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Industry knowledge of Mould

Industry knowledge of Mould


Q1: What’s differences between Injection Molding and Blow Molding?

A1: There are several significant differences between injection molding and blow molding:

  • manufacturing process itself

  • tolerances and margins of error

  • design considerations

  • role of the process for intended result

Main difference between injection molding and blow molding:

  • Injection molding – produces a part that is solid such as a reusable coffee cup lid

  • Blow molding – produces hollow parts such as water bottles

The blow molding process can produce plastic parts with very complex shapes. However to achieve this the wall thickness may vary from place to place depending on how much the material has to stretch when it is being blown. The thickness of a plastic part created through injection molding is determined by the relationship of the mold and the core.

You will be farther ahead if you are able to determine the best molding process for your plastic product in the product development stage. 

Q2: What is process of blow molding?

A2: The blow molding process begins with melting down the plastic and forming it into a parison or in the case of injection and injection stretch blow moulding (ISB) a preform. The parison is a tube-like piece of plastic with a hole in one end through which compressed air can pass.

The parison is then clamped into a mold and air is blown into it. The air pressure then pushes the plastic out to match the mold. Once the plastic has cooled and hardened the mold opens up and the part is ejected.

Q3: What is blow molding?

A3: Blow molding ( BrE moulding ) is a manufacturing process by which hollow plastic parts are formed.

Q4: How many types of blow molding?

A4: In general, there are three main types of blow molding: extrusion blow molding, injection blow molding, and injection stretch blow molding.

Q5: What is molding (moulding)?

A5: Molding or moulding (see spelling differences) is the process of manufacturing by shaping liquid or pliable raw material using a rigid frame called a mold or matrix. This itself may have been made using a pattern or model of the final object.

Q6: What is mould or mold?

A6: A mold or mould is a hollowed-out block that is filled with a liquid or pliable material such as plastic, glass, metal, or ceramic raw material. The liquid hardens or sets inside the mold, adopting its shape. A mold is the counterpart to a cast. The very common bi-valve molding process uses two molds, one for each half of the object. Piece-molding uses a number of different molds, each creating a section of a complicated object. This is generally only used for larger and more valuable objects.

Q7: Considerations for Mold Base Material Selection?

A7: Material used for mold bases is pretty straight forward. The materials are common and have been around for a long time; however, choosing the right material will help save time and money. Generally, mold base material can be broken down into three categories: hot rolled steel, chrome-moly materials and stainless steel.

Q8: What is the hot rolled steel mold material?

A8: Hot rolled steel materials vary from low carbon steel (A-36 or 1020) up to medium carbon steel (1045 or 1050). These steels are easy to machine and have reasonable tensile strength. They are easy to find and are very cost-friendly. They are usually chosen when the customer has very low production runs associated with the project.

Q9: What is chrome-moly mould material?

A9: Chrome-moly materials range from 4130, P20, 4140, etc., have a hardness range from 28-34 HRC and have good mechanical properties.  They are ideal for cavity and core plates as well as other plates required in the mold base. They can be machined fairly well; however, in some cases with heavy machining or grinding, a need to stress relieve the material may be required.

Q10: What is stainless steel mold material?

A10: Stainless steel (a modified 420 F material that is used for holder block applications) is pre-hardened to 30-35 HRC. It offers good corrosion resistance and has very good machinability. The material is very stable and does not require stress relieving. In applications where humidity is a problem or corrosive material is bing used this material works well.