Developed and designed a series of products of special film-coated sand

Continuous high-temperature type coated sand

It has high strength and high temperature resistance for a long time under high temperature, and is suitable for the production of complicated thick-walled casting iron parts such as automobile engine oil sump, cylinder head, and shipping container corner.

Easy to collapse type of coated sand

Strong strength, and has a good ultra-low temperature collapse characteristics, suitable for the production of rare metal castings.

Other Special Requirements

In order to adapt to the development of different new products to design a series of special coated sand such as: extrusion casting with coated sand, cold coated sand, wet coated sand, anti-slag, anti-vein pattern, anti-orange peel coated sand.

Common shortcomings in the use of coated sand, the formation of causes and solutions to countermeasures

Moulting

Stamping mould is not scientific, the core box temperature is not uniform, so that the ultra-low-temperature position of the strength is slightly lower and moult; coated sand with a low melting point, slow curing speed, thermal strength is slightly low

Improve the mould design, so that the temperature all over the proportion; using high melting point, fast curing speed, thermal strength of the epoxy resin, add to enhance the curing speed of the hardening agent

Loose surface of mould (core)

The working pressure of core shooting is too high or too low, the exhaust of the abrasive is not smooth, the abrasive because of the large gap on the surface of the box and the sand running, and the poor circulation or air permeability of the coated sand.

Adopt effective working pressure of sand injection, improve the discharge system to avoid air closure; use the raw material with small deformation as core box; use the film sand with poor circulation and air permeability.

Type (core) deformation, rupture

The abrasive tool is not uniform in heat, or the thickness of the core varies greatly, resulting in inconsistent retraction during cooling; the epoxy resin with a larger dry shrinkage rate is used; deformation of the core joint insert or unevenness of the sand core storage and placement; poor sustained high-temperature characteristics of the coated sand; too high a pressure for pouring.

Improve the mould design; make the temperature evenly distributed; use forming trays to store sand cores; use epoxy resin with medium dry shrinkage rate; use heat-resistant and low surge coated sand; improve the pouring system.

Core penetration

Low strength or looseness of sand core parts, thinness and thickness of knots

Adjust the working pressure of sand injection; Improve the discharge system; Improve the mould design to make the temperature evenly distributed; Adopt epoxy resin with high melting point, fast curing speed and strong thermal strength, and add hardening agent to enhance the curing speed.

Castings out of air holes

The core exhaust is not smooth; resin sand casting gas amount or gas rate is not suitable; sand core dry curing is not in place

Improve the discharge system, enhance the practical effect of the exhaust pipe; use the original sand with high concentration or coarse grain shape market; use low gas coating sand; use strong epoxy resin, reduce the use of epoxy resin.

Casting slag

Low SiO2 content of the original sand; low density on the surface of the core.

Adjust the working pressure of sand injection, improve the practical effect of core box exhaust pipe, make the surface of sand core more dense; use heat-resistant coated sand or zirconium sand coated sand.

Castings internal structure casting defects

The epoxy resin in the overcoated sand ignites at high temperature causing heat, which eases the rate of ferrofluid condensation and causes casting defects.