Steel castings manufacturing process
The manufacturing processes of castings must be executed with the maximum accuracy, performance and quality, thus ensuring the final customer´s satisfaction.
The steel castings processes may be different from each other foundries, but the manufacturing process applied in Fundiciones Estanda follows the following steps:
Project and design
The starting point for the procedure for making castings is the order received from the client.
Initially it is necessary to study the feeding and filling system of the pieces to be built, and make the necessary patterns and core boxes. Studies and computer simulations of steel castings solidification are made to ensure the highest quality of the goods to be obtained during the process.
The construction of the patterns and core boxes, tools used for making sand moulds and sand cores, where the liquid steel is poured until solidification, is subcontracted to qualified modelers.
Moulding and coremaking section
The sand moulds are made in the respecting moulding facilities.
In Fundiciones Estanda two technologies of sand moulding are used , depending on the type and size of the goods to be manufactured :
- “Green moulding ": small and medium pieces.
- “Chemical – Moulding” : large and highly demanding pieces.
Core making section is an auxiliary molding section, and is the part of the process where sand cores are made using the core boxes.
The sand is prepared in the mills and dumped on casting patterns for compaction and compression, shaping the future piece sand mould. Once the sand mould is compacted, the casting pattern is separated and reused for making new sand moulds.
The manufactured cores done in the coremaking section are placed inside the sand moulds in order to determine the inner shape of the workpiece.
The next step is the union and closing of the sand moulds , and finally the moulds are moved to the storage area where the melted steel is poured into the moulds.
Melting and casting
For obtaining the liquid steel the scraps and ferroalloys are melted in electric induction furnaces of medium frequency placed in the melting section.
Depending on the type of seel alloys to be manufactured (wear-resistant steels, impact resistant steels, stainless steels , heat resistant steel , carbon steel) the steel is melted at a temperature between 1450 °C and 1650 °C.
After the melting process, the steel is download to the ladle, and finally the liquid steel is poured into the sand moulds deposited in the casting zone.
After the solidification of the steel, the solid piece ( as cast) is obtained . This solid piece (as cast) must be submitted to the subsequent processes to reach the design and final shape desired by the customer.
Demoulding of the castings is produced with the separation of the molding sand (containing sand) of the casting good , operation that is performed by a vibrating shake-out system.
As a result of this two parts are separated:
- The casting good, which will follow the rest of the manufacturing processes,
- and on the other part , the sand, that be used for recycling.
Demoulded steel goods are ready for shot-blasting.
The solid pieces/goods (as cast) are collected in a basket which is subsequently introduced into a shot-blasting machine , where the rest of sand that still remain attached to the casting is removed by projecting steel granules.
After the shot- blasting process the goods are prepared for the next step, the sleves-feeder cutting process, removing the entries and the channels designed from the feeding system of the good.
Cutting operations: air-gaz cutting , arc-air electrodes cutting, manipulators for feeders breaking
The solid piece/good (as cast) part is subjected to special heat treatments, in order to achieve the mechanical properties of strength, hardness and toughness.
Fundiciones Estanda performs standard heat treatments, annealing, tempering, quenching and hardening in heating furnaces to natural gas.
The measurement of the mechanical properties achieved in the steel such as tensile strength, yield strength, impact resistance and hardness are made in different test equipment of the mechanical and metallographic analysis laboratory.
Once the heat treatment is finished, the goods pass to the deburring processes.
In this process are performed the operations to remove existing burrs on the workpiece.
Quality control and inspection
All casting processes are subjected to specific quality control procedures (dimensional and visual inspection, hardness, magnetic particles control, X-ray,…), ensuring that the defects found and any stage of the process do not pass to the following processes .
The whole manufacturing process of steel casting ends with the machining of the castings to obtain the final dimensions and tolerances required by the customer.
The main machining operations that are performed by Estanda Foundry : and turning, milling, drilling and balancing.