How to Calculate machine tonnage require for high pressure die casting Part?

Die Casting
Die Design

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Q: How to Calculate machine tonnage require high pressure die casting part?

Ans: -To Calculate machine tonnage for HPDC die casting part we need to follow three steps:

1.   Die clamping force

2.  Fill ratio

3. Mould size

Q. What is die clamping force?

Ans: -Die clamping force is the force applied to mold by a clamping unit of HPDC die casting machine. The clamping force must be greater than the separating force. Which caused by the injection of molten metal into the mold.

The clamping force >Separating Force 

Clamping Unit

Q. How to calculate the Separating force

(Opening Force)?  

Ans: -Opening force refers to the force acting on the cavity to make the die expand during the production of die casting. The opening force can be calculated by the following formula:

F=PXA

F: Opening Force

P: Specific Injection Pressure

A: Projected Area   

Q. Specific Injection Pressure?

Ans: -Molten metal is ladled through the shot hole into the cold chamber and the shot plunger pushes the metal into the die. The pressure applied by the plunger to push the metal into the die is specific Injection Pressure.

Injection pressure use for Different Type of Casting:

1.For Standard Casting =600 kg/cm2

2.For Technical Casting=600-800 kg/cm2

3.For Pressure Testing Casting=800 kg/cm2  

                     Specific Injection Pressure

 Q. Projected Area?

Ans: -The Projected area is two-dimensional area measurement of a three-dimensional object by projecting its shape on plane.

Total projected area=Casting Projected area + Slide Projected area + Runner projected area + Overflow projected area 

projected area 

Example

ü Casting projected area=56000 mm2

ü Overflow + Runner Projected Area=22400 mm2(40% of total casting projected area)

ü Slide Projected area=Projected area must be selected in the plane that is normal to be direction of core travel x tanø

Angel of wedge = The angle of Finger cam angle + 2̊

Force FY= F X TanФ

Ф= Angel of a wedge lock

Example:

Slide Core 1 Projected Area=Area normal to the direction of travel x tanФ=5000xTan20̊

                         =5000x0.36

                       =1800 mm2

Slide Core 2 Projected Area=4500xTan20̊=1620mm2

So,

Total Projected Area=56000+22400+1800+1620mm2

                               =81820 mm2

Q. Separating force (Opening Force)?

Ans: (For Technical Casting=600-800 kg/cm2)

        (800 Kg/cm2 =8kg/mm2)

Opening Force =Specific Pressure x Total Projected Area

             =8 Kg/mm2 X 81820 mm2

             =654560 kg/mm2(1 TON =1000Kg)

             =654.56 T

Q: Die clamping force?

Ans: -the clamping force must be grater then the separating force.

Locking force require =FX1.2

                                 =654.56X1.2

                                 =785.472 Tons

We select the 900T machine

Q. What is fill ratio, how it is important for selecting machine tonnage?

Ans: - It is the percent of molten metal in the cold chamber compared to the total volume of the cold chamber. Another way of saying it would be the percentage of metal compared to the percentage of air in the cold chamber

     For example, 50% full (of metal) = 50% air remaining

the percentage of fill is important because it is used to calculate the optimum slow shot velocity. This can have a quality impact on the casting.

Fill ratio (30-40%) is good for Automobile Die Casting Component quality.

How to get a fill ratio?

Fill Ratio = Shot Wt.  /  Sleeve Mass

Q How to get Shot Weight?

Ans: Shot Weight is The complete weight of shot in which casting, overflow, runner, a biscuit is included.

So,

Shot Weight= Casting Wt. + Overflow Wt. + Runner Wt. + Biscuit

For Example

Weight of the component = 2600 grams

Overflow Wt. + Runner Wt.=1040 grams (40% of Component Wt.)

Biscuit Wt. = πr 2 h

For Getting Biscuit Wt. we need to know what is plunger ø we are using.

For getting Plunger ø we need to follow Die Casting Machine manufacturers catalog.

We Select Med One Plunger Tip Diameter ø90

Q: Biscuit Wt.?

Ans:

h=Biscuit HT

For Example, is Normal Condition we consider biscuit thickens is 20mm

So, h=20mm

     r=45mm

     Density=2.75cm^3

     Volume=127170mm^3

     Biscuit Wt.=349717.5/1000g  (1cm^3=1000mm^3)

              =349.71g

Shot Weight= Casting Wt. + (Overflow Wt. + Runner Wt. )+ Biscuit

          =2600+1040+349.71

          =3989.71g   

Active Sleeve Length= (Plunger Stroke-Plunger Tip Protrusion)+Sprue Bush-Cone HT

Sprue Bush Length =250.5mm

Diffuser Corn HT=12mm

Plunger Tip Portrusion=350mm

Plunger Stroke=750mm

Active Sleeve Length=

(Plunger Stroke-Plunger Tip Protrusion )+Sprue Bush-Cone HT

=(750-350)+250.5-12

=638.5mm

Sleeve Volume = Plunger Area X Active Sleeve Length

               = 6361.72 X 638.5

               = 4061958.22mm^3

  Sleeve Mass =(4061958.22x2.7)/1000

             =10967.287gm

Mold size 

Note:
1. Mold and Cylinder Don’t lay to Tie Bar.

2. Mold height must be under between Min and Max die height of  HPDC Machine 

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