Development of oil filtration solution for cast iron honing by Transor India
Fine filtration of solution for oil used for honing operation of cast iron components.
The filtration system originally installed was a combination of magnetic prefilter plus a simple gravity-based paper filter. The size of cast iron particles after honing operation is in the range of 0.5 microns to 5 microns. This filter was unable to effectively separate the cast iron dust from the coolant. The coolant life, component quality and machine life were a major matter of concern from cost, quality & HSE point of view.
Installation & commissioning of the system:
Transor India took up the challenge to develop an efficient filtration for this honing coolant. Multiple offline and online trials were conducted at both Pune and Mohali on dirty oil, oils of different makes and viscosities, and a range of different Transor carbon fiber, and paper filter elements.
Actions for finding & implementing solution
- Conducted a filtration trial (August 2017) on existing dirty oil (Hardcastle Petrofer Hicut Hone, viscosity – 5 cSt) using Transor paper candle and carbon fiber candle elements.
- Carbon fiber candle elements were found to deliver satisfactory flow and quality of oil in the trial compared to paper candle elements.
- A fully automatic filtration unit was installed at Mohali in July 2018. These unit contained 80 backflushable carbon fiber candle elements, with a design life of 12 months. This unit was connected to 2 honing machines.
- This unit worked satisfactorily till October 2018. At this point, the filter pressure became too high, indicating the filter elements were choked and not delivering required output flow. This early failure of filter elements indicated that the backflushing of cast iron dust stuck to the filters was not effective.
- The corrective action taken for this issue was replacement of single filter vessels containing carbon fiber elements with 4 filter vessels each containing one backflushable paper Transor compact filter element.
- These paper candles were also choked within a month.
- Ineffective backflushing may be caused by a combination of filtered material (cast iron in this case), additives in oil which reduce efficacy of compressed air backflushing, concentration of dust in the coolant, and viscosity of oil.
- To find out root cause of early filter element failures, trials were conducted in Pune using different oils and cast-iron dust, per following chart:
- Based on these results, it was recommended to Godrej to use lower viscosity oil, and this was sourced again from Hardcastle.
- Trials were performed on this oil and new compact filter elements, 4 different times using different pressures for filter compression.
- Rare earth magnetic separator was also added as prefilter to increase element life. But desired life of filter was not being achieved.
- Finally, it was recommended to Godrej to change oil make as a last effort.
- Honing oil from Lubeco, Pune was filled in unit alongwith new filter elements in Sep 2019.
- This change in oil led to a dramatic improvement in filter pressure. This configuration is now in use with very good results, low filter pressure and adequate flow.
Benefits were achieved for Godrej & Boyce as desired in terms of manufacturing costs related to tool life, rework/rejects of components and coolant life. Additionally due to increase in coolant life, environmental will benefit and load on ETP is reduced.
- Continuously supply clean coolant & reduce frequency of coolant disposal – Achieved.
- Increase the average coolant life from 4 months to >12 months – > 200% increase)
- Decrease in no. of rejects from 100 per month to <5 per month – 2000% decrease)
- Increase in life of honing tool from 1000 hours to 5000 hours – 400% increase)
Transferability (other sites, other BGs)
This system configuration can be easily used at any site using neat oil based coolant for cast iron honing.