MechChem Africa November-December 2023

Advanced polyurethane products and 3D printing MechChem Africa talks to Saahil Bhartu, product engineer at UMP, about the advantages offered by adopting 3D printing to manufacture complex moulds for the manufacture of polyurethane products.

Saahil Bhartu, Product Engineer at UMP presents a 3D printed design of a complex hydrocyclone helix.

U MP was founded in 1947 by Brian Christiane as a polyure thane moulding company. “Back in those days, people started putting artistic patterns into concrete, and the way that was done was to make a poly urethane stencil which, when applied to the wet concrete, creates a permanent artistic pattern. Brian Christiane started out mak ing these patterns, but soon realised that polyurethane (PU) was a very interesting lining material,” begins Saahil Bhartu, who is the product engineer for moulded poly urethane products and 3D printing at UMP. “Because PU is a very abrasion-resistant material, our founder realised it was ideal for lining pipes transporting mineral slur ries such as coal, iron-ore and phosphate. So UMP became the first company in South Africa to develop PU-lined piping. And our business grew from there. We started doing more and more pipes, which quickly became our core business. We then started custom moulding polyurethane products, went on to include design and development, and are now a full-service engineering, design, development, casting and manufacturing company for an extended range,” he tells MechChem Africa. “Our business is split into two, though.

on curing, “which works in our favour when it comes to removing a mould, but from a design perspective, we still have to make sure the angles used and shapes will allow the mould to be easily released once the PU has hardened.” All sizes of pipe can be accommodated, with the largest ever done by UMP being 900 NB pipes and bends, while section lengths as long as 9.0 m can be accommo dated for laying long pipelines. PU is also used extensively for lining flat products. “For vibrating screens, for example, we do a lot of sheeting work, and we make sets of PU blocks for use as vibra tion dampers. If you put these blocks under the legs of rotating machinery, vibration can be completely absorbed with none being transferred into the ground or to neighbour ing equipment. “We manufacture spares for flotation cells, impellers and centrifugal pump liners and a host of products that help to protect moving steel parts such as agitators and mixers from coming into contact with abra sive slurries,” he says. The shift to 3D printing Describing the traditional process for manu facturing liners for pump impellers, he says

As well the PU side, we have taken on an in creasing role in fabrication, predominantly for mining companies. This began with the fabrication of steel inserts for our lining systems and the manufacture of moulds and their supports, but we now offer fabrica tion services for piping and modular Bailey bridges, for example,” he says. “We also do a lot of work for pump and hydrocyclone OEMs, as well as OEMs involved with bulk materials handling ma chines, such as FLSmidth, Thermo Fisher Scientific, Azmet technologies, Kwatani and Sandvik, to name a few,” he adds. Describing the hot casting process for lining pipe with PU, Bhartu says UMP will first design an internal mould or mandrel to match the pipe section being lined. “The pipe section and mould is put onto an oven and heated. We then introduce a prepolymer and a curing agent in liquid form, and we spin the pipe. The polyurethane cures against the pipe surface due to the heat, forming a smooth lining with an even thickness. “We can also do spray lining if the sur face finish is not that important,” he says, adding that polyurethane shrinks a little Polyurethane moulding and 3D printing

42 ¦ MechChem Africa • November-December 2023