What is vacuum forming? Learn all stages
Vacuum forming is popular as a subtype of thermoforming and is one of the oldest and most common methods for processing plastic materials to produce different plastic products such as dc fan mold.
Vacuum-formed products are everywhere around us and play an important role in our daily life.
What is the process of vacuum forming?
The process involves heating a plastic sheet to an elastic state and then applying it to a mold. The vacuum is common to use to pull the resin sheet into the forming tool. Then the sheet is removed from the mold.
Modern equipment provides a high speed of the production process and makes it possible to manufacture products of complex design and high-quality shape.
For vacuum forming, almost all thermoplastic blanks come in sheet form. The most commonly used materials are listed below.
Typically used materials in vacuum forming
Here is a list of the most common materials for producing plastic products as well as dc fan molding.
- Acrylonitrile Butadiene Styrene ABS
- Polyester Copolymer PETG
- Polystyrene PS
- PC polycarbonate
- Polypropylene PP
- Polyethylene (sheet and foam sheet) PE
- Polyvinyl chloride PVC
- Acrylic PMMA
Typical vacuum formed products
- Bathtubs and shower trays
- Pots
- Skiing
- Similarly, Boats
- Car equipment
- Door trims for cars
- Moreover, Refrigerator shelves and plastic parts
- Sandwich boxes
- In addition, Parts of car cabins
- Exterior elements of shops
Features of the use of vacuum forming and limitations
Advantages of vacuum forming
Vacuum forming has a number of technological advantages in comparison with other types of polymer forming. The use of low pressure in this process provides a relatively low cost of tooling equipment.
It is an ideal process to produce dc fan mold using a low-pressure technique. Also, the low pressure allows you to make quality products from inexpensive materials. The working cycle is rather short.
Another big plus feature
Unlike other thermoplastic forming processes that use polymer raw materials in the form of resins or powders, vacuum forming works with extruded polymer sheets. After a full cycle of vacuum forming, there are usually elements on the product that require cutting.
But after a specific cutting process, manufacturers get high-quality products just like dc fan molding.
Recycled thermoplastic waste is easy to reuse, which is also a huge plus.
Different stages of vacuum forming - dc fan mold
Heaters for plastic sheets in vacuum forming
Typically, infrared heating elements with an aluminum baffle plate are good to use for vacuum forming thermoplastics. Regardless of the type of thermoplastic, the main condition for the manufacture of high-quality parts (dc fan molding) is uniform heating of the sheet over its entire area and thickness.
To achieve this, all heated zones must be equipped with temperature controllers and regulators. Despite the high quality of ceramic infrared heaters, they have one drawback - a high thermal mass affects the heating element for a long time (about 15 minutes). It also affects a slower response when changing the heater power settings.
Quartz heaters
Quartz heaters are increasingly used for vacuum forming. Some manufacturers immediately equip equipment with these heating elements. Quartz infrared heaters have less thermal mass, so the response time takes a few seconds.
Pyrometers provide precise control of the heating temperature by measuring the melting point of the sheet and interacting with the control of work processes. It greatly helps to get precise quality dc fan molding.
Accurate temperature readings are also available with a computer-controlled system working in unison with pyrometers.
Why dual heaters are recommended?
Dual heaters are recommended for processing thick resin sheets. They provide a more even temperature distribution and speed up the production cycle. Dual quartz heaters are useful when molding high-temperature materials with critical molding temperatures.
Automatic adjustment of thermoplastic level (not available on all vacuum forming machines)
An auto-adjusting sheet level option is available thanks to a built-in photoelectric beam device that scans the distance between the bottom heater and the plastic sheet.
If the plastic sheet sags, then a small amount of air injects into the lower chamber. Thus, the sheet lifts. And it really helps to get a good product of dc fan molding.
Pre-stretch function (not available on all machines)
Once the plastic has reached its molding temperature or elastic state, we can pre-stretch to provide a uniform wall thickness when the vacuum supplies. The method for controlling bubble height is to get consistent results.
Vacuum, air pressure, and auxiliary plug are common to use to facilitate molding of the heated, stretched plastic.
Auxiliary function for pushing the sheet into the mold (not available on all machines)
Vacuum forming with this function is common to use when direct vacuum forming does not allow the thermoplastic sheet to be evenly distributed over all areas of the mold.
To spread the sheet more evenly, a plow-like device is common to use to push the sheet into a mold before a vacuum is created. This process allows more thermoplastic material to reach the bottom of the mold, thus the thermoplastic completely fills all corners of the mold without the risk of thinning the plastic.
It allows you to produce a dc fan molding without any fault.
Cooling and venting (not available on all machines)
A liquid spray option is also available, which resembles a fog, in which nozzles comes to the fans and a fine mist of chilled water is directed onto the sheet.
Combined with fans, this mist can speed up the cooling cycle by up to 30%. The presence of temperature control units, regulate the temperature inside the mold, provide an accurate and constant cooling time when cooling crystallizing polymers such as PP, HDPE, and PET.
Trimming and finishing - dc fan mold
After the formed part has cooled down and removed from the machine, excess material removes. And only then holes and gaps are drilled into the product. Other postforming processes include finishing, printing, strengthening, reinforcement, and assembly.
Various trimming methods are common to use to remove excess material from the finished product such as dc fan molding. The cutting method depends on the type of equipment, the size of the part made, the stretch ratio and the thickness of the material.
Fine gauge parts are usually cut on a mechanical nip press, also called a roller press.
Final words
After all the work is easy to do, the part made by vacuum forming goes completely finished and easy to use for its intended purpose.
We invite you to see an illustration of the vacuum forming process.
