Critical Roller Features
Hi-Quality Balanced Tube
STEEL: HD NYLON: ALUMINIUM
It is critical that the Total Indicator Run Out (TIR) is kept to a minimum. Excessive TIR and MIS (Mean Indicator Slope) causes belt flap, vibrations and reduces bearing life. It is even more critical when producing low noise rollers, which are becoming increasingly important in today's environment.
Greater Bearing Life
There are a number of principles that need to be followed to achieve increased bearing life. To achieve the best possible service life, shaft selection is critical and must be designed to reflect the correct running capability of the conveyor and incorporate the below:
Flooded belt loading
This helps minimize angular misalignment in the bearing caused by shaft deflection.
As the shaft is only supported at each end, it must also accept the load from the shell to the bearings at each end. It is critical to minimize the angular deflection at the bearings. Bearings must have a L10 basic rating life of 65,000 hours (or as specified by the client) for bearing loads encountered at the operating design duty, calculated in accordance with AS2729.
The shafts consist of cold drawn mild steel-polished round bars in accordance with JIS-G3123 SGD 3 and other equivalent standards. Black shafts -JIS-G 3101-SS400 equivalent to ASNZS3679 are machined for "step-down" for respective bearing fitting. Particular attention is given to the bearing seat machining and seal location.
The end discs are fabricated from ASNZS1594, JIS-G-3131-pickled and oiled-coils. The fabrication of the end housing consists of a multi-stage precision automatic pressing operation, which provides such a high degree of accuracy for bearing and seal location, that no further machining is necessary. The end housings are chemically degreased after manufacture.
Roller Seal Packages
One of the most important aspects to the service life of a roller, is the sealing arrangement. RKM have 3 sealing arrangements available, depending on the duty requirements.
RKM-RS Premium Seal Package, RKM-TK2 Seal Package, RKM- Low Roll Resistant Seal Package
Starting from the external side, the various protective elements are:
Protective anti-corrosive shield located firmly on the shaft, which acts as a barrier against the entry of foreign particles
Low friction rubber lip seal to prevent the entry of liquid
Steel cover cap with a large chamber where any dust particle that might enter is trapped
Triple labyrinth male preloaded with grease seal is installed
Triple labyrinth female preloaded with grease seal covers the male labyrinth to form the last barrier of defence before the bearing
Rear seal is fitted to protect the bearing from mill scaling and any inherent contaminant.
Idler Roller Bearings
High quality bearings are essential to the life of a roller. RKM use a range of quality bearings, SKF, NTN, NSK and the RKM bearings. Rollers are fitted with single row deep groove ZZ type ball bearings with a C3 internal clearance unless otherwise specified. The bearings are factory greased for life with a suitable Lithium based grease with a NLGI consistency Of2 for bearings K6206 and consistency Of3 for bearings 26306, this Offers minimum roller drag and gives maximum resistance to water wash out.
Housing Tube Weld Detail
The idler shells and end housings are 3mm CF fully fillet welded in a special double-ended automatic circumferential welding machine which gives a minimum of7096 weld penetration and ensures that the shell tubing is concentric at the ends during the welding process, thereby ensuring minimum run-out for the roller as per the BS EN 288 part3 ~Acceptance Criteria: ISO 5817:1992 Quality Level or AS/NZS 1554 part I-Category-GPand sp.