Die Casting – Guide to Buying Manufacturing in China

Die casting, as we know, is a process where molten metal is injected into a specially designed steel mold – called a die – at high pressure. When the liquid metal cools and solidifies, it takes the shape of the die. These parts, called castings, are a big part of our daily lives. You will find them in the appliances you use at home, the car you drive to work, the machines and devices you operate at your workplace, your mobile phone, your skincare products, and in numerous other objects and places.

This blog explores what you, as a buyer looking for die casting services, must keep in mind in order to receive a final product that ticks all your boxes. As a China sourcing agent, Sourcing Allies can help connect you with trustworthy manufacturers and factories in the world’s die casting capital. Just remember, your collaboration is crucial to a happy sourcing experience.

What is my role as a buyer when it comes to die casting?

In die casting, a buyer is not merely a customer who receives the manufactured goods at the end but rather, an active collaborator who works with the manufacturer from the onset. When Sourcing Allies helps you get cast parts from manufacturers in China, we will require specific design inputs from you. These include:

‍The first step in the product development process is the creation of a 3D model. For simple products, we can work with 2D drawings that show the part’s basic dimensions, weights and tolerances. (Tolerance is the acceptable degree of variance in dimensions). However, for a more intricately designed part, we will require a 3D file. A 3D file comes in various formats. A STEP file is one such format. It doesn’t really matter what format you submit your 3D file in. We will then send the 3D file to the manufacturer. Based on it, the manufacturer lets us know if the part can be produced and extracted from the tool without problems and how much each part will cost.

‍Along with design files, some of our customers provide us with an existing sample of a product. We might use the sample to highlight defects and make improvements or simply to emphasize the surface finish requested by the buyer.‍

‍Initially, we ask for a clear 2D drawing showing the essentials, such as material type, surface finish and tolerances. But it is useful to have other details, such as the product’s final intended use or what type of environment it will be used in (say, a corrosive or particularly humid environment or one with lots of vibration). It also helps to know the product’s history – if it breaks, cracks or distorts in certain areas under certain conditions. For example, a buyer might tell us that their die cast aluminium part is perfectly fine when it comes out of the tool and when it is machined but suddenly distorts when it is powder coated during surface treatment. Details like these help us make decisions that improve the manufacturing process. A buyer must be as specific as possible about their requirements – whether it be their choice of metal, or the wall thickness or surface finish they are looking for. This helps us communicate their requirements to the manufacturer clearly and precisely.

What is tooling, and why is it important?

It is important to get the tool design right. Sometimes, a customer will specify that they want a tool made in a particular way for a particular reason. However, generally, the tool design is left to the supplier’s specialist toolmaker. This process is called tooling. Apart from dies, additional tools used could include jigs, fixtures, mold inserts, cutting tools and so on. A common machining technique used in tooling is Electrical Discharge Machining (EDM), which uses electric sparks to cut and shape metal. Thereafter, the tools are heat-treated and surface texture, if required, is added.