THE COST OF THE PIN
The cost of the pin itself is a small part of the total installed cost (pin + hole preparation + insertion). Nonetheless, the following general information is offered: -
< Slotted spring pins and cotter pins are the lowest in cost, size for size.
< In small diameters, A2 stainless may cost no more than zinc plated steel, except in high volumes. In large diameters, the difference is considerable.
< Pins from 8mm diameter and above increase in cost considerably compared to smaller sizes.
THE COMMERCIAL AVAILABILITY OF THE PIN < Before specifying a pin, check that it is commercially available in the quantities and delivery times you require – some types of pin are available in a wider size range than others. < Avoid inch sizes where possible.
< Avoid non-standard parts if possible. Where no standard part is suitable, choose a type of pin that can be made without special tooling or material. Slotted and coiled spring pins as
well as most cotter pins and grooved pins need tooling and sometimes specially made lots of material when they differ to any great extent from the standard. Solid dowels and taper pins do not present this problem.
THE COST OF HOLE PREPARATION Cost differences are considerable between the types of pin: -
< Some pins need only a plain drilled hole with fairly wide tolerances. These are slotted and coiled spring pins, grooved pins, cotter pins and R-pins.
< Some pins require a drilled and reamed hole where an interference fit is needed. This applies to all types of dowel.
< Taper pins need a drilled and taper-reamed hole.
< On hinged applications, there should be a slight difference in the hole size between the fixed and rotating part of the assembly. This can often be avoided by the use of grooved pins such as DIN 1475 where the pin diameter itself allows for this.
THE COST OF ASSEMBLY < Very short pins are difficult to manipulate except where the insertion equipment is available. < Very long pins when engaged the full length require a high insertion force. < Slotted spring pins to ISO 8752 require a higher insertion force than coiled spring pins.
< Where bowl-fed automated assembly machines are used, avoid pins which are not symmetrical. Avoid standard slotted spring pins as the open slot can cause interlocking of the pins in the feeder.
41 T: +44 (0) 1536 461140 F: +44 (0) 1536 461662
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