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Thermoforming Questions and Answers – Solutions to the Problem of Vacuum in the Process of Vacuum

Thermoforming Vacuum Forming Knowledge: Thermoforming Processing of sheet problems Are you solving?

Problems and Solutions of Sheet in Hot Forming

1. Bubble or bubble

① heating temperature is too high, should be appropriate to reduce the temperature;

② heating speed is too fast, should be appropriate to slow down the heating rate;

③ sheet distance heater too close, should be appropriate to increase the spacing between the two;

④ sheet damp, the sheet should be pre-drying or preheating treatment, sheet moisture-proof packaging should be opened at the processing site;

⑤ sheet heat uneven, the application of thermal shielding network to adjust the surface of the sheet heated state, so that all parts of the heat;

⑥ sheet type or formula is unreasonable, should replace the other types of sheet or adjust the formula.

2. Pre-stretched foam is not homogeneous

① sheet heat is not uniform, should be slow heating or set the thermal shielding network;

② sheet thickness is uneven, should be replaced with thick and thin sheet;

③ air pressure distribution is not uniform, should be homogenized air, so that uniform pressure distribution.

3. Fold or fall

① heater temperature is too high, should be appropriate to reduce the heater temperature;

② heating speed is too fast, should be appropriate or slow down the heating rate;

③ sheet distance heater too close, should be appropriate to increase the spacing between the two;

④ sheet heating time is too long, should be appropriate to shorten the heating time;

⑤ processing of raw materials, high melt index, the melt strength is too low, the sheet thermoforming after the hot sagging, should replace the lower melt index resin processing sheet;

⑥ sheet orientation is too small, the sheet is too hot after sagging, should be replaced with high degree of flexibility of the sheet, the heating temperature is best controlled in the minimum molding temperature range of the sheet;

⑦ forming area of ​​the drawing ratio is too large, should use the plunger pressure, or appropriate to improve the pressure, plunger or mold moving speed;

⑧ mold structure design is unreasonable, should modify the mold structure design: First, replace the male mold with a negative mold; the second is to maximize the sharp and fillet radius of the product; third is to redesign the mine and booster.

4. The molding is not complete or the surface pattern is not clear

① sheet heating time is too short or the heater temperature is too low, should be appropriate to extend the heating time or improve the heating tube temperature;

② heater heating power is too small, should be appropriate to increase the heater heating power;

③ sheet heat uneven, forming defects are always repeated in the same place, the application of thermal shielding mesh to adjust the heating state of the sheet, so that all parts of the heat;

④ before the clip before the clip is not preheated, clip should be preheated before the holder;

⑤ vacuum hole block, vacuum is low, should clear and clear the vacuum hole;

⑥ too few the number of holes or pore size is too small, the vacuum is low, should be appropriate to increase the vacuum hole or increase the vacuum hole diameter, if possible, can be used instead of vacuum slot narrow hole;

⑦ vacuum tank or vacuum pump capacity is too small, vacuum traction is not enough, should be appropriate to increase the vacuum tank or vacuum pump capacity, increase the vacuum pipe valve, in the three links and bend to avoid sharp bend;

⑧ pressure forming pressure is insufficient, should be in the mold structure conditions permit, the use of 137 – 206Pa pressure, can also use the frame booster or plunger pressure.

5. Charred

① sheet heating time is too long, the sheet surface is too hot, should be appropriate to shorten the heating time;

② heater power is too large, the heater temperature is too high, heating speed is too fast, should be appropriate to reduce the heater temperature, slow down the heating rate.

6. White

① sheet in the low temperature of the process conditions were cold draft. The sheet temperature should be increased. Speed ​​up coverage and evacuation;

② the use of the sheet is dry coloring. Replace the appropriate sheet. Or use a hot air gun to blow hot air at the white to reduce or eliminate the white surface of the sheet.

7. cold spot

① help the plunger temperature is too low, should be appropriate to increase the pressure of the plunger

② mold is too low, and cold mold or cold plunger contact with the sheet can not be traction, should be appropriate to increase the mold temperature;

③ mold cooling system design properly, should be appropriate to increase the cooling pipe or cooling tank, check the cooling water flow or not;

④ sheet temperature is too high, should be appropriate to reduce the heating temperature, slow heating, can be used before the molding of compressed air slightly cooling the surface of the heated sheet.

                                          – For more information, please pay attention; thermoforming equipment, welcome to consult!


Post time: Sep-18-2017
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