Key Plastic Properties Related to catheter tipping


The ability of a molten plastic to fill the entire cavity under pressure after being heated is called fluidity, and is generally tested with a professional fluidity test mold.

The fluidity of different grades of the same type of plastic are not the same, different structure of the plastic parts of the plastic flow put forward different requirements, the fluidity of the plastic and molding temperature and pressure and other conditions are closely related.

Usually, if the fluidity is too large, on the one hand, the melt will not fill tightly, resulting in loose products, affecting product quality; on the other hand, the fluidity is too large, the periphery of the injection molded parts are prone to appear Phi Fong (burr) sticking to the mold and nozzle stretching, resulting in the clogging of the water outlet. The plastic fluidity is too small, for the structure of the complex process of long plastic parts, injection flow difficulties, easy to appear lack of glue, shrinkage and other phenomena, resulting in a large number of scrap; or must be injected with high-pressure conditions, which is likely to result in excessive stress in the plastic parts. We have to choose the plastic molding with suitable fluidity according to the product structure, size, thickness.

Processing temperature of plastic

The processing temperature of plastics is the temperature at which the viscous flow state is reached, and the processing temperature is not a point but a range (from the melting point to the decomposition temperature). When thermoforming plastics, the appropriate processing temperature should be selected based on the size, complexity, thickness, insertion, temperature tolerance of the colorant used, and machine performance.

The following are the approximate processing temperature ranges of some commonly used plastic materials:

Common Thermoplastic Processing Temperatures

1. Polyethylene (PE)
– Low Density Polyethylene (LDPE): 150°C – 220°C
– High Density Polyethylene (HDPE): 180°C – 260°C

2. Polypropylene (PP)
– 200°C – 250°C

3. polyvinyl chloride (PVC)
– Hard PVC: 170°C – 210°C
– Soft PVC: 160°C – 200°C 4.

4. Polystyrene (PS)
– 180°C – 280°C

5. Polyethylene terephthalate (PET)
– 250°C – 290°C

6. Polycarbonate (PC)
– 260°C – 310°C

7. polymethyl methacrylate (PMMA)
– 210°C – 250°C

8. Polyamide (Nylon, PA)
– PA 6: 220°C – 260°C
– PA 66: 260°C – 290°C

9. polyurethane (PU)
– Depending on the specific type, a wide range is possible: 175°C – 250°C

10. ABS plastic
– 200°C – 250°C

11. polyethylene oxide (POM)
– 180°C – 230°C

Common Thermoset Processing Temperatures

1. Phenolic Resin (PF)
– 150°C – 180°C (pre-molding processing temperature)

2. unsaturated polyester (UP)
– Usually cures at room temperature, but heating accelerates curing. 3.

3. epoxy resin (EP)
– Can be cured at room temperature to slightly higher temperatures depending on the curing agent and system. 4.

4. polyurethane (PU)
– Depending on the specific type, a wide range is possible: room temperature to 160°C.

It should be noted that the above temperatures are for reference only and that the actual processing temperatures will have to be adjusted according to the specific make and model of material, the additives and the actual conditions of the tip molding machine. In addition, processing temperatures that are too high or too low can lead to quality problems in the finished product, such as scorching, degradation, stress cracking, or lack of strength. Therefore, precise control of processing temperatures is critical to ensuring product quality.

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