Title: Fabrication of G-Clamp Abstract: The purpose of this project is to allow students to understand the common manufacturing processes and learn to apply these knowledge to real life situations. While fabricating a g-clamp, processes like filing, drilling, sawing, thread tapping, welding, engraving, hammering and grinding are needed to be done to successfully fabricate a g-clamp. Parts of the g-clamp were first prepared and undergone processes before joining everything together to ease complexity and increase effiency. These processes are performed aided by corresponding tools and equipment. Skills, techniques and safety precautions taken played a very important role while these tools and equipment are handled. Since students are beginners in manufacturing processes, most processes are taught and supervised by the instructor of this project. Objectives: - To learn the usage of common engineering tools and machines. - To learn the usage of common engineering tools and machines associated in process planning for the fabrication of a G-Clamp. Introduction: G- clamps are tools commonly used in mechanical workshops. A G-clamp holds metal or wood workpieces while conducting other manufacturing processes. Sometimes G-clamps are known as C-clamp due to its C-shaped frame. Otherwise, the name G-clamp or G-cramps are often used due to its G-shape of the overall piece (screw + frame). Typically, G-clamps are tough, strong, and resistant to corrosion, not brittle and have low ductility. Therefore, materials like steel, cast iron or pot iron are the most suitable to manufacture a Gclamp. A G-clamp commonly have 4 parts, a bracket, rod holder, screw rod and a rod tip. Each parts have their corresponding fuctions. Bracket : -C-shaped frame -Hold workpiece & screw rod Screw rod: - rod with taped threads externally - tighten-:screw clockwise -loosen: screw anticlockwise Rod End: -blind hole -Tapped internally - trough hole (drilled) -To hold the
Rod Tip: -through hole -to hold the workpiece firmly Rod Holder: -Tapped internally -through hole -to hold the screw rod
The first step before clamping the workpiece is unscrewing the screw in a anticlockwise direction and slip the mouth opening into a corner of a table. Then, place the workpiece surface facing the jaws into the opening of the clamp and tighten the screw with clockwise direction. A too high pressure exerted on the workpiece must be avoided to prevent cracking and other surface defects. Apparatus: 1. Filing (round files, flat files, Semi-round files) 2. Clamps (table clamps) 3. Grinding equipment 4. Welding equipment 5. Drilling equipment 6. Thread taping equipment(tap and dies) 7. Punching 8. Sand blasting 9. Hammer 10. Product shape mold & perpendicular measuring sheet 11. engraving machine. Materials: 1. Sand Paper 2. Spray paints 3. Newspapers
Procedure: Process planning: The fabrication of the G-Clamp consists of 4 components. Each components are prepared according to sequence. 1. Bracket 2. Rod holder 3. Screw rod 4. Rod tip
Fabrication of Bracket 1. Drawing shape 1.1.The “C” shape mold is placed on the workpiece. 1.2.The outline shape of the G-Clamp was traced closely according to the mold with a marker pen so that it is smaller than the mold hole 2. Dimensions 2.1.The exact dimensions were marked on the workpeice. 2.2.Workpiece is clamped firmly onto the table clamp
2.3.The surface of the workpiece is filed until all the rust is removed and to remove excess metal until it could pass through the mold. 2.4.Sharp edges are filed using sandpaper and files.
Fabrication of Rod Holder 1. Drilling 1.1.A small point is punched to act as a hole to be drilled. 1.2.A through hole with diameter 8.2mm was drilled in the holder using an electric table drill. 2. Thread Tapping 2.1.The rod holder is clamp firmly to vise of the milling machine 2.2.A 3/8 in tap was tapped to fit a 9.5 mm diameter threaded screw rod. 2.3.During tapping, oil is added into the hole one drop at a time to reduce friction. 2.4.The holder of the tap is rotated anticlockwise after being rotated at a clockwise direction for half revolution release stresses on the sharp edges of the tap 2.5.The tap was held vertically throughout the process. 2.6.The rod holder is removed from the vise and clamped onto the table clamp 2.7.The rod holder is then hand tapped with plug tap and bottoming tap. 2.8.Oil is added while hand tapping one drop at a time to the hole. 3. Welding (before “Fabrication of Screw Rod Assembly” and “Fabrication of Rod Tip”) 3.1.A small section of the filler wire coating is removed by hammering. 3.2.Welding mask is wore. 3.3.The rod holder is welded on to the bracket. 3.4.The workpiece is allowed to cool down around 10minutes and then immersed in cold water. 3.5.The surface of the weld is grinded and filed with a grinding machine and files to achieve a smooth surface. Fabrication of Screw Rod Assembly Rod end 1. Drilling 1.1.The rod end with 8.2mm diameter is held firmly to vise of drilling machine. 1.2.A blind hole of 5mm is drilled. 2. Thread Tapping 2.1. The end rod is clamp firmly to vise of the milling machine. 2.2.A 3/8 in tap was tapped to fit a 9.5 mm diameter threaded screw rod. 2.3.During tapping, oil is added into the hole one drop at a time to reduce friction. 2.4.The holder of the tap is rotated anticlockwise after being rotated at a clockwise direction for half revolution release stresses on the sharp edges of the tap
2.5.The tap was held vertically throughout the process. 2.6.The Rod End is removed from the vise and clamped onto the table clamp 2.7.The rod holder is then hand tapped with plug tap and bottoming tap 2.8.Oil is added while hand tapping one drop at a time to the hole 3. Welding 3.1.A small section of the filler wire coating is removed by hammering. 3.2.Welding mask is wore. 3.3.The Rod End is welded on to the Screw Rod. 3.4.The workpiece is allowed to cool down around 10minutes and then immersed in cold water. 3.5.The surface of the weld is grinded and filed with a grinding machine and files to achieve a smooth surface.
4. Drilling 4.1.A middle line is marked vertically on the Rod end and a 7mm height from the bottom of the Rod End is marked with a horizontal line 4.2.A small hole is punched on the intersections of the two lines. 4.3.A through hole is drilled on the small hole 5. Handle 5.1.The handle is inserted into the hole 5.2. a hexagonal nut is screwed into the other end of the handle 5.3.Excess length of the handle is sawed and punched using a hammer to create a blunt end and to secure the hexagonal nut from falling off. 5.4.Insert the whole screw rod assembly into the rod holder before fabrication of rod tip and welding the rod holder onto the bracket Fabrication of Rod Tip 1. Drilling 1.1.A through hole is drilled 2. Hammering 2.1.The Rod Tip is inserted into the smooth end of the screw rod with the smaller diameter hole face towards the screw rod. 2.2.The G-clamp is clamped tightly to the table clamp. 2.3. The end of the screw rod is lightly hammer-punched to secure the Rod tip without falling off but able to rotate in the screw rod Finishing 1. Full name, student ID and course name is engraved with a engraving machine. 2. Final surface filing is filed using a sand paper to remove sharp edges, dull surfaces and rust. 3. The final product then spray painted with taped screw rod to avoid spoiling the thread on the screw rod.
Precaution Taken: 1. During Welding: 1.1.Welding mask is wore throughout welding process. 1.2.The welding table is cleared of flammable objects like aerosol cans 1.3.The wires of the torch is made sure not in contact with any water or electrical conductive liquids. 1.4.Other students are called to stay away from the welding table while welding is undergoing. 2. During Drilling: 2.1.Long hairs are tied up and hair at fringes are pined up using booby pins 2.2.A distance is kept between student’s head and the chuck/ spindle of the drilling machine. 2.3.Drilled discontinuously to prevent production of continuous chips that are long, hot and sharp. 3. During Hammering : 3.1.Index finger and thumb is made sure to be away from the hammering site of the workpiece to prevent injury. 4. During Thread Taping: 4.1.Stresses are released after tapping half revolution to prevent internal cracking. 4.2.Lubricant is used to prevent friction. 4.3.Workpiece is screwed tightly to the vise. 4.4.Chips are removed before tapping to prevent cracking and dimensional damage. 5. At all processes: 5.1.Workpiece is made sure to be clamped firmly to the table clamp. 5.2. A distance is kept between the eyes and the tools to prevent injury. 5.3.Advises and instructions given by the lab assistants are follow strictly
Problems Encountered: During Spray Painting, the paint spray was too thick, causing the engraved word to be nearly covered completely. Besides, the finished product was flipped before all paints are completely dry, caused sticky surfaces sticked onto the newspaper and ruined the paints During engraving, uneven pressure was exerted onto the bob of the knife causing the knife to slip while engraving. Initial engraving lines that act as a route for the engraving knife were neglected. The word molds were not screwed tightly before engraving cause unnecessary vibration that creates an uneven engraved surface. During initial thread tapping, the tap holder was rotated impatiently and with brute force caused a slight crack inside the Rod end. Filing was time consuming and energy consuming that caused insufficient time to finish the project. During drilling, some hot and sharp chips produced were bounced onto hands while holding the vise in position during drilling.
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