Moulding

TECHNOLOGY OF SELF-HARDENING LOOSE SANDS

1. Loose self-hardening sands made from liquid glass – Floster sands

The requirements of environmental protection and quality improvement, dimensional precision and smoothness of casting surfaces resulted in the need for changing the previously applied technologies of classic sands.

The use of loose self-hardening sands enabled us to obtain the following effects:

• elimination of manual thickening of sands by means of pneumatic rammers (reduced noise, vibrations, dust pollution),
• elimination of the need to dry the moulds prior to pouring,
• ensuring stable technological parameters of self-hardening sands, thanks to the use of high-speed continuous-mixing aggregates installed on moulding workstations,
• increasing the output of moulding workstations,
• reducing by approx. 20 - 30 % the costs of sand, through the use of 50 - 70 % reclaim in place of fresh sand.

2. Two-layer sands (facing sand and backing sand)

As part of the specific purpose project, financed by the Scientific Research Committee, in cooperation with the Foundry Engineering Institute in Krakow, the production technology of moulds from two-layer sands has been developed and implemented.

The benefits of the use of this technology are as follows:

• improving the knock-out properties of sands from the moulds,
• considerable improvement of the castings’ surface quality,
• lowering the costs of cleaning the castings,
• reducing by approx. 50 - 55 % the costs of the sands as compared to the costs of uniform sands prepared with the use of organic binder,
• joint regeneration of used two-layer sands and Floster sands and utilising the obtained reclaim in place of fresh sand.

3. Core sands

In place of dried core sands, the technologies of producing the cores from sands with non-organic binders (Floster) and organic binders (furan and alkaline resins) have been implemented.

As a result of the implementation, the following effects have been obtained:

• production of cores of various degrees of complexity and dimensional precision,
• obtaining very good knock-out properties of the sand – pouring out the sand from places which were previously very hard to reach,
• improving the quality of surfaces recreated by the core,
• the possibility of free selection of the type of core sand for a given assortment of castings.