Machined springs: better performers in a critical duty
Machined springs, according to Abssac, provide very precise, linear
deflection rates, because virtually all residual stresses are eliminated.
This is not the case for a wire-wound spring, which can have internal
stresses that must be overcome before it deflects. And then there are
multiple start spring configurations, the most common being the single
start spring comprising a single continuous coil element, starting at one
end and terminating at the other - rather like its wire-wound counterpart.
A double start spring has two intertwined continuous coil elements,
essentially two independent helixes in the same cylindrical space. The
illustration shows a double helix titanium compression spring with
guaranteed flat end surfaces and integral circlip groove. Multiple start
flexures (triple start, etc) are similar extensions of this concept.
Their advantages include redundancy - if one element should fail, the
remaining will maintain an albeit reduced function - and no 'squirming'
on deflection, as all internal moments are resolved within the spring
itself.