General Fiberglass sculpture consists of 2 layers of 300 felts + 3 layers of 0.4 cloth, and hand lay-up molding at one time. Bosong sculpture manufacturers can achieve 55% resin content and 3-3.5mm thickness when making molds in 11 layers. Layer, the thickness reaches 12–13mm, the resin is VE, is relatively thick, the resin content is in the range of 70%, there is a formula for this problem, but to join the level of the worker, and the process generally calculates 300 grams of felt sol thickness 0.5mm About 450 grams is about 0.8, and 800 grams of cloth thickness is 1.2-1.5mm.

The control of the thickness of Fiberglass sculpture and the number of layers is a technical problem that will be encountered in the design and production of hand lay-up process. When we know the required thickness of Fiberglass products, we need to calculate to determine the resin, filler content and Specification and number of layers of reinforcing material used.

Then calculate its approximate thickness according to the following formula.

t = (G1n1, ten G2n2 + …) × (0. 394 + 0. 909k1 + 0.4 x k1k2), in the formula: t — calculated thickness of glass fiber reinforced plastic products (mm); G1, G2 — glass fiber cloth or felt of various specifications Mass per unit area (kg / ㎡);

n1, n2 — layers of cloth or felt of various specifications;

0.394—thickness constant of fiber substrate;

0.909—thickness constant of polyester resin;

0.400—the thickness constant of the filler;

k1—the ratio of resin content to glass fiber content;

k2—the ratio of filler content to resin content.

Calculated from the above thickness constants:

1kg / m² glass fiber felt thickness is 2.341mm (70% of chopped felt absorption, resin k = 0.837)

The thickness of 1kg / m² glass fiber cloth after absorbing rubber is 1.228mm (the absorption of fiber cloth is 50%, and the resin k = 0.837)

The thickness of R800 glass fiber cloth is 0.9824mm

The thickness of R600 glass fiber cloth after absorption is 0.7368mm

The thickness of R400 glass fiber cloth after absorption is 0.4912mm

The thickness of R240 glass fiber cloth after absorption is 0.2947mm

The thickness of M450 chopped felt after suction is 1.0534mm

The thickness of M300 chopped felt after suction is 0.7023mm

The thickness of M30 surface felt is 0.07mm

Example: Find the thickness of the laminated glass fiber reinforced plastic sculpture from 1 layer of EM300 and 4 layers of EM600, filler (density 2.5g / cm³) and 60% unsaturated polyester resin (density 1.27g / cm³).

Solution: The mass ratio of resin to glass fiber felt is 70/30 = 2.33 (the absorption of chopped felt is 70%) The total weight per unit area of ​​glass fiber 1 × 0.3 + 4 × 0.6 = 2.7g / m² Glass fiber felt thickness 2.7 × 0.391 = 1.056mm resin thickness 2.7 × 2.33 × 0.837 = 5.265mm filler thickness 2.7 × 2.33 × 40/60 × 0.4 = 1.676mm (the ratio of filler and resin is 40/60) total thickness of the layer 1.056 + 5.265 + 1.676 = 8mm.

Calculation of Fiberglass Sculpture Layers
n = A / [mf (kf + c · kr)], where A is the total thickness of the product, mm; mf is the mass per unit area of ​​glass fiber, kg / m²;

kf is the thickness constant of the reinforcing material, [mm / (kg.m-2)], kr is the thickness constant of the resin, [mm / (kg.m-2)], C is the mass ratio of resin and reinforcing material, n Number of layers for reinforcement.

Example: Fiberglass products are made of 0.4mm medium-alkali gingham and unsaturated polyester resin (density is 1.3g / cm³), the glue content is 0.55, and the wall thickness is 10mm. Find the number of cloth layers.

Solution: Check the thickness constant table: kf = 0.408 kr = 0.769 Check: 0.4mm medium-alkali check cloth mf = 340g / m²

The mass ratio of resin to glass fiber felt is 55 / (100-55) = 1.222 n = A / [mf (kf + c · kr)] = 10 / [0.34 × (0.408 + 1.222 × 0.769)] = 22 layers
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