14-08-2012, 03:57 PM
SCISSOR CAR JACK
SCISSOR CAR JACK.docx (Size: 1.55 MB / Downloads: 119)
Introduction to the selected product
A Scissor Jack is a piece of equipment which is used to lift and support a heavy weight, such as a car. Jacks are the primary tool used when changing the tire of a car in a roadside emergency. The jack used as original equipment in modern cars is the scissor jack. It is designed to lift the weight off the wheel which needs service, such as changing a flat tire.
Operation
A scissor jack is operated simply by turning a small crank that is inserted into one end of the scissor jack. This crank is usually "Z" shaped. The end fits into a ring hole mounted on the end of the screw, which is the object of force on the scissor jack. When this crank is turned, the screw turns, and this raises the jack. The screw acts like a gear mechanism. It has teeth (the screw thread), which turn and move the two arms, producing work. Just by turning this screw thread, the scissor jack can lift a vehicle that is several thousand pounds.
Identification of materials and suppliers of various components
Material Selection
Scissor jacks are usually made of materials that are very strong and are suitable for withstanding heavy loads. The two main materials used for making good quality jacks are:
• Steel
• Aluminum
When selecting the material suitable for the construction of the Scissor jack one has to consider the properties that will enable it to function with no expected failure and at the same time the weight and ease of machining the product. Therefore the main areas that can be classified in this case are the strength of the material, weight, ease and cost of manufacturing.
According to (http://xnet3.ussauto/steelvsal/cost.htm) steel at all volumes, is much more cost effective compared to that of aluminum, however aluminum has other superior properties especially its weight over steel. Aluminum is around one-third the density of steel at 2.72 mg/m cubed compared to steel's 7.85 mg/m cubed. The light weight and low melting point of aluminum makes it easier and more efficient to machine than steel. Aluminum's fatigue performance is half that of steel, which is an advantage steel has over aluminum in car jack life durability. Therefore Steel is the most viable material selected for the manufacture of the car scissor jack.
Material Suppliers
Many studies have shown that the cause of most mechanical and structural failures and accidents is directly correlated with the type and quality of the materials used.
Before selecting a company from a list of steel suppliers we need to consider the following:
a) Good reputation for service
b) High quality steel.
Walker Steel Company is an ISO 9001:2008 certified worldwide sheet steel supplier based in the United Kingdom. It is also one of the most reputable steel suppliers in the United Kingdom.
Walker steel run a totally integrated IT system which links customer requirements direct to production and transport, ensuring real time information and precise traceability of material. Recent developments include a proven web based stock system, which allows customers to keep stock at their own premises, with a fully automated re-order operation and batch invoicing capability. Thus, improving their own lead time to client, limiting the amount of cash locked in stock and reducing internal costs on stock management.
Development of the process plan for the car scissor jack.
This jack has been designed to minimize manufacturing costs. The parts have been designed to be symmetric thus minimizing the number of unique parts required. For example the left and right upper arms are the same exact part utilizing the same dies during production. The left and right pins only differ in that one has a thru-hole while the other is tapped. There seems to be only two gauges of sheet steel used in the construction of this jack. This minimizes the number of separate raw materials that would have to be purchased to construct the product. By minimizing the number of different raw materials required, larger amount of necessary material can be ordered resulting in savings from buying larger quantiles.