water cooled pipe corrugator moldsI have many times had to discuss the benefits of air cooled vs. water cooled mold blocks when evaluating a pipe corrugator for use in a customer’s application. Over the years I have seen many systems, and realize both air and water have advantages, the key to a good decision is understanding what will bring you the most value for the investment in your geographic area and unique plant environment.

Looking at the pipe corrugator for its simplest requirement, the mold block must cool the thickest section of plastic to a temperature which it can release from the mold blocks without distortion and further shrinkage or warpage; and it must produce an acceptable surface finish.

This is a fairly simple process; it takes a certain number of seconds of plastic to mold contact time, with the molds at a temperature to provide a stable profile with an acceptable surface finish. But the reality is – its not so simple to keep the molds at a constant temperature which provides optimum cooling and surface finish. Many factors influence the process. Air or water cooled corrugators both work, but which is the best choice for you?

Following is a list of factors you should consider to make a good decision on the best corrugator cooling system for your product and plant.

Pipe quality factors

  • plant operating temperatures & variability
  • temperature stability
  • is an integral bell being made?
  • are you making singlewall or doublewall?
  • expectation of surface finish
  • mold hot spots
  • pipe and bell diameter control specification.
  • Is the finished pipe subject to tight dimension control specifications?

Corrugator maintenance factors

  • long term system maintenance
  • amount of dust on the site, and in plant
  • availability of cooling medium, cold air or water.
  • mold thermal expansion, the longer the corrugator the more mold expansion.
  • aluminium or steel mold blocks
  • water leakage
  • dirt on the mold surface reducing cooling

Corrugator investment factors

  • corrugator length
  • cooling systems, blowers, chillers, both?
  • mold block design
  • fast return technology

Operating Expenses

  • cost of quality
  • output to inventory
  • start up expenses

In the coming weeks I’ll be adding a posting discussing each of these sections further. I highly recommend you thoroughly question the corrugator supplier to ensure you are choosing the proper cooling system. Both air and water work, but they both have strengths and weaknesses – you need to understand them!

For more information check out my website at www.profilepipe.com

Tony Kime

5 Responses to “Pipe Corrugator Cooling Technology”

  1. sameer says:

    sir , we are in manufacturing of corrugated pipes and are facing with problem of cooling mandrels .can u guide us to get max cooling from cooling mandrels ,with some mandrel designs so that we can increase our line speed to maximum

    waiting for your valuable suggestions
    regards

    sameer

  2. Tony Kime says:

    Sameer

    I will be happy to give you some help. Can you tell me a bit more about what your are making and the type of process. Please answer the following questions for me, or send me an email.

    What is the major problem you are trying to cure?
    Are you trying to make inline bells, if so what design?
    What is the type of corrugator you are using?
    Are you using a blow molding or vacuum forming process?
    What diameters of pipe are you trying to make?
    What raw material are you using to make pipe?
    What are your inlet and outlet temperatures to the cooling mandrel?
    What amount of vacuum is being supplied to the cooling mandrel?
    Are there one or two cooling zones on the cooling mandrel?

    I will be happy to give you some thoughts with answers to these questions.

  3. sameer says:

    WE ARE MANUFACTURING CORRUGATED PIPES OF HDPE OF SIZES 40 MM
    TO 300 MM OD ON CHINESE CORRUGATORS WITH VACUUM FORMING ,AIR COOLING FOR MOLDS AND CHILLED WATER FOR MANDREL ( INLET TEMP 9deg C , OUT LET 12deg C).
    WE ARE MAKING 200 MM NOW WHICH WE ARE GOING UPTO 0.9 M/MIN ONLY.
    NO VACUUM FOR MANDREL AND NO TWO COOLING ZONES ,LENGTH IS @ 600MM.

    REGARDS
    SAMEER
    TIRUPATI PLASTOMATICS
    JAIPUR ,
    INDIA

  4. Brad Nelson says:

    Question, why do I only find electric heating elements for resin dryers? I worked with a company for 15 yrs building/installing food processing dryers and doing a cost study shows a 50% energy savings using natural gas burners v.s. an electric heat source. Any thoughts?

  5. Tony Kime says:

    Brad, I haven’t seen any studies comparing the efficiency of gas to electric, but I can believe gas to be more efficient as this seems to be the typical common knowledge I think it will also be impacted by your local cost of each.

    On the topic of resin drying, the very first opportuity is to try reusing the waste heat coming off the extrusion process. If there is any possibility to capture through a duct network the cooling air off the extruder and corrugator and route this through your incoming resin, you will have both a drying effect, but also a pre-heating effect.

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