Plastic Injection Mold Calculations

Identification of Thermoplastics S.No

Name of Material

1

Polystyrene

2

Acrylic

Abbrevation

Relative Density

PS

1.05

Ease of Ignition

Whether self Character of extinguishing Flame Yellow Dense Readily burns No Black Smoke sooty Properties of Material

S.No

Name of Material

Density g/cm3

Bulk Factor

Specific Heat Heat Moulding Capacity Distortion Temperature Temperature J/KgoK

1

Polystyrene

1.05

1.9 - 2.15

90

200

1344

2

Acrylic

1.2

1.8-2

85

225

1470

Odour of burning

Behaviour of material

Oppressive Flowery

Melts and bubbles

Total Heat Content KJ/Kg 239.4 302.4.

Metal Industry Development Institute Product Design and Development Machine Specification S.No Category

1

Description

Size

Unit

Screw Diameter

22

mm

Shot Weight

29

gm

Shot Size

32

cm3

3008

kg/cm2

37

cm3/sec

Screw Stroke

85

mm

Plasticising Capacity

31

kg/hr

Screw Speed

0-440

rpm

Clamping Force

245.52

KN

Height

395

mm

Width

365

mm

1.73

Sec

17

Sec

Injection Injection Pressure Unit Injection Rate

Platen Size 2

Clamping Unit

General Dry Cycle Cycle Time

Material Properties S.No 1 2

Description Material Type Acrylic Density of mould

5

Mass of the component 5.05 (m) Projected area of the 2166.52 component Volume of the mold 3556.58

6

Surface Area

7

Elastic Modulus

8

Poisson's Ratio

9

Shear Modulus

10

Tensile Strength

11

Compressive Strength

12

Yield Strength

13

Thermal Expansion

14

Specifice Heat

15

Damping Ratio

3 4

Unit

gm mm2

Shot Capacity Shot Capacity of the machine 1

98

gm

Shot Weight Capacity with material B Material A

Polystyrene

Density of Material A Material A Bulk factor of A Shot Weight Capacity of material A Material B Material B Density of Material B Bulk factor of B Shot Weight Capacity of Material B Shot Weight capacity with material B 2

#DIV/0! Gram

Shot Capacity Swept Volume

32

cm3

Density of Plastic r

1.2

gm/cm3

C for amorphous plastics

0.93

C for crystalline plastic

0.35

Shot Capacity of the machine with the given material

35.712

gm

Plasticising Capacity Plasticising Capacity of the machine

Unit 31

Kg/h Kg/h

Plasticising Rate of material A (Polystyrene) Specific Heat Capacity of Polystyrene

J/KgoK

Specific Heat capacity of material

J/KgoK

Moulding Temperature of Polystyrene Moulding Temperature of material Total Heat Content Polystyrene

239.4

J/Kg

Total Heat Content Material

302.4

J/Kg

Plasticising Capacity of the machine with the given material

24.54167

Plasticising Rate of material Plasticising Rate Kg

Mass of moulding (m) Number of mouldings per hour Plasticising Rate

0

For maximum efficiency athe machine operated at 80 to 85% of the shot weight or plasticising capacity

Clamping Force Projecting area of moulding Injection Pressure Clamping Force

2166.52

mm2

63

MN/m2

136.49076

KN

Cycle Time 5.05

gm

Plasticising Capacity of the machine (P)

24.541667

Kg/h

Minimum cycle time attinable (tc)

0.740781

Sec

Mass of Shot (m)

S.No

Description

UNIT

Determination By Shot Capacity Based on 85% of rated shot capacity 1

Rated Shot capacity of the mateial (W)

35.712

gms

Mass of the component per cavity (M)

5.05

gms

Number of cavity based on shot capacity

6.010930693

Determination By Plasticising Capacity Based on 85% of rated Plasticising capacity Overall cycle time (TC) 2

17

Rated Plasticising Capacity (P)

24.54166667

Kg/hr

Mass of molding per cavity (m)

5.05

gm

Number of cavity based on Plasicising capacity

19.50644023

Determination By Clamping Capacity Based on 85% of rated Plasticising capacity 245.52

KN

Cavity Pressure (Pc)

63

Mpa

Projected area (Am)

2166.52

mm2

Rated clamping capacity C 3

Number of cavity based on clamping capacity 1.798803084

Number Of Cavities

Mass of components (g) 0.3 to 0.5

Factor 1.5

0.5 to 1

1.4

1 to 3

1.3

3 to 5

1.25

5 to 10

1.15

10 to 20

1.1

above 20

1.05