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An affordable time-to-market solution for making plugs and moulds for the Marine sector

News International-French

13 Jan 2012

Two of the greatest challenges in producing plugs and models using traditional techniques are the significant cost and time intensive production processes.  Huntsman Advanced Materials claims to have the solution, with its quality range of RenPaste® epoxy seamless modelling pastes.

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In looking to improve time-to-market delivery schedules and implement more cost-effective construction methods, many boat builders are increasingly turning to use seamless modelling pastes (SMP).

SMPs have a number of distinct advantages.  For example, they offer excellent milling characteristics.  Once milled, no joints or voids are visible and the material is seamless.  They also provide greater dimensional accuracy and make it possible for complex shapes to be constructed.  Less operator skill is required and less finishing is needed to prepare the surface. 

The biggest cost when making SMP models is not the SMP paste, but the labour costs as well as the cost of application and CNC machine time.
Huntsman Advanced Materials advises its customers that an SMP paste should perform consistently to allow fast application while avoiding replication and costly repair work.

Types of SMP:  Polyester SMP is a low cost, low quality material.  Issues associated with this low cost, low quality material include catalyst dosing and mixing problems, high shrinkage and high dimensional distortion.

Polyurethane (PU) SMP is generally lower cost than epoxy SMP.  Often characterised by low temperature resistance (low Tg), high shrinkage and poor dimensional stability.  Inconsistent rheology and reactivity tend to result in application problems and repair work is often high.

Epoxy SMPs tend to be slightly more expensive than PU.  However, in offering low shrinkage, excellent dimensional stability and a consistent high performance in application and use, epoxy SMPs are now very much in demand.

Hand or machine application:  Special pumping / dosing machines are needed to mix and dispense SMP. 

Hand application is increasingly being replaced by using a robotic arm or CNC machine to apply the paste automatically.  This allows an increase in application rate up to 5 kgs per minute as well as the accurate control of the thickness of the paste.  In general, it is only necessary to remove a few millimetres of material during milling.  This less labour intensive process saves both time and material.  When applied by hand, the paste tend to be thicker and the application inconsistent, resulting in additional material waste.

RenPaste® 4666, the most recent addition to Huntsman’s epoxy SMP range, has been designed for machine systems while still being suitable for refined hand application as well.  This has been achieved through the ‘chemical thixotropy’ concept developed by Huntsman which allows the user to alter the SMP rheology by simply changing the mixing parameters. 

The ‘chemical thixotropy’, a Programmable Paste Rheology (PPR) concept changes the SMP’s characteristics from a fluid that can be applied quickly in thickness up to 10mm, to a viscous material capable of up to 40mm thick, with no slump on vertical surfaces and without excessive exotherm.  The user can select the paste rheology required for individual jobs – from high speed automated application to thick hand application.

Whichever application method is used, the high quality which results from this SMP’s adjustable rheology reduces the need for additional repairs or re-working of the model.  In addition, the fine surface quality obtained after milling of RenPaste® 4666 reduces any further finishing time.  The paste also exhibits excellent dimensional stability and low shrinkage on precision models.

By following the criteria of using an epoxy SMP which performs consistently and allows fast application, a better quality of product requiring less repair work can be constructed and a faster ‘time to market’ achieved.

Huntsman leads the SMP market with its RenPaste® range of epoxy seamless modelling pastes.  These low odour systems have no volatile organic compounds or aromatic hardeners, low flammability and relatively low toxicity. 

All of the SMPs within the range are based on the company’s unique ‘chemical thixotropy’ concept, producing fast pumping liquid components to develop rapid and reliable anti-slump properties - ensuring good results first time, every time.

About Huntsman
Huntsman is a global manufacturer and marketer of differentiated chemicals. Its operating companies manufacture products for a variety of global industries, including chemicals, plastics, automotive, aviation, textiles, footwear, paints and coatings, construction, technology, agriculture, health care, detergent, personal care, furniture, appliances and packaging. Originally known for pioneering innovations in packaging and, later, for rapid and integrated growth in petrochemicals, Huntsman today has more than 11,000 employees and operates from multiple locations worldwide. The Company had 2009 revenues of approximately $8 billion.

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