Hur man väljer en begagnad formsprutningsmaskin

How to choose a second-hand injection molding machine

The important factors that usually affect the selection of injection molding machine include mold, product, plast, formkrav, etc. Därför, the following information must be collected or obtained before making a selection: 1. Mold size (width, höjd, tjocklek) , weight, special design, etc.; 2. The type and quantity of plastic used (single raw material or multiple plastics); 3. The appearance size (length, width, höjd, tjocklek) and weight of the injection molded product; 4. Molding requirements, such as Quality conditions, production speed, etc. After obtaining the above information, you can follow the steps below to choose a suitable plastic injection molding machine:

1. Choose the right type:

Since there are many types of second-hand injection molding machines, it is necessary to correctly judge which type of injection molding machine or which series the product should be produced at the beginning, such as general thermoplastic or bakelite raw materials Or PET raw materials, etc., are single-color, double-color, Flerfärgad, mellanlager eller blandad färg, etc.

Dessutom, some products require high stability (sluten slinga), hög precision, ultra-high injection rate, high injection pressure or rapid production (multi-loop), etc., och lämplig serie måste också väljas för produktion.

2. Can fit the sprutform:

Bestäm om “big column inner distance”, “mold thickness”, “minimum mold size” och “mold plate size” av maskinen är lämpliga enligt formstorleken, för att bekräfta om formen kan placeras.

Notera: ①Bredden och höjden på formen måste vara mindre än eller minst en sida är mindre än det inre avståndet på den stora kolonnen; ②Bredden och höjden på formen bör helst ligga inom formplattans storleksintervall; ③ Formens tjocklek bör ligga mellan formtjockleken på formsprutningsmaskinen; ④The width and height of the mold must meet the minimum mold size recommended by the injection molding machine, and it is not acceptable if it is too small.

3. Take out injection molding products:

Bestäm om “mögelöppningsslag” och “mold ejection stroke” är tillräckliga för att den färdiga produkten ska tas ut av formen och den färdiga produkten.

①The mold opening stroke must be at least twice the height of the finished product in the direction of opening and closing the mold, and must include the length of the vertical sprue;

②The ejection stroke must be sufficient to eject the finished product.

4. Can lock the plastic solution:

Mängden av “klämkraft” bestäms av produkten och plasten.

When the raw material is injected into the mold cavity at high pressure, it will generate a force to support the mold. Därför, formsprutningsmaskinens fastspänningsenhet måste ge tillräckligt “klämkraft” to keep the mold from being stretched. The calculation of the clamping force requirement is as follows:

① Obtain the projected area of ​​the finished product in the direction of the opening and closing mold from the appearance size of the finished product; /cm2); ③The pressure in the mold varies with the raw material, och den allmänna råvaran är 350 ~ 400kg/cm2; more than double. So far, spänningsenhetens specifikationer har fastställts preliminärt, och modellens tonnage har grovt bestämts. Sedan, the following steps must be carried out to confirm which injection unit has a more suitable screw diameter.

5. Shot to fill the injection mold cavity:

Bestäm det som krävs “injection volume” and select the appropriate “skruvdiameter” based on the weight of the finished product and the number of mold cavities.

To calculate the weight of the finished product, the number of mold cavities (one mold with several cavities) needs to be considered;

For the sake of stability, injektionsvolymen måste vara mer än 1.35 gånger vikten av den färdiga produkten, det är, vikten av den färdiga produkten måste ligga inom 75% av injektionsvolymen.

6. Injection parameters of injection molding machine:

The conditions such as “skruvkompressionsförhållande” och “injektionstryck” are judged by the plastic. Some engineering plastics require a higher injection pressure and a suitable screw compression ratio design to have a better molding effect. Därför, in order to make the finished product injection better, the injection pressure and compression ratio must also be considered when selecting the screw. . I allmänhet, a smaller diameter screw provides higher injection pressure.

7. Insprutningshastighet of injection molding machine:

Confirmation of “injektionshastighet”. Some finished products require high injection rate and fast injection to form stably, such as ultra-thin products. I detta fall, it may be necessary to confirm whether the injection rate and injection speed of the machine are sufficient , whether it needs to be equipped with pressure accumulator, closed loop control and other devices. Generellt, under samma förutsättningar, the screw that can provide higher injection pressure usually has a lower injection rate, and on the contrary, the screw that can provide lower injection pressure usually has a higher injection rate.

Därför, when selecting the diameter of the screw, injektionsvolymen, injektionstryck och injektionshastighet (injektionshastighet) need to be considered and traded off. Dessutom, multi-loop design can also be used to shorten the molding time with synchronous compound actions.

Om du har några frågor om formsprutning ,snälla fråga gärna FLYSE team,vi kommer att ge dig bästa service!