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How to Calculate Twintex Roving Pultrusion

Protrusion is the process of making reinforced plastic shapes in a heated die. The amount of roving packages needed for glass fiber composites in the production of laminate parts can be determined by performing a mathematical calculation. To do this, you need to first obtain your variables that include glass yield, the specific gravity of the laminate part and the weight of water. Once you have all of the variables, you can then calculate the amount of Twintex roving you will need.

Instructions

- 1
  Determine the cross-section area for the part. If the part is cylindrical, multiply 3.14 by the radius and by the radius again (3.14 x radius x radius). If the part measures 0.5 inches in diameter, then the cross-section area will be 3.14 x .05 x .05 = 0.785 square inches.
- 2
  Find the specific gravity of the laminate part. Specific gravity is the density of the material compared to the density of fresh water at a temperature of 39 degrees Fahrenheit. Density of water at this temperature is 1 g/ml. If the density of the laminate part is 1.95 kg, then the equation for specific gravity is 1950/1000 = 1.95.
- 3
  Determine the glass yield for the laminate part. If the part weighs 113 yd./lb., then the equation used is expressed as: 1/113 yd./lb. x 3 ft./yd. This gives you a result of 0.00265.
- 4
  Multiply the cross-section area by 12 inches per foot x 1.95 for the weight of water. This equation will be: 0.785 x 12 in./ft. x 1.95 x 0.0361 lb./in. cubed. This will give you a weight of 0.663 lb./ft.
- 5
  Multiply 0.663 by 70 percent (0.70). This gives you a result of 0.464 lb./ft.
- 6
  Write out the equation used to determine the roving count. This equation is expressed as: roving count = 0.464/0.00265. The result will be 175.

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