Plastic Bearings Case Study:
Clever Integration Saves Time & Money
When BNL was commissioned by an access and video control specialist to design pan and tilt bearings for the company’s new surveillance dome, the end result was a complex, custom-designed, lighter and less expensive complete sub-assembly.
BNL’s specialist design expertise and knowledge of plastics has seen the replacement of heavy, noisy and expensive steel pressings and gears with lightweight, quiet and cost-effective plastic pulleys and belts. As well as the two double-row bearings of the pan and tilt function, the assembly has been designed to include many additional integrated features, cutting costs and shortening the supply chain by reducing components. Where ty-wraps would traditionally be used, BNL has integrated routing channels into the design to keep the electronic cables tidy, and replaced metal screws with fully integrated moulded clips. These integrated moulded features have not only halved the component count, but significantly reduced maintenance time, meaning the unit can be stripped down in minutes.
The majority of the bearing assembly is moulded from acetal, which being particularly suited to plastic bearing manufacture, is BNL’s most commonly used material. To add extra strength and rigidity, the three arms at the top of the assembly are moulded from a 60% glass-filled nylon type material. When making material choices, BNL had to take both the motor and outside temperatures, the rigidity of the assembly and the high speed of the system into consideration. Under manual control, the pan and tilt speed is proportional to the degree of zoom, allowing accurate target acquisition and tracking. A 360° per second top speed permits near instantaneous response to alarms, so a smooth precision movement with the minimum amount of vibration is required. BNL’s reduction in the weight and size of the bearing assembly ensures the camera a quicker period to settle into its pre-set positions.
For this project, BNL has gone one step further with its bearing solution, taking on full project management of the sub-assembly. By managing the purchasing of components such as tilt sensors, timing belts, PCBs and motors and assembling them at the same time as the bearings, BNL has taken much of the hassle out of the project for the customer.
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