Principles of Major Manufacturing Processes Prepared by: Behzad Heidarshenas Ph.D in Manufacturing Processes 1
Overview of Casting Technology Casting is usually performed in a foundry Foundry = factory equipped for making molds melting and handling molten metal performing the casting process cleaning the finished casting Workers who perform casting are called foundrymen EMU - Manufacturing Technology
The Mold in Casting Mold is a container with cavity whose geometry determines part shape Actual size and shape of cavity must be slightly oversized to allow for shrinkage of metal during solidification and cooling Molds are made of a variety of materials, including sand, plaster, ceramic, and metal EMU - Manufacturing Technology
Open Molds and Closed Molds Cavity is open to atmosphere Cavity is closed Two forms of mold: (a) open mold, simply a container in the shape of the desired part; and (b) closed mold, in which the mold geometry is more complex and requires a gating system (passageway) leading into the cavity. EMU - Manufacturing Technology
Two Categories of Casting Processes 1. Expendable mold processes uses an expendable mold which must be destroyed to remove casting Mold materials: sand, plaster, and similar materials, plus binders 2. Permanent mold processes uses a permanent mold which can be used over and over to produce many castings Made of metal (or, less commonly, a ceramic refractory material) EMU - Manufacturing Technology
Sand Casting Mold Sand casting mold. EMU - Manufacturing Technology
Overview of Sand Casting Sand casting is a cast part produced by forming a mold from a sand mixture and then pouring molten liquid metal into the cavity in the mold. The mold is then cooled until the metal has solidified Most widely used casting process, accounting for a significant majority of total tonnage cast Nearly all alloys can be sand casted, including metals with high melting temperatures, such as steel, nickel, and titanium Castings range in size from small to very large Production quantities from one to millions EMU - Manufacturing Technology
A large sand casting weighing over 680 kg (1500 lb) for an air compressor frame EMU - Manufacturing Technology
Steps in Sand Casting 1. Pour the molten metal into sand mold CAVITY 2. Allow time for metal to solidify 3. Break up the mold to remove casting 4. Clean and inspect casting Separate gating and riser system 5. Heat treatment of casting is sometimes required to improve metallurgical properties EMU - Manufacturing Technology
Sand Casting Production Sequence Figure: Steps in the production sequence in sand casting. The steps include not only the casting operation but also pattern-making and mold-making. EMU - Manufacturing Technology
METAL FORMING EMU - Manufacturing Technology
12 Material Properties in Metal Forming Desirable material properties: Low yield strength High ductility These properties are affected by temperature: Ductility increases and yield strength decreases when work temperature is raised Other factors: Strain rate and friction
Basic Types of Deformation Processes 13 1. Bulk deformation Rolling Forging Extrusion (stock has high V/A) Wire and bar drawing 2. Sheet metalworking Bending Deep drawing Cutting (stock has low V/A)
14 Bulk Deformation Processes Characterized by significant deformations and massive shape changes "Bulk" refers to workparts with relatively low surface area-to-volume ratios Starting work shapes include cylindrical billets and rectangular bars
Rolling 15 Basic bulk deformation processes: rolling
Forging 16 Basic bulk deformation processes: forging
Extrusion 17 Basic bulk deformation processes: (c) extrusion
Wire and Bar Drawing 18 Basic bulk deformation processes: (d) drawing
19 Sheet Metalworking Forming and related operations performed on metal sheets, strips, and coils High surface area-to-volume ratio of starting metal, which distinguishes these from bulk deformation Often called pressworking because presses perform these operations Parts are called stampings Usual tooling: punch and die
20 Sheet Metal Bending Basic sheet metalworking operations: bending
21 Deep Drawing Basic sheet metalworking operations: drawing
Shearing of Sheet Metal 22 Basic sheet metalworking operations: shearing