It is a work holding device that holds, supports and locates the workpieceand guides the cutting tool for a specific operation. Jigs are usually fitted with hardened steel bushings for guiding or other cutting tools. a jig is a type of tool used to control the location and/or motion of nother tool. A jig's primary purpose is to provide repeatability, accuracy, and interchangeability in the manufacturing of products. A device that does both functions (holding the work and guiding a tool) is called a jig. 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
It is a work holding device that holds, supports and locates the workpiece for a specific operation but does not guide the cutting tool. It provides only a reference surface or a device. What makes a fixture unique is that each one is built to fit a particular part or shape. The main purpose of a fixture is to locate and in some cases hold a workpiece during either a machining operation or some other industrial process. A jig differs from a fixture in that a it guides the tool to its correct position in addition to locating and supporting the workpiece.
Molten metal before casting Casting iron in a sand mold In metalworking and jewellery making, casting is a process in which a liquid metal is somehow delivered into a mold (it is usually delivered by a crucible) that contains a hollow shape (i.e., a 3-dimensional negative image) of the intended shape. The metal is poured into the mold through a hollow channel called a sprue. The metal and mold are then cooled, and the metal part (the casting) is extracted. Casting is most often used for making complex shapes that would be difficult or uneconomical to make by other methods.
Casting processes have been known for thousands of years, and have been widely used for sculpture (especially in bronze), jewellery in precious metals, and weapons and tools. Traditional techniques include lost-wax casting (which may be further divided into centrifugal casting and vacuum assist direct pour casting), plaster mold casting and sand casting.
The modern casting process is subdivided into two main categories: expendable and non-expendable casting. It is further broken down by the mold material, such as sand or metal, and pouring method, such as gravity, vacuum, or low pressure. From Wikipedia, the free encyclopedia
Humble bolts seems like a mundane and boring machine component. However, we engineers always get a little excited at threaded fasteners, simply for the incredible variety available and their significant capability in any engineering application. You see them in bridges and buildings, aircraft, cars and of course, our motorcycles.
Why would you choose to use threaded fastener? Usually, for flexibility in assembling or disassembling components. Sometimes the cost of using a threaded fastener to secure a joint might be cheaper than other options (such as welding a joint together). In our motorcycles, there will be a combination of reasons.
A threaded fastener (lets just simplify and say “bolts” from now on, it will save me typing “threaded fastener” another 100 times) works like a spring. Remember our discussion in the Basic properties of metals article about the tensile test. A bolt works in tension (meaning the load is parallel to its long centreline axis). When you put a bolt through, say, two pieces of steel, and tighten the nut, the steel plates do not compress appreciably, so the distance between the nut and the bolt head is essentially fixed. However if the bolt is being tensioned, it is stretching between the nut and the bolt head, which are up tight against our theoretical steel plates. If the bolt is stretching, then it is exerting an equal but opposite clamping force on the two steel plates. This diagram might help illustrate the point.
It is this clamping force which is important. The clamping force is intended to prevent any slip between the parts. The amount of operational forces the engineer expects the assembly to withstand in service, will, in turn, dictate how much clamping force is required between the parts. This clamping force will then inform the bolted joint design. How many bolts can I fit on this assembly? What size bolts can I fit here? Are there particular geometry features that I have to consider which limits my bolt choice? Do I have to change the shape of the part to fit enough bolts into the assembly?
Over the industrial age through to modern times, various thread forms have been developed by different industries in different countries. This is what they look like in cross section: