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Office Chair with Pivoting Back Rest

A major office furniture company designs and manufactures a wide range of office chairs, many with pivoting back rests. The back rest used a free fit machined pin retained with an e-clip as the hinge pin. Both the machined pin and the e-clip were installed manually. The installation of the retaining e-clip was time consuming and problematic. Once the pin was installed in the chair it left very little space for the assembler to install the e-clip and ensure that it was seated properly. Failure of a properly secured e-clip on the machined pin resulted in field failure as the main pivot pin would work its way out of the chair. SPIROL worked with the customer to help solve this warrantee problem and enhance their product quality.

In addition to their desire to eliminate the field failures and warrantee claims, the customer indicated that the back rest must freely rotate on the hinge pin. A cost target was provided which was the cost of the machined pin, and the e-clip. The cost of the assembly operation was not provided. However, the current design did not lend itself to being automated, and it was clear that the intricate, multi-step assembly operation was time consuming and prone to human error.

The back rest used a free fit machined pin retained with an e-clip as the hinge pin

The SPIROL Series LP500 Solid Pin is a self-retaining pin

SPIROL recommended the customer replace the two piece hinge pin with a single self-retaining SPIROL LP500 Series Solid Pin. This pin is specifically designed for use in plastic applications and is ideal for plastic hinges with a free-fit requirement. The unique fetter barb design retains the pin in the outer hinge ear and eliminates the possibility of pin walk out. The SPIROL recommendation eliminates the need for an expensive machined pin that required the costly retention groove for the e-clip. Additionally, since the LP500 Series Solid Pin is self-retaining it is installed in a single operation, and does not require a secondary clip. The installation process was easily automated which significantly increased factory productivity.

SPIROL’s solution required minimal changes to the current chair design. It improved the chair’s quality as well as reduced the cost of the components by 25%. Additional (non-quantified) savings were achieved through the reduction in assembly labor. The customer’s payback on this change was 5 months.

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Solid Pins

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