Injection Molding Frequently Asked Questions
Q: What about injection molding in China?

Injection Molding is one of the most popular forms of processing plastics as it enables us to mold fairly complex shapes at high production rates. And hold fairly tight tolerances while maintaining good dimensional stability. Thermoplastic resin used in the injection molding process can be reground and reprocessed however some physical properties of the plastic may be lost through each generation of regrinding. With the number of engineered plastic resins available today, many cost-saving opportunities exist utilizing plastic in place of metal when manufacturing large volumes.

Q: How much does an injection molded part cost in China?

Typically an injection molded part can cost anywhere from a fraction of a cent to a few dollars. The cost of an injection molded part is dependent on many factors such as size and complexity of the part which will affect production rates, the plastic resin being molded, the number of cavities in the mold. Many things contribute to this cost with the biggest factor probably being the complexity of the part as well as the size of the part. This can be deceiving because a very simple-looking part could be very difficult to build a mold. Because it has an undercut that will require moving parts in the mold to move out of the way allowing the part to be ejected freely when the mold opens.


What factors affect the cost of injection molding? There are different factors that may affect the total cost of the injection molding project. If you are first involved in the injection molding industry, there are some articles on our website that are quite helpful to you before you go deep into a manufacturing company in China to start making your molds. By fully understanding the possible impact on mold development or the price of plastic injection molding, you will be able to take these factors into account when designing the final mold. And show your design to the mold engineers, who will help you optimize your design and reduce your development costs.


Q: Who owns the injection mold after you pay the mold?

In most cases, the injection mold is owned by the customer who designed and is purchasing the parts. Unless specific contract terms are agreed upon, the customer usually will have the right to take their mold anywhere to have parts molded, however, there is some risk involved in making sure the right equipment is available and that an acceptable process can be established in the new environment.

Q: How long does it take to build an injection mold?

Typically an injection mold can take anywhere from a few weeks to a few months to build. Many factors can contribute to this time such as a supplier’s backlog or amount of resources available as well as the complexity of the part of the complexity of the mold design and the number of cavities needed. It depends on the complexity of the parts.  Simple molds can be completed in two weeks.  More complex molds could take several months.  At CN-MOULDING, we precision build molds that will last under the pressures of a high production environment.

Q: What is the typical life expectancy of an injection mold?

Most mold makers build molds to industry standards such as SPI Class 101 which should guarantee a mold life of 1 Million Shots. This means if your mold has 4 cavities you should get 4 Million parts from your mold without any problem. Depending on the complexity of the part and the plastic resin used, this amount may vary. It is not unlikely for your mold to last for well over 1 Million shots. If your part is complex and the mold has small intricate steel inserts or you are using an abrasive plastic resin such as a glass-filled polycarbonate, mold wear will be more progressive shortening the life of your mold.

Q: What is a mold cavity?

The cavity is the part of the injection mold that forms the part. An injection mold could have one single cavity or multiple cavities of the same part or a family of different parts. Multiple cavities will increase that injection mold cost however lower the cost for the injection molded parts since multiple parts could be made during one molding cycle.

Q: What is a parting Line? 

Where the two halves of an injection mold come together is known as the parting line. A witness line of where the mold was parted can usually be seen on the molded part. Sometimes the parting line may be stepped rather than flat all the way around the part. What is the difference between the “A” half and the “B” half of an injection mold? Half of the injection mold sits stationary in the mold.

Q: How do I know if injection molding is the right process for my product? 

The geometry of the part, the number of parts needed, your tooling budget, and the application the part is being used for will all influence your decision to injection mold the part.

Q: What type of information is required for quoting a molding project?

Please contact us by E-mail. After that we’ll need more specifics as the annual quantity needed, material preference, part prints or CAD files, part samples (if available), description of the part application, time frame for prototype parts, and time frame for production parts.

Q: What are your criteria for a new molding project?

Since we are a customer contract molder, we can make any kind of product base on your design, an item that can be made using the injection molding process as well as an item that can be made from a material that can be injection molded.

Q: What part size limitations do you have?

Our specialty is in the range of 2m*1.8m*1.2m large size to
80mm*60mm*50mm small size

Q: What material should I use for my project?

Most material is application-specific. If you don’t have a material selected for your application, we can help and offer some guidance. Often several resins can be sampled, but the customer has final approval before proceeding.

Q: What is the typical process of a new project?

We will evaluate your part design and modify it to be efficiently injection molded.  Then, we will build the mold for the part.  Next, your mold will be put into an injection molding press to make production parts.

Q: Do you offer a prototype tooling service in China? 


Yes, but only to evaluate the prototype part prior to producing production tooling.  We build prototype tools as a service.  We are a high-volume molder and the number of production parts from a prototype tool is limited.

See rapid prototype

Q: What types of molding services do you offer?

We produce various volume production parts (100pcs to 500K +), we design the mold for production, make the mold, and run production parts.

Q: Do you offer extended molding services such as assembly, packaging, or painting?

We offer some packaging at the press, also offer custom packaging, decorating or assembly, plastic thermoforming at the press. Additional secondary operations can be performed by approved 3rd party vendors with whom we work.