When the standard range does not fit: special sizes and custom development

When a joint needs a spring the catalogue does not carry, the answer is not always a redesign. SCHNORR offers an extensive standard range together with a multitude of special size disc springs, plus customer specific solutions and special developments, and specialises in tailor made solutions developed in partnership with customers, going further than DIN or EN.

Every so often a design lands where the standard range stops. The bore is fixed by a casting, the force is set by a hydraulic circuit, the temperature belongs to a process nobody is going to change. At that point there are three options: change the assembly, accept a compromise on force, or have the part made to suit.

Start by checking that it really is special

A surprising number of apparently custom requirements are met by a standard part in a different stack arrangement. Series stacking makes deflections additive at the same force. Parallel stacking makes forces additive at the same deflection. Combining both realises various characteristic curves. Before commissioning anything, it is worth asking whether the requirement is a new part or a new arrangement of an existing one.

What custom actually covers

• Special size disc springs outside the standard dimensional range.
• Customer oriented solutions and special developments for a specific application.
• Material and surface combinations chosen for a particular environment rather than a catalogue default.
• Bespoke safety washers and locking elements where the geometry has to suit a specific head or counterbore.

The framing SCHNORR uses is worth noting: tailor made solutions developed in partnership with customers, beyond DIN and EN. Those standards define quality requirements, dimensions and calculation methods. They do not define every joint an engineer has to solve.

What makes a development conversation go quickly

The same three inputs as any spring enquiry, with one addition. Force and installed height. Space envelope. Duty, temperature and environment. Then the constraint that makes it special, stated plainly, whether that is a fixed bore, a certification requirement, a magnetic limit or a temperature that rules out standard steel.

Stating the constraint rather than the desired part number usually shortens the process, because it leaves room for the option nobody had considered.

Why heritage matters here more than in the catalogue

For a standard part, history is marketing. For a development project, it is capability. Adolf Schnorr began serial production of disc springs after the market response to his early work, and eventually stopped making tools altogether to concentrate solely on springs. The original SCHNORR safety washer followed in the early 1960s. That accumulated engineering is the reason SCHNORR describes itself as a development partner of choice, creating added value in security, quality and economy.

And the practical question: how much volume does it take?

That is the right question to ask early, because it decides whether a special size, a modified standard part or a stack of standard parts is the sensible answer. Put it in the first enquiry along with the technical inputs, and the recommendation you get back will be the one that suits your programme rather than the one that suits the catalogue.

• SCHNORR offers an extensive standard range of disc springs together with a multitude of special sizes, customer oriented solutions and special developments.
• SCHNORR specialises in tailor made solutions developed in partnership with customers, going further than DIN or EN.
• Many apparently custom requirements can be met by re-arranging standard parts, because series stacking adds deflection and parallel stacking adds force.
• DIN EN 16983 and DIN EN 16984 define quality requirements, dimensions and calculation, not every application.
• Adolf Schnorr moved to serial production of disc springs and eventually concentrated production solely on springs.
• The original SCHNORR safety washer was developed in the early 1960s.
• SCHNORR positions itself as a development partner creating value in security, quality and economy.