Posted to News on 22nd Jun 2009, 00:00
Coiled spring pins solve oil pump problem for automotive design
The automotive industry historically has used machined solid dowels to align various engine components to the block. The sole purpose of the dowels is to provide finished assembly alignment to the engine block. In an effort to reduce cost, total assembly weight and installation forces a manufacturer approached Spirol Industries' Applications Engineering Department to determine the best alignment pin for a new design of engine oil pump.
Following a comprehensive design review, Spirol recommended the use of a standard duty coiled spring pin as the alignment pin in the new oil pump application. Coiled pins are designed such that their pre-installed diameter is larger than the recommended hole. The diameter of the coiled pin is compressed during insertion which prevents deformation of the hole in the pump resulting in a good 'press fit' between the pin and the hole. Once installed, the coiled pin retains itself by exerting constant radial force against the hole wall as it attempts to recover back to its pre-installed diameter.
Retention values can be quite high depending on the hole size, host material and duty of the pin. Standard duty coiled spring pins offered the optimum balance of strength and flexibility that exceeded all of the performance requirements for this application. This low cost solution was within Spirol's standard range.
By replacing the rigid solid dowel with a coiled spring pin, the customer was able to achieve the primary goal of reducing cost: indeed, the customer has realised annual component cost savings of £25,000. Savings were also achieved through the reduction in hole preparation time, reduction in weight of the final assembly, lowering of installation forces and the decrease in total assembly time.
