REAL CASE SCENARIO

REAL CASE SCENARIOTEAM KARTIIT KHARAGPUROBJECTIVETo propose a suitableMANUFACTURING PROCESSMATERIALto reduce the cost of K-2s uprights without significant design changes for an annual volume of 25,000 vehicles.

SPECIFICATION OF UPRIGHTS

FRONT UPRIGHT

REAR UPRIGHTSCURRENT DESIGN OF THE UPRIGHTS The method employed by us in manufacturing the uprights was CNC machining.

The cost per car was $ 333.91Therefore, cost for 25,000 cars is $ 8,347,750SELECTION CRITERIA FOR MANUFACTURING PROCESS 1 Cost of process 2 Material selection 3 Lead time of process 4 Reliability of the productPossible ProcessesAfter considering many processes we arrived at the five most appropriate for the manufacturing of our uprights. They were:

Sand CastingCNC MachiningWire EDMForgingDie Casting

The viability of each process is discussed in detail below:Comparison between different processPROCESSINITIAL CAPITAL INVESTMENTSURFACE FINISHSTRENGTHLEAD TIMEScale of productionSand castinglowlowLowhighsmallCNC machininghighhighhighlowlargeWire EDMhighhighhighhighsmallDie castinghighmediummediumlowlargeforginghighhighhighlowlargeTherefore, we are left with two best process for manufacturingPARAMETERSDIE CASTINGFORGINGProduction errorsHas some metallurgical defectsno defectsChange in homogeneityTight control of heating and cooling requiredno changeLongevity of dies. lowerhigherstrengthmediumhighComplexity of diesCan be complexCannot be very complexOperating costlowerhigherStrength and surface finish of forged product is higher than that of a die casted product.Operating costs for die casting are lower than forging.Considering the advantages and disadvantages of both the processes, we select die casting since the drop in strength and surface finish is more than compensated by the lower operating cost of die casting process.PROCESS SELECTED- DIE CASTINGDie casting processAfter deciding upon the die-casting process there are several decisions to be madeChoice of upright material and die casting equipmentChoice of number of dies and die material Die Design (Orientation and Cores)Post casting processes

CHOICE OF UPRIGHT MATERIAL AND DIE CASTING EQUIPMENT

Non-ferrous alloys, like those of aluminium, copper, magnesium and zinc are generally used in die-casting. Since our priorities are low cost and structural integrity rather than weight, Aluminium is the obvious choice.

High melting point metals like aluminium use cold chamber die casting method.Al seriesStrength(ksi)Corrosion resistanceHeat treatable2XXX27 to 62poor Yes 3XXX16 to 41goodNo 4XXX25 to 55mediumSome alloys are heat treatable and others aren't5XXX18 to 51goodNo 6XXX18 to 58 goodYes 7XXX32 to 88poorYes THEREFORE , MOST SUITABLE MATERIAL ALUMINIUM 6 SERIES (6061)CHOICE OF DIE MATERIAL

AISI H13 hot work steel is an excellent die material for Aluminium die casting. H13 is produced from vacuum degassed tool steel ingots. This manufacturing practice plus carefully controlled hot working provides optimum uniformity, consistent reponse to heat treatment, and long service lifeThe maximum service life for dies in aluminium die casting is around 100,000 cycles which is well above the required 25,000 cycles.

NUMBER OF DIES

Cycle time for die casting is typically very short, ranging from a few seconds to a minute.

Taking the upper limit of cycle time, the total time required to manufacture 25,000 units of one upright is a mere 416 hours and 40 minutes.

Since time is no constraint, we only need one set of dies per upright.Die DesignDesign features

Two runnersMultiple water channels for uniform coolingThin zigzag air vents (2mm wide and 0.2 mm high) (only allows air to pass)Draft allowance in cover is more than in ejectorEjector pad with 5 ejector pins

We designed the die in a way that no cores are require, hence eliminating their cost.

Post casting ProcessesMACHINING - machining is required for getting smooth surface finish of wheel hub mounts and brake calliper mounts of uprights after die casting process .

DRILLING- drilling is required for making holes for A arm mounts, brake calliper mounts and tie rod mounts.

CUTTING- cutting is required for the removal of extra metal that is left after die casting process as runners.

TAPPING- tapping is required to create screw threads in the holes drilled.

RATEPER CARTOTALMass of front upright1.39 kg per uprignt2.78 kg 69500 kgMass of rear upright2.90 kg per upright5.80 kg145000 kgTotal mass of uprights per car 8.58 kg214500 kgAdditional mass for machining allowances 10%0.858 kg21450 Total mass of uprights 9.438 kg235,950 kgCost of 6061 Aluminium $ 0.2921 per kg $ 2.757$ 68,921 cost for die casting process$ 4 per kg$ 37.752$ 943,800Total volume to be machine 13.105 cm352.42 cm31310500 cm3Cost of machining$ 0.04 per cm3$ 2.0968 $ 52420 holes8 per upright32800000Cost of Drilling $ 0.35 per hole$ 11.2$ 280000cost of tapping$ 0.35 per hole$ 11.2$ 280000Length to be cut 4.8 cm per upright19.2 cm480 mCost of cutting$0.10 per cm$ 1.92$ 48000Cost of dies$ 20000 per die$ 80,000Total cost$ 17.5314 per upright$ 70.1256$ 1753141Cost CalculationCONCLUSIONManufacturing process-die castingMaterial to be used aluminium 6 series (6061)Total cost when CNC machining was employed$ 8,347,750Total estimated cost for the manufacturing of uprights using die casting process $ 1,753,141 Total cost per upright (CNC MACHINING)$83.47Total cost per upright(DIE CASTING)$ 17.5314 Reduction in cost $8,347,750 - $ 1,753,141 = $ 6,594,609THANK YOU