How We Do It - Gravity Casting Process
Ming Ming Aluminium Co., Ltd. is a premium supplier of gravity cast parts. We serve customers based on the T.O.R.S. principle and the following procedure to ensure that our production satisfies the customer’s needs and requirements.
Gravity casting, or gravity die casting, is a type of permanent mould casting techniques. At Ming Ming, we start this procedure by reviewing the customer's technical requirement for gravity casting parts. The following steps such as prototyping, creation of mould, PPAP, mass production, and post-production are closely monitored and controlled.
STEP 1 Discussion with the customer about the castability of the desired cast
We would need the potential customer to provide 2D drawing and the 3D CAD model for technical review. If extra machining for the cast is necessary, we will need the design for machining as well.
This procedure of technical review confirms the castability of the desired cast and ensures that the cast could meet the customer’s requirements.
STEP 2 Pattern making/Prototyping
After the design is confirmed, the pattern is moulded into a 3D shape by using materials such as wood, clay, and plastic. 3D sand printing is currently also used for this purpose. A sand core prototype might also be made during this stage. The prototypes are then used to produce samples for the customer to confirm the design. The customer might suggest some adjustments, based on the sample.
STEP 3 Creation of the mould
The mould creation starts after the pattern and the sample are finalised and confirmed by the customer.
Reusable metal moulds and sand cores are created. CAD is also used to simulate the casting process, i.e., gating.
At Ming Ming Aluminium, permanent moulds, i.e., steel moulds, are used for gravity casting.
Coring inside the mould is often also required in order to form desired holes and recesses. Ming Ming uses sand, mixed with thermosetting resin, to make sand cores for such purposes.
STEP 4 Production part approval process (PPAP)
A few samples are casted by using the created metal mould and, together with PPAP documents, sent for the customer’s approval. After Ming Ming receives PWS from the customer, the mould is ready for mass production.
STEP 5 Mass production: melting of aluminium ingots and automatic pouring process
Metal is melted and then the molten aluminium alloy is poured into the mould under gravity in an automatic device.
Ming Ming Aluminium uses automatic tilting gravity casting machines, by which the molten metal can flow into the mould cavity smoothly and with low turbulence.
After the cast is solidified and cools down, the gate is removed by using a saw.
Heat treatment after casting is used for improving the mechanical property of casts.
After heat treatment, the quenched cast could show minor deformation. Ming Ming will uses gauges to go through a thorough measurement check and then fine-tune the cast, if necessary.
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This step is for smoothing the rough surface and removing surface contaminants.
The final step is to refine cast parts through CNC milling and precision CNC turning so that the final parts will meet the design required by the customer. CNC milling cuts the parts in different angels and ensures the parts are cut into the desired shape. CNC turning is used for drilling, grooving, and reaming; it shapes exterior and interior of cylindrical, taper, and curved parts.