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How to select best plastic injection molding machine?

2021/12/16 By hqt

plastic injection molding machine

What are the main features of Toggle Injection Molding Machine

Here are some examples taking into account the basic requirements. Certain models of plastic injection molding machine may have their own characteristics that are unique to a given product.  It may tilt the customer’s choice in their favor. When working with a schematic diagram, you must adhere to the following parameters.

plastic injection molding machine

The distance between the columns uniquely determines the geometric parameters of the shapes used. Before assembling the entire system, it is required to check how compatible the molds are with the selected injection molding machine model.

 Inconsistency leads to the impossibility of mutual pairing and work in general. The width and height of the mold must be less than the distances at which the columns are located. It is also necessary to take into account that there must be compliance with:

  • the size of the plate
  • the opening parameters
  • and also the column part must withstand the mass of the replaceable mold together with the processed plastic

Typically, injection molding machine manufacturers recommend certain indicators, therefore, when buying; it is advisable to require instructions from the seller, at least partially.

What is the ideal size for plastic injection molding machine?

When accounting for this indicator, there is no big trick. For example: you have an injection molding machine with 520×520 plates, with a distance between the columns 420×420.

For this plastic injection molding machine, a mold is suitable not only up to 400×400, but also 400×520, that is, so that it passes between the columns on one side and does not go beyond the plate on the other side.

Thus, you can fit the mold with a large number of places, and therefore, increase productivity and reduce the cost of the final product.

For such solutions, for example, the manufacturer of injection molding machines Top Star Machine has a special TM Series Toggle Injection Molding Machine series with non-standard plates.

Estimated clamping force of the plastic injection molding machine

This indicator is strictly predetermined for each type of plastic mass. The appearance of cracks and adhesions, as well as colored parts will have an uneven color with streaks, spots and stripes.

Therefore, it is necessary to use a strictly defined value developed by the clamping force. This figure is so important that manufacturers often enter it in the markings of the brand, model or modification of a particular plastic injection molding machine.

What are the mechanical locking devices?

After the injection of the polymer mass into the mold under enormous pressure, a counter resistance force arises, trying to separate the component parts. Mechanical locking devices are often based on crank-link mechanisms to achieve the required performance for each injection molding machine.

What do you know about the calculation?

The calculation is not difficult. Similarly, it depends on the product itself and the brand of the base polymer used for its casting. In the initial version, without corrections and coefficients, you can approximately calculate this value.

It is in order to understand how suitable this or that model of plastic injection molding machine for your purposes. You need to multiply the following numbers to get the desired result.

What is the locking force of TPA?

The locking force of the TPA, it is usually prescribed in the passport or product modification.

The pressure of the melt on the walls of the mold:

 You can find these numbers in the reference book of polymeric materials. But it is necessary to do this strictly according to the brand. Otherwise, under the same name, substances that are completely different in properties are often found.

Product projection area:

It must be calculated with a high degree of accuracy, because this is the fundamental factor. The calculation must be carried out in the SI system, that is, the area must be calculated in square meters.

The number of seats (cavities) for a specific mold:

We can calculate the calculated area solely by the geometric parameters of the finished product, without unnecessary amendments, which will only complicate the calculations.

For most commercial plastics of common brands, the pressure is no more than 300-400 kg per cm2. High rates are characteristic only of specialized materials with fillers or reinforcement.

Most plastic injection molding machines have long come to the canonical indicator of the clamping force relative to the injection pressure. Usually, the first digit is about 1.17-1.25 times larger than the second. If the number you received lies in this range, then this already means that everything is calculated correctly.

Calculated injection force of plastic mass

Shaping is carried out in a cavity, and the product always has a certain geometric shape and mass, in determining by preliminary calculations. Now a large number of injection molding machines are supplied complete with injection units, but there is always the possibility of compatibility with products from other manufacturers.

 This allows assembling systems that strictly meet the technological requirements for the production of a certain type of parts. If selected without calculations, then the volume of the part should be 1.25-1.40 times less than the injection volume.

Total Working Volume of Injection Molding Machine

 A useful amendment to this rule is that the total working volume of the plastic injection molding machine should be 3/4 of the indicator useful.

plastic injection molding machine 2021

This will significantly extend the service life of the machine during long-term operation as part of continuous production lines. Some models allow the injection and clamping unit to combine into a single module, which saves valuable space in the casting shop.

At the same time, the forces in the clamping units are much greater than in the separate design, it usually exceeds 100 tons, which gives a better result at the output.

Selection according to the correct removal of the product

For this calculation, it is usually necessary to call a specialist in setting up plastic injection molding machine and injection lines. He will be able to determine to what extent the mold opening stroke and ejection depth are sufficient to ensure a successful removal of the finished product.

These are quite complex quantities; you need to be careful when choosing, because most injection molding machines have precise regulation. But working to the limit also discourag due to the too large lever arm formed when opening.

Conclusion

The selection of an injection molding machine is a difficult task that requires the involvement of specialized specialists. Small nuances can significantly complicate or simplify work, reduce or increase productivity. Before choosing, you should always carefully study the characteristics of the equipment.

When selecting, pay attention to the flexibility of using a certain model and modification. One unit will allow you to use a large number of molds. Moreover, it adjusts to the characteristics of the consumer market and profitable highly specialized orders.

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