Knowledge about vacuum packaging

Knowledge about vacuum packaging

Vacuum forming is the process of heating, vacuum forming, and cooling resin sheets such as PVC, PS, PET, etc. in a vacuum forming machine to form them according to the shape of the mold.

Then, they are stamped into individual products on a punching machine using a knife die, and finally processed into packaging products through folding, punching, and other processes. This type of packaging product has the characteristics of cheap materials, simple process, low investment, and considerable profits.

It is suitable for packaging small daily necessities, small appliances, toys, and other goods, but not suitable for packaging products with high buffering requirements and heavy products.

Main production processes of vacuum molded products
The main production processes of vacuum molded products include molding, pulling, punching, folding, punching, packaging, etc. The following will introduce them separately.


1) Demolding
After the customer confirms the sample, the gypsum mold used for sampling is used as the mother mold, and after electroplating copper, the production mold is made according to a certain quantity and position, which is called the lifting mold.

There are three types of conventional molds: gypsum molds, copper molds, and aluminum molds. Gypsum molds are mainly used for sampling and cannot be used for mass production. Their production time is generally 24 hours. The copper mold is a gypsum mold electroplated with a layer of copper, which enhances strength and wear resistance, and is not expensive.

It is the most commonly used mold in production, with a general production cycle of 100 hours, at least 3 days, and a service life of about 100000 pieces. When the quantity reaches one million or more, aluminum molds can be made.

Aluminum molds are made of pure aluminum, which is costly and requires machining. Generally, the mold making time is 3 days. Aluminum molds have good production quality, fast heat dissipation, high product accuracy, and long service life. If customers require precise products and copper molds cannot meet the accuracy requirements, even if the quantity is small, aluminum molds must be made.


2) Pull tab
The vacuum forming machine heats, vacuum forms, and cools the raw material coils into predetermined sizes, which is the main process of vacuum forming. The length of the pull tab should be between 600 and 1170mm according to actual needs.

Different materials and thicknesses have different requirements for temperature regulation, requiring the start-up personnel to have considerable experience. The machine adjustment test for pulling sheets generally consists of three sheets. The length of each injection of the vacuum molding machine is called the pulling length, which can be determined based on the length of the mold.


3) Punch press
The products produced by pulling are usually multiple products (according to the number of molds arranged), which need to be punched into a single product using a knife die on a punching machine. This process is called a punching machine.


4) Folded edge
For some products that require folding the edges and corners of both or more sides of the vacuum molded product to insert paper cards, this process needs to be added. This process is completed by the folding machine.


5) Punching
If the customer has special requirements, this process should be added when punching on the blister.


6) Packaging
Attention must be paid to the packaging of vacuum molded products, and the appropriate packaging method should be determined based on the severity of customer requirements, product materials, shape, etc.

If there are no special requirements from the customer, they can be packed in boxes or plastic bags. For products that are white or have bright colors, are prone to rubbing or cannot stick dust or fingerprints, gloves are often worn during production.

Vacuum forming materials
The commonly used vacuum molding materials include PVC (about 50%, density 1.36g/cm3), PS (about 30%, density 1.06g/cm3), and PET

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