A Quick Guide to Resolving Extrusion Blow Molding Problems

Extrusion Blow Molding Machine

If you’re in the market for an extrusion blow molding machine, it’s imperative that you buy from a trusted source. As you probably know, top-of-the-line extrusion blow molding machines run seamlessly and produce stellar products. Even with that, there are times when different problems arise. These could be the result of using subpar material, a damaged mold, or not running the process correctly.

Of course, when facing a challenge, you can always reach out to the extrusion blow molding machine manufacturer you purchased the machinery. However, you might start by looking at this guide for resolving some of the more common problems.

  • Oval Necks and Rocker Bottoms — An oval-shaped neck and rounded bottoms that rock is the result of warpage. Usually, uneven or inadequate cooling of the blown product before removing it from the mold is the cause. For this, increase the flow. If a high stock temperature is the cause, drop it down in small increments to see if that helps.
  • Wall Defects — Another problem has to do with defects in the wall of the extruded product. When operating an extrusion blow molding machine, make sure there’s no moisture in the melt. For this issue, be sure the resin warms up and that any moisture evaporates before going into the extruder.
  • Cold Spots — When running extrusion blow molding machines, cold spots can sometimes appear on the wall of the blown object as non-homogeneous areas. Typically, insufficient back pressure is the reason. Another potential cause is non-uniformity in the melt.
  • Weld Thinning — When this occurs, the most common culprit is a stock temperature that’s too high. What happens is that as the molds close, making the pinch-off, the process doesn’t force enough material into the weld line. As a result, there’s a weak weld. In this case, you can slowly reduce the stock temperature on the extrusion blow molding machine. If that doesn’t help, try adjusting the length of the pinch-off land.
  • Tearing — People who operate extrusion blow molding machines also deal with tearing problems. There are several possible causes for this. First, the length of the pinch-off land is too long. Therefore, you would need to shorten it. Another possibility is a worn pinch-off. The resolution for this is to either roll it back temporarily or refurbish it.
  • Poor Surface — If the bottle surface has pits, there’s a good chance you’re working with an imperfect parison. However, a subpar mold surface could also be the problem. If that’s the issue, you’ll need to refinish them. The goal is to create a matte finish. That way, air can vent quickly, allowing the parison to conform to the surface while the mold’s still hot.

Buy Quality Machinery

The best way to avoid problems is by purchasing machinery from a reputable extrusion blow molding machine manufacturer. Pet All Manufacturing is a leading source for this and other products. Contact us today for more information.

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