Rotational Moulding

Rotational moulding is a manufacturing technique where large moulds filled with pelletized or powdered plastic are rotated in various directions under heat. The plastic melts and progressively lays up against the inside of the mould. The process can be used for above and below ground liquid storage tanks. Our role is to use our FEA software to be able to minimize the material thickness of the tank which saves our clients’ money.

Case Studies

PROFORM SLIMLINES

David Beneke Consulting was commissioned by Proform Solutions to undertake a finite element analysis (FEA) of two slimline above ground water storage tanks – one of 600 litre capacity and the other of 1,050 litre capacity. These tanks are manufactured from linear low density polyethylene (LLDPE) using the rotational moulding process. The purpose of the FEA was to determine the minimum constant wall thickness for each tank which satisfied the requirements of AS/NZS1170.0 and AS/NZS4766. 

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YARRAWONGA PLASTICS SLIMLINES

David Beneke Consulting was commissioned by Trymak product development to undertake a finite element analysis (FEA) of two slimline above ground water storage tanks – one of 2,200 litre capacity and the other of 3,200 litre capacity. These tanks are manufactured from linear low density polyethylene (LLDPE) using the rotational moulding process. The purpose of the FEA was to determine the minimum constant wall thickness for each tank which satisfied the requirements of AS/NZS1170.0 and AS/NZS4766.

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TAYLEX UNDERGROUND TANK

David Beneke Consulting was commissioned by Trymak Product Development on behalf of Taylex Tanks to undertake a finite element analysis (FEA) of a 5,000 litre underground septic tank. This tank was significantly different to those of traditional roto-moulded construction in that the inner and outer walls of the tank are of composite foam core construction. The outer and inner layers of each wall section are composed of a thin layer of linear low density polyethylene (LLDPE). The material in between is a LLDPE foam core. The purpose of the FEA was to determine the minimum overall thickness of the cross section and the minimum thickness of the inner and outer skins which satisfied the requirements of AS/NZS1170.0, AS/NZS1546.1 and the draft underground tank standard. 

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DOMM ELLIPTICAL SLIMLINES

David Beneke Consulting was commissioned by Hercules Constan Lawyers acting for Domm Developments to investigate the structural performance of two elliptical shaped slimline above ground water storage tanks using finite element analysis (FEA). The first tank was 2,000 litre capacity whilst the other was 1,600 litre capacity. Both tanks were manufactured from linear low density polyethylene (LLDPE) using the rotational moulding process.

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OPD ROAD BARRIER

David Beneke Consulting was commissioned by ØPD Solutions, Norway to undertake a finite element analysis (FEA) and material optimisation of interlocking road barriers. These road barriers are manufactured from linear low density polyethylene (LLDPE) using the rotational moulding process. The purpose of the FEA was to determine the minimum constant wall thickness when the barrier was filled with either non-potable water or soil.

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GLOBAL SEPTIC TANKS

David Beneke Consulting was commissioned by Trymak Product Development to undertake a finite element analysis and material optimisation of a 3,000 litre and 5,000 litre underground septic tanks. Both tanks were to be manufactured using the rotational moulding process and as such it was important to reduce material costs to a minimum.

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VISCOUNT PLASTICS SLIMLINES WITH VE ANALYSIS

David Beneke Consulting was commissioned by Viscount Plastics to undertake a finite element analysis (FEA) of a 2,000 litre capacity, above ground water storage tank rotationally moulded from linear low density polyethylene (LLDPE). As opposed to previous analysis work where the creep modulus was constant over time the analysis conducted in this case incorporated a visco-elastic (VE) material model.

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CARTAGE TANK

David Beneke Consulting was commissioned by West Coast Poly to undertake a finite element analysis (FEA) of a 17,000 litre cartage tank rotationally moulded from linear low density polyethylene (LLDPE). This tank was mounted on a structural steel frame which was then in turn mounted on either a truck with articulated trailer or on a non-articulated truck.

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