MATERIALS TEST 6: Metal Forming
The grain of the plate is horizontal in a part that is ________________________, and a cut through the grain would be poor in terms of stress. As a result, the potential for crack development along the grain boundaries is nearly as great as in casting.
Cut from Stock
What is the most effective method of casting non ferrous metals?
High Pressure Die Casting
Characteristics of _________________________: -a.k.a. tools/dies -expensive -require large production volume to make them economically feasible -greater lead time for preparation -last minute changes are extremely expensive to make
Non Expendable Mold
Disadvantages of ___________________: -draft angle = required -undercuts aren't possible unless there are movable cores or a side action that moves obstructions out of the ejection path -permanent molds with cores made of expendable materials are classified as semi-permanent -these are expensive -these are limited to low-melting point metals (so that the metal doesn't melt the mold itself) ---> non-ferrous
Non Expendable Mold
A ____________ is normally defined as metal that is less than 0.25" thick. Anything thicker than that is considered a plate.
Sheet
____________________ can have a uniform grain structure. If enough stress is applied to a cast "S" bar, a stress crack will soon develop along the grain boundaries. Surface defect will cause stresses, called stress concentrations, that will enhance the potential for failure.
Casting
Design Considerations for ______________: -depending on the thickness/type of material, parts ranging from less than 5mm - 500mm in diameter can be produced -length of draw can be up to 5x the diameter -high tooling cost, moderate unit cost -scrap is produced when sheet is cut, but scrap is recyclable -medium - high volume production -good surface finish -steel, zinc, copper, aluminum alloys -rapid cycle time (seconds to minutes) depending on number of operations
Deep Drawing
Characteristics of _____________________: -when the depth of the draw is GREATER than the diameter of the shape -process can produce seamless sheet geometrics without need for further forming/joining procedures -various shapes can be made -straight, tapered and curved sides can be drawn -undercuts can be achieved with progressive dies which might greatly increase the tooling cost
Deep Drawing (Cold Metal Pressing)
Advantages of __________________: -high production -good size tolerances and accuracy -low part price (depending on volume, complexity and size of part) -thin walls -excellent surface finish -high tooling and low unit cost -rapid cycle time depending on size/complexity of part
Die Casting
Characteristics of ___________________: -extremely useful if quantities justify it -where holes in sheet forming process is not waste in a die casting if they are incorporated -3 main methods -parts are produced to high tolerance and so require little/no finishing -external threads and inserts can be casted into product -requires finishing to remove excess metals on product
Die Casting
Design Considerations of ___________________: -not ideal for ferrous metals because their melting points are too high... Aluminum, Magnesium and Zinc are great -molds are expensive with long lead times for tooling and casting -very similar design constraints to injection molding including ribs, draft angles (1.5 degrees), recesses ,external features, mold flow, and partition lines -best suited for small parts, otherwise molds get very large and expensive -weight of metal parts = usually ounces - 30 pounds -medium - large production volume
Die Casting
Main methods of ______________: -high pressure -low pressure -gravity
Die Casting
Advantages of _____________ Extrusion: -most materials are relatively inexpensive -ease of finishing -inherent strength in part
Direct
Characteristics of _____________________: -metal forming process that forms thin parts through plating a metal skin onto a base form (mandrel), which is removed after plating -process differs from electroplating in that this process produces a part that is thicker and has self-supporting structures -new importance in fabrication of micro and nano-scale metallic devices and components -fine process controls enable the production of high precision parts with features measured in microns -high tolerances and excellent edge definition -finer geometries are possible -metal is pure with superior properties over wrought metal because of the refined crystal structure of pure metal -tolerances of 1.5 - 3 nanometers -principle limitation: need to strip the product from the mandrel
Electroforming
Design Considerations of __________________: -low tooling cost -moderate - low unit cost -little waste -high volume production -high quality surface finish -high level of density -nickel, copper, gold, silver are metals used -moderate cycle time (1-2 hours)
Electroforming
Characteristics of _________________________: -destroyed during part removal -drafts and undercuts are not major considerations -however, draft and elimination of undercuts are still required to removed the part from the mold -surface finish and appearance considerations are important
Expendable Mold
Characteristics of ______________________: -uses preheated material which is forced through a die producing a long continuous profile -suitable for all metals -aluminum increasingly becoming a more common material -most effective in producing long strips with same profile (DIRECT) -has an extensive production base -shapes formed can be solid, semi-hollow, or hollow -any profile is possible to meet a large variety of design requirements
Extrusion (Direct and Impact)
Characteristics of ____________________: -one of the oldest metal forming processes (horse shoes, swords, axe heads) -many different types of this process which are used to produce an array of products from crankshafts to ice axes -three main types: drop, press, and roll -suitable for low volume production or one-offs -produces parts with properties not otherwise achievable -no undercuts are possible without secondary forming -process can be closed die or open die
Forging
Design Considerations for _______________________: -design must consider partition lines, draft angles, ribs, radii and fillets -radii are important as they encourage the flow of metal and reduce tool wear -moderate - high tooling cost, moderate unit cost -excellent grain structure -high use of energy is required, but little waste is produced -carbon steel, steel alloys, stainless steel, aluminum, copper and aluminum -rapid cycle time (less than 1 minute) depending on size, shape and material
Forging
_____________, in which the grain follows the shape of the part, is superior to the other methods in countering stress and is one of the main benefits of forging or any plastic state metal forming.
Forging
_______________________ changes are important in all forming operations and may eventually cause some problems, especially as the metal ages.
Grain structure
__________________ Die Casting is ideal for short production runs because it is not as economical as the other die casting methods.
Gravity
Advantages of _________________: -inexpensive tooling costs and reduced set-up time -shock lines, draw marks, wrinkling and tearing associated with matched die forming are eliminated -******** with a ******** and at a lower per unit cost due to the unibody structure and elimination of welding process -ideal for complex shapes and irregular contours -low unit cost -little material and energy waste -one-off - high volume production -quality depends on initial metal material properties and its potential for variation -aluminum, brass, copper, low carbon steel and stainless steel -rapid cycle time, depending on size and complexity of part
Hydroforming
Characteristics of _________________: -cost effective way of shaping ductile metals like aluminum, brass, copper, low carbon steel, and stainless steel int lightweight structurally stiff and strong pieces -specialized type of die forming that uses high pressure hydraulic fluid to press room temperature working material into a die -complex shapes with concavities can be produced, which would be difficult/impossible with standard solid die stamping -widely used in automotive industry (high end sports cars and bicycles) -relatively inexpensive production method due to interchangeability of tools and punches for different part requirements -sheet process and tube process are primary techniques -Sheet and Tube are primary techniques
Hydroforming
Characteristics of ______________________: -no draft required -varying wall thickness -precise tolerances and increased part strength -high production rate with low tooling cost -limits in size, in diameter and in lengths of up to 24"
Impact Extrusion
Design Considerations for ____________________: -low - medium tooling cost, low unit cost -low material waste -medium - high volume production -good surface finish -aluminum, magnesium, copper -rapid cycle time
Impact Extrusion
__________________ Process: -large forge press is used to form small to medium sized parts with thin walls and no draft -a blank is placed in a die and is struck by a plunger causing the material to become plastic -it is extruded upward between the plunger and the die wall for forming a variety of short shapes, including thin-wall symmetrical containers -part is ejected
Impact Extrusion
Advantages of ____________________: -total design freedom -draft/undercuts aren't a problem -excellent surface finish -elimination/reduction of machining -excellent dimensional tolerancy -all cast-able alloys are usable
Investment Casting (Lost Wax)
Characteristics of ___________________: -a versatile metal casting process -more expensive than die casting but the appearances outweigh the price differences -can be used to produce parts as little as a few grams - 35 kg -used for prototypes right up to mass production -does not have the same limitations as other die casting processes due to no part having to be ejected -mold can be extremely complex, consisting of many parts -these molds are injection molded
Investment Casting (Lost Wax)
Design Considerations for _____________________: -wall sections do not have to be uniform thicknesses -wall thickness will depend on the alloy used -warping and distortion needs to be considered when cooling -low cost wax injection tooling -non-permanent molds -moderate to high unit cost -little waste material -low - high production volume -very high quality finish -complex shapes with high integrity -range of steels -long cycle time (24 hours)
Investment Casting (Lost Wax)
Characteristics of _________________________: -heated above melting temperature and poured/injected into mold -most efficient metal forming process -minor need for machining/assembly -excellent for complex parts and a desired wall thickness with a minimum number of required secondary operations
Liquid State Forming (casting)
_______________________ process: metals are heated past melting point and poured into molds. Excellent for complex parts.
Liquid State Forming (casting)
Characteristics of ____________________: -a recent development that uses plastic injection molding equipment -metal powder is combined with a plastic binder material -after being ejected, product goes through sintering process which dissolves plastic binder -complex tooling comprised of many moving parts which increase tooling cost greatly -ideal for mass production -wide variety of texture/surface finishes can be incorporated into the mold
Metal Injection Molding (MIM)
Characteristics of _____________________: -primarily for ferrous alloys, some copper -reduce umber of components and subsequent finishing processes -provides intricate complex parts -thin wall (0.015 in.) -high part and tooling cost -required drafts = 0.25 degrees -limited size of part -weight = ounces - 30 pounds -medium to large production volume
Metal Injection Molding (MIM)
Design Considerations for ____________________: -little waste, but plastic binder can't be recycled -high tooling cost, moderate - low unit cost -high volume production, but can be low for some applications -very high quality surface finish -high level of density -rapid cycle time (30-60 seconds) -long de-binding and sintering process (2-3 days)
Metal Injection Molding (MIM)
Characteristics of _________________: -belongs to a branch of production that falls under the term "chip forming" (meaning any cutting technique that produces chips of material as a result of the cut) -used as a post-forming method, as a finishing method, and for adding secondary details to a part (like threads) -common methods include cutting, turning, boring, facing, drilling, reaming, milling, and broaching -very versatile in terms of producing different shapes -can be applied to virtually any solid material -high degree of accuract
Metal Machining
Design Considerations of ___________________: -can be a very slow and labor intensive process -parts can be restricted to stock sizes of material used -low material utilization due to wastage when cutting -low - moderate tooling cost, moderate - high unit cost -high material waste -low - medium production volume -high quality, hand made finish -aluminum and steel -moderate cycle time (depending on size and complexity of part)
Metal Machining
Characteristics of ____________________: -despite being an industrial process, this has retained elements of craft -used to form flat metal sheets into cylinders, cones and hemispheres -there can be a lot of post production processes -very adaptable process and for low production runs is inexpensive -ribs, undulations, and surface texture can be integrated into the process -can be used for meshes and perforated sheet metal
Metal Spinning
Design Considerations for _____________________: -limited to rotationally symmetrical parts -changing of tools can be labor intensive -post production (like heat treating) can increase costs -small - very large parts are possible: up to 2.5 meters in diameter and tolerances down to 1.5mm -low tooling cost, moderate unit cost -low energy, some waste -one-offs and low - medium production volume -surface finish is dependent on skill of operator and process speed -aluminum, mild steel, stainless steel, brass, copper, and titanium -moderate - rapid cycle time depending on size, complexity and material thickness of part
Metal Spinning
Characteristics of ________________: -rapid and precise for shallow profiles -tooling cost is HIGH so only high volume production -forming round, square and polygonal shapes is easy -ribs can be used to reduce wall thickness, weight and cost
Metal Stamping
Design Considerations for _________________: -carried out on a vertical axis, so undercuts must be produced in a secondary process -needs progressive work stations to increase part complexity -0.4mm - 2mm material only, 6mm possible but complexity must be greatly reduced -high tooling cost, low - moderate unit cost -all scrap can be recycled -high volume production -high quality and precise bends as a result of matched tooling -carbon steel, stainless steel, aluminum, magnesium, titanium, copper, brass and zinc -rapid cycle time (1 second - 1 minute)
Metal Stamping
Characteristics of ___________________: -controlled stretching and compressing of sheet metal -heavily used in the automotive and aerospace industry -used to produce the entire chassis and body work of cars -large curves are ideal for this method -any shape is possible -size is not restricted because parts can be joined later -great for detail that superforming can't achieve
Panel Beating
Design Considerations of ____________________: -high cost due to high skill level to produce good quality finish -material thickness is limited to 0.8mm - 6mm for aluminum and 0.8mm - 3mm for steel -low - moderate tooling cost, moderate - high unit cost -efficient use of material and energy -one-off - low production volumes -high quality hand made finish -steel, aluminum and magnesium -moderate cycle time (depending on size and complexity of part)
Panel Beating
Characteristics of ___________________: -used to create the mold void -in expendable molds, it is made of wax, wood, plastic, or metal -in non-expendable molds, the void is machined out of a solid block -is a likeness of the final product/cast part, but must be larger to account for shrinkage of metal casting during cooling *each alloy has a specific shrink rate... a skilled maker of these can give the designer valuable insights into the art of casting and should be consulted at the earliest stage during the design process
Patterns (positive)
Designers like Konstantin Grcic, Rose Lovegrove and Antonia Citterio utilize _________________ metal forming processes to produce many of their designs.
Plastic State
The objective of ______________ is not only to shape the metal but to control the grain structure so that the strength of the formed part is enhanced.
Plastic State Forming
_______________________ process: heat pre-shaped metals to allow them to be easily formed. Can be labor intensive.
Plastic State Forming
_______________________ process: layers of metal are built to form a complex and unique product. Very high equipment cost.
Rapid Prototyping
Characteristics of ___________________: -metal sheet forming process is used to produce "2D" continuous profiles with constant thickness -1.2m/second (72 mph) speed of process -holes and ridges are carried out simultaneously to reduce cycle time -tooling cost is minimal -standard and custom parts are possible -hollow tubes and box sections are seam welded -length are generally limited to 2m for ease of handling
Roll Forming
Design Considerations for _________________: -set up and changeover of tools can be expensive -bends can only be made in the line of production -depth of the cross-section will affect the tooling cost -width of profiles is commonly limited to 0.5m -high specialized tooling cost, low - moderate unit cost -efficient material/energy use -batch production of minimum 1500m -good part accuracy -stainless steel, carbon steel, galvanized steel, aluminum, zinc -very rapid cycle time but depends on complexity, long changeover time
Roll Forming
Characteristics of ___________________: -a manual process used to shape molten ferrous and non ferrous metals -relies on gravity to draw molten metal into the die cavity and so produces rough parts that have to be finished by abrasive blasting, machining or polishing -uses standard sand mixed with clay to form a green cast or with synthetic material to form dry casts
Sand Casting
Design Considerations for _______________________: -must consider draft angles, ribs, recesses, mold flow, and parting lines -wall thickness = 2.5mm - 130mm -must know the cooling rates of different metals to use this technique effectively -must consider all stages from pattern-making to finishing -low tooling cost, moderate unit cost -one-off - medium volume production volume -poor surface finish and high level of porosity -moderate cycle time
Sand Casting
Normally limited to sheet, rod and tube and usually done at room temperature, ___________________ forming can be labor intensive but requires low capital costs for tooling
Solid State
_______________________ process: bar/sheet/other solid piece of metal that's shaped at room temperature. Can be labor intensive but requires low capital costs for tooling.
Solid State Forming
Characteristics of ____________________: -aluminum magnesium (more recently), and titanium alloys can be used -components can undergo a range of post-forming operations to achieve the final desired part/assembly -can be used in large forms like aircrafts -all grades of aluminum can offer unique qualities when combined with this method of plastic state forming -4 types: cavity forming, bubble forming, back pressure forming, and diaphragm forming
Super Forming
Design Considerations for _____________________: -maximum size differs depending on technique used -excellent inherent structure quality -allows suitable mechanical properties for internal fittings such as kicking panels and light fittings -low - moderate tooling cost, moderate - high unit cost -scrap is recycled into new sheets of aluminum -low - medium volume production -very good surface finish -rapid cycle time (5-20 minutes)
Super Forming
Characteristics of _____________________: -long been utilized by designers and architects, because it is relatively inexpensive and reduces cutting and joining, thus minimizing waste and cost -tubular steel is very popular -mandrel bending is more versatile than ring rolling as a number of bends can be applied to a single length -mandrel bending can be relatively inexpensive, however ring rolling can have a high tooling cost
Tube Bending
Design Considerations for ____________________: -metal stretches better than it compresses -bend up to 80mm thick material but depends on the available tooling -minimum bend radius is about 50mm -too may bends may not be possible in a short part -ring rolling is limited to bending radii above 200mm -no cost for standard tooling: moderate - high cost for specialized tooling, low unit cost -high quality -little waste and efficient energy usage -one off - high volume production -steel, aluminum, copper, titanium -rapid cycle time (seconds to minutes) depending on number of operations
Tube Bending
What are the four major categories of metal forming?
liquid state, plastic state, solid state, and rapid prototyping