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Scottish Plastics and Rubber Association Scottish Plastics and Rubber Association

World Premiere of a 16,400 Chihuahua, Environmental, Health and Safety Product

John McLoughlin

The last of this season’s technical meeting ended on a high note with an audience of over 34 including teachers from the study tour, students and industry members.

The speaker was John McLoughlin an engineering designer who has over 40 years in the industry and has been involved in the design of many plastic products including cutlery, bottles, components for the famous JCB back hoe loader and more recently, plastic kerb stones.

His presentation began with an overview of the plastic kerb stone, known as Durakerb©, from the initial patent in 2000 to BBA approval in 2008.  Amongst many awards it has picked up was the prestigious Horner’s Award for Design and Innovation.  Durakerb has since been absorbed into Econpro Ltd and is sold exclusively through the Charcon Division of Aggregate Industries.  By 2014, around 350,000 had been installed, including 4,000 metres in the 2012 Olympic Village. It continues to gain ever greater acceptance because of its easy installation, light weight and extreme toughness.

Duradrain
The audience were then treated to the first public unveiling of the all new Duradrain©, a plastic kerbstone with an integrated drainage channel.  After the first tentative ideas in 2006, John described how the development progressed from initial sketches to a product that has achieved a D400 rating,  i.e. it can withstand 400 kiloNewtons (around 40 tonnes!) loading on installation.

 

The Duradrain is made from recycled polypropylene with crushed limestone as filler and has the appearance of concrete.  It is constructed of two interlocking units, the top half having a wall thickness of ~18mm and lower half ~13mm,  which are joined using ultrasonic spot welding.  With strategically placed drainage holes and ribs Duradrain has an unparallel combination of toughness, strength, low weight (14kg/m compared to 30kg/m for concrete) and high hydraulic (flow) capacity.  Finished with a surface treatment Duradrain has good adhesion to wet concrete which is used during installation.

Thermal image of the Duradrain when demoulded
The manufacture of Duradrain requires the polypropylene flake and crushed limestone to be mixed by direct extrusion with no direct heating, sufficient heat being generated by shear forces alone as the screw drives the mix down the barrel.  The extruded slug is then compression moulded, using a clamping force of 80 tonnes and a cycle time of 8 minutes.

This has been no easy development with 2 companies dropping out along the way, with Aggregate Industries joining the party for the critical final development phases. During the 6 years of development an extensive program of simulation has been called on, including computational fluid dynamics (CFD) to look at water movement through the channel, finite element analysis (FEA) and cooling (Moldcool™). 

Simulation of time to reach ejection temperature
The result is a very impressive product that will appeal to specifiers on performance, health and safety, environment and cost.  A whole range has been developed which can be connected using alignment features, with polyurethane mastic for sealing joints.

Les Rose, SPRA Council Member, July 2014

Oh! — and where do the 16,400 Chihuahua’s come in? Well, apparently, they weigh around 40 tons.

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Events Diary

PDM Event

11 June 2019
Manchester Central Convention Complex

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Technical Info from SPRA

  • Materials Thermoplastics, Thermosets, Elastomers, Additives.
  • Processes Moulding, Extrusion, Thermoforming, Ancillaries.
  • Design Product, Mould, CAE, Testing.
  • Applications Healthcare, Packaging, Electronics, Other Markets.
  • Environment Waste, Recycling, Sustainability, Legislation, Energy.
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