PET preform injection machine or injection molding is a process for producing parts in high volume, which is usually used in mass production processes, and in this process, a part is made thousands or even millions of times in a row.
The PET injection machine is used to produce all kinds of PET transparent plastic products, such as PET preforms, household and laboratory disposable containers, and other PET products.
What is PET?
Polyethylene terephthalate (PET) is also known as polyester. Currently, GF-PET is the most popular type among customers. The rheology of PET is very good in the melt state, while pressure has a greater effect on its viscosity than temperature. Therefore, it is mainly used to change the fluidity of PET melt.
Choosing a PET injection molding machine
PET has a very short shelf life after its high melting point. Therefore, an injection system with multi-stage temperature controller and less self-frictional heat generation during plasticization is required. The actual weight of the molded product (including recycled materials) cannot be less than 2/3 of the injection volume of the machine. Based on these requirements, Pars has developed small and medium-sized PET plasticizing systems in recent years, which are selected when the clamping force is higher than 6300 tons/square meter.
Mold design of preform PET injection machine
PET preforms are usually molded by hot runner molds. Therefore, the best thing is to design a thermal insulation between the mold and the machine plates, whose thickness should be about 12 mm to withstand the high pressure. Venting should be sufficient to prevent localized overheating or cracking, but vent depth usually does not exceed 0.03 mm.
Melt temperature
Measurable by various methods, usually between 270 and 295 °C. and 290-315℃ for reinforced GF-PET.
Injection speed of PET preform injection machine
Usually, the injection speed should be fast enough to avoid premature solidification during injection molding. But if it is too fast, the high cutting rate will make the material brittle. The injection is usually completed within 4 seconds.
back pressure
The less it is, the better to avoid wear. Usually the back pressure is not more than 100 bar, but in most cases it is unnecessary.
PET preform injection machine
1. High and efficient production
Once you develop the templates, the process is very fast, with cycle times as low as 10 seconds. This is great for medium to high volume production for anything from 10,000 pieces to over 100,000 depending on the molds you use.
Sometimes you can increase production by using a multi-part mold where multiple parts are produced in one cycle to increase the build rate.
2. Low cost per piece
For high output production, the cost per piece is very low. Even for medium volumes – in the range of 10,000 to 25,000 pieces – you can reduce costs by using aluminum molds instead of steel.
3. Reproducibility
You can produce the same products over and over again. This is ideal when you need parts with high tolerances and high reliability in high volumes.
4. Selection of large materials
There is a wide range of plastic materials to choose from depending on the properties you need from your final piece. And you’re not limited to plastic, Protolabs also offers liquid silicone rubber molding.
You can even use fillers in the molding material which adds more strength to the finished part and you also have a wide range of colors to choose from. Talk to us about what you need to get your share – there are generally different options.
5. Less waste
The molding process produces very little waste compared to many other manufacturing processes. Even if there is unused or waste plastic, you can recycle it for future use.
6. high details
This process involves injecting molten plastic into a mold under very high pressure. This presses the plastic hard against the molds, allowing for intricate and complex shapes as well as great detail.
7. Little or no misprocessing
In general, you need very little post-production, as pieces usually have a good post-production aesthetic. We can produce the tool with a special coating that shows immediately on the molded part. You can even engrave your logo or text on it.
Advantages of preform PET injection machine
The main advantage of the plastic injection machine or injection molding is the ability to produce on a mass scale. After paying the initial costs, the price per unit during the production of the injection mold is very low. With the production of more parts, the price also decreases drastically. Other advantages include the following:
Injection molding produces lower waste than traditional manufacturing processes such as CNC machining, which destroy a significant percentage of the original plastic block or sheet. However, it can be negative in cases like 3D printing where there is a lower scrap rate.
Note: Plastic waste resulting from injection molding production is usually obtained from four areas:
- Sprue
- Runners
- Entrance
Any overflow material that leaks out of the mold itself
sprue PET preform injection machine
It can be simply said that the sprue is a channel that directs the molten plastic from the nozzle of the injection molding machine to the entry point of the entire injection molding tool. This piece is separate from the mold tool itself.
Runner runners PET preform injection machine
A system of channels that meet the sprue, usually inside or as part of the mold tool, and direct the molten plastic into the part cavities within the mold tool. There are two main categories of runners (hot and cold).
The inlet valve of the PET preform injection machine
Finally, the inlet, which is the part of the channel after the runner that leads directly into the part cavity. After one injection cycle (usually only a few seconds) the entire molten plastic cools, leaving solid plastic in the sprues, runners, gates, part cavities, as well as some overflow potentially at the edges of the parts. if the sealing is not 100% correct).
By using thermoplastic materials, recyclable materials are reused. Sometimes even materials that fall on the factory floor. They mill the sprues/runners and any recycled parts. Then those materials are added back to the raw materials that go to the injection molding press. This material is called “regrind”.
All kinds of PET preforms including PET bottle preforms, hot bottle preforms, wide mouth glass preforms and 3-5 gallon bottle preforms can be produced with PET plastic injection machine.
PET preform plastic injection machine uses excellent system which can solve the problem of high vibration of mold unlocking and uneven operation, thus affecting the life of the machine and bringing optimal performance. Set an open and close template key. Mold opening is fast and smooth to reduce machine wear. Impact-free high-pressure clamp to extend the life of the device. The hydraulic system fully uses imported hydraulic components of famous brands, which improves the oil circuit by combining inserts and slide valves, and also effectively increases the system response speed and speed. PET shot weight range from 777g to 3350g machines to choose exactly what you need and other energy waste.
Clamping unit of preform PET injection machine
Increased stiffness and clamping force The connecting rod is one-piece and completely cast, so to ensure good strength and smooth movement, the post lock shaft remains fixed during opening and closing, thus reducing mold wear. Self-lubricating bushing is used. Remarkably, due to its specific wear resistance and low friction coefficient. Lift service increases the draw bar. Complete auxiliary solution for high speed PET injection molding system. (3 in 1 mold dehumidifier)
Injection unit of PET preform injection machine
A larger spiral designed for PET materials creates a large injection weight. The spiral L/D ratio is 24:1, which is better for plasticizing PET materials. Hydraulic motor with better winding ceramic heater for better energy saving PID temperature control for injection unit
Price and purchase of preform PET injection machine
The purchase price of preform PET injection machine is determined according to the features and options, including the most important feature of production speed and daily production rate of the product. Contact our experts 24 hours a day for information on prices and advice.