Scabbing is one of the common challenges faced by green sand foundries. This is caused because of the expansion of silica grains at elevated temperatures. This expansion causes high compressive stress, especially when the WTS(Wet Tensile Strength) is poor, breaking the metal-mould interface. Liquid metal infiltrates this space forming a thin layer of metal which comprises the scab.

This case study is of our client, who is one of the largest auto parts and equipment manufacturers in Madhya Pradesh, India, with an output of 1800 MT/month. Scabbing in their castings lead to 0.37% rejections. This not only took a hit on the revenue, but also led to increased usage of raw materials, adding to the costs.

This is when Refcoat stepped in and introduced "CERAKARB" - nanotechnology based carbon additive which helped save more than Rs.1,00,00,000 per year*(Approx. 150,000 USD).

Post our study of their sand system, we committed to providing the following benefits within just 82 circulations.

  • Reduced carbon and bentonite consumption
  • Reduced shot-blasting time
  • Improved surface finish
  • Reduced rejections
  • Reduced sand-sticking post shake-out

We started dosing CERAKARB-40 into the sand system and in just 82 circulations, we delivered the following as promised -

Parameter Before With CERAKARB-40 Savings
Bentonite (%) 0.88 0.63 28.4%
Carbon (%) 0.44 0.27 38.6%
Scabbing Rejection 0.37 0 100%

"Our technology will help reduce bentonite consumption while increasing the Wet Tensile Strength – which automatically results in lesser expansion and erosion defects".

GCS levels in the system were maintained even with reduced bentonite consumption.

The environmental benefit of burning 38.6% lesser carbon in a year contributes substantially towards a greener and cleaner tomorrow.

  • Approximate cost for the above financial savings calculation. Bentonite - Rs.6,000/- per MT ; Carbon - Rs.18,000/- per MT ; Castings - Rs.70,000/- per MT ; 1 USD = Rs.65/-.