Question

Thermoforming A process of pulling down a heated plastic sheet onto a mold and then forcing the plastic toward the mold walls by vacuum, air pressure, or mechanical pressure. Advantages cost of equipment, tooling, and molds are low it is not a complex forming method material costs are relatively low can produce very large parts - Disadvantages output rate is low and cycle time is higlh - dimensional accuracy is only fair - products will tend to have thinning in corners large amount of scrap waste is possible Thermoforming Homework: Type a one paragraph summary of the thermoforming process → Locate five products examples of thermoforming. Cut and paste each picture below the summary.

Answer 1

Thermoforming is a process for forming thermoplastic sheets or films over a mold through the application of heat and pressure.In this process, a sheet is clamped and heated to the glass transition temperature,T_g,of the polymer and forced against the mold surfaces through the application of vacuum or air pressure.Because of low strength of materials formed,pressure difference caused by the vacuum is sufficient for forming.However thicker and more complex parts need air pressure, which may range from 100 to 2000 kPa,depending on the type of material and thickness of the sheet.The sheets used in thermoforming are available as a coiled strip or as lengths and widths of various sizes.Molds for Thermoforming are made up of aluminum because high strength is not required and tooling is relatively inexpensive.Typical parts made by thermoforming are packaging,trays for cookies and candy,advertising signs and panels for shower stalls.Usually the production rate is very high for thermoforming process due to the simple manufacturing process.However products with holes or openings cannot be formed because pressure difference cannot be maintained during the forming.Because thermoforming is a combination of drawing and stretching operations materials should exhibit high,uniform elongation.Usual defects encountered in thermoforming include (a) non uniform wall thickness (b) tearing of sheet during forming (c) improper filled molds and (d) lack of surface details.

  
YOGURT LIGH &FIT DANNON IGHT FIT YANILLA VANILLo
    

INIECTION USP 0.9% 0.308 milliosmols per m