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Die Head Refurbishment

In the market, there are various types of die heads available for different production purposes. The types of die heads vary based on the size, shape, and material type of the product produced. A die head is, generally, manufactured to meet customer’s specific extruding capacity and materials. It shall ensure even distribution of melted polymers, delivering uniform thickness for high-quality products. The main polymers materials are LDPE, HDPE, PP, PE. If virgin polymers are, so to speak, merciful on the die flow surfaces. We can not say the same about quality of the recyclates, at least, not yet. Poorly filtrated and heterogeneous recyclates cause severe wear of the flow surfaces. As all we know, design and manufacturing of the die heads take time and require significant investments. Therefore, die head refurbishment is a budgetary solution for producers in the most cases. In this article we, briefly, describe extrusion die related problems, damage causes and repair methods based on our experience and developed over years practices.

Types of extrusion dies and heads

Our Die Head Workshop has repaired and refurbished various extrusion dies and heads with different damages.

  • Blown-film die heads (mono- and multilayer, spiral and stackable types),
  • Small cast film dies
  • Tubing die heads
  • Blow molding dies
  • Crossheads
Extrusion die after die head service, FINTER Oy, die head refurbishment
8-layer blown-film die
Crosshead service and refurbishment at FINTER
Crosshead before & after
Die Head Service and Refurbishment at FINTER
7-layer blown-film die
Mirror finish, die head service, die head refurbishment at FINTER, polishing at FINTER
3-layer blown-film die

Types of damages and defects

The extrusion dies and heads arrive with different symptoms and damages. We can, roughly, categorise them based on what has caused them:

  • Natural wear of parts (lips, dividers, mandrels, housing)
  • Die drooling (escape of the molten polymer)
  • Design or manufacturing flaws
  • Thermal damages
  • Mechanical wear
  • Coating wear
  • Human factor

Here are some cases of the damages caused either at the production or during die manufacturing process:

Removing defects from the steel surface by griding and polishing

Hard Chromium coating wear caused by highly abrasive materials and manual cleaning

Die Head Service and Refurbishment at FINTER

Die Head Makeover

Refurbishment is a relatively affordable upgrade of your extrusion dies. However, we had couple cases when refurbishment was no longer a feasible solution due to severe damages and purchase of a new die was the only possible and right option. Luckily, those cases are rare ones, at least, in our practice. Therefore, we recommend to invest into timely repair of the dies and prolong their service life.

Depending on the results of the incoming inspection we suggest the refurbishment solutions and alternatives, if any. Briefly, the refurbishment process includes burning, prepolishing for inspection purposes, refurbishment planning, required repairs and recoating.

Die Head Refurbishment at FINTER
Burn-off in the oven
Die Head Service and Refurbishment at FINTER
Filling of the deeper dents
Die Head Recoating at FINTER
Recoating

Longly, the refurbishment is a complex process which require time and investment. Project timing is a crucial variable in this case. Some projects require longer cycles due to severe damages, old coating stripping, occasional failures of the electrochemical processes or vacuum technologies. In the latter, the success rate is higher than in conventional wet processes. But unexpected situations and conditions may occur in either process.

When considering your die refurbishment you need to understand that you repair an old extrusion tool, which would have improved properties, reduced friction and become more energy efficient after the makeover. It is repaired in the best possible and available in the market practices. It will be LIKE new again, but never new.

Die Head Refurbishment at FINTER

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