There are many benefits associated with vacuum backed shell moulding, which can be used to put together precise castings and components. Vacuum backed shell moulding can be used to create large cast iron parts than conventional shell moulding processes, and can be automated to produce a high degree of dimensional accuracy, as well as the ability to create parts that do not require subsequent machining. It’s worth, then, investigating vacuum shell moulding services from Newby Foundries if you want to try a new approach for your next manufacturing run.
With vacuum backed shell moulding, cavities are created from a hardened sand structure, or ‘shell’; sand is combined with a resin for heating and hardening into a shell around patterns. The application of vacuum pumps means that moulds can be processed with much less risk of damage, preventing cracks and imperfections from being created; pumps can similarly be used to remove gas, and to aid in the removal of patterns for re-use.
Vacuum-based methods of this kind can also be used for permanent mould casting, whereby moulds can be used multiple times; a vacuum acts, in this respect, as a way to maintain mould quality, and can make it easier to prevent gases from being dissolved and affecting structural integrity. To this end, casting methods that use vacuums are better for intricate parts such as gears and pistons, as well as for fuel injection housings.
A vacuum can similarly be used for mould casting that doesn’t require moisture or binding agents; the forces created by a vacuum can be used to maintain the shape of a mould, and can be used with different patterns represented by match-plates, as well as with cope and drag segments that feature air holes for suction. Again, vacuum forces are capable of holding shapes, and reduce the risk of imperfections forming as the result of gas build-ups.
Vacuum backed shell moulding consequently represent one of many casting methods for metals that use pressure to limit impurities, increasing the potential for manufacturers to gain a high degree of dimensional accuracy. Production volumes for vacuum backed shell moulding can also range from medium to high quantities, and can typically be carried out up to a weight limit of 100 kg, and to size limits of 800 x 300 mm, or 600 x 400 mm. Compared to shell casting or greensand casting, vacuum backed shell moulding offers a greater weight and size limit.
It’s therefore possible to use vacuum backed shell moulding for creating larger component parts, and for developing highly precise moulds. Vacuum-based methodologies for shell moulding and casting, whether using sand casting, resin, or other approaches, also have the general advantage of being highly resistant to deformation, and are suitable for projects that involve high upfront investments, generating confidence that final products will be durable and will not require additional machining.
Rob Jones is a freelance blogger who covers manufacturing and industry news. He recommends learning more about vacuum backed shell moulding at Newby Foundries. He also blogs on how to make the most of different metal strengths when designing components.