An Ester Cured Alkaline Resin binder (Commonly known as Alphaset Resin):
Among the popular no bake organic binder systems namely Acid cured Phenolic. Alkyd & pepset for making moulds & cores at ambient temperature, no one was found environment friendly. To overcome this problem. environment friendly alkaline phenolic binder system has been developed.
A two part cold set binder & hardner is a mixture of organic esters, used for making moulds & cores. Both batch and continuous mixers can be used.
Advantage offered by the system:
- Free from Nitrogen, Sulphur & Phosphorous.
- Water soluble Resin (Core box, patterns & mixers can be washed & cleaned with water).
- Non corrosive hardners.
- Easy stripping from the pattern. No sticking.
- Can be used with all types sands of high acid demand values.
- No casting defects with steel castings (Free from veins, scabs, erosions & hot tears) due to excellent high temperature properties superior to other no bake resins.
- Collapsibility is very good.
- Lowest gas evolution.
- Offer reclaimability.
- Excellent Casting surface.
- High productivity and rapid strength development.
- Excellent core storage.
- Use of reclaimed sand up to 80% but the resin application rate would be same as that of new sand.
- Resin Storage Life- up to 2 months.
- Low Bench Life and sand compatibility.
Recipe & Air Set Properties:
Resin: 1.8 to 2.2% by Wt. of Sand
Hardner: 20-22% by Wt, of Resin
Bench Life can be varied- 4 minutes to 12 minutes.
- Cost wise acid cure phenolic no bake -Cheapest
- Alkyd & Ester cured phenolic -More or less equal
- Pepset -Costliest
- Acid cured phenolic no bake suffers from sand alkalinity, fumes during mixing & pouring and hot tearing.
- Alkyd system: Poor hot strength & poor casting finish.
- Pepset having irritating smell during mixing, has tendency to veining and Nitrogen build up during reclamation.
- Alkaline Phenolic no bake gives cleanest environment, maximum resistance to hot tearing & finning & excellent casting finish. However it has low flexibility for bench life adjustment & poor sand compatibility.
- However by putting continuous mixer & a vibration unit for sand compaction. This system can be standardized to avail maximum benefit including cleaner environment.