The Process begins with the customer’s enquiry and specifications. This would normally include drawings of the item concerned produced by a draughtsman or on a CAD system. If necessary, Novacast personnel would discuss with the customer any issues arising from these drawings of design, tolerance, accuracy,  and material.

The quality required and regularity of call off will also influence the production process and the type of pattern equipment, the number of Coreboxes required, to produce the castings to the specifications required as economically as possible.

With all of this information Novacast will produce a competitive quotation for the customer’s consideration. The resolution of these issues will decide if the core or cores are handmade by a craftsman coremaker using the CO2 process or if they are to be blown on a machine using a low gas evolution self setting process.

The moulding process would incorporate the use of a loose pattern or alternatively a pattern or patterns set up for batch production on either the self setting Esterset process or greensand process.

The Coreboxes and patterns can be produced from wood, metal or resin, or a combination of all three. The choice of tooling would be governed by cost and durability over the required production period combined with the best skilled craftsmanship employed to ensure consistency of results. Customer’s existing patterns can almost always be used in our process, but may sometimes require modification. During the moulding process for Airset moulds a continuous mixer is used. The operator, at a touch of a button, can vary the ratio and reactivity of the resin and hardener that is mixed with the sand to slow or accelerate the setting time according to the size and complexity of the mould he is making. He also has the facility to use all new sand, a blend of new and reclaimed sand or entirely reclaimed sand.

This enables him to face the patterns with new washed and graded sand and then switch to back this with blended or reclaimed sand thus enhancing the surface finish of the casting. Novacast is able to reclaim 70% of the sand used, thus improving the environment by preventing this from going to landfill sites. From new tooling and pattern equipment Novacast will produce sample castings, so that all aspects can be checked before a production run. This enables dimensional checks as well as evaluation of the running and feeding system, to ensure the integrity of the casting as regards defects, which may be caused by the solidification and cooling of the castings. This is also an opportunity for the customer to decide if drawing alterations and subsequent pattern or core alterations are needed for his own purposes and the final use of the casting.

Skilled craftsman are used in the manufacturing process and once the mould and cores have been assembled and are ready for casting, the metal is melted, treated and prepared for pouring. This can be done with the use of several melting furnaces. These fall into two groups, fixed crucible tilting furnaces which are used for large quantities of molten metal or lift out crucible furnaces used for flexibility. This flexibility enables independent melts of a variety of different metals in the same shift, thus enabling the planning of production and deliveries to be very positive. Temperature, modification of the metal structure and removal of gas taken into the solution during melting is carefully controlled in the furnace.

Once the castings and moulds have cooled they are taken to the sand reclamation plant, where they are broken up and all outside and internal sand is removed from the casting.
 

The castings then go to the fettling shop where all the running and feeding system is cut off and those areas ground or linished to the correct profile. All surfaces will then be either sandblasted or shot blasted to ensure all residue of sand is removed.

If the castings require heat treatment they would be sent to an accredited sub contractor for this process to be carried out. Inspection with reference to the drawing and specification also takes place at this stage. If machining is to be carried out then Inspection takes place once again after this process and finally if surface finish is required for example Alacrome, Plating, Lacquering, Anodising or Painting then final inspection takes place after this prior to packing and despatch to the customer.

When certification is required this can take the form of a “Certificate of Conformity” and/or “Certificate of Analysis” or test results from test bars and coins for specific mechanical or physical properties will be recorded and certified when requested.
 

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Crankcase/compressors are high integrity castings which must be pressure tight and free from defects.  Because of the number of internal ports and airways in the casting it is necessary to tightly control all aspects of production to achieve the desired end result of a casting that under pressure, will not leak to atmosphere or from port to port.  The running and feeding system, the melting practice and the making and assembling of the mould and cores need to be accurate to attain the desired end result. This type of casting is typical of the castings used in the railway braking industry and Novacast have considerable experience in producing them. A brief description, illustrated with photographs of the production of one of the crankcase types follows:- The following sequence of photographs illustrates the way in which the mould and cores are assembled together.

1. The bottom(drag) half of the pattern framed up & ready to receive the self setting sand which will form the mould.

2.The top half of the mould is made and ready to strip from the pattern.

3. Withdrawn by crane from the pattern.

4. Top half of the mould.

5. The bottom half produced in the same way

6. Some of the 16 cores which will be assembled into the mould.

7. Some of the cores which form undercut features and provide locating prints for some of the ports in position in the mould.

9. A small port core right in the bottom of the mould is glued in position prior to the large internal core being set in the mould.

10. The bottom half of the main core is lowered carefully into position.

11. The sequence of views shows how a nest of port cores are assembled at one end of the casting prior to the top of the main core being placed in position.

12. Glue is carefully applied on the joint of the main core in readiness for the top half core to be placed on it, ensuring alignment & position.

13. The top half of the main core in position.

15. The top half of the mould is lowered onto the bottom.

16. The mould is closed.

17. The casting as it is removed from the mould with running system and feeders.

18. The fettled casting: - The wires protruding from the ports are the supporting wires which prevent these fragile cores breaking under the pressure of the metal.  These are removed after Heat Treatment.