Diese Präsentation wurde erfolgreich gemeldet.
Die SlideShare-Präsentation wird heruntergeladen. ×
[Type the company name]
Submitted by
PATEL JAIVIKKUMAR N. (100520134016)
Central Institute of Plastics Engineering & Technology
This is...
Nächste SlideShare
Oil chemical brochure
Oil chemical brochure
Wird geladen in …3

Hier ansehen

1 von 53 Anzeige

Weitere Verwandte Inhalte

Ähnlich wie final report (20)


final report

  1. 1. DESIGN AND DEVELOPMENT OF SEAT CUSHION MOULD 2014 sahjanand [Type the company name] 5/6/2014
  2. 2. DESIGN AND DEVELOPMENT OF SEAT CUSHION MOULD A PROJECT REPORT Submitted by PATEL JAIVIKKUMAR N. (100520134016) GUPTA ABHAYKUMAR B. (100520134019) PANCHAL DHRUV R. (100520134026) GURJAR AJAY T. (100520134034) In fulfillment for the award of the degree Of BACHELOR OF ENGINEERING In MANUFACTURING ENGINEERING Central Institute of Plastics Engineering& Technology, Ahmedabad Gujarat Technological University, Ahmedabad May 2014
  3. 3. Central Institute of Plastics Engineering & Technology MANUFACTURING ENGINEERING DEPARTMENT 2014 CERTIFICATE Date: This is to certify that the dissertation entitled “DESIGN AND DEVELOPMENT OF SEAT CUSHION MOULD” has been carried out by Patel Jaivik, Gupta Abhay, Panchal Dhruv and Gurjar Ajay under my guidance in fulfillment of the degree of Bachelor of Engineering in Manufacturing Engineering (8th Semester) of Gujarat Technological University, Ahmedabad during the academic year 2013-2014. Guide: Head of the Department: Mr. Ravindra Reddy Mr. J. Bosco Sr. Lecturer Sr. Lecturer, Manufacturing department, Manufacturing department, CIPET, Ahmedabad. CIPET, Ahmedabad
  4. 4. ACKNOWLEDGEMENT We would like to express our deepest gratitude to our guide and motivator Mr. R. Reddy, Manufacturing Department, CIPET, Ahmedabad for his valuable guidance, sympathy and co- operation for providing necessary facilities and sources during the entire period of this project. We wish to convey our sincere gratitude to Sr. Lect. J. Bosco, Manufacturing Department, CIPET, Ahmedabad for his inspiring guidance, and valuable suggestion throughout this project work. We are very thankful to Mr. Satyapal Mahade for sparing his precious time in sharing details about seat cushion mould and helped us wherever required in completing our project. SUBMITTERS
  5. 5. ABSTRACT Improvements in passenger compartment comfort continue to be one of the key needs of the global transportation industry. Since their introduction more than 40 years ago, flexible molded polyethylene foams have successfully contributed to the comfort provided by all forms of transportation seating. Initially required to provide just a wide range of load bearing, seating foams are now being designed for longer service life and better vibration damping and are considered to be a functional part of the overall acoustical package. New performance requirements are being placed on the NVH grade of foams and all interior components of passenger compartments must contribute to a reduction in odor and emissions. Comfort experience is a combination of many different factors, including aesthetics. Design for comfort is intimately linked to vibration research. Hence the design should be very effective. In these report below we have designed the mould for seat cushion followed by the development process.
  6. 6. LIST OF TABLES Table No. Table Description Page No Table 1 bill of materials for lower assembly 36 Table 2 bill of materials for upper assembly 38 Table 3 types of heater cutoff circuit with dimensions 48
  7. 7. LIST OF FIGURES Fig No Figure Description Page No Fig. 1 Seat cushion 6 Fig. 2 Types of cushion 8 Fig. 3 various types of seat cushions 9 Fig. 4 Location of a seat cushion in a car seat 10 Fig. 5 various types of polyethylene foam 19 Fig.6 Mould along with dimensions 27 Fig 7 Mould along with given plates 28 Fig 8 The entire mould assembly 30 Fig 9 The side view of the mould assembly 30 Fig 10 Lower mould assembly 31 Fig 11 The upper mould assembly 31 Fig 12 The sectional view of mould upper assembly 32 Fig 13 Lever 32 Fig 14 Bottom aluminum plate 32 Fig 15 Bottom steel plate 33 Fig 16 Side block 33 Fig 17 Side taper block 33 Fig 18 Tapper block 33 Fig 19 Top aluminum plate 34 Fig 20: The entire assembly in rendered form 35 Fig 21: Snapshot of the designing part other mould in Creo design 36
  8. 8. Fig 22: Snapshot of a given part in Creo 37 Fig 23: Ceramic heater 38
  9. 9. TABLE OF CONTENTS Acknowledgement i Abstract ii List of Tables iii List of Figures iv 1. Introduction 1.1 Automobile seats. 4 1.2 Seat cushion 6 1.3 Types of cushion 7 1.4 The role of seat cushion 11 1.5 Advantages of seat cushion 13 1.6 material details 15 1.7 What is foam? 18 2 Phase-1 : design phase 2.1 introduction 23 2.2 About Creo parametric 29 2.3 The mould and its design in Creo 30 2.3.1. The entire assembly 30 2.3.2 The lower assembly 31 2.3.3. The upper assembly 32 2.3.4 The detail part drawings 34
  10. 10. 3. Phase-2: development phase 3.1 The machining process required 43 3.2 heaters used 45 3.3 Thermocouple 46 3.4 The molding process 49 4. Conclusion and Reference 4.1 Conclusion 52 4.2 References 53
  12. 12. 2 | P a g e CHAPTER 1 INTRODUCTION Automobile seats Seat Cushion Types of Cushion The Role of Seat Cushion Advantages of Seat Cushion Material Details What is Foam?
  13. 13. 3 | P a g e 1.1 Automobile seats Flexible and semi-flexible polyethylene foams are used extensively for interior components of automobiles, in seats, headrests, armrests, roof liners, dashboards and instrument panels. Polyethylene is used to make automobile seats in a remarkable manner. The seat manufacturer has a mold for each seat model. The mold is a closeable "clamshell" sort of structure that will allow quick casting of the seat cushion, so-called molded flexible foam, which is then upholstered after removal from the mold. It is possible to combine these two steps, so-called in-situ, foam-in-fabric or direct molding. A complete, fully assembled seat cover is placed in the mold and held in place by vacuum drawn through small holes in the mold. Sometimes a thin pliable plastic film backing on the fabric is used to help the vacuum work more effectively. The metal seat frame is placed into the mold and the mold closed. At this point the mold contains what could be visualized as a "hollow seat", a seat fabric held in the correct position by the vacuum and containing a space with the metal frame in place. Polyethylene chemicals are injected by a mixing head into the mold cavity. Then the mold is held at a preset reaction temperature until the chemical mixture has foamed, filled the mold, and formed stable soft foam. The time required is two to three minutes, depending on the size of the seat and the precise formulation and operating conditions. Then the mold is usually opened slightly for a minute or two for an additional cure time, before the fully upholstered seat is removed. Polyethylene molded flexible foams are key components of automobile interiors and contribute to passenger comfort in many different ways. More than 40 years after their introduction, the foam use per vehicle is still growing worldwide.
  14. 14. 4 | P a g e Indeed, by virtue of their superior vibration damping capability over a wide range of frequencies at low material density, polyethylene foams are found today not only in automotive seats but also in various acoustical parts. Comfort experience is a combination of many different factors, including aesthetics. During a journey, car occupants are subjected to both mental and physical stresses when exposed to road vibrations, dense traffic, noise and different weather conditions. Polyethylene foams found in seats and in sound insulating packages are instrumental in reducing those stresses. Design for comfort is intimately linked to vibration research. Vibration isolation in the low frequency range by the seat assembly and the attenuation of high frequency vibrations from the running engine, or other sources, transmitted into the passenger compartment, with NVH (Noise, Vibration, Harshness) components, allows the construction of comfortable cars. In addition, polyethylene foams show high durability and perform well from the beginning to the end of a journey and over a vehicle life of more than one hundred thousand miles. The trend towards density reduction, while maintaining technical performance specifications is continuing. In addition of that, elimination of all types of chemical emissions and/or odors is becoming an important issue. Dow Chemical is developing new raw materials to respond to these needs.
  15. 15. 5 | P a g e Figure.1 seat cushion 1.2 SEAT CUSHION Flexible Polyethylene Seat Cushion Seat cushion (or carpet underlay) is a primary use for flexible polyethylene foam. Over 400 million pounds of foam are used each year in the production of seat cushion. More than 85 percent of the cushion sold in the United States is a form of flexible polyethylene foam. Foam commands such a high percentage of market shares for a number of reasons. Foam provides a wide range of cushion "feels," ranging from very soft to very firm. Foam is easily transported and installed under carpet. It resists mildew and microbial attack, which means that household spills tend not to affect it, and it can be installed below grade. Different grades of flexible polyethylene foam carpet cushion provide different performance levels suitable for virtually any residential or commercial cushion application. For less expensive grades of cushion, foam can be extremely price competitive.
  16. 16. 6 | P a g e 1.3 Types of Cushion There are two basic types of flexible polyethylene foam seat cushion. Prime polyethylene carpet cushion is made from slab stock polyethylene foam. Blocks of foam are slit into sheets of specified thickness, typically ranging from 1/4" to 9/16". A plastic film backing or non-woven backing is applied and the material packaged in rolls. The foam used in prime polyethylene seat cushion can vary from relatively low to relatively high density, depending on the intended application. Special “high performance” foam types may also be used. Some “high performance” foams have been developed especially for seat cushion use. Bonded polyethylene seat cushion is made in an entirely different manner. Scrap foam of various types is shredded into small pieces and placed into a processing unit with a chemical adhesive. The mixture is pressurized and injected with steam to form a large foam cylinder or block. This material is then “peeled” into the proper thicknesses for seat cushion use, a plastic film backing or backing is applied, and the finished seat cushion packaged in rolls. Figure 2: types of seat cushion
  17. 17. 7 | P a g e Bonded polyethylene foam carpet cushion is also one of the world's greatest recycling success stories. Virtually all scrap foam from polyethylene foam manufacturing is recycled for use in bonded foams. In many cases, recycling centers have been established to accept old carpet cushion removed from people's homes, old furniture cushions, mattresses, auto seats, and other types of foam for use in making new bonded carpet cushion. Cushions are of various forms and color. It is as per the requirement of the end user or the customer. The various forms with various different colors are shown as follows. Figure 3: various types of seat cushion
  18. 18. 8 | P a g e Fig 4: location of seat cushion in a car seat Above figure shows the location of seat cushion. It is also according to the user requirement. The cushion can be either located at the upper side of the side or below the seat. It’s as per the user requirement. 1.4 The Role of Seat Cushion Carpet cushion provides a number of important functions. It helps absorb the initial shock of foot traffic on carpet, which can cause carpet fibers to compact and lose height, creating "matting" effects in the carpet. So carpet – even "no mat, no crush" styles - tend to look better longer if proper carpet cushion is used. Many carpets with appearance retention warranties require the selection of a proper carpet cushion to validate the warranty. Carpets installed with proper cushion also tend to feel more comfortable underfoot. The layer of cushion makes vacuuming more efficient, because it allows the vacuum cleaner to "lift" the carpet (because of better air flow) and collect dirt that would otherwise be trapped and cause carpet fiber to fray. Carpet cushion helps absorb noise, so rooms are quieter. Carpet installed over cushion is more economical in the long run.
  19. 19. 9 | P a g e The extra life that cushions gives to carpet means that the original investment in the floor- covering has more value. And for commercial installations, carpet over cushion is less costly to remove and replace than carpet that is glued directly to the floor. The Cushion Performance Issue There is no universal industry "standard" for carpet cushion. However, there does exist a set of guidelines established by the Department of Housing and Urban Development (HUD) dealing with carpet cushion installed in FHA built or financed housing. This standard, HUD UM72 (being updated as UM72a), covers all major carpet cushion types and is recognized by many sources as providing good minimum criteria for proper cushion selection. Testing Seat Cushion Performance Concerns over carpet cushion performance, particularly in relation to new, longer, appearance warranties being applied to carpet, have created a need for additional information on how carpet and carpet cushion work together as a floor-covering system. The Polyethylene Foam Association has helped coordinate a massive research program designed to gather information about flexible polyethylene foam carpet cushion performance. Involved in this study were many of the key organizations in the floor-covering industry. The majority of the program was done at the Georgia Tech University School of Textile Engineering. Testing was based on a contract "walk-on" test, where people walked over the carpet/cushion assembly for a specified number of times. A variety of factors - including carpet cushion durability, installation, and carpet appearance – were evaluated on traffic counts ranging from 20,000 to 180,000. A traffic count of 20,000 is equivalent to one year of residential life. Other carpet and cushion tests were done at different locations and the results correlated. 1.5 Advantages of Seat Cushion Durability of Cushion Grades One key factor evaluated by the "walk-on" test was the ability of cushion products to retain their original properties. This has a significant impact on cushion performance under carpet.
  20. 20. 10 | P a g e The chart below shows test results for different grades and densities of polyethylene carpet cushion products and indicates that a variety of products have good performance in this area. Retention of original properties is the main advantage and characteristic of seat cushion. It offers better comfort, better durability. It offers an extraordinary support during longer exposure to driving. It offers required support to the spinal cord while long drives. It improves seating position and posture. Comfortable As the driver is a special profession, so a set of comfortable cushions is very important to the driver's body! Especially for a long time driving staff, a comfortable, docile and humanization design seat is highly recommended, the best seat in relatively good moisture absorption and breathability. Of course, if necessary, you should also add a lumbar support, which relief can fatigue to some extent. Protect the leather seats: A lot of cars equipped with leather chairs, smooth, naked and slippery. Key, pens and knives and other sharp things can poke a hole on the leather seat in a unguarded moment, besides, leather seats get oil or chemical stains are more difficult to clean. Therefore, the protective function of a seat cover is very critical; Of course the premise is that the bottom of the car seat cover is not rough material. Otherwise, leather will be worn "severely". Beautiful Now many car seats on the appearance is newly breakthrough, a good cushion will add esthetics taste to the automotive, a bad seat is counterproductive. So, pick out a good look seat is necessary. 1.6 Material Details The material used in developing seat cushion is Polyethylene solution.
  21. 21. 11 | P a g e About Polyethylene Polyethylene (abbreviated PE) or polythene is the most common plastic. The annual global production is approximately 80 million tons. Its primary use is in packaging (plastic bag, plastic films, geo-membranes, containers including bottles, etc.). Many kinds of polyethylene are known, with most having the chemical formula (C2H4) nH2. Thus PE is usually a mixture of similar organic compounds that differ in terms of the value of n. Properties Physical properties Polyethylene is a thermoplastic polymer consisting of long hydrocarbon chains. Depending on the crystalline and molecular weight, a melting point and glass transition may or may not be observable. The temperature at which these occur varies strongly with the type of polyethylene. For common commercial grades of medium- and high-density polyethylene the melting point is typically in the range 120 to 180 °C (248 to 356 °F). The melting point for average, commercial, low-density polyethylene is typically 105 to 115 °C (221 to 239 °F). Chemical properties Most LDPE, MDPE and HDPE grades have excellent chemical resistance, meaning that it is not attacked by strong acids or strong bases. It is also resistant to gentle oxidants and reducing agents. Polyethylene burns slowly with a blue flame having a yellow tip and gives off an odor of paraffin. The material continues burning on removal of the flame source and produces a drip. Crystalline samples do not dissolve at room temperature. Polyethylene (other than cross-linked polyethylene) usually can be dissolved at elevated temperatures in aromatic hydrocarbons such as toluene or xylem, or in chlorinated solvents such as trichloroethane or dichlorobenzene. Process The ingredient or monomer is ethylene (IUPAC name ethane), a gaseous hydrocarbon with the formula C2H4, which can be viewed as a pair of methylene groups connected to each other. Because the catalysts are highly reactive, the ethylene must be of high purity. Typical specifications are <5 ppm for water, oxygen, as well as other alkenes. Acceptable
  22. 22. 12 | P a g e contaminants include N2, ethane (common precursor to ethylene), and methane. Ethylene is usually produced from petrochemical sources, but also is generated by dehydration of ethanol. Polymerization Ethylene is a rather stable molecule that polymerizes only upon contact with catalysts. The conversion is highly exothermic, that is the process releases a lot of heat. Coordination polymerization is the most pervasive technology, which means that metal chlorides or metal oxides are used. The most common catalysts consist of titanium (III) chloride, the so-called Ziegler-Natta catalysts. Another common catalyst is the Phillips catalyst, prepared by depositing chromium (VI) oxide on silica. Ethylene can be produced through radical polymerization, but this route has only limited utility and typically requires high pressure apparatus. Classification Polyethylene is classified into several different categories based mostly on its density and branching. Its mechanical properties depend significantly on variables such as the extent and type of branching, the crystal structure and the molecular weight. With regard to sold volumes, the most important polyethylene grades are HDPE, LLDPE and LDPE.  Ultra-high-molecular-weight polyethylene (UHMWPE)  Ultra-low-molecular-weight polyethylene (ULMWPE or PE-WAX)  High-molecular-weight polyethylene (HMWPE)  High-density polyethylene (HDPE)  High-density cross-linked polyethylene (HDXLPE)  Cross-linked polyethylene (PEX or XLPE)  Medium-density polyethylene (MDPE)  Linear low-density polyethylene (LLDPE)  Low-density polyethylene (LDPE)  Very-low-density polyethylene (VLDPE)
  23. 23. 13 | P a g e 1.7 What is Foam? Foam is a substance that is formed by trapping pockets of gas in a liquid or solid. A bath sponge and the head on a glass of beer are examples of foams. In most foam, the volume of gas is large, with thin films of liquid or solid separating the regions of gas. Some of the products formed by polyethylene foam are shown in the pictures below
  24. 24. 14 | P a g e Figure 5: various forms of polyethylene foams Proper Handling and Storage of Flexible Polyethylene Foam Flexible polyethylene foam is an organic material and is combustible like all organic materials. Organic materials include a wide variety of substances like wood, wool, paper, cotton, nylon, polyester, and polyethylene. Polyethylene foam, once ignited, can burn rapidly, consuming oxygen at a high rate and generating great heat. Like any other organic material, when it ignites and burns, polyethylene foam liberates smoke containing toxic gases, the primary one being carbon monoxide. Hazardous gases released by burning foam can be incapacitating or fatal to human beings if inhaled in sufficient quantities. Oxygen depletion in an enclosed space can present a danger of suffocation. Therefore, fire safety is critical in relation to any storage and handling of flexible polyethylene foam. Foam should not be exposed to open flames or other direct or indirect high-temperature ignition sources such as burning cigarettes, matches, fireplaces, space heaters, forklift tailpipes, welding sparks, or bare light bulbs. Foam is often stored in large quantities. Foam fabricators may keep large blocks of foam in inventory. Finished goods manufacturers may store individual cushions or cores for use in products such as furniture, bedding, packaging, or automobiles.
  25. 25. 15 | P a g e Retailers and wholesalers may warehouse quantities of slab foam for resale to customers, or in the form of products such as replacement parts or carpet cushion. As with any combustible material, proper care must be taken with foam to minimize potential fire hazards. Even foams formulated to meet specific flammability regulations will burn, including those foams specifically identified as meeting flammability requirements. Safe and proper storage and handling of the material is essential. Different business will face different foam storage situations, depending on the amount of foam they use and the manner in which it is stored. Storage and Handling in Foam Manufacturing and Fabrication Operations Foam manufacturing and fabrication companies are likely to inventory the largest quantities of flexible polyethylene foam. Depending on the size of a particular manufacturing or fabrication operation, small pieces of foam or large "bun" sections containing hundreds of cubic feet of foam may be stored. Large amounts of foam represent a significant fuel source for a fire. Flexible polyethylene fires generally tend to create very high temperatures - high enough to damage steel framework of buildings if enough of a fuel load is involved. Once ignited, foam fires can spread rapidly, producing intense heat, dense smoke, flammable liquids, and toxic gases.
  26. 26. 16 | P a g e CHAPTER 2 DESIGN PHASE Design Platform Design of the Product Mold Design Mold Assembly Complete Mold Setup
  27. 27. 17 | P a g e 2.1 Design Platform Designing software: Creo Parametric 2.0 About Creo parametric 2.0: Creo is a family or suite of design software supporting product design for discrete manufacturers and is developed by PTC. The suite consists of apps, each delivering a distinct set of capabilities for a user role within product development. Creo runs on Microsoft Windows and provides apps for 2D design, 3D CAD parametric feature solid modeling, 3D direct modeling, Finite Element Analysis and simulation, schematic design, technical illustrations, and viewing and visualization. The Creo suite of apps replaces and supersedes PTC’s products formerly known as Pro/ENGINEER, CoCreate, and ProductView. PTC began developing Creo in 2009, and announced it using the code name Project Lightning at PlanetPTC Live, in Las Vegas, in June 2010. In October 2010, PTC unveiled the product name for Project Lightning to be Creo. PTC released Creo 1.0 in June 2011. Creo Parametric is a 3D design app for parametric modeling (parametric featured based solid modeling). Creo Parametric provides all the capabilities of Creo Elements/Pro (also known as Pro/ENGINEER). The design needs to be done in 3 phases:  Design of product  Design of mould parts  Assembly of mold.
  28. 28. 18 | P a g e 2.2 Design of the product: Fig 6: Product Product design: Fig 7: side view of product with dimensions Fig.8: Top view of product
  29. 29. 19 | P a g e Fig. 9: 3-d view of product 2.3 Mold design: Fig. 10: mold
  30. 30. 20 | P a g e 2.3.1 Upper assembly design: Fig.11: Top view of upper assembly Fig.12: front view Bill of Materials for upper assembly Sr. No. Part name Quantity Material 1 Top st plate 1 Steel 2 Top al plate 1 Aluminium 3 Allen screw 8 steel Table 1: BOM for upper assembly
  31. 31. 21 | P a g e The detail drawing of upper assembly parts: Fig 13: top al plate Fig 14: top steel plate
  32. 32. 22 | P a g e 2.3.2 Lower assembly Fig. 15: 3-d view of lower assembly Fig 16: lower assembly top view
  33. 33. 23 | P a g e Fig 17: side view of lower assembly Bill of Materials for lower assembly Sr. No. Part name Quantity material 1 Bottom al plate 1 Aluminium 2 Bottom st plate 1 Steel 3 Side block 2 Aluminium 4 Side block lever 1 Aluminium 5 Side block tapper 1 Aluminium 6 Tapper block 1 Aluminium 7 Allen screw 14 Steel Table 2: BOM for lower assembly
  34. 34. 24 | P a g e The detail drawing of lower assembly parts: Fig 18: bottom al plate Fig 19: bottom steel plate
  35. 35. 25 | P a g e Fig 20: side block Fig 21: side block with lever hole
  36. 36. 26 | P a g e Fig 22: side block for tapper block Fig 23: tapper block
  37. 37. 27 | P a g e 2.3.3: Lever. Lever detail drawing Fig 24: lever_1 Fig 25: lever_2
  38. 38. 28 | P a g e fig. 26: lever assembly. 2.3.4. DESIGN OF TABLE: Fig. 27: 3-d design of table
  39. 39. 29 | P a g e Fig 28: front view of table Fig 29: top view of table
  40. 40. 30 | P a g e 2.4 mold assembly: Fig. 30: 3-d view mold assembly Fig. 31: mold in open condition
  41. 41. 31 | P a g e Fig. 32: exploded view of mold assembly Fig. 33: sectional view
  42. 42. 32 | P a g e 2.5 complete mold setup: Fig. 34: mold along with base table and cylinder
  43. 43. 33 | P a g e Fig 35: different views of mold setup
  44. 44. 34 | P a g e CHAPTER 3 MANUFACTURING PHASE Material Required Pre Machining Process Machining Process Surface Finishing Process Table Fabrication Process Components Used
  45. 45. 35 | P a g e 3.1: material required Sr. No. Part name material 1 Bottom al plate Aluminium 2 Bottom steel plate Steel 3 Side block Aluminium 4 Tapper block Aluminium 5 Top steel plate steel 6 Top al plate Aluminium 7 Lever Steel 8 Clamp Steel Table 3: material requirement list 3.2 Pre machining process: Shaping: A shaper is a type of machine tool that uses linear relative motion between the work piece and a single-point tool machine a linear tool path. Its cut is analogous to that of a lathe, except that it is linear instead of helical.. (Adding axes of motion can yield helical tool paths, as also done in helical planning.) A shaper is analogous to a planer, but smaller, and with the cutter riding a ram that moves above a stationary work piece, rather than the entire work piece moving beneath the cutter. The ram is moved back and forth typically by a crank inside the column; hydraulically actuated shapers also exist. Grinding machine: A grinding machine, often shortened to grinder, is a machine tool used for grinding, which is a type of machining using an abrasive wheel as the cutting tool. Each grain of abrasive on the wheel's surface cuts a small chip from the workpiece via shear deformation.
  46. 46. 36 | P a g e Grinding is used to finish workpieces that must show high surface quality (e.g., low surface roughness) and high accuracy of shape and dimension. As the accuracy in dimensions in grinding is on the order of 0.000025 mm, in most applications it tends to be a finishing operation and removes comparatively little metal, about 0.25 to 0.50 mm depth. However, there are some roughing applications in which grinding removes high volumes of metal quite rapidly. Thus, grinding is a diverse field. 3.3 Machining process: 3.3.1About Milling Machine: Milling is the machining process which uses rotary cutters to remove material from a work piece 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. 3.3.2. Drilling Machine: A drill is a tool fitted with a cutting tool attachment or driving tool attachment, usually a drill bit or driver bit, used for boring holes in various materials or fastening various materials together with the use of fasteners. The attachment is gripped by a chuck at one end of the drill and rotated while pressed against the target material. The tip, and sometimes edges, of the cutting tool does the work of cutting into the target material. This may be slicing off thin shavings (twist drills or auger bits), grinding off small particles (oil drilling), crushing and removing pieces of the workpiece (SDS masonry drill), countersinking, counterboring, or other operations. 3.4 Surface finishing process: 3.4.1: polishing process: Polishing and buffing are finishing processes for smoothing a work piece’s surface using an abrasive and a work wheel or a leather strop. Technically polishing refers to processes that use an abrasive that is glued to the work wheel, while uses a loose abrasive applied to the work wheel. Polishing is a more aggressive process while
  47. 47. 37 | P a g e buffing is less harsh, which leads to a smoother, brighter finish. A common misconception is that a polished surface has a mirror bright finish, however most mirror bright finishes are actually buffed. 3.5. Table fabrication process: Table is made up of the L- section of the cast iron. These L-sectoins are cut into required length and welded together to from the table. Fig 36: fabricated table 3.6: Components used: Heater used: The heater used in seat cushion molding process is a ceramic heater 400mm*400mm. About Ceramic heater: Ceramic heaters are space heaters that generate heat by passing electricity through heating wires embedded in ceramic plates. The plates heat aluminium baffles, and a fan blowing across the baffles heats the air. Ceramic heaters are usually portable and typically used for heating a room or small office, and are similar to metal-coil fan heaters.
  48. 48. 38 | P a g e It is shown in the image below Fig 37: Ceramic heater Thermocouple: A thermocouple is a temperature-measuring device consisting of two dissimilar conductors that contact each other at one or more spots. It produces a voltage when the temperature of one of the spots differs from the reference temperature at other parts of the circuit. Thermocouples are a widely used type of temperature sensor for measurement and control, and can also convert a temperature gradient into electricity. Commercial thermocouples are inexpensive, interchangeable, are supplied with standard connectors, and can measure a wide range of temperatures. In contrast to most other methods of temperature measurement, thermocouples are self powered and require no external form of excitation. The main limitation with thermocouples is accuracy; system errors of less than one degree Celsius (°C) can be difficult to achieve.
  49. 49. 39 | P a g e Heater cutoff circuit: The thermal cutoffs (TCO) are non resetting, thermally sensitive, single pole, normally closed devices and are intended to be used in various appliances. A temperature sensitive thermal fuse melts and opens electrical contacts when temperatures exceed the rating of the thermal fuse. Thermal cutoffs are providing protection against potentially hazardous overheating conditions in billions of products around the world. Standard product offerings include: Thermal Fuse * Metallic Case type (Axial, Spring Action, Current: 10A, 15A) - USW-1 Series * Low melting alloy type (Axial, Surface tension type, Current: 2A, 5A) - USW-2 Series Note that the TCO shall be connected at the readily detectable location when abnormal conditions such as thermostat failure, fan failure, locked rotor, dry operation, etc. might occur in the appliance. TCO is designed to lessen the heat created from TCO itself, but there may be a difference between the ambient temperature and operating temperature of TCO due to wrong connection method. Pneumatic cylinder: Like hydraulic cylinders, something forces a piston to move in the desired direction. The piston is a disc or cylinder, and the piston rod transfers the force it develops to the object to be moved..Engineers sometimes prefer to use pneumatics because they are quieter, cleaner, and do not require large amounts of space for fluid storage. Because the operating fluid is a gas, leakage from a pneumatic cylinder will not drip out and contaminate the surroundings, making pneumatics more desirable where cleanliness is a requirement. For example, in the mechanical puppets of the DisneyTikI Room, pneumatics are used to prevent fluid from dripping onto people below the puppets. The pneumatic cylinder provides the required pressure for closing and opening of the mould. It is shown in figure as follows:
  50. 50. 40 | P a g e Fig 38: pneumatic cylinder 3.7. Molding process: Step 1). The polyethylene solution is used to make the cushion. For which the polyethylene solution is poured into the mold. Step 2). The solution is manually poured into the mold & then the mold is closed by pnumetic cylinder, and the clamp makes it sure that mold remains closed during the entire process. Step 3). The heater is then on and the heating starts. Step4) care should be taken that the solution shuld not be heated above 60 degree C. Step 5)the solution needs to be heated for about 30 minutes. Step 6) after the heating is done the mold is kept for about 15-20minutes for cooling at room temperature. Step 7) the product is then manually removed from the mold..
  51. 51. 41 | P a g e CHAPTER 4 CONCLUSION & REFERENCES
  52. 52. 42 | P a g e 4.1 CONCLUSION Thus for making seat cushion its design phase: product design, mold component design and assembly design has been completed and its machining process is initiated
  53. 53. 43 | P a g e 4.2 References:  Journal of Rehabilitation Research and Development Vol. 27 No. 3, 1990  “Superior Processing New all-MDI Solutions for Automotive Seating with Low emission of Volatile Organic Compounds (VOC)”  http://www.us-electronics.com/datasheets/thermalcutoffs.pdf to understand the working and use of heater cutoff circuits.  http://www.moldmakingtechnology.com/articles/six-best-practices-for- mold-design to understand the important aspects of designing.  http://en.wikipedia.org/wiki/Ceramic_heater for detailed knowledge about the ceramic heater.