Manufacturing Engineering 2020
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| 🇬🇧 | 🇬🇧 |
| Name the components of a 2 part sand mold: | 1) pouring cup 2) Sprue 3) riser 4) runner 5) Parting Line 6) mold Cavity 7) draft 8) core 9) cope 10) core print 11) drag 12) flask |
| Benefits of a top riser | Their location allows for more space for the pattern and gating system because less spacing is required to feed the liquid metal from the top. |
| What is a Match-plate pattern? | Pattern used to produce two identical parts in a single flask,where the cope and drag are connected to the pattern |
| What is lost foam casting? | When the pattern is made out of a material that dissipates after after the completion of the casting process. |
| Whats the down side of expendable mold casting? | The molds(pattern) are non-reusable. |
| What is a pouring cup and a sprue? | Where the material is poured, and travels down the sprue. |
| What does a runner do in sand casting and what is it connected too? How is the runner added to a mold cavity? | It distributes the liquid to the gate and/or riser, it slows down the flow of the liquid to allow for uniform flow to the mold cavity. The runner is added to the mold cavity via the pattern, leaving behind the passage ways for the liquid. |
| What is the pattern | An approximate duplicate of the final casting used to form the mold cavity. |
| Define the flask | The rigid wood or metal frame that holds the molding material. |
| Define cope & drag | Top and bottom parts of the pattern, flask, mold or core |
| Define the core | Object used to make internal features in the casting |
| Define core print | Support pieces for the core |
| Define mold cavity | The hollow area where the mold material formed around the pattern and core |
| Define the gating system & gate | The network of connected channels that deliver the molten material to the mold cavities. The gate controls the flow rate so no turbulence is produced when the liquid enters the mold cavity. |
| What is the parting line | Where the cope and drag leave meet; this leaves a line on the mold cavity and a line on the part; thus a parting line. |
| Draft | The taper on the casting or pattern that allow it to be withdrawn from the mold |
| Define core box | The mold or die used to produce the cores. |
| Define the chaplet | Of similar material of what we are casting and used to keep the core from shifting, forms in the material |
| What is a riser | Reservoir located in the cope supplies additional material during the shrinkage phase in the solidification process |
| What is a Chill? What is a benefit to having a chill? | Colder section within a mold allowing for directional solidification to occur in mold shapes that other wise would support directional solidification.It can be used to direct grain lines. |
| What are the expendable mold casting processes? | Single-use molds with multiple-use patterns, and single-use molds with single-use patterns |
| What are the most frequently casting metals? what are the most commonly casting metals and why? | Iron, steel, stainless steel, brass, bronze and alloy aluminum, copper, magnesium, certain zinc, and nickel-based superalloys. Cast iron and aluminum because of low cost, good fluidity, adaptability to a variety of processes, and a wide range of product properties that are available. |
| What is the complete process of sand casting a part? | Pattern board is placed between the cope and the drag with the drag side up; essentially the flask starts upside down. Sand is packed into the drag, and a board is placed over the drag, then the drag is flipped exposing the cope where the sprue and riser pins are placed; these pins are attached to the pattern and will be removed once the pattern is removed. Then the cope is packed with sand. The cope is removed, with the packed sand held in place, the pattern is then removed(drawn) exposing the open side of the drag, then the runner and gate are curved into the open side of the drag and cope. The core is positioned, and the mold is reassembled, and the molten metal poured. After solidification, the workpiece is removed from the sand for further processing. |
| What material are the patterns made of in full-mold, lost-foam, and investment casting | Full-mold,lost-foam(expanded polystyrene(ESP)), wax for investment casting |
| Write complete investment casting for flask-cast method process | Inject wax or plastic into die to make pattern; attach pattern to sprue via gates; put pattern in metal flask; fill flask with slurry and let dry; heat flask to melt pattern; fill cavity with hot molten metal via gravity or pressure or vacuum or centrifugal force; remove cast from gate and sprue. |
| Write the Investment casting steps for the shell-casting procedure | Make pattern out of wax or plastic, add gates and sprue, coat pattern with ceramic slurry and sifted refractory grain over pattern(making the mold), after mold has dried melt out pattern,heat flask to melt pattern; fill cavity with hot molten metal via gravity or pressure or vacuum or centrifugal force, remove mold material and sprue and gate |
| What is the full mold process? | Full-mold casting is an evaporative-pattern casting process which is a combination of sand casting and lost-foam casting. It uses an expanded polystyrene foam pattern which is then surrounded by sand, much like sand casting. The metal is then poured directly into the mold, which vaporizes the foam upon contact |
| What is the lost-foam casting process? | A lost foam casting is created by a type of evaporative-pattern casting process where a polystyrene foam pattern is used to form a mold. The foam pattern is coated with a refractory slurry and is embedded in a flask with a ceramic bead medium compacted around it to support the foam's external form. |
| What are the benefits of full-mold and lost-foam processes | No draft requirement, able and easily-compared to sand casting-to make complex patterns, smooth surface finish, no complex core geometry, no parting line |
| What are sand, investment, full-mold, and lost-foam casting process classified as? | Sand: single use mold multiply use pattern, Investment: Single use molds with single use patterns; lost foam is multiply use mold single use pattern |
| What is annealing? | Annealing is the process of redistributing the grains in a cast. |
| What are the limitation of lost-foam and lost-wax casting? Metals casted in this process? | Costly pattern for small quantities, easily damaged patterns and labor, and limited size for the latter. Aluminum, iron,steel, nickel alloys, stainless steel, and copper and all the above for the latter(any castable metal) |
| Advantages and disadvantages of shell-mold casting; what metals are commonly casted with this? | Faster production rate than sand molding, high dimension tolerance with smooth surfaces but requires expensive metal patterns and limited part size; cast iron, cast alloys of aluminum and copper. |
| Whats the difference between permanent mold casting and die casting | Former: molten metal flows via gravity; latter: molten metal is forced in via high pressure. |
| What are the basic operations of a gooseneck? | An unretracted piston blocks the flow of molten metal in a furance with the gooseneck submerged within it,piston goes to retracted position, molten metal flows into chamber/ gooseneck, then the piston forces the molten metal through the gooseneck, runner, gate and into the die where it solidifies. |
| Basic operations of a cold chamber die cast? | Molten metal is heated to its operation temp outside the chamber(shot sleeve) then poured in, piston forces molten metal into die cavity where it is held under pressure until it solidifies,The die opens and the plunger advances, to ensure the casting remains in the ejector die. Cores, if any, retract,Ejector pins push the casting out of the ejector half of the die and the plunger returns to its original position. |
| What is Centrifugal casting used for? | Centrifugal casting or rotocasting is a casting technique that is typically used to cast thin-walled cylinders. It is typically used to cast materials such as metals, glass, and concrete. A high quality is attainable by control of metallurgy and crystal structure. |
| Name 2 of the most common multiple-use-mold casting processes. | Hot and cold chamber casting |
| Because the molds are generally made from metal what the limitation? | Processes are restricted to casting the lower-melting-point nonferrous metals and alloys |