How To Care For Your FENN Rolling Mill
FENN is proud to design and build 2-HI & 4-HI cold or hot rolling mills, custom mills, as well as offer rolling mill upgrades for aging equipment. Whether you have a new or existing FENN rolling mill, there are recommended routine maintenance tasks that should be performed to ensure the integrity and accuracy of the mill and finished product. FENN provides standard maintenance training with the purchase and install of every new mill.
The finished obtained on the work material will mimic the finish of the rolls, therefore rolls must be kept clean and polished. If rolls are mirror-finished they should be oiled or coated with a good rust inhibitor when not in use. Keep dirt, chips, and other foreign matter away from the running-in table, since stock will carry them into the rolls. Items such as roll wipers are frequently incorporated to remove any debris from the rolls to prevent marring of the surf. If using roll wipers, make sure the wipers are frequently replaced to maximize their benefit to the rolls.
Anytime the mill rolls are installed into the housings, make sure to level the upper and lower rolls relative to one another. This will give you better evenness in your finish product and reduce the chance of future roll damage.
Both rolls must be reground equally, with variation in diameters not to exceed .0005”. If diameters differ, the stock surface will be marked due to roll slippage. When rolls are reground be sure that roll journals are not reground due to the tight fit with the bearing. If the roll journals are worn down and need to reground for an even finish, the journals will need to be either sleeved to make up the clearance for the bearing or the rolls will need to be replaced. If you have any questions regarding this, please contact a FENN representative.
Bearings should be removed at regular intervals to determine by inspection that they are clean and that they are receiving proper lubrication. A well-maintained bearing shows no marking in the individual rollers and the rollers turn freely.
The fit of the adjusting screws in the brass nut can be made exceptionally precise with our modern machining methods. Wear in the screw threads or wear in the threads of the nut will lead to inaccuracy in vertical roll adjustment. Any play, resulting from overloading or other cause, indicates deformation of nut, and impairs the accuracy of the mill. Play, or unusual binding, must be immediately investigated and corrected. The thrust bearing in the screwdown absorbs play under load but needs to be replaced over time to protect the rest of the screwdown assembly.
Mills are engineered with definite maximum load limits, considering bearing pressure limitations, the possibility of roll deformation, gear construction, etc. Modern FENN rolling mills include safety measures to shut down the equipment and prevent the operator from overloading the system in order to protect the rolls and the bearings; however, this is not the case with older FENN mills. While all possible precautions are taken to prevent damage, exceeding designed pressures introduces this hazard – you are urged to consult FENN’s technical product manager, Tom Mushroe, with any doubt or questions you may have. FENN offers upgrade and rebuild programs for existing mills, contact us to learn what may be possible for your rolling mill.
Be sure that the oil/grease supply is clean, and that oil/grease is changed at the prescribed intervals. Interval levels for oil/grease will be determined based on frequency of equipment use. Below is a diagram that shows an example of common grease points.
Accessories should be given the same care as the mill itself. Thorough understanding of their capabilities and proper use ensures maximum output of the highest quality stock, often while saving time and material. Learn more about some of FENN’s wide range of mill accessories.
Please contact FENN if you require additional training from an experienced FENN technician. FENN can send technicians to your facility to provide service and training on existing equipment.