HISTORY• Deep drawing is one ofthe most important andwidely used metal forming• This process firstdeveloped in the 1700sconsequently has beenstudied extensively untilhas become an importantmetalworking process.
DEFINITION• “Deep drawing is the manufacturingprocess of forming sheet metal stockcalled blanks, into geometrical shapes.”• Common shapes for deep drawn productsinclude cylinders for aluminium cans andcups for baking pans. Irregular items,such as enclosure covers for truck oilfilters and fire extinguishers, are alsocommonly manufactured by the deepdrawing method.
MECHANICS OF DRAWING• A blank diameter D is drawn into die by meansof a punch of diameter .The punch and die haveradii R. The sides of punch and die separated byclearance. Which is about 10% greater than thesheet thickness. The punch applies a downwardforce F to deform the material. While thedownward holding force is applied by blankholder.
PROCESS• A round blank is first cut from flat stock .Theblank is placed in the draw die, when pushes theblank through the die on the return stroke thecup is stripped from the punch by the counter-bore in the die .The tope edge of the shellexpands slightly in order to make this possible .The punch has an air vent to prevent a vacuumfrom being formed when the part is strippedfrom the punch.
DEEP DRAWING STATIONTYPES• BLANKING• DRAWING• PIERCING• TRIMMING
BlankingBlanking is the process ofcutting the initial sheet coil stockinto round or shaped flatsrequired for deep drawing.
DRAWING• Drawing is the process offorming the metal with apunch and die, and is the heartof the deep drawing process.
PIERCING• Piercing is the process ofpunching holes in the metalstock that are required for thefinished part.
DETAIL• During the first stage of process thepunch contact the blanks .This sectionforms the flat bottom of the cup and isnot distorted by the punch.• Upon further penetration of the punch themetal is bent or wrapped around thepunch nose and die radius.
TOOL MATERIAL• Punches and dies are typically madeof tool steel, however carbon steel ischeaper, but not as hard and istherefore used in less severeapplications, it is also common to seecemented carbides used where highwear and abrasive resistance ispresent..
EXPLINATIONLubricants are used to reduce frictionbetween the working material and thepunch and die. They also used forremoving the part from the punch. Someexamples of lubricants used in drawingoperations are heavy-duty emulsions,phosphates, white lead, and wax films
RECOMMENDED METALSDeep drawing applications also benefit from the wideamount of metals that can efficiently be subjected to theprocess. The following metals are currently used tomanufacture products through deep drawingAlloyAluminumBrassBronzeCold rolled steelCopperInvarIronKovarMolybdenumNickelSilverStainless steelTungsten
WRINKLES• Wrinkles - caused due toexcessive clearance betweenthe punch and die. Also causeddue to improper pressure padpressure and die and punchradius.
RUPTURES• Ruptures - caused byincorrect draw ratio anotherreason is improper die andpunch radius.
EXCESS THINNINGExcess thinning- of the cup wallcaused by incorrect die andpunch clearance and radii andalso excessive pressure bypressure pad.
ADVANTAGES• Tool construction costs are lower in comparison tosimilar manufacturing processes.• The technique is ideal for products that requiresignificant strength and minimal weight.• The process is also recommended for productgeometries that are unachievable through othermanufacturing techniques.• Deep drawing is especially beneficial whenproducing high volumes, since unit cost decreasesconsiderably as unit count increases
DISADVANTAGES• Material thickness has a large effect onprocessing price.• Special sleeves required to assist in driving theparts into the dies.• This process is costly for low production rate.
COMPARISONDEEP DRAWING• Deep drawing is themanufacturing process offorming sheet metal stock,called blanks, into geometricalshapes.• Only used for limited diedesign.• It can be suffer from springback.• No Preheating required,process done at room temp.SUPERPLASTICFORMING• Super plastic forming is used toelongate the material beyond100% of it length.• It can also be only used forlimited die design.• It does not suffer from springback.• Preheating required before thesuper-plastic forming.
COMPARISON• Suitable for massproduction.• Low productioncost.• Several steps arerequired for deepdrawing.• Low labour cost.• Also suitable formass production.• High productioncost.• It is also a one stepprocess.• Low labour cost.
APPLICATIONS IN PAKISTANINDUSTRY1. PAKISTAN ENGINEERING CO. LTD(LAHORE)Concrete Mixers; Storage Tanks For Oils
APPLICATIONS IN PAKISTANINDUSTRY2. SINGER PAKISTAN LTD (KARACHI)Washing Machine ; Gas Appliances;Refrigerator; Deep Freezer
APPLICATIONS IN PAKISTANINDUSTRY3-LIBRA ENGINEERING (KARACHI)Deep Drawn Components, Sheet MetalComponents.
Why Do We Need Metal FormingTools?Metal forming tools are important for anyproject that involves metal. You certainly cantbend or form a heavy duty steel plate to tightrequirements by hand; you need a machine thatis powered by more than just elbow grease.Common business that need metal shaping toolsinclude car production plants, airplanemanufacturers, and small businesses that deal iniron works and metal fencing.
TYPES• WHEELING MACHINE• AIR POWER HAMMER• SHRINKER STRETCHER• BEAD FORMING MACHINE• TUBE FORMING MACHINE• FORMING DIES
WHEELING MACHINEThe Wheeling Machine, also called anEnglish Wheel, is a popular type of metalforming tool that is used to create doublecurves in metal. The user puts a flat metalsheet (usually aluminium or mild steel)through this C-shaped machine to geteven curves. These machines are usuallyused for the curving elements of cars,boats, and other complicated machinery.
AIR POWER HAMMERAn air power hammer is a tool that hasreplaced the need to use a handheldhammer for blacksmithing projects. Thismetal forming tool uses a powerful forceto bend even the toughest metals intodesired shapes. Shaping is done bymodifying the condition of the metal (suchas stretching it out first) and then turningit into another form.
SHRINKER STRETCHER• Another metal forming tool is the ShrinkerStretcher tool. These machines are built tostretch or shrink various types of metal,usually mild steel. A special adapter, called a"jaw" is required for this type of machine.The Shrinker Stretcher is air-powered andeasily switched from a shrinking setting to astretching setting with a simple change ofthe jaw.
BEAD FORMINGMACHINE• Uniform beads are small circular pieces ofmetal that have been smoothed around theedges. Metal beads could be used for jewelleryor as components in major machinery. Thebeads are formed when the two interlockingpieces slide against each other continuously.
TUBE FORMING MACHINE• Tube forming machines refer to various types ofequipment that are used in order to form tubing, which isthe process of altering tubing into complex shapes. Atube is defined as a long and thin hollow cylinder that ismost commonly used to either convey a fluid or gas, or tofunction as a passage. As a result, tube forming machinesare generally either dedicated machines or automatedmanufacturing cells. Some examples of applications andindustries that utilize tube forming machinery include:marine, for use in exhaust products, heat exchangers,piping systems and more;
DRUM MAKING MACHINE• Horizontal drum making machine iscomplete line machine includes cutting,welding, forming, seaming, steel drumbody production line and painting line.The whole equipment is automatic,controlled by programming controller.The feeding and transporting devices aredriven by hydraulic system
FORMING DIES• It is sometimes difficult to distinguishbetween a bending and forming dies . aforming operation is generally along curvedaxes rather than a straight axes.• Forming operations may strengthened thework piece and add rigidity.• The particular type of forming operationsare classified in group.
TYPES OF FORMING DIES• Solid form Dies• Pad-type Dies• Curling Dies• Embossing Dies• Coining Dies• Bulging Dies• Assembly Dies
SOLID FORM DIES• Solid form dies generally consist ofa male and female die shaped tocontour of work piece. This typeof tooling is generally used forforming operation in progressivedies.
CURLING DIES• A curling die rolls a raw edge of sheetmetal into a roll .The purpose is tostrengthen the raw edge provide aprotective edge and improve theappearance of the product .A lubricantshould be used during curling operation.
EMBOSSING DIES• Embossing is a shallow formingoperation in which the work piecematerial is stretched over a maledie and caused to conform to themale die surface by a matingfemale die surface .
BULGING DIES• Bulging is an internal formingoperation used to expand portionof a drawn shell or tube. Theforming force is applied frominside the work piece and istransmitted through a mediumthat will flow and not compress.
ASSEMBLY DIES• In this type of dies are used for assemblingtwo or more parts held in position and thenlocked in position by riveting staking crimpingor press fitting. The operator may bephysically place the parts in position in die. Alarge quantity of parts may justify a morecomplicated die that would automaticallyassemble the parts in the die while being froma hoper.