. The operation time is also reduced due to increase in speed, feed and depth of cut because of high clamping rigidity. INTERCHANGEABILITY AND QUALITY A fixture facilitates the production of articles in large quantities with high degree of accuracy, uniform quality and interchangeability at a competitive cost. SKILL REDUCTION There is no need for skillful setting of work on tool. Fixture makes possible to employ unskilled or semi skilled machine operator to make saving in labors cost. COST REDUCTION Higher production, reduction in scrap, easy assembly and saving in labor cost results in ultimate reduction in unit cost. It increases the versatility of machine tool. It becomes possible to accommodate several components at setting and thus taking advantages of multiple machining. Fixture reduce the expenditures on quality control of machine Parts.
1.5 ESSENTIAL FEATURES OF FIXTURES Reduction of idle time: The design of fixtures should be such that the process of loading and unloading the components takes the minimum possible time and enables on easy locations and clamping should be such that idle time is reduced to minimum. Replaceable parts: The locating and supporting surface, as far as possible should be replaceable that is not permanently fastened. When worn out, they may be replaced by new ones. Moreover, they should be standardized so that there is interchangeable manufacture is possible. Hardened surface: All locating and supporting surfaces should be of hardened materials as far as conditions permit, so that they dont quickly worn out and their accuracy is retained for a long time. Inserts or pads: It is a very necessary provision in all fixtures. Inserts or pads of the soft materials like brass, leathers or fibers should be riveted to those faces of the clamps which will come
in contact with the finished surface of the work piece, so that these surfaces are not spoiled as a result of the metallic contact. Fool-proofing: Since the use of fixtures allows for the employment of unskilled worker, the design of such equipment should be such that it would not to permit the work piece or the tool be inserted in any position other than the correct one. Economic soundness: The equipment to be used should be economically sound that is the cost of its designing and the manuf