Injection mould defect analysis-weld line, material flow line

  •  Appearance of the weld line

Weld line often appears in the place which every fluid meet. Especially in the high-polished surface in mould, weld line in the plastic product just like a mark or slot, it is obviously in the plastic products with dark color or transparent plastic molding productsWeld line’s location is always depending on the material flow direction.

  • Physical reason of the weld line

The location of weld line is where melt material separate but connect again area. It will form weld line and material flow line in the place two melt material meet again. The bigger core around melt material is, the more obvious the melt line will be. But the small weld line will not affect products quality and strength.

However, if the flow distance is too long or the pressure is not high enough, inadequate filling will lead to a slot. The quantity of gate and the location of gate also determine the weld line’s quantity and location. The smaller fluid -striker angle is, the more obvious the weld line will be.

In most circumstance, technology debugging cannot solve weld

line or material flow line. We can reduce their brightness, or move them to invisible or inconspicuous place.

  •  Reasons connecting to the machining parameter and improvement
Injection speed is too slowIncrease the injection speed
Mold wall temperature is too lowIncrease the mold wall temperature
Mold temperature is too lowIncrease the mold temperature
Pressure is too lowIncrease the pressure; change the pressure as soon as possible
  • Reasons connecting to the design and improvement
Unreasonable gate positionResetting gate position and move it to position which is not visible
No venting hole in material flow runner Venting hole size should meet the material characteristic(ABS:0.02mm depth,PA:0.01 depth)

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Advantages of Hot Runner systems for plastic molds

1) no outlet material after processing is not required, so that the entire molding process is fully automated, saving time and increasing efficiency.

2) the pressure loss is small. Hot runner temperature and the injection molding machine nozzle temperature equal to the raw surface to avoid condensation inside runner, injection pressure loss.

3) outlet material will be reused plastic performance degradation, and use the hot runner system has no outlet material can reduce the loss of raw materials, thereby reducing production costs. Temperature and pressure in the cavity uniform, small plastic parts stress, uniform density, in the smaller injection pressure, a relatively short molding time, better than the average of the injection system of the injection molding product. For transparent parts, thin pieces, large plastic parts or high demand plastic parts can show its advantages, but also can be used to produce a larger product smaller models.

Hot runner mold

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4) thermal spray nozzle using standardized series design, with a variety to choose from a nozzle head, good interchangeability. The unique design of the processing of electric heating coil, heating temperature uniformity can be achieved, and long service life. Hot runner system is equipped with manifold plate, temperature control, etc., compact design, a wide variety, easy to use, stable and reliable quality.

Do you need hot runner mold for your business or your new products? Here I offer you some finally suggestion, if you want your plastic mold to running for over 1 million shot, then we suggest you to make hot runner mold, because this will save your cycle time and save the runner waste, if the mold life requirement less than 0.2 million then we suggestion use could runner, of course this is not always the same it is depending on the part size if part size is over 300 mm, then hot runner will be better option, you can go to our mean website to know more about this.