Aside from all the proper adjustments and operating parameters required to gain the most screening efficiency, the need for good preventive maintenance practices is a must for longer-lasting screens and reliable performance.
Here are seven components to a rock-solid maintenance program.
1. Establish an oil-sampling program. Although a commonly overlooked practice, a regularly scheduled oil sampling is an operator’s best insurance against catastrophic component failure and costly downtime.
The valuable insights provided by samplings – such as detecting a worn bearing – allow operations to schedule maintenance downtime around periods of prime production.
2. Employ recommended lubrication practices. Always consult the owner’s manual for the manufacturer’s recommended lubrication practices.
Install the correct amount of oil, and use the recommended type of oil. Change the oil at proper intervals, making sure the oil in storage is clean and clean containers are used to transport the oil. Make sure the machine is completely level so oil does not pool at the low side of the machine.
3. Maintain proper belt tension. Belt tensioning must be right on target for optimum screen performance – not too loose and not too tight. Ideally, the belts should only be tight enough to not slip during start-up.
If necessary, use a belt gauge to set the correct tension. If belts squeal during start-up or operation – or whip excessively – this may indicate insufficient belt tension.
Over-tightened belts can cause serious damage such as pulling the vibrating frame out of square with the support frame. Operating in this twisted position introduces stresses that may lead to spring failure, metal fatigue, or cracking and broken welds.
4. Prevent material buildup. Accumulation of dust and stone around moving parts is one of the largest single causes of part failures, particularly for pivot motor bases, support springs, roller bearings and the vibrating frame. Impact between the vibrating frame and accumulated material may lead to tower vibrations, as well as potential side sheet and support deck cracking.
5. Maintain proper screen media support and tensioning. Uniform tension must be maintained on the screen surface to prevent whipping and to maintain contact between the screen surface and the bucker-up rubber on the longitudinal support bars. Improper tensioning may cause severe damage to costly screen media.
6. Inspect for wear. Inspect cross members for signs of premature wear – especially in wet-screen applications where wear is accelerated.
Cover and protect the cross members, decking and housing tubes with rubber or urethane liners.
Prior to installing screen media sections, make sure they are appropriately square and flat so that they will seat properly on the longitudinal support bars.
7. Operate with proper clearances. Wherever possible, provide a minimum of 24-in. side clearance on each side of the machine. This enables the operator to adjust screen cloth tension and check the unit’s condition and operation.
Allow sufficient clearance in front of the screen at the discharge end, or in the rear at the feed end, for replacing screen sections. Set the clearance at least 1 ft. longer than the longest screen panel.
Avoid providing places for dust and stones to accumulate and interfere with the movement of the vibrating frame.
Information for this article derived from Pit & Quarry University, an educational resource of Portable Plants’ sister publication.