Blackwell Plastics partners with OEM manufacturers and sub-tier suppliers in South Texas including Houston, San Antonio, Austin and Corpus Christi to provide plastic injection molding and plastic extrusion of engineering grade resins that satisfy demanding industrial applications. Blackwell Plastics supports plastic injection molding and plastic extrusion projects from design to fulfillment.

Tuesday, January 4, 2011

Irish + Alcohol = Problem

What happens when you combine a large concentration of pubs, young Irishman, and street signage? A lot of broken signs!  One of our customers received reports from the field that there signs were having the metal support cables snapped. As it would turn out, the inebriated Irishman thought it was fun to rotate the signs on there bases until they snapped the internal cables holding the signs up.

To combat the problem we decided to re-design the base of the sign so the hooligans wouldn't be able to break the cables if they twisted them. The solution was a two piece self righting swivel base. The upper and lower were originally both going to made in Acetal, but having two like materials created wear issues. The upper was changed to a super tough Nylon for better wear characteristics.  The swivel design was successful in preventing the cable's from breaking, but the swivel still had one major issue. The drunken Irish would still twist the signs which eventually wore the points of the swivels down to a flat. Glass fibers in the Nylon increased the amount of wear on the leading edge of the swivels. Once the leading edges became worn flat they had a tendency to get stuck pointing in the wrong direction making the signs useless for pedestrians.

To overcome the problem many different ideas were tossed around. We considered metal plates on the tips, re-shaping the tips, and new materials to prevent wearing. In the end we decided to make two changes. The first change was to run the nylon parts with a hotter mold, this brings more plastic to the surface of the part and buries the glass fibers deeper in the plastic.  The second change was to add a self lubricating additive to the Acetal to lubricate the wear surface. As the two parts wear on each other the lubricant would migrate to the surface to prevent wear on leading edges.

By using a lubricating additive and reducing the amount of contact with glass fibers in the parts we were able to reduce the wear characteristics of the parts . The parts will now be able to resist the constant twisting and abuse they will see in the field.  The signs will now allow sober Irishman the ability to safely navigate the streets of Ireland.  For help solving any of your issues please call 713.643.6577 or visit our website at

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