EPD 332 Tooling Design

Group 5

Jig & Fixture Design

Group Leader : Ong Chern Chung 104962

Group Members: 1. Ho Chi Leng 104949

2. Tan Kai Yin 104968

3. Mohd Tasnim Bin Hassan @ Yahya 104958

School of Mechanical Engineering

Date of Submission: 11th March 2012

Lecturer:

Dr.Mohd.Salman Abu Mansor

Purpose of Tool Design

1. Tool Design

Tool design is the process of designing and developing the tools, methods, techniques necessary to improve manufacturing efficiency and productivity.

2. Tool Design Objectives

To accomplish the main objective, the tool designer must achieve the following objectives: Provide simple, easy-to-operate tools for maximum efficiency Reduce manufacturing expenses by producing parts at the lowest possible cost Design tools that consistently produce parts of high quality Increase the production rate with existing machine tools Design the tool to make it foolproof and to prevent improper use Select materials that will give adequate tool life Provide protection in the design of the tools for maximum safety of the operator

3. Tool Design in Manufacturing

Main Objective of Tool Design

Lower Manufacturing Costs

Maintaining QualityIncreased Production

Concurrent Engineering Teams

Product Designers

Process Planning Engineers

Tool DesignersQuality Control Designers

Production Management

Machining Technicians

Concurrent engineering is a process that allows the design team to be invloved in a compressive plan for product design and prodution.

Advantages :

Result in fewer design errors Team members contribute based on their area of expertise Problems are not discovered on the production floor, but are corrected early in the

concurrent process Saves time and money Speeding up the process of getting product to market earlier Company will have a distinct economic advantage in global market

4. Planning the Design Product design changes are continuosly reviewed to determine tooling changes that

might be necessary. This is to eliminate or minimize the last-minute costly changes. The team meets regularly to provide any necessary updates or changes in the

production plan. The team members usually use e-mail, electronic transfer of materials and teleconferencing to communicate with each other.

Team members may consist of customers, designers, and builders in different locations that may take them halfway around the world.

5. Parts Drawing The parts drawing that the tool designers receives are transmitted electronically and

may include a solid model. The solid model allows the designer to view the three

dimensional part geometry. The prototype, a single physical part provided prior to

formal production, is a valuable tool for understanding more complex part geometries.

Prototype are usually manufactured using:i) Conventional Computer Numerical Control (CNC)ii) Stereolithographyiii)Layered Object Manufacture ( LOM)

Whether analyzing the prototype and the part drawing, the designer must consider the following factors that directly influence the design chioces:i) Overall size and shape of the partii) Type and condition of the material used for the partiii) Type of machining operation to be performediv) Degree of accuracyv) Number of pieces to be madevi) Locating and clamping surfaces

StereolithographyStereolithography (SLA), also known as 3D printing, optical fabrication, photo-solidification, solid free-form fabrication and solid imaging, is an additive manufacturing technology used for producing models, prototypes, patterns, and production parts.

Layered Object Manufacture ( LOM)Laminated object manufacturing (LOM) is a rapid prototyping system developed by Helisys Inc. (Cubic Technologies is now the successor organization of Helisys) In it, layers of adhesive-coated paper, plastic, or metal laminates are successively glued together and cut to shape with a knife or laser cutter.

6. Production PlanThe production plan is an itemized list of the manufacturing operations and the sequence of the operations chosen by the process planning engineer. The production plan include the following: Type and size of the machine tool specified for eaach operation Type and size of cutters specified for each operation Sequence of operations Previous machining operations performed on the part

7. AlternativesBesides given the part drawing and the production plan, the tool designer is informed of the amount of time and money that is available to spend on the design. One of the important step in tool design is determining the alternative solutions to ensure that the best method is chosen.

The tool designer need to answer the questions above and others related to the specific task to develops the alternative solutions. From this alternative solutions, the most efficient, dependable and cost effective design is chosen.

Should the tool be single-purpose or multi-purpose?

Will the savings justify the cost of the tool?

Should multiple-spindle or single-spindle machines be used?

What type of gauge, if any, should be used to check each operation?

8. Challenges To The Tool Designer In addition to technical design duties, the tool designer need to understand also about

obtaining materials, toolroom supervision, and tool inspection.

Tool room supervision

Tool inspection

9. Design The tool designer is responsible for developing the drawings and sketches of the tool

design ideas.

10. Supervision The extent of a tool designer’s supervision is normally determined by the size of the

company. One resource a tool designer may often use to help resolve design problems is the

group of skilled people in the tool room. The skilled toolmakers can often see solutions that may not be obvious to the

designer; hence it is always a good idea to build a good working relationship with your toolmakers.

Good working relationship between designer and the tool maker make the task at hand easier and by using the available expertise make more sense than trying to do the job alone.

11. Procuremento Tool designer normally relies on vendors or salespeople to supply materials and parts

that meet the design specifications.o A few factors to be consider when selecting a vendor:

Choose company that offers the most service to its customers Services such as design assistance and problem solving, where their product is

involved Whether the vendor can supply special parts or components when necessary Which vendor can meet the designer’s needs in the most timely, efficient, and

dependable manner

12. Inspection Inspection is normally conducted in two phases:

First: The tool itself is inspected for compliance with the tool drawing. Second: Several test parts are produced with the tool and are carefully checked to

ensure that they conform to the specifications shown on the part print. After the tool has been turned over to the production department, the tool designer

should make periodic checks during production to ensure that the specified tolerances are maintained.

13. Requirements To Become A Tool DesignerTo perform the functions of a tool designer, an individual must have the following skills:

Ability to make mechanical drawings and sketches

An understanding of modern manufacturing methods, tools, and techniques

A creative mechanical ability

An understanding of basic toolmaking methods

A knowledge of technical mathematics through practical trigonometry

CAD drafting skills

File management

Electronic communication skills

Geometric dimensioning and tolerancing

Jigs and Fixtures

Jig is a guiding device and fixture is a holding device. Jigs and fixtures are used to locate and hold the work that is to be machined. Jigs and fixtures are production-workholding devices used to manufacture duplicate parts accurately. The correct relationship and alignment between the cutter, or other tool, and the workpiece must be maintained. To do this, a jig or fixture is designed and built to hold, support, and locate every part to ensure that each is drilled or machined within the specified limits.

Jigs

A jig is a special device that holds, supports, or is placed on a part to be machined. It is a production tool made so that it not only located and hold the workpiece but also guides the cutting tool as the operation is performed. Jigs are usually fitted with hardened steel bushings for guiding drills or other cutting tools.

As a rule, small jigs are not fastened to the drill press table. If, however, holes above 0.25 inch in diameter are to be drilled, it is usually necessary to fasten the jig to the table securely.

Classes of jigs

Jigs may be divided into two general classes:

i. Boring jigs.Boring jigs are used to bore holes that either are too large to drill or must be made an odd size.

ii. Drill jigs. Drill jigs are used to drill, ream, tap, chamfer, counterbore, countersink, reverse spotface, or reverse counter sink.

The basic jig is almost the same for either the same for either machining operation. The only difference is in the size of the bushings used.

Types of jigs

1. Drill jigs They may be divided into two general types:- Open type.

Open jigs are for simple operations where work is done on only one side of the part.

- Closed type.Closed, or box, jigs are used for parts that must be machined on more than one side.

The names used to identify these jigs refer to how the tool is built.

2. Template jigs They are normally used for accuracy rather than speed. This type of jig fits over, on, or into the work and is not usually clamped. Templates are the leasr expensive and simplest type of jig to use. They may or may not have bushings. When bushings are not used, the whole jig plate is normally hardened

3. Plate jigs.They are similar to templates. The only difference is that plate jigs have built-in clamps to hold the work. These jigs can also be made with or without bushings, depending on the number of parts to be made. Plate jigs are sometimes made with legs to raise the jig off the table for large work. This style called a table jig.

4. Sandwich jigs.They are a form of plate jig with a back plate. This type of jig is ideal for thin or soft parts that could bend or warp in another style of jig. The use of bushings is determined by the number of parts to be made.

5. Angle-plate jigs.They are used to hold parts that are machined at right angles to their mounting locatotrs. Pulleys, collars, and gears are some of the parts that use this type of jig. A variation is the modified angle-plate jig, which is used for machining angles other than 90 degrees.

6. Box jigs.They can be called as tumble jigs also, usually totally surround the part. This style of jig allow the part to be completely machined on every surface without the need to reposition the work in the jig.

7. Channel jigs.They are the simplest form of box jig. The work is held between two sides and machined from the third side. In some cases, where jig feet are used, the work can be machined on 3 sides.

8. Leaf jigs.They are small box jigs with a hinged leaf to allow for easier loading and unloading. The main differences between leaf jig and box jig are size and part location. Leaf jigs are normally smaller than box jigs and are sometimes made so that they do not completely surround the part.

9. Indexing jigs.They are used to accurately space holes or other machined area around a part. To do this, the jig uses either the part itself or a reference plate and a plunger. Larger indexing jigs are called rotary jigs.

10. Trunnion jigs.They are a form of rotary jig for very large or odd-shped parts. The part is first put in to a box-type carrier and then loaded on the trunnion. This jig is well suited for large, heavy parts that must be machined with several separate plate-type jigs.

11. Pump jigs.They are commercially made jigs that must be adapted by the user. The lever-activated plate makes this tool very fast to load and unload. Since the tool is already made and only needs to be modified, a great deal of time is saved bt using this jig.

12. Multistation jigs.They are made in any of the forms already discussed. The main feature of this jig is how it locates the work. While one part is drilled, another can be reamed and a third counterbored. The final station is used for unloading the finished parts and loading fresh parts. This jig is commonly used on multiple-spindle machines. It could also work on single-spindle models.

Fixtures

1. A fixture is a means through which a part is securely fastened to the machine tool table to accurately locate, support and hold the part during the machining operation.

2. In addition to the function of holding the work piece, the fixtures also provide for setting the cutting tool for the actual machining operation.

3. Generally a fixture is supposed to be securely fastened to the machine tool table.4. Fixtures are widely used in large batch production to ensure the easy setup and

achieving the desired accuracy.5. It can be used in a variety of machine tools such as lathe, milling, grinding, and

others. Though the milling fixtures are the most widely used in view of the complex requirements for the milling operation.

Machine considerations1. There are some considerations about physical characteristics of work piece.

a. Roundb. Irregularc. Larged. Small

2. Another important considerations are types of motions, there have two basic motion:a. linear b. rotary

Type of fixtures1) Plate fixtures

From a plate by adding locators and clamps Reference surface parallel to the mounting surface

2) Angle plate fixtures Modified of plate fixture Reference surface is perpendicular to the mounting surface

3) Vise – jaw fixtures Vise – jaw fixtures are the expensive type of fixture to make Their use is limited only by the sizes of the vises available

4) Multistation fixtures Primarily used for high speed, high volume production run, where thye

machining cycle must be continuous This form allows the loading and unloading operation to be performed while

the machining operation is in progress It also known as a duplex fixtures in a simplest form

5) Profiling fixtures Used for to guide tools for machining contours that the machine cannot

normally follow These contours can be external or internal

Classification of fixtures

Fixtures are normally classified by the type of machine on which they are used. There are some classifications of fixtures.

1) Milling fixtures The most common type of fixture in general used today The simplest type of milling fixture is a milling vise mounted on the machine

table The entire workpiece must be located within the area of support of the fixture

2) Lathe fixtures In turning operations, the workpieces revolves and the cutting tool is

stationary Since lathe fixtures are designed to rotate, they should be as lightweight as

possible Lathe fixtures must be balancaed. While perfect balance is not the normally

required for low speed turning operations, high rotational speeds require the fixture to be well balanced

3) Surface grinding fixtures It s used a magnetic chuck to hold the workpiece Provide adequate room or slots to permit the escape of coolant and to allow

easy removal of built-up grinding sludge

4) Boring fixtures Boring fixtures like milling fixtures, should have some provision for setting

the position of the cutting tool relative of the part In cases where a boring fixture is to be used in a very large machine, such as a

boring mill or vertical turret lathe it is also good practice to include areas on the fixture to insure proper alignment with the machine

Classification of Fixture

Milling Fixture

Fixture

Straddle Milling Fixture

Lathe Radius Fixture

Fixture!

Conclusion

• A fixture is a work-holding or support device used in the manufacturing industry.

• A jig is a guiding device, and a fixture is a holding device.

• To sum up, jigs and fixtures help to save labor and even less skilled workforce can effectively work complex machines through their assistance.