What is Molding: Definition and 12 Discussions

Blow molding (or moulding) is a manufacturing process for forming and joining together hollow plastic parts. It is also used for forming glass bottles or other hollow shapes.
In general, there are three main types of blow molding: extrusion blow molding, injection blow molding, and injection stretch blow molding.
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 molding (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. Water channels are carved into the mold to assist in cooling.

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  1. B

    Glass bottle with a prolonged neck that continues into the inner space

    Is it possible to create following two shapes from glass using currently known glass mass production techniques? Shape #1: bottle with a prolonged neck that continues into the inner space, like this (cross section): | | | | /| |\ / | | \ / \ / \ | | |...
  2. marcus1944

    Calculating Cavity Pressure in Injection Molding: Tips and Considerations

    Im currently trying to calculate the pressure inside an injection mold. Does anyone have experience with similar problems? I need to use coeficient of Thermal expansion and volume. please help .
  3. CuriousGyorgy

    Can high molasses content in brown sugar lead to mold growth?

    Hi folks, I saw a previous (closed) thread stipulating that mold can't grow on sugar. I have an old package of dark Muscovado sugar from Mauritius stored in the original plastic bag; it has small area of white here and there on the clumps of sugar which looks like mold. Water and nutrients are...
  4. A

    How do I mold an elastic part for cheap?

    Hello. I'm an engineering student so don't make fun of me. I'm trying to mold an elastic cylinder. My plan for doing this is to: 1. Print out a plastic mold. 2. Buy elastic material. 3. fill the mold with elastic material. 4. wait 24 hours. I'm trying to make the cylinder as elastic as...
  5. B

    Powder Injection Molding, Binders

    Hi, I was just curious, I needed verification, I am reading up on PIM process and I see they use "binders" to keep the shape of the powders before sintering, anyways as I've been reading the binder consists of a surfactant, a filler and a backbone, I was just curious as to what ratios are there...
  6. S

    Design preperation for metal molding

    Hello everybody I have designed two small metal pieces (approx 30x30 mm) currently in 3D design that I now want to prepare for production by casting/molding. They are both intended for mass production hence price is a big concern, even the very small designchanges that may lead to reduction of...
  7. U

    Powder Metallurgy - Metal Injection Molding Equipment Sourcing

    Hi Everyone, We are an Engineering & Services Company mainly working for Power Generations in industrial field, now we have decided to work in powder metallurgy especially in metal injection molding field, for this purpose we need information about the technology & equipment used in this...
  8. J

    Thermal expansion: Plastic Molding

    Homework Statement ABS plastic melts (and solidifies) at 105 °C. You want to inject it into a steel mold. When the part comes out at 20°C you want it to be 7.250cm long. Edit: If this isn't clear, it wants to know how big the steel mold should be. α for ABS plastic α= 53.0x106/C°, for steel α=...
  9. S

    Molding Plastics: Polystyrene & Valves

    Hi What is the easiest plastic to mold and shape once heated, and that is fairly strong once cooled down. I was thinking of polystyrene form yogurt tubs or CD cases, because apparently if you heat it above 95 degrees it is easy to extrude and form I want to make a connection to a valve...
  10. W

    Calculation for injection molding

    Hi all, Here are some questions for injection molding: 1. How to calculate total mold volume? 2. How to calculate how many parts can be produced? 2. How to calculate clamping force? Further details of the question is in the attachment. Thx for any answers might given. ^^
  11. I

    Injection Molding Machines - Plastic Gears

    Hello, I need some help with the general very basic cost analysis of an injection molding machine and a mold for a particular part (Plastic Gear). For example, a Gear made out of Nylon plastic resin. The gear dimensions are roughly 2 cm diameter (20 teeth). Something like the black one...
  12. T

    What is the best material for thermo molding fins on a helix wind turbine?

    Im building an outside vertical axis wind turbine. i need to build the (about 20) plastic fins that are going to be used to form the helix (which is the wind turbine) im trying to build the fins that are used on the helix wind turbine. a good video of it is on youtube: a crappy picture of...