CHAPTER 1
INTRODUCTION
1.1
Project Title
The component shown in Figure 1.1 need to be drilled all holes and machined on the surface marked. A suitable jig or jigs and a fixture or fixtures are required to be designed. Use modular fixturing technique.
Figure 1.1: Component
1.2
Introduction to Tool Design
Tool design is the process of designing and developing the tools, methods, and techniques necessary to improve manufacturing efficiency and productivity. Tool design is also an integral part of the product-planning process, interacting with product design, manufacturing, and marketing.
1.3
Tool Design Objectives
The main objective of tool design is to lower manufacturing costs while maintaining quality and increased production. To accomplish this, the tool designer must satisfy the following objectives:
i.
Provide simple, easy-to-operate tools for maximum efficiency.
ii.
Reduce manufacturing expenses by producing parts at the lowest possible cost.
iii.
Design tools that consistently produce parts of high quality.
iv.
Increase the rate of production with existing machine tools.
v.
Design the tool to make it foolproof and to prevent improper use.
vi.
Select the materials that will give adequate tool life.
vii.
Provide protection in the design of the tools for maximum safety for operators.
CHAPTER 2
TOOL DESIGN
2.0
Tool Design
Tool design is the process of designing and developing the tools, methods, and techniques necessary to improve manufacturing efficiency and productivity. It gives industry the machines and special tooling needed for today’s high-volume production. It
is a specialized area of manufacturing engineering which comprises the analysis, planning, design, construction and application of tools, methods and procedures necessary to increase manufacturing productivity.
2.1
Creative Tool Design
Tool design is basically an exercise in problem solving. Creative problem solving ca be described as a five-step process:
1.
Defining Requirements The new tooling might be required either for the first-time production of a new product, or to improve production of an existing part. When improving and existing job, the goal might be greater accuracy, faster cycle times, or both. Tooling might be designed for one part, or an entire family.
2.
Gathering and Analyzing Information In the second design phase, all data is collected and assembled for evaluation. The main sources of information are the part print, process sheets, and machine specifications. When collecting this information, make sure that part documents and records are current. Note taking is an important part of the evaluation process. Complete and accurate notes allow designer to record an important information. All ideas, thoughts, observations, and any other data about the part or tool are then available for later reference. Good notes also minimize the chance that good ideas will be lost.
Checklist for Design Considerations
Workpiece:
Size
Shape
Required accuracy
Material type
Material condition
Locating points
Locating stability
Clamping surfaces
Production quantity
Pending part-design revisions
Operations:
Types of operations
Number of separate operations
Sequence
Inspection requirements
Equipment:
Machine tools
Cutting tools
Special machinery
Assembly equipment and tools
Inspection equipment and tools
Equipment availability and scheduling
Plant space required
Personnel:
3.
Safety equipment
Safety regulations and work rules
Economy of motion
Operator fatigue
Power equipment available
Possible automation
Developing Several Options This requires the most creativity. A typical workpiece can be located and clamped many different ways. An important strategy for successful tool design is brainstorming for several good tooling alternatives, not just choosing one path right away.
4.
Choosing the Best Option Choosing the best option is a cost or benefit analysis of different tooling option. Some benefits, such as greater operator comfort and safety, are also important. Other factors, such as tooling durability, are difficult to estimate. Cost analysis is sometimes more of an art than a science.
5.
Implementing the Design The final phase of the tool-design process consists of turning the chosen approach into reality. Final details are decided, final drawings are made, and the tooling is built and tested. Guidelines for Economical Design:
Use standard tooling components The economics of standardized parts apply to tooling components as well as manufactured products. Never build any component that you can buy.
Use prefinished materials. Prefinished and performed materials should be used where possible to lower costs and simplify construction.
Keep tolerances as liberal as possible Tighter tolerances normally add extra cost to the tool with little benefit to the process.
Simplify tooling operation. Elaborate designs often add little or nothing to the function of the jig or fixture. Reducing design complexity also reduces misunderstandings between the designer and the machine operator.
The guidelines should be considered during the final-design process. Application of these rules makes the work holder less costly, and improves its efficiency and operation.
CHAPTER 3
JIGS AND FIXTURES
3.1
Introduction
The successful running of any mass production depends upon the interchangeability to facilitate easy assembly and reduction of unit cost. Mass production methods demand a fast and easy method of positioning work for accurate operations on it. Jigs and fixtures are production tools used to accurately manufacture duplicate and interchangeable parts. Jigs and fixtures are specially designed so that large numbers of components can be machined or assembled identically, and to ensure interchangeability of components. In order to do so, a jig or fixture is designed and built to support, hold, and locate every part to ensure that each is drilled according to its specifications. Both terms are frequently used incorrectly in shops. A jig is a guiding device and a fixture a holding device.
Jigs and fixtures are used to locate and hold the work that is to be machined. These devices are provided with attachments for guiding, setting, and supporting the tools in such a way that all the workpiece produced in a given jig or fixture will be exactly identical in every way. The employment of unskilled labor is possible when jigs and fixtures can be used in production work. A jig or fixture can be designed for a particular job. The form to be used depends on the requirement and shape of the workpiece workpiece to be machined.
3.2
Elements of Jigs and Fixtures
Generally, all the jigs and fixtures consist of the following elements: i.
Locating elements Locating elements are used to establish and maintain the position of a workpiece by constraining the movement of the workpiece. These position the workpiece accurately with respect to the supporting elements tool in the jigs and fixtures. A locating element is usually a fixed component and is used to establish, maintain the position of a part by constraining the movement of the part. For workpiece of greater variability in shapes and surface conditions, a locator can also be adjustable.
ii.
Clamping elements Clamping elements hold the workpiece securely in the located position during operation. A clamp is a force-actuating mechanism. The forces exerted by the clamps hold a part securely against all other external forces.
iii.
Tool guiding and setting elements To aid the setting or guiding of the tools in the correct position with respect to the workpieces.
3.2
Jigs
A jig is any of a large class of tools in woodworking, metalworking, and some other crafts that help to control the location or motion (or both) of a tool. The primary purpose for a jig is for repeatability and exact duplication of a part for reproduction. An example of a jig is when a key is duplicated, the original is used as a jig so the new key can have the same path as the old one. Since the advent of automation and CNC machines, jigs are often not required because the tool path is digitally programmed and stored in memory. The most-common jigs are drill and boring jigs. These tools are fundamentally the same. The difference lies in the size, type, and placement of the drill bushings. Boring jigs usually have larger bushings. These bushings may also have internal oil grooves to keep the boring bar lubricated. Often, boring jigs use more than one bushing to support the boring bar throughout the machining cycle.
Jig that expedites repetitive holes center location on multiple interchangeable parts by acting as a template to guide the twist drill or other boring device into the precise location of each intended holes center. In metalworking practice, typically a hardened bushing lines each hole on the jig to keep the twist drill from cutting the jig as shown in Figure 3.1. Jigs or templates have been known long before the industrial age. There are many types of jigs, and each one is custom-tailored to do a specific job. Many jigs are created because there is a necessity to do so by the trades men. Some are to increase productivity, to do repetitious activities and to do a job more precisely.
Figure 3.1: Jig
Jigs may be divided into two general classes: boring jigs and drill jigs. Boring jigs as shown in Figure 3.2 are used to bore holes that either is too large to drill or must be made an odd size. Drill jigs are used to drill, ream, tap, chamfer, counterbore, countersink and reverse. Basic jig is almost the same for either machining operation. The only difference is in the size of the bushings used.
Figure 3.2: Boring Jig
3.3
Fixtures
Fixtures have a much-wider scope of application than jigs. These work holders are designed for applications where the cutting tools cannot be guided as easily as a drill with fixtures, an edge finder, center finder, or gage blocks position the cutter. Examples of the more-common fixtures include milling fixtures, lathe fixtures, sawing fixtures, and grinding fixtures. Moreover, a fixture can be used in almost any operation that requires a precise relationship in the position of a tool to a workpiece.
Fixtures are essential elements of production processes as they are required in most of the automated manufacturing, inspection, and assembly operations. Fixtures must correctly locate a workpiece in a given orientation with respect to a cutting tool or measuring device, or with respect to another component, as for instance in assembly or welding. Such location must be invariant in the sense that the devices must clamp and secure the workpiece in that location for the particular processing operation. There are many standard work holding devices such as jaw chucks, machine vises, drill chucks, collets, etc. which are widely used in workshops and are usually kept in stock for general applications.
Fixtures are normally designed for a definite operation to process a specific workpiece and are designed and manufactured individually. Jigs are similar to fixtures, but they not only locate and hold the part but also guide the cutting tools in drilling and boring operations. These work holding devices are collectively known as jigs and fixture. Set blocks and feeler or thickness gauges are used with fixtures to reference the cutter to the work piece. A fixture should be securely fastened to the table of the machine upon which the work is done. Though largely used on milling machines, fixtures are also designed to hold work for various operations on most of the standard machine tools. Fixtures vary in design from relatively simple tools to expensive, complicated devices. Fixtures also help to simplify metalworking operations performed on special equipment.
Fixtures are most often identified by the machine tool where they are used. Examples include mill fixtures or lathe fixtures. But the function of the fixture can also identify a fixture type. So can the basic construction of the tool. Thus, although a tool can be called simply a mill fixture, it could also be further defined as a straddle-milling, plate-type mill fixture. Moreover, a lathe fixture could also be defined as a radius-turning, angle-plate lathe fixture. The tool designer usually decides the specific identification of these tools. It use set blocks and thickness, or feeler, gages to locate the tool relative to the workpiece as shown in Figure 3.3.
Figure 3.3: Set Block
Fixtures are normally classified by the type of machine on which they are used. Fixtures can also be identified by a sub classification. For example, if a fixture is designed to be used on a milling machine, it is called a milling fixture. If the task it is intended to perform is straddle milling, it is called a straddle milling fixture. The same principle applies to a lathe fixture that is designed to machine radii. It is called a latheradius fixture.
The following is a partial list of production operations that use fixtures: Assembling, lapping, boring, milling, broaching, planning, drilling, sawing, forming, shaping, gauging, stamping, grinding, tapping, heat treating, testing, honing, turning, inspecting and welding.
3.4
Advantages of Jigs and Fixtures
i.
Productivity Jigs and fixtures eliminate individual marking, positioning, and frequent checking. This can reduce operation time and increase productivity. Two or more workpieces can be machined simultaneously. Besides, jigs and fixtures enable complex parts to be machined by being held rigidly to the machine.
ii.
Interchangeability Jigs and fixtures facilitate uniform quality in manufacturing. There is no need of selective assembly. Any parts of the machine fit properly in assembly and all similar components are interchangeable. Marking out and setting before machining can be eliminated.
iii.
Skill Reduction Jigs and fixtures simplify locating and clamping of the workpieces. Tool guiding elements ensure correct positioning of the tools with respect to the workpieces, the make the use of lower skilled labor possible.
iv.
Cost Reduction Higher production, reduction in scrap, easy assembly and savings in labor costs result in substantial reduction in the cost of workpieces produced with jigs and fixtures. They decrease the expenditure on the quality controls of the machine parts.
CHAPTER 4
MACHINING
4.0
Machining
Machining can me defined as the process of removing material from a workpiece in the form of chips to removes unwanted material produce the desired shape. Most machining has a very low set-up cost compared to forming, molding and casting processes. However, machining is much more expensive for high volumes. Machining is necessary where tight tolerances on dimensions and finished are required.
4.1
Drilling
Drilling is easily the most common machining process. Drilling involves the creation of holes that are right circular cylinders. This accomplished most typically by using a twist drill. The chip must exit through the flutes to the outside of the tool. This causing the cutting front is embedded within the workpiece, making cooling difficult. The cutting area can be flooded, coolant can be delivered through the drill bit shaft.
Figure 4.1: Drilling Machine
4.2
Milling
Milling is as fundamental as drilling among powered metal cutting processes. Milling is versatile for a basic machining process, but because the milling set up as so many degrees of freedom, milling is usually less accurate than turning and grinding unless especially rigid fixturing is implemented.
Figure 4.2: Milling process at the cutting area
CHAPTER 5
SUPPORTS, LOCATORS AND BUSHINGS
5.1
Types of Support
5.1.1
Solid support
Solid support is the simplest type of support to use on tool base. This type of support can be installed into the tool base. It is used when machined surface acts as a locating point.
Figure 5.1: Rest Button
5.1.2
Adjustable Support
Adjustable support is used when the surface is rough or uneven. Normally used with one or more solid locator to allow any adjustment needed to level the work. Example: Screw Rest Button, Gripper Contact Bolts-Serrated Carbide Tipped, Gripper Swivel Contact Bolts.
Figure 5.2: Screw Rest Button
Figure 5.3: Gripper Contact Bolts-Serrated Carbide Tipped
5.2
Types of Locator
5.2.1
Pin-type
Pin type locators are used for smaller holes and for aligning members of the tool. It is a precision locating pins with a tapered tip foe easy loading and a shoulder to resist downward forces.
Figure 5.4: Pin Type Locator
5.2.2
Diamond or Relieved Locator
Diamond pin is normally used along with the round pin to reduce the time it takes to load and unload the tool. In use, the round pin locates the part and the diamond pin prevents the movement around the pin.
Figure 5.5: Diamond Locator
Figure 5.6: Two locating pins mounted on a plate restrict the movement
5.2.3
Vee Locator
Vee locators are used mainly for round work. They can locate flat work with the rounded or angular ends and flat discs. One advantage of vee locator is that it has centralizing feature.
Figure 5.7: Vertical V block
Figure 5.8: Horizontal V Block
5.2.4
Fixed-Stop Locator
It is used for parts that cannot be placed in either a nest or a vee locator. They are either machined into the tool body or installed.
Figure 5.9: Fixed-stop Locator
5.3
Type of Bushing
5.3.1
Renewable Bushing
Renewable bushing is generally used with linear bushing and lockscrew. There are 2 types of renewable bushing, slip-renewable (Figure 5.10) and fixedrenewable bushing (Figure 5.11). Fixed & slip renewable bushes are used where more than one operation is performed in the same hole of the component, such as drilling, and then reaming or counter boring. The renewable bush is held in place by a locking screw .Lock screws are used with fixed and slips renewable bushes to ensure that they do not turn or move during operation.
Figure 5.10: Slipe-renewable bushings
Figure 5.11: Fixed-renewable bushings
5.3.2
Press-Fit Bushings
There are 3 types of press-fit bushing, head, headless and serrated. It is permanently pressed into the jig plate, usually flush with the top surface. They are generally used for single-operation drilling or reaming. Headless bushings can be mounted closer together than headed bushings, but offer less resistance to heavy axial loads.
Figure 5.12: Headless bushing
Figure 5.13: Head bushing
Figure 5.14: Serrated bushing
5.3.3
Linear Bushing
There are 2 types of liner bushing, head and headless. Liners are permanent bushings used to hold renewable drill bushings. They are used to provide a hardened hole for renewable bushing. The liner's internal diameter has a precise sliding fit with the renewable bushing's outer diameter. The liner accurately locates the renewable bushing and protects the jig plate from wear and damage caused by frequent bushing replacement.
Figure 5.15: Headless and head linear bushing
5.3.4
Template Bushing
An economical bushing designed for thin template jig plates from 1/16 to 3/8" thick. Bushings are held in place by a Retainer. The outer diameter serrations prevent the bushing from spinning. Bushings can be removed and reused by breaking the Aluminum Retainer Ring.
Figure 5.16: Template bushing
5.3.5
Oil-Groove Bushing
Oil grooves are specially designed coolant passageways in a bushing's internal diameter wall. Oil grooves are available on almost any bushing type, including press fit, head press fit, and renewable. Use when you need complete drill lubrication and cooling, such as when drilling hardened steel, or when bushings are used as bearings. It is permit positive and complete lubrication of the bushing for continuous high speed drilling operation.
Figure 5.17: press fit, head press fit, and renewable oil groove bushing
5.3.6
Knurled Bushing
This bushing is designed for cast-in-place or potted installation. Diamond-knurled outer diameter provides excellent holding strength against both rotational and axial forces. Since the bushing's OD is not ground, the internal diameter must be accurately located during casting or potting to ensure accuracy in the finished tool.
Figure 5.18: Knurled bushing
5.3.7
Serrated Bushing
This bushing can be cast in place or potted, just like a Diamond-Groove Bushing, or can be pressed into an installation hole. The straight knurl provides excellent resistance to rotation, but provides less resistance to axial forces than a diamond knurl. Since the bushing's outer diameter is not ground, the internal diameter must be accurately located during casting or potting to ensure accuracy in the finished tool.
Figure 5.19: Serrated bushing
5.3.8
Chip-Breaker Bushing
Specially designed chip-breaking notches on the drill-exit end is use to break up chips from tough, stringy materials, to reduce friction and heat build-up. Reduces bushing wear at the drill-exit end and reduces the chance of tool or workpiece damage. A chip-breaker bushing should extend beyond its liner to allow chips to escape.
Figure 5.20: Chip-breaker bushing
CHAPTER 6
OPERATION
6.1
Operation Description
The part was formed by casting. To obtain the desired final product, further machining processes need to be done. The operations listed below are to be carried out.
i.
Drilling operations a. Drilling two holes with ϕ 0.375 inches b. Drilling a hole with ϕ 0.75 inches
ii.
Milling operation 1 a. Milling of surface of two 0.375 inches holes b. Milling of surface of two 3.500 x 0.800 inches c. Milling of surfaces 2.500 x 0.800 inches
iii.
Milling Operation 2 a. Milling of surfaces 3.500 x 2.500 inches
iv.
Milling Operation 3 a. Milling of surfaces of 0.700 inches holes
Box Jig is used to perform the drilling operations. The box jigs is designed with two identical bushings (two holes with ϕ 0.375 inches) and one other different bushing
(hole with ϕ 0.75 inches). Box jig is chosen because the part can completely machines on every surface without the need to reposition the part in the jig. This can reduce time and the inaccuracy caused by the reposition of the part.
Fixture 1 locates the part by using a round pin press-fit and a diamond pin pressfit. This reduces the time it takes to load and unload the tool. The combination of round pin and diamond pin can restrict eleven direction of movement of the workpiece. The last vertical degree of freedom is restricted by using a customized angle plate. A customized supporter is used to support the workpiece.
Fixture 2 utilizes the holes drilled in earlier process. A round pin and diamond pin is used to restrict eleven direction of movement of the workpiece. A customized part with a pin welded is used to restrict the last vertical direction of movement. This is because the length of diamond and round pin with this diameter is not suitable for the design. Another customized supporter is used to support the workpiece.
Fixture 3 is by used customized supporter so that is suitable with the design. Socket head cap locator is used to clamp this supporter.
Drilling Operation
No.
Part
Standard
1.
Head Press Fit Bushing
H-40-8
2.
Head Press Fit Bushing
H-64-8
3.
Knurled Head Screw
CL-23207
4.
Quarter Turn Screw
CL-2-QTS
Milling Operation 1
No.
Part
Standard
1.
Customized supporter
-
2.
Customized Angle-plate
-
3.
Press-fit Round Pin
CL-374-RPT
4.
Press-fit Diamond Pin
CL-374-DPT
5.
Socket Head Cap Screw
CL-5/16-18X1.75SHCS
6.
Shoulder Screw
CL-35-SS
7.
Washer
CL-9-FW
8.
Hex Nut
CL-5-HN
9.
Rectangular Tooling Plate
CL-MF25-0150
Milling Operation 2
No.
Part
Standard
1.
Customized Holder
-
2.
Customized Supporter
-
3.
Socket head Cap Screw
CL-5/16-18X2.50SHCS
4.
Diamond Pin
CL-3-DPX
5.
Round Pin
CL-3-RP
6.
Rectangular Tooling Plate
CL-MF25-0150
Milling Operation 3
No.
Part
Standard
1.
Customized Supporter
-
2.
Socket Head Screw
CL-5/16-18X3.50SHCS
3.
Rectangular Tooling Plate
CL-MF25-0150
6.2
Tool
All the drill tool used are referred to the Arno catalogue. The tool used to drill ϕ 0.375 inch is HA950-1107-60SPW20. While the ϕ 0.75 hole is drilled using HI1753-2438118SPW25.
The milling cutter we use for this process is UNISL200 from metamasa catalog. The diameter of the cutter is 20mm and the length is 141mm
6.3
Production Plan
PRODUCTION PLAN P/N
PART NAME
DRAWING NO
PROCESS PLANNER
REVISION NO
QUANTITY
ORDER NO
DATE
PAGE 1 OF 1
19/11/12 OPERATION
DESCRIPTION DESCRIPTION
DEPT.
MACH.TOOL
DRILL 2 ϕ0.375” HOLES THRU
*10
DRILL PRESS
DRILLING
*10-01
*10
DRILL PRESS
DRILLING
*10-02
*20
DRILL PRESS
MILLING
*10-03
*20
HORIZONTAL MILL
MILLING
*20-10
*20
HORIZONTAL MILL
MILLING
*20-10
*20
HORIZONTAL MILL
MILLING
*20-10
*20
HORIZONTAL MILL
MILLING
*20-10
NO
1
2
3
4
5
6
7
DRILL ϕ0.75” HOLE THRU
MILL FACE 2 - Ø0.375 INCH TOP SURFACE
MILL END 2 – 0.800 x 3.500 INCH
MILL END 0.800 x 2.500 INCH
MILL FACE 3.500 x 2.500 INCH
MILL FACE 2 - Ø0.75 INCH TOP SURFACE
7
HORIZONTAL MILL CUTTER
Ø 20 MM
MODULAR FIXTURE
6
HORIZONTAL MILL CUTTER
Ø 20 MM
MODULAR FIXTURE
5
HORIZONTAL MILL CUTTER
Ø 20 MM
MODULAR FIXTURE
4
HORIZONTAL MILL CUTTER
Ø 20 MM
MODULAR FIXTURE
3
HORIZONTAL MILL CUTTER
Ø 20 MM
MODULAR FIXTURE
2
DRILL
1.5”
TUMBLE BOX JIG
1
DRILL
1.5”
TUMBLE BOX JIG
TOOL DESCRIPTION
SIZE
SPECIAL TOOL NO.
7.0
Conclusion
As the conclusion, from this project, we learn more about tooling for production. We must always design the simplest and easiest to operate tools for maximum production. We also must use as much as possible the standard tools that does not need for new design if available. We also learned that it is important to make a tool foolproof to prevent improper use and to ensure correct dimension for the part. However, the safety of the operators must also be taken seriously.In this project, we designed drilling operations and milling operations in order to perform machining process to obtain the final product.
APPENDICES
Standards Parts Used in Drilling Operations
1. Head Press Fit Bushing for ϕ 0.375”
2. Head Press Fit Bushing for ϕ 0.75”
3. Knurled Head Screw Clamp
4. Quarter Turn Screw
5. Φ0.375” inch Hole Drill Tool
6. Φo.75” Hole Drill Tool
Standards Parts Used in Drilling Operations
1. Rectangular Tooling Plate
2. Flat Washer
3. Hex Nut
4. Socket-Head Cap Screw
5. Shoulder Screw
6. Round and Diamond Pin
7. Press-Fit Round and Diamond Locator
8. Milling Cutter
