Thermoforming Vacuum Method is used to make Wall thick plastic sheet. The thermoplastic sheet metal is heated and to place mold cavity then remove vacuum to make require shape of mold. it is called vacuum forming process. The thickness of metal range of 0.025 mm to 6.5 mm. It metal placed over the open mold. Then the heat panel is placed above the sheet. The Mold process completed after the heater is removed and sheet is clamped over the mold. For high thickness sheet is heated in both side.The Vacuum forming mould material is used for product such as wood, thermosetting resin and plaster used.
Step by Step for Vacuum Forming Process:
(1) A flat plastic sheet is softened by heating (2) soften sheet is placed over the mold cavity (3) a vaccum draws the sheet into the cavity (4) after cooling and solidification, part is removed and subsequently trimmed
The vacuum is applied through vacuum hole for the mold. The vacuum mean release the air from the mold. Now the metal go to down into the mold and attain the mold. The mold part is removed after curing and clamp remove. In this method is negative forming the drawn depth which is 1/3 to 1/2 of maximum width. The wall thickness of comer consider for less than that of one close to clamp. It is not possible . so same shape produced by positive forming. In this stage male (Positive) mold is used.
The sheet is heated and placed over the male die and clamped on the mold. The vacuum is applied in between the mold and sheet metal. The sheet metal draws over the mold. In this method the material is better distribution and with deeper shape can be formed. In this method also called drape forming.
vacuum forming process another method :
Another method for the vacuum is applied to pressure box after male mold for heating stage. In this heated sheet is stretched by vacuum pressure into the mold shape. Now plastic sheet is forced together the positive mold drawn over it. The vacuum is applied to plastic sheet from mold and air pressure also applied through the pressure box.
In this positive forming and pressure is effectively applied into the sheet. which is improve the performance of quick produced the part and-also improve wall thickness of product. The infrared type heater is used to this forming. The uniform heat is applied on the sheet. so the forming process is uniformly together. The metal having low strong with atmospheric pressure carried out.
The following Vacuum forming mould material used for make plastic:
Some Vacuum forming mould material as follow,
- high and low density polythelene
- ABS(Acrylonutrile butadiene styrene)
The Main Vacuum Forming Advantages
- The Prototypes production quick and accurate
- High Production
- More Flexibility
- Cost Effectiveness
Important vacuum forming disadvantages
- Limit the shape
- not applicable for complicated shape
vacuum forming Example of Products